A&P II - 2 at Middle Tennessee State University - StudyBlue Explain why the stethoscope is not placed directly over the heart valve of interest. Because the sound is distorted as it travels through tissues. Heart sound S1 (lubb) loud sound associated with closing of left AV valve. *marks start of ventricular contraction Heart sound S2 (dubb) somewhat shorter, softer sound associated with semilunar valve closing. *marks start of ventricular filling Heart sound S3 very faint sound, associated with blood flowing into ventricles. *often heard in children What causes a heart murmur? When a valve malfunctions and allows regurgitation. In addition to listening to the heart, what are some other uses of auscultation? Lungs What accounts for the small increase in the speed of blood flow from the capillaries through the veins? Convergence and because of help from muscular contractions. What three processes move substances across capillaries? Diffusion, filtration, and reabsorption. Give a definition of diffusion. Under what conditions will substances diffuse the fastest? High concentration to low concentration; Steepness of the concentration gradient, permeability, and size.

Contrast how the flowing substances diffuse across the capillary walls: a) plasma protein, b) gases and lipid-soluble substances, c) ions like sodium, d) glucoses and amino acids a) sinusoids Which pressure is stronger toward the end of a capillary bed? Why is this? BCOP; because water and solutes are reabsorbed from interstitial fluid. What happens to the excess fluid that is lost from the capillaries via filtration? Picked up by the lymphatic system. Explain how extensive hemorrhaging will affect capillary exchange? It will lower blood pressure, including CHP; thus balance shifts, and more reabsorption than normal occurs. What condition increases the concentration of plasma proteins and thus raises BCOP? Dehydration. What is meant by edema? Swelling of tissues. Edema can occur by either _________ CHP or _________ BCOP. increasing; decreasing While blood flow can be increased to certain parts of the body by diverting it from other parts, what is one area of the body that must always have a substantial flow of blood? The brain. What are the three regulatory mechanisms that control blood flow and pressure?

Autoregulation, neural mechanisms, endocrine mechanisms How does autoregulation differ from neural regulation? Autoregulation causes immediate, localized homeostatic adjustments by controlling the precapillary sphincters. Neutal regulation changes blood pressure by affecting peripheral resistance, heart rate, and stroke volume. List several examples of local vasodilators. Nitric oxide, increased tissue CO2 levels or decreased O2 levels, lactic acid, increased local temperature, chemicals released during localized inflammation. Give an example of a local vasconstrictor. Chemicals, such as prostaglandins, released by damaged tissues. Neural, or autonomic, mechanisms can change blood pressure by affecting what three things? Peripheral resistance, heart rate, stroke volume. What is meant by cardiac output? How is it calculated? What is meant by stroke volume? Cardiac output is the volume of blood pumped by the left ventricle per minute; CO = HR * SV; Stroke volume is the amount of blood that is pumped out of the heart per beat. How does intense exercise affect cardiac output? Heart rate increases therefore more blood is pumped out of the heart per minute.

If a person's heart rate is 80 bpm and their stroke volume is 100 ml, what is their cardiac output? 8000 ml/min or 8 L/min If what part of the brain are the cardiovascular centers located? Medulla oblongata. What are the names of these two major centers? What does each do? Cardiac centers: speeds up the heart, controlled by sympathetic NS; slows the heart, by parasympathetic. Vasomotor: regulates the diameter of arteries through sympathetic motor neurons. What do baroreceptors monitor and how do they work in general? Monitors changes in blood pressure in various location and work by detecting the amount of stretch in the walls of arteries. Where are the main baroreceptors located? Baroreceptors are located at start of systemic circuit in aortic arch and carotid sinuses and at the end of the systemic circuit in the vena cavae and right atrium. What three variables may chemoreceptors monitor? Receptors that monitor arterial blood for changes in pH or in the pressure of dissolved gases. Where are the main chemoreceptors? Carotid bodies, aortic bodies, and on the ventral surface of the medulla oblongata.

How would the cardiovascular centers in the medulla oblongata change heart rate and the diameter of peripheral blood vessels, if... a) baroreceptors detect rising blood pressure? b) baroreceptors detect falling blood pressure? c) chemoreceptors detect rising CO2 levels(or falling O2/pH?) d) chemoreceptors detect rising O2 levels(or falling CO2/rising pH?) a) slow heart rate, peripheral vasodilation, and lower BP b) rise heart rate, vasoconstriction, and raise BP c) increase breathing rate d) vasodilation What effect would increased secretion if catecholamines (E,NE) from the adrenal medulla have on heart rate, peripheral blood vessels, and blood pressure? Increase heart rate and peripheral vasoconstriction, and raise BP (short-term) Where is ADH (antidiuretic hormone) synthesized? Where is it released from? What effect would it have on blood volume and pressure? Hypothalamus; released in response to a decrease in blood volume; helps maintain blood volume and BP. Where is EPO (erythropoeitin) produced? What stimulates increased secretion of EPO? What does EPO do?

Kidneys; drop in blood pressure; stimulates production and maturation of RBCs, therefore increases blood volume, viscosity, and oxygen-carrying capacity of blood. Where is angiotensin II produced? What are some of its effects? Lungs; stimulates adrenal cortex to produce aldosterone, stimulates post. pituitary to release ADH, stimulates thirst, stimulates cardiac output and peripheral vasoconstriction. What hormones are released from the heart itself that help to lower blood pressure? How do these hormones help lower blood pressure? Natriuretic peptides; increasing Na+ excretion by kidneys, increasing urine output, reducing thirst, and stimulating peripheral vasodilation. What are four major functions of the blood? Transport O2 and CO2, nutrients, waste products, hormones, heat, pH balance, immunity, and limiting blood loss. What are several solutes that occur in the plasma? What is the main electrolyte in the plasma? Nutrients, electrolytes, wastes, gases, hormones, and plasma proteins; Na+ List the three major types of plasma proteins. What are their functions of each?

1) Albumin: transports substances and major contributor to blood colloid osmotic pressure 2) Globulin: transport, immunity, and clotting 3) Fibrinogen: soluble precursor of fibrin (forms blood clot) What is the difference between plasma and serum? Plasma is mostly water while serum is the fluid that remains after you allow blood to clot and remove the solids. Which comes first, a colony forming unit or a pluripotent stem cell? Pluripotent stem cell Describe the structure of an erythrocyte. Explain how its structure helps it carry out its functions? Disc shape with a sunken center, thick rim, tiny. It allows gases to quickly diffuse to and from hemoglobin. What can't RBCs do that many cells in the body can do? Cannot divide (mitosis) and lack almost all organelles. What type of metabolism do RBCs rely exclusively on? Anaerobic metabolism. In general, what determines a person's blood type? Glycoproteins and glycolipids attach to surface of cell membrane. Why are RBCs red? Because cytoplasm contains lots of hemoglobin, a red-colored protein that reversibly binds to oxygen.

Describe the structure of hemoglobin? To what part of it does oxygen actually bind? A large protein that consists of 4 peptide chains, each chain is joined to a nonprotein heme group (a ring of carbon, hydrogen, and nitrogen around a central iron ion); the ferrous iron Fe2+ What's the functional difference between adult and fetal hemoglobin? Fetal hemoglobin has a slightly different amino acid sequence which binds O2 more tightly and thus helps the fetus obtain oxygen from its mother. Describe how iron is absorbed into our body and where it is stored. Include the terms ferrous, transferrin, ferritin, and gastroferritin. Ferrous iron is essential for Hb synthesis, our food contain Fe+2 & Fe+3, stomach acid converts the Fe+2 & Fe+3, Fe+2 binds to gastroferritin, gastroferritin transports Fe+2 to the small intestine where the iron is absorbed into the blood, in the blood Fe+2 binds to a plasma protein called transferrin, transferrin transports some ferrous iron to the liver for storage and stored as ferritin.

The rest of the iron is sent to the red bone marrow and skeletal muscle where it is used to make hemoglobin or myoglobin. Explain how erythrocytes are produced. It begins with a pluripotent stem cell which transforms into an erythrocyte colony-forming unit. EPO binds to receptors on the surface of the erythrocyte colony-forming unit and stimulates it to transform into an erythroblast. Erythroblasts multiply, make hemoglobin, discharge their nuclei, and eventually mature into erythrocytes. Explain the role of hypoxemia and EPO in regulating the numbers of RBCs in the body. Kidneys detect hypoxemia(=too little O2 in the blood) and thus increase their secretion of EPO. The increased EPO stimulates increased RBC production, which in turn enables the blood to carry more oxygen. How long do RBCs typically live? Describe where in the body they are usually destroyed once they become too old? RBCs live and circulate for ~4 months. Gradually spectrin breaks down and the cell cannot replace it because it doesn't have a nucleus or organelles.

Thus the RBC becomes more fragile, less elastic and then breaks apart, especially in the spleen and liver (sinusoids). Macrophages (special WBCs) in the liver and spleen ingest and recycle fragments of the RBC membranes. Why is it so important that hemoglobin be carefully broken down? Because it can become lodged in the kidneys and stop the kidneys from functioning. Explain the full process in which hemoglobin is broken down. Broken down into globin and heme parts by macrophages, then globlin part is further degraded into individual amino acids. The heme is broken further into ferrous iron and organic components. Why are feces usually brown in color? Urobilinogen excreted with the feces. What causes jaundice? How does one measure hematocrit? The % of blood volume composed of RBCs. What are two reasons why hematocrit, hemoglobin concentration, and RBC numbers are usually higher in males than females? 1) Androgens stimulate RBC production 2)menstrual blood losses Of course WBCs occur in the blood, but where are they much more abundant?

Connective tissues In general, how does the structure of a typical WBC compare to that of a RBC? Have an obvious, often complex-shaped nucleus, and have all the usual organelles. What are the five classes of leukocytes in the blood? Which type is most abundant to the least abundant? Neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Describe the basic structure and function of neutrophils? Nucleus usually with 3-5 lobes, medium size, functions to ingest bacteria, thus, increased numbers of may be a sign of bacterial infection. Eosinophils are not very common in the blood, but where are they very abundant? Mucous membranes The numbers of circulating eosinophils would be expected to change with what other factors? Time of day, season, & menstrual cycle. Which leukocyte secretes histamine and heparin? What is the function of each of the chemicals? Basophils; Histamine is a vasodilator and increases permeability of blood vessels and heparin is an anticoagulant that prevents clots. What are some of the many functions of lymphocytes?

1) secrete antibodies 3) destroy cancerous cells 4) destroy cells infected with viruses What type of leukocyte is the largest in size, has a horseshoe-shaped nucleus, and can differentiate into a macrophage? Monocytes What silly phrase can be used to remember the names of the WBCs as well as their relative abundance? "Never let monkeys eat bananas" What type of cancer involves excessive numbers of WBCs? leukemia Where in the body may WBCs be stored until they are needed? Red bone marrow Briefly describe WBC life-cycle? Pluripotent stem cells differentiate into colony-forming units, which give rise to specific percursor cells. In what type of infection would you expect to see increased numbers of neutrophils? of eosinophils? Bacterial; parasitic Of the three formed elements in the blood, which is the least abundant? Which is the most abundant? White blood cells; red blood cells Describe the basic structure of a platelet. Complex internal structure with numerous organelles, anucleate, & capable of amoeboid movement. Describe the many functions of the platelets.

Secrete vasoconstrictors, stick to each other to form platelet plugs which can seal breaks in small, damaged vessels, secrete clotting factors, help form an enzyme that eventually dissolves the clot, secrete chemicals that attract certain WBCs to inflammation sites, ingest bacteria, & secrete growth factors that encourage mitosis in fibroblasts and smooth muscle and thus help maintain and repair blood vessels. How is the formation of platelets similar to that of the other formed elements? How is it quite different? They have their beginning in pluripotent stem cells in the red bone marrow; but instead of then developing colony-forming units, the stem cell itself develops into a, which makes many copies of its DN megakaryoblast A and then matures into a megakaryocyte. Bits of cytoplasm and plasma membrane are broken off of the megakaryocyte and beome platelets. In general, how long do platelets live compared to RBCs? Where are platelets stored? ~10 days; stored in spleen. What are the three major stages of hemostasis? Describe what happens in each stage.

a) vascular spasm: cutting the blood vessel wall, stimulates the smooth muscle in the wall to contract b) platelet plug formation: platelets begin sticking to the exposed surfaces of the injured vessel, also sticking to each other to form a platelet plug, as platelets aggregate, they release several chemicals that aid the clotting & repairing processes. c) blood clotting: two major pathways in which clots form. What are the two major pathways in which clots form? How do they differ from each other? Extrinsic pathway: the first clotting factor, called thromboplastin is released by tissues outside the blood; Intrinsic pathway: the first clotting factor, called Factor XII, is released by platelets within the blood. Which of these pathways is initiated by thromboplastin? which by Factor XII? Extrinsic; intrinsic Where are most clotting factors produced? Liver Why is clot formation sometimes called a reaction cascade? When one gets activated, it usually serves as an enzyme that activated the next clotting factor, which then activates the next clotting factor and so on. Both the extrinsic and intrinsic pathways eventually form thrombin. What is the function of thrombin?

An enzyme that cuts the plasma protein fibrinogen into short pieces of fibrin. What do endothelial cells and platelets release that help repair broken blood vessels? Platelet-derived growth factor (PDGF) What is heredity disease, usually more common in males, in which the blood doesn't clot as it should because of too little of a particular clotting factor? Hemophilia, usually Factor VIII List the major pathogens that infect the human body. Bacteria, fungi, viruses, and parasites. Besides the lymphatic system, what are some other components of the immune system? Integumentary, digestive, & respiratory. What are the major cells of the lymphatic system? Lymphocytes What part of the blood is lymph most similar to? How is it different? A fluid like plasma but with relatively few suspended proteins. What are the smallest of the lymphatic vessels called? Lymphatic capillaries(lacteals); lined with endothelial cells but are wider and thinned walled than capillaries. Because of their structure, fluid can enter the lymphatics but cannot leak back into the tissues and drain into larger and larger lymphatics. What is the function of the one-way valves that occur in the lymphatics?

Keep lymph moving in one direction. All of the lymphatic eventually drain into what two ducts? Describe for each of these ducts where they collect lymph from? Thoracic duct: collects lymph from inferior body and upper left side of body Right lymphatic duct: collects lymph from the upper right side of the body. Into which vein does each of these lymphatic ducts drain? Thoracic duct drains into left subclavian vein; Right lymphatic duct drains into right subclavian vein. What is meant by a lymphoid tissue? Where do lymphoid tissues occur? Connective tissues (often areolar) dominated by lymphocytes; tonsils and digestive system. How many tonsils are there usually in the body? List them. 5; pair of palatine tonsils, pair of lingual tonsils, & single pharyngeal tonsil Describe where lymphoid tissue occurs in the digestive system/ Clusters occur deep to intestinal lining and in walls of appendix. Lymph nodes are scattered throughout the body, but where are they especially abundant? Neck, armpits, and groin. What is the basic function of the lymph nodes? Like water filters that purify the lymph before it enters the venous blood supply.

Besides the lymph nodes, what are two other lymphatic organs? Thymus and spleen. Describe how the size of the thymus changes throughout life. Relative to body size, largest in infants, smallest in the elderly. Where is the single largest collection of lymphoid tissue in the adult body? Spleen What are the three major functions of the spleen? Removes old or damaged RBCs, stores some iron, and detects pathogens in the blood & helps initiate immune response by B and T cells. Where is the spleen located? What are the two major regions of the spleen? Lies anterior and lateral to the stomach, on left side and lateral to the left kidney. Describe the make-up of red pulp versus white pulp. Mostly RBCs & macrophages; lymphoid tissues (mostly lymphocytes) What about the spleen makes it prone to hemorrhaging? What's meant by splenectomy? It's relatively fragile & tears easily; removal of the spleen. List the three major classes of lymphocytes that occur in the blood. T cells, B cells, and NK cells. Why are T-cells called "T" cells? How abundant are they compared to the other types?

Because they are thymus-dependent; ~80% of the lymphocytes in circulation. Why are B cells called "B" cells? How abundant are they compared to the other types? Because they are bone marrow-derived; ~10-15% of circulating lymphocytes. What does the NK in NK cells stand for? What are some of the major functions of NK cells? Natural killer; attack foreign cells, normal cells infected with viruses, cancer cells, their "roaming" throughout the tissues is called "immunological surveillance." Which of the three types of lymphocytes ultimately produces antibodies? Technically, what specific type of cell produces antibodies? WHat do antibodies bind to? B-cells; plasma cells; antigens T-cells are to cell-mediated immunity as B-cells are to ________ immunity. Humoral Where are most lymphocytes produced? Red bone marrow Where do B-cells and NK cells mature? Where do they migrate to after maturing?

In the marrow, one type of stem cell produces daughter cells that mature into B-cells & NK cells; most of the B-cells migrate to the lymph nodes, spleen, or other lymphoid tissues; NK cells migrate throughout the body & "patrol" for abnormal cells. Where do T-cells mature? Where do they migrate to after maturing? thymus; spleen or other lymphoid tissues. What organ secretes thymosins? What is the basic function of these hormones? Thymus; stimulate the stem cells to eventually produce mature T-cells. What is meant by a "nonspecific" defense? Those that help defend against invasion in general & respond the same regardless of the exact threat. List the seven major nonspecific defenses. 1) external barriers 7) fever Describe how the skin and mucous membranes act as nonspecific defenses. The multiple layers of the integument make it harder for pathogens to invade, sebaceous & sweat glands secrete antimicrobial chemicals; The sticky mucus traps pathogens and the movement of the mucus helps flush pathogens away. Where are sebum, dermcidin, & lysozyme produced?

skin & mucous membranes What is said to be the "first line" of celluar defense? Phagocytes What does phagocytosis mean? List some types of WBCs that are phagocytes. Phagocytes "ingest" a pathogen it's destroyed with a lysosome; neutrophils, eosinophils, monocytes, and macrophages. After ingesting a pathogen & securing it within a vesicle, what organelle fuses with the vesicle & actually destroys the pathogen? Lysosome What class of cells are responsible for "immunological surveillance?" NK cells What do perforins do to pathogens? What type of cell secretes perforins? Create pores in the membrane which cause it to lyse; NK cells Approximately, how many complement proteins are there? What are some of their many functions? 11; lyse microbes, attract phagocytes, stimulate inflammation. From where are interferons released? What do interferons functions as? How do normal cells respond to interferons?

By activated lymphocytes, macrophages, & cells infected with viruses; hormones that bind to cell membrane receptors of normal cells; this causes these cells to produce antiviral proteins, which prevent viruses from replicating, if the cell gets infected. What are some ways in which inflammation helps the body defend itself against pathogens? Attracts neutrophils to the area which in turn attract the activity of phagocytes & enzymes, and may inhibit enzymes of pathogens. What is a pyrogen? What type of immune cell releases pyrogens? Circulating proteins that can reset the thermostat in the hypothalamus; macrophages. What part of the brain do pyrogens affect? Hypothalamus In what sense is a fever beneficial? Raises our metabolism, which may get the immune system working faster, may inhibit some viruses and bacteria. What four features characterize the immune response? 1) specificity 4) memory Specificity the host produces antibodies or T cells that are specific for each antigen, specificity occurs because each T or B cell has receptors that will bind to only one specific antigen.

versatility ability to respond to a huge diversity of invaders, arises in part from the huge diversity of different antibodies we are capable of producing and from the large number of different types of lymphocytes. tolerance the immune system doesn't respond to all antigens, some it tolerates, especially those that it recognizes as part of it own body memory after responding to a particular pathogen once, the immune system "remembers" Our bodies contain millions of different ___________ each one of which is specific for a different antigen. lymphocytes During maturation, what happens to lymphocytes that do react to "self" antigens? destroyed. What two types of daughter cells are produced when lymphocytes (either B cells or T cells) become activated? active and memory What are the two interactive immune responses?

antibody-mediated immunity (humoral immunity) & cell-mediated immunity (celluar) antibody-mediated immunity (humoral immunity) in general, B cells defend against pathogens in body fluids, the advantage of this is that antibodies can quickly be widely distributed and attack the pathogen where it occurs in body, but some T cells also play a role, a T cell but some T cells also play a role, a T cell called helper T cell stimulated the activity of B cells. cell-mediated immunity (celluar immunity) T cells defending against abnormal cells and pathogens inside cells, antibodies don't help if cells are infected because antibodies cannot cross the phospholipid bilayer. How easily, if at all, can antibodies cross the cell membranes of infected cells? Antibodies don't help if cells are infected because antibodies cannot cross the phospholipid bilayer. What is the difference between innate & acquired immunity? Innate immunity is genetically determined. Acquired immunity is not present at birth; we become immune to a specific antigen only after being exposed to it. What is the difference between active & passive immunity? Active immunity is the body responds to an antigen by making its own antibody ("the immune response") Passive immunity is produced by transfer of antibodies from another person.

Active immunity can be natural or induced. Give an example of each. natural: 14, strep throat, immune response produced antibodies against that particular strain of streptococcus bacteria. induced: injection with an antibody Passive immunity can be natural or medical. Give an example of each. natural: from your mother across breast milk(?) medical: inject antibodies against the rabies virus into a person bitten by a rabid skunk. What type of cell is most likely to initiate the immune response: a plasma cell, B cell, phagocyte, or T cell? Both B & T cells. What are the Different Types of Body Fluids? (with pictures) What are the Different Types of Body Fluids? Last Modified Date: 08 January 2017 Copyright Protected: 10 most extreme places on Earth The bodies of living humans contain many different types of fluids that play an important role in their function. Blood plasma is the liquid part of blood that carries blood cells, hormones , proteins, and other substances throughout the body. Lymphatic fluid and mucus both play a role in protecting the body from disease. The process of digestion is aided by saliva and gastric juice.

Other fluids found in the human body include cerebrospinal fluid, sweat, tears, the aqueous and vitreous humors of the eye, and body fluids related to human reproduction, such as semen and vaginal secretions. Blood cells are suspended in a fluid called plasma, which is mainly composed of water and a mixture of other dissolved substances, or solutes. Plasma is an important transport mechanism within the human body, as it carries substances like hormones, vitamins, amino acids , and antibodies to where they can be stored or put to use. The plasma also contains proteins called clotting factors that help the blood to coagulate, slowing down the rate of blood loss when a person has an injury that causes blood to hemorrhage. When these clotting factors are removed from the blood plasma, it is known as blood serum. Ad One of the fluids that directly contributes to the body's defense is lymphatic fluid, a fluid that is very similar in composition to blood plasma. This fluid originates in the circulatory system, but passes out of the network of veins and arteries into a space between cells known as the interstitial space.

While in the interstitial space, the fluid is known as interstitial fluid, which "bathes" the body's cells and takes microbes and pathogens away with it. The small percentage that enters the lymphatic system is called lymphatic fluid. Mucus is a viscous fluid that also aids in the body's defense by trapping foreign particles that try to enter the body through the respiratory system. Some body fluids help break down food that is consumed so the body can absorb nutrients and gain energy. Saliva is secreted by the salivary glands found under the tongue. It contains enzymes that begin the digestive process by breaking down starches and fats in food while it is still in the mouth. After this partially digested food is swallowed, it enters the stomach, where the highly acidic gastric juice continues the process of digestion. Cerebrospinal fluid provides a protective cushion for the brain . Sweat, or perspiration, helps humans maintain a comfortable body temperature. Tears are secreted by the lacrimal glands and help to clean and lubricate the surface of the human eye.

Fluids in the inner and outer portions of the eye that maintain pressure in the eye and provide nutrients and immune defense to that organ are called the vitreous and aqueous humors, respectively. Human males produce a fluid called semen that functions as a delivery system for sperm cells, while human females produce vaginal secretions that facilitate sexual intercourse by lubricating the vagina. Ad Bloodborne Pathogens Self-Study Unit Environmental Health & Safety Bloodborne Pathogens Self-Study Unit BLOODBORNE PATHOGENS are AN OCCUPATIONAL HAZARD for employees who may be exposed to blood and other potentially infectious materials that may result from the performance of an employee's duties. *Information in this unit was provided by UNCH Hospital Epidemiology, was adapted for use at UNC-CH, and was amended for use by USC. Note: This self-study unit is intended for university employees. Employees should also refer to their specific department's Exposure Control Plan and other policies and procedures. INTRODUCTION On December 6, 1991, the Occupational Safety and Health Administration (OSHA) published their standard for occupational exposure to bloodborne pathogens in the Federal Register.

A component of this standard requires the employer to provide annual education regarding the occupational hazard of bloodborne pathogens. There are 13 required components of this education all of which are incorporated in this study module. It is important to remember that OSHA standards are federal law and compliance is mandatory . However, it is more important to recognize that this standard was established to help protect the healthcare worker from the serious workplace hazard of bloodborne pathogens. EXAMPLES OF BLOODBORNE PATHOGENS any body fluid contaminated with blood or saliva in dental procedures body fluids in emergency situations that cannot be recognized Also considered potentially infectious are unfixed tissue or body organs other than intact skin, and blood, organs, and tissues from experimental animals infected with HIV or HBV.

TRANSMISSION HIV, hepatitis B virus, and hepatitis C virus are the viruses most likely to be transmitted via the following routes in an occupational setting: needle stick / sharps injuries mucous membrane and non-intact skin exposure to contaminated blood or other potentially infectious materials ( scratches, cuts, bites, or wounds ) HUMAN IMMUNODEFICIENCY VIRUS ( HIV ) AIDS is the acquired immunodeficiency syndrome, a serious illness that harms the body's ability to fight infection, and is caused by the HIV virus. During the incubation period, which may last for many years, there may be no signs that a person is infected with HIV; however, the person can still pass the virus on to others. *The cumulative prevalence of HIV is estimated to be 1 million *100% progress to chronic infection *The risk of HIV infection after a single positive needle stick is .3% ( CDC, 1996 ) There is no known cure or vaccine available at this time; however, research is focused on developing treatments and a vaccine.

CLINICAL MANIFESTATIONS OF HIV INFECTION The spectrum of HIV infection ranges from an asymptomatic state to severe immunodeficiency and associated opportunistic infections, neoplasms, and other conditions. Initial infection can be followed by an acute flu-like illness. As the disease progresses, severe and lasting symptoms may include: recurrent fevers, rapid weight loss, anorexia, diarrhea, lymphadenopathy, night sweats, myalgia, arthralgia, rash, malaise, sore throat, white spots or unusual blemishes in the mouth, and headache. The natural history of HIV infection can vary considerably from person to person. The risk of disease progression increases with the duration of infection. HIV may attack the nervous system causing damage to the brain and spinal cord. Most people infected with HIV develop AIDS and normally mild or rare diseases may turn into potentially fatal conditions such as pneumocystis carinii pneumonia. This lung infection is highly uncommon among healthy individuals. HEPATITIS B VIRUS Acute viral hepatitis is a common and sometimes serious viral infection of the liver leading to inflammation and necrosis.

There are at least five distinct viral agents that cause acute viral hepatitis: HAV, HBV, HDV (delta), HCV, and HEV (an enterally transmitted non A, non B hepatitis agent). Hepatitis B (HBV) or "serum hepatitis" was first reported in 1833 following the administration of smallpox vaccine containing human lymph to shipyard workers. *The cumulative prevalence of HBV is estimated to be 1 million, as is HIV. *5% progress to chronic infection. *The risk of HBV infection after a single positive needle stick is 30% ( CDC, 1996 ) Hepatitis B is far more common than HIV and is present in very high concentrations in the blood of infected persons. Anyone with HBV can spread the disease to others: before signs of illness appear for an unknown time after signs of illness appear even if he or she never has signs of infection There are 2 phases of HBV: 1) The Acute Phase - occurs just after a person becomes infected and can last from a few weeks to several months. Some individuals recover after the acute phase, but others remain infected for the rest of their lives.

Of those who become infected, only about 1/3 become symptomatic. Many people who are infected never have any signs of the disease and most people recover completely from Hepatitis B. 2) The Chronic Phase - Those who remain infected and become chronic carriers. The virus remains in their liver and blood. Nearly 10% of adult victims become carriers. CLINICAL MANIFESTATIONS The clinical presentation of acute HBV ranges from asymptomatic, subclinical illness to fulminant hepatic failure. The disease has a long incubation period from 30 to 180 days. Initial symptoms are nonspecific, typically include malaise, anorexia, vomiting, fever, rash, and polyarthritis. These symptoms last 3-10 days. This is followed by the onset of jaundice and /or dark urine. Fulminant viral hepatitis is defined as the development of severe acute liver failure with hepatic encephalopathy within 8 weeks of the onset of symptoms with jaundice. HEPATITIS B VACCINE Recombinant vaccines that consist of highly purified HBsAg particles expressed in yeast were licensed in the U.S. in 1986.

Given as a series of three injections, the vaccine produces a high antibody titer in over 90% of recipients under the age of 40-50 years. Older age, obesity, heavy smoking, and immunologic impairments have been associated with lower anti HBs responses. The higher the antibody titer after vaccination, the longer anti HBs persists. When the anti HBs titer falls below 10 MlU/ml, HBV infections may occur but are always subclinical and usually without detectable serum HBsAg. There is no need for a booster dose of vaccine in those with positive HBs titers. All USC employees who have reasonably anticipated exposure to blood or other potentially infectious materials will be offered the hepatitis B vaccine free of charge through Occupational Health Services. OSHA considers the hepatitis B vaccine so important that employees will be required to sign a declination statement if they choose to not receive the vaccine. If you would like to delcline the vaccine please click here. Those declining the vaccine may receive it at any later time as long as they remain an employee of USC. HEPATITIS C VIRUS Hepatitis C is a non A, non B virus; an RNA virus of various strains which undergo frequent mutations.

*Cumulative prevelance is estimated to be 4 million *85% progress to chronic infection *Risk of HCV infection after single positive needle stick is 3-10% ( CDC, 1996 ) The incubation period ranges from 2-6 months, most commonly 2-3 months. The period of communicability ranges from one or more weeks before onset of symptoms to months / years. 85% persist indefinitely and are chronic carriers. There is no pre or post-exposure prophylaxis or vaccine available at the time. There is no effective immune globulin preparation. Treatment is not without side effects and HCV is the leading cause of liver transplants. The physical and emotional health impact, not to mention the long term consequences and economic burden, is very significant. CLINICAL MANIFESTATIONS of HCV Approximately 1 in 5 persons have no symptoms with acute HCV infection. Early signs of HCV are often nonspecific, ie: Fatigue, fever, headaches, nausea, vomiting, loss of appetite, abdominal pain, jaundice, dark-colored urine, clay-colored stools, abnormal liver function tests, and positive HCV serologies.

HCV can cause: inflammation of liver cells, cirrhosis, hepatocellular carcinoma, immunologic abnormalities, and other complications. Alcohol clearly worsens the course of HCV. METHODS TO PREVENT THE TRANSMISSION OF BLOODBORNE PATHOGENS: 1) Administrative Controls: Exposure Control Plan USC's Exposure Control Plan for Bloodborne Pathogens is available to all employees. To receive a copy please call Environmental Health and Safety at 777-5269. This document contains a complete listing of all job categories that have been identified as having the risk of occupational exposure to bloodborne pathogens. Also the plan outlines management of employee exposures and methods to prevent exposure in the workplace. Directly behind the Exposure Control Plan is a copy of the OSHA standard. Every employee should be familiar with the Exposure Control Plan and the OSHA standard for bloodborne pathogens. 2) Standard Precautions Standard Precautions (formerly referred to as Universal Precautions) are essential to reducing the occupational acquisition of a bloodborne pathogen. Standard Precautions mean that we treat every patient as if they are infected with a bloodborne pathogen such as HIV,HBV, or HCV.

Standard Precautions also require that exposed employees use personal protective equipment to prevent direct contact with blood or body fluids. The consistent practice of Standard Precautions is the best method that employees can use to protect themselves from occupationally acquiring a bloodborne disease. 3) Engineering Controls An engineering control is a device that removes the hazard from the workplace. Employers are required to provide engineering controls that have been demonstrated to significantly reduce an occupational hazard. Examples of engineering controls used at USC for bloodborne pathogens are sharps disposable containers, self-sheathing needles, and safer medical devices such as sharps with engineered sharps injury protection and needleless systems. 4) Work Practice Controls Work practice controls are designed to change the way in which a task is performed to reduce the likelihood of exposure to bloodborne pathogens. Examples of work practice controls are: needles are not recapped; specimens are transported in a secondary container; and sharps are disposed of immediately after use by placing them in a sharps container. Healthcare workers are responsible for carefully disposing of all sharps (e.g., syringes with needles attached, scalpels, razors) immediately after use.

5) Personal Protection Equipment Personal protective equipment (PPE) is specialized clothing and equipment worn by an employee for protection against a hazard such as blood or other potentially infectious materials. PPE should be readily available and provided to the employee at no cost. Employees should never put themselves at risk of exposure to bloodborne pathogens by not using the appropriate protective equipment. PPE should be removed after use. Care should be taken not to contaminate the skin. Soiled gowns, gloves, etc. should be disposed of in the regular trash immediately at the point of use and hands thoroughly washed. Goggles and safety glasses should be cleaned regularly. UNIVERSAL BIOHAZARD SIGN The universal BIOHAZARD sign is used to alert employees that containers, specimen refrigerators, or secondary containers used to transport specimens may contain infectious materials. Individual tubes of blood or primary specimen containers do not need to be labeled, however, secondary containers used for manually transporting specimens must display the BIOHAZARD sign. Additionally, equipment that may have internal contamination that cannot be accessed for decontamination should be labeled with a BIOHAZARD tag denoting the area of suspected contamination. This alerts the maintenance or medical engineering employee to use precautions when handling the equipment.

CONTAMINATED EQUIPMENT Equipment such as blood pressure cuffs and stethoscopes must be cleaned if contaminated with blood or other potentially infectious materials. An EPA approved disinfectant detergent (i.e., Vesphene) or a 1:10 or 1:100 dilution of bleach and water should be used. TRANSPORTING SPECIMENS Specimens should not be hand carried; all specimens must be transported in a secondary container displaying a BIOHAZARD label. The primary specimen container and accompanying tags and/or labels must be free of any contamination. DISPOSING OF MEDICAL WASTE Certain items are required by South Carolina state law to be incinerated and are referred to as regulated medical waste. Regulated medical waste includes: microbiological cultures, pathology specimens, blood products (includes blood, serum, plasma, emulsified human tissue, spinal fluid, pleural and peritoneal fluid), full sharps containers. The following table indicates the method of disposal for each type of waste.

Disposal of Regulated Waste Microbiological Waste Incineration; steam sterilization Contaminated Sharps Incineration; steam sterilization then sanitary landfill Pathological Waste Incineration Blood contaminated waste should be placed in the orange plastic trash bags labeled with the BIOHAZARD sign. These bags are located in individual departments. Remember the biohazard bags are a plastic that can easily be punctured. All healthcare and laboratory workers must dispose of all sharps in the designated sharps containers to prevent sharp injuries to housekeeping staff. Wet, Contaminated Linen Contaminated linen should not be sorted or handled any more than necessary for disposal. Fluid resistant linen bags are available for use when disposing of wet, contaminated linen. Linen should be double bagged when necessary to prevent leaking. DERMATITIS OF THE HANDS Working with hand dermatitis puts you at greater risk of infection from bloodborne pathogens. All employees who develop dermatitis should be evaluated and treated prior to work involving exposure to blood.

EXPOSURE INCIDENTS The following events are considered an exposure incident: percutaneous injury involving a potentially contaminated needle or other sharps, splash of blood or other potentially infectious materials to the eyes, mouth, or mucous membranes blood or other potentially infectious materials contacting broken skin. STEPS TO TAKE IN THE EVENT OF AN EXPOSURE Do not delay treatment for any reason. If possible, immediately wash or flush the exposed area with soap and / or water. During normal working hours: Monday - Friday, 8:00 am - 5:00 pm, please report to the School of Medicine Employee Health Center at the Richland Family Medicine Center located on campus of Palmetto Richland Memorial Hospital. After normal working hours ( between 5:00 pm and 8:00 am the following work day),on weekends and holidays, please report to the Emergency Department at Palmetto Richland Memorial Hospital. Be sure to inform the personnel that the injury is an exposure to bloodborne pathognens and / or a needle stick.

For employees or students working in satellite clinics and hospitals that are located out of town: Report to the nearest hospital's Emergency Department * If you do not receive immediate attention, please call the USC Campus Police at ( 803) 777-9111. You have completed this self-study unit. Call Environmental Health and Safety at 777-5269 for questions and discussion. We would like to assess your learning and also document your participation in this self study. To do this, we have provided a short multiple choice test. To take this test, you may click on the highlighted Post-test now. Also you must complete and return to Health & Safety the Hep B Vertification and Declination form . Immunity: Types, Components and Characteristics of Acquired Immunity Immunity: Types, Components and Characteristics of Acquired Immunity Article Shared by Immunity: Types, Components and Characteristics of Acquired Immunity! Definition: Immunity is the ability of the body to protect against all types of foreign bodies like bacteria, virus, toxic substances, etc. which enter the body. Immunity is also called disease resistance. The lack of immunity is known as susceptibility.

ADVERTISEMENTS: The science dealing with the various phenomena of immunity, induced sensitivity and allergy is called immunology. Types of Immunity: There are two major types of immunity: innate or natural or nonspecific and acquired or adaptive. (A) Innate or Natural or Nonspecific Immunity (L. innatus = inborn): Innate immunity is inherited by the organism from the parents and protects it from birth throughout life. For example humans have innate immunity against distemper, a fatal disease of dogs. As its name nonspecific suggests that it lacks specific responses to specific invaders. Innate immunity or nonspecific immunity is well done by providing different barriers to the entry of the foreign agents into our body. Innate immunity consists of four types of barriers— physical, physiological, cellular and cytokine barriers. 1. Physical Barriers: ADVERTISEMENTS: They are mechanical barriers to many microbial pathogens. These are of two types. Skin and mucous membrane. (a) Skin: The skin is physical barrier of body. Its outer tough layer, the stratum corneum prevents the entry of bacteria and viruses.

(b) Mucous Membranes: ADVERTISEMENTS: Mucus secreted by mucous membrane traps the microor­ganisms and immobilises them. Microorganisms and dust particles can enter the respiratory tract with air during breathing which are trapped in the mucus. The cilia sweep the mucus loaded with microorganisms and dust particles into the pharynx (throat). From the pharynx it is thrown out or swallowed for elimination with the faeces. 2. Physiological Barriers: The skin and mucous membranes secrete certain chemicals which dispose off the pathogens from the body. Body temperature, pH of the body fluids and various body secretions prevent growth of many disease causing microorganisms. Some of the important examples of physiological barriers are as follows: (a) Acid of the stomach kills most ingested microorganisms, ADVERTISEMENTS: (b) Bile does not allow growth of microorganisms, (c) Cerumen (ear wax) traps dust particles, kills bacteria and repels insects, (d) Lysozyme is present in tissue fluids and in almost all secretions except in cerebrospinal fluid, sweat and urine. Lysozyme is in good quantity in tears from eyes.

Lysozyme attacks bacteria and dissolves their cell walls. Lysoenzyme is also found in saliva, (e) Nasal Hair. They filter out microbes and dust in nose, (f) Urine. It washes microbes from urethra, (g) Vaginal Secretions. It is slightly acidic which discourages bacterial growth and flush microbes out of vagina, (h) Sebum (sweat). It forms a protective acid film over the skin surface that inhibits growth of many microbes. 3. Cellular Barriers: These are certain white blood corpuscles (leucocytes), macroph­ages, natural killer cells, complement system, inflammation, fever, antimicrobial substances, etc. (i) Certain Leucocytes: Neutrophils and monocytes are major phagocytic leucocytes. (a) Polymorpho-nuclear Leucocytes (PMNL- neutrophils): As they have multilobed nucleus they are normally called polymorphonuclear leucocytes (PMNL-neu- trophils). Neutrophils are short lived and are highly motile phagocytic killers. Neutrophils are formed from stem cells in the bone marrow.

Neutrophils are the most numerous of all leucocytes. They die after a few days and must therefore, be constantly replaced. Neutro­phils constitute about 40% to 75% of the blood leucocytes in humans. (b) Monocytes: They are the largest of all types of leucocytes and somewhat amoeboid in shape. They have clear cytoplasm (without cytoplasmic granules). The nucleus is bean-shaped. Monocytes constitute about 2-10% of the blood leucocytes. They are motile and phagocytic in nature and engulf bacteria and cellular debris. Their life span is about 10 to 20 hours. Generally they change into macrophages after entering tissue spaces. (ii) Macrophages: Monocytes circulate in the bloodstream for about 8 hours, during which time they enlarge and then migrate into the tissues and differentiate into specific tissue macrophages. Macrophages are long lived and are highly motile phagocytic. Macrophages contain more cell organelles especially lysosomes.

Macrophages are of two types, (a) Some take up residence in particular tissues becoming fixed macroph- ages and (b) whereas other remain motile and are called wandering macrophages. Wandering macrophages move by amoeboid movement throughout the tissues. Fixed mac­rophages serve different functions in different tissues and are named to reflect their tissue location. Some examples are given below: i. Pulmonary alveolar macrophages in the lung ii. Histiocytes in connective tissues iii. Kupffer cells in the liver iv. Glomerular Mesangial cells in the kidney v. Microglial cells in the brain vi. Osteoclasts in bone (iii) Natural Killer Cells (NK Cells): Besides the phagocytes, there are natural killer cells in the body which are a type of lymphocytes and are present in the spleen, lymph nodes and red bone marrow. NK cells do not have antigen receptors like T cells and В cells.

NK cells cause cellular destruction in at least two ways: (a) NK cells produce perforins which are chemicals that when inserted into the plasma membrane of a microbe make so weak that cytolysis (breakdown of cells particu­larly their outer membrane) occurs and creates pores in the plasma membrane of the target cells. These pores allow entry of water into the target cells, which then swell and burst. Cellular remains are eaten by phagocytes. (b) Another function of NK cells is apoptosis which means natural cell death. It occurs naturally as part of the normal development, maintenance and renewal of cells, tissues and organs. Thus functions of NK cells are to destroy target cells by cytolysis and apoptosis. NK cells constitute 5%-10% of the peripheral blood lymphocytes in humans. (iv) Complement (Fig. 8.7): Complement is a group of 20 proteins, many of which are enzyme precursors and are produced by the liver. These proteins are present in the serum of the blood (the fluid portion of the blood excluding cells and clotting factors) and on plasma mem­branes. They are found circulating in the blood plasma and within tissues throughout the body.

They were named complement by Ehrlich be­cause they complement the actions of other components of the immune system (e.g., action of antibody on antigen) in the fight against infec­tion. Jules Bordet is the discoverer of complement. Complement proteins create pores in the plasma membrane of the microbes. Water enters the microbes. The latter burst and die. The pro­teins of complement system destroy microbes by (i) cytolysis (ii) inflammation and (iii) phago­cytosis. These proteins also prevent excessive damage of the host tissues. (v) Inflammation: Inflammation is a defensive response of the body to tissue damage. The conditions that may produce inflammation are pathogens, abrasions (scraping off) chemical irritations, distortion or disturbances of cells, and extreme temperatures. The signs and symptoms of inflammation are redness, pain, heat and swelling. Inflammation can also cause the loss of function in the injured area, depending on the site and extent of the injury. Inflammation is an attempt to dispose of microbes, toxins, or foreign material at the site of injury to prevent their spread to other tissues, and to prepare the site for tissue repair.

Thus, it helps restore tissue homeostasis. Broken mast cells release histamine. Histamine causes dilation of capillaries and small blood vessels. As a result more blood flows to that area making it red and warm and fluid (plasma) takes out into the tissue spaces causing its swelling. This reaction of the body is called inflammatory response. (vi) Fever: Fever may be brought about by toxins produced by pathogens and a protein called endogenous pyrogen (fever producing substance), released by macrophages. When enough pyrogens reach the brain, the body’s thermostat is reset to a higher temperature, allowing the temperature of the entire body to rise. Mild fever strengthens the defence mechanism by activating the phagocytes and by inhibiting the growth of microbes. A very high temperature may prove dangerous. It must be quickly brought down by giving antipyretics. 4. Cytokine Barriers: Cytokines (Chemical messengers of immune cells) are low molecular weight proteins that stimulate or inhibit the differentiation, proliferation or function of immune cells. They are involved in the cell to cell communication.

Kinds of cytokines include interleukins produced by leucocytes, lymphocytes produced by lymphocytes, tumour necrosis factor and interferon’s (IFNs). Interferon’s protect against viral infection of cells. (B) Acquired Immunity (= Adaptive or Specific Immunity): The immunity that an individual acquires after the birth is called acquired or adaptive or specific immunity. It is specific and mediated by antibodies or lymphocytes or both which make the antigen harmless. It not only relieves the victim of the infectious disease but also prevents its further attack in future. The memory cells formed by В cells and T cells are the basis of acquired immunity. Thus acquired immunity consists of specialized В and T lymphocytes and Antibodies. Characteristics of Acquired Immunity: It is the ability to differentiate between various foreign molecules (for­eign antigens). (ii) Diversity: It can recognise a vast variety of foreign molecules (foreign antigens). (iii) Discrimination between Self and Non-self: It can recognise and respond to foreign molecules (non-self) and can avoid response to those molecules that are present within the body (self) of the animal.

(iv) Memory: When the immune system encounters a specific foreign agent, (e.g., a microbe) for the first time, it generates immune response and eliminates the invader. This is called first encounter. The immune system retains the memory of the first encounter. As a result, a second encounter occurs more quickly and abundantly than the first encounter. The cells of the immune system are derived from the pluripotent stem cells in the bone marrow. Pluripotent means a cell that can differentiate into many different types of tissue cells. The pluripotent stem cells can form either myeloid stem cells or lymphoid stem cells. Myeloid stem cells give rise to monocytes, macrophages and granulocytes (neutrophils eosinophil’s, and basophils). RBCs and blood platelets (lymphoid stem cells) form В lym­phocytes (B cells), T lymphocytes (T-cells) and natural killer (NK) cells. Components of Acquired Immunity: Acquired immunity has two components: humeral immunity or Antibody mediated immune system (AMIS) and cellular immunity or cell mediated immune system (CMIS). I.

Antibody Mediated Immune System (AMIS) or Humoral Immunity: It consists of antibodies (specialised proteins produced in the body in response to antigen) that circulate in the body fluids like blood plasma and lymph. The word ‘humor’ pertains to fluid. В lymphocytes (B cells) produce antibodies that regulate humoral immunity. The T-lymphocytes themselves do not secrete anti-bodies but help В lymphocytes produce them. Certain cells of the bone marrow produce В lymphocytes and mature there. Since В lymphocytes produce antibodies, therefore, this immunity is called antibody mediated or humoral immunity. Humoral immunity or antibody-mediated immune system (AMIS) provides defence against most extracellular bacterial pathogens and viruses that infect through the respiratory and intestinal tract. Formation of Plasma В cells and Memory В cells: When antibodies on В cell’s surface bind antigens (any substances that cause antibodies formation) the В cell is activated and divides, producing a clone (descendants of a single cell) of daughter В cells. These clones give rise to plasma В cells and memory В cells. This phenomenon is called clonal selec­tion.

(a) Plasma В Cells (Effector В cells): Some of the activated В cells enlarge, divide and differentiate into a clone of plasma cells. Although plasma cells live for only a few days, they secrete enormous amounts of antibody during this period. (b) Memory В Cells: Some activated В cells do not differentiate into plasma cells but rather remain as memory cells (Primed cells). They have a longer life span. The memory cells remain dormant until activated once again by a new quantity of the same antigen. Role of AMIS: The AMIS protects the body from (i) viruses (ii) some bacteria and (iii) toxins that enter the body fluids like blood and lymph. II. Cell-Mediated Immune System (CMIS) or Т-Cell Immunity: A healthy person has about a trillion lymphocytes. Lymphocytes are of two types: T lymphocytes or T cells and В lymphocytes or В cells. As we know both types of lymphocytes and other cells of the immune system are produced in the bone marrow. The process of production of cells of immune system in the bone marrow is called haematopoiesis.

Because T lymphocytes (T cells) mature in the thymus, this immunity is also called T- cell immunity. The T-cells play two important functions—effector and regulatory. The effector function includes cytolysis (destruction of cells by immune processes) of cells infected with microbes and tumour cells and lymphokine production. The regulatory functions are either to increase or to suppress other lymphocytes and accessory cells. Types of T-cells and their Functions: 1. Helper T cells (TH): TH cells are most numerous of the T cells. They help in the functions of immune system. They produce a growth factor that stimulates В-cell proliferation and differentiation and also stimulates antibody production by plasma cells; enhance activity of cytotoxic T cells. 2. Cytotoxic T cells (Tc) or Killer cells: These cells are capable of killing microorganisms and even some of the body’s own cells directly hence they are called killer cells. The antigen receptors on the surfaces of the cytotoxic cells cause specific binding with antigens present on the surface of foreign cell. Cell after binding, the cytotoxic T cell secretes hole-forming proteins, called perforins, that punch large round holes in the membrane of the foreign cell.

Then fluid flows quickly into the cell from the interstinal space. In addition, the cytotoxic T cell releases cytotoxic substances directly into the foreign cell. Almost immediately, the foreign cell becomes greatly swollen and it usually dissolves shortly thereafter. Thus they destroy body cells infected by viruses and attack and kill bacteria, fungi, parasites and cancer cells. 3. Memory T Cells (Primed Cells): These cells are also formed by T-lymphocytes as a result of exposure to antigen and remain in the lymphatic tissue (e.g., spleen, lymph nodes). They recognize original invading antigens even years after the first encounter. These cells keep ready to attack as soon as the same pathogens infect the body again. They proliferate and differentiate into cytotoxic T cells, helper T cells, suppressor T cells, and additional memory cells. 4. Suppressor Cells (Regulatory T cells (TR)): These cells are capable of suppressing the functions of cytotoxic and helper T cells. They also inhibit the immune system from attacking the body’s own cells. It is believed that suppressor cells regulate the activities of the other cells. For this reason, the suppressor cells are classified as regulatory T cells.

Natural Killer (NK) Cells: NK cells attack and destroy target cells, participate in antibody dependent cell mediated cytotoxicity. They can also attack parasites which are much larger than bacteria. Types of Acquired Immunity: Acquired (= Adaptive) Immunity is of two types: active immunity and passive immunity. 1. Active Immunity: In this immunity person’s own cells produce antibodies in response to infection or vaccination. It is slow and takes time in the formation of antibodies. It is long lasting and is harmless. Active immunity may be natural or artificial. (a) A person who has recovered from an attack of small pox or measles or mumps develops natural active immunity. (b) Artificial active immunity is the resistance induced by vaccines. Examples of vaccines are as follows: Bacterial vaccines, (a) Live- BCG vaccine for tuberculosis, (b) Killed vaccines- TAB vaccine for enteric fever. Viral vaccines, (a) Live – sabin vaccine for poliomyelitis, MMR vaccine for measles, mumps, rubella, (b) Killed vaccines- salk vaccine for poliomyelitis, neural and non-neural vaccines for rabies. Bacterial products. Toxoids for Diphtheria and Tetanus.

2. Passive Immunity: When ready-made antibodies are directly injected into a person to protect the body against foreign agents, it is called passive immunity. It provides immediate relief. It is not long lasting. It may create problems. Passive immunity may be natural or artificial. (a) Natural passive immunity is the resistance passively transferred from the mother to the foetus through placenta. IgG antibodies can cross placental barrier to reach the foetus. After birth, immunoglobulin’s are passed to the new-born through the breast milk. Human colostrum (mother’s first milk) is rich in IgA antibodies. Mother’s milk contains antibodies which protect the infant properly by the age of three months. (b) Artificial passive immunity is the resistance passively transferred to a recipient by administration of antibodies. This is done by administration of hyper-immune sera of man or animals. Serum (pi. sera) contains antibodies. For example, anti-tetanus serum (ATS) is prepared in horses by active immunisation of horses with tetanus toxoid, bleeding them and separating the serum. ATS is used for passive immunisation against tetanus.

Similarly anti-diphtheric serum (ADS) and anti-gas gangrene serum (AGS) are also prepared. Immune Response: The immune response involves primary immune response and secondary immune response. (a) The primary immune response: After an initial contact with an antigen, no anti­bodies are present for a period of several days. Then, a slow rise in the antibody titer o(arbitrary units) occurs, first IgM and then IgG followed by a gradual decline in antibody titer. This is called the primary immune response. (b) The secondary immune response: Memory cells may remain in the body for decades. Every new encounter with the same antigen results in a rapid proliferation of memory cells. This is also called “booster response”. The antibody titer after subsequent encounters is far greater than during a primary response and consists mainly of IgG anti­bodies. This accelerated, more intense response is called the secondary immune response. Antibodies produced during a secondary response have an even higher affinity for the antigen. A person who had been suffering from diseases like measles, small pox or chicken pox becomes immune to subsequent attacks of these diseases.

It includes spleen, lymph nodes, tonsils, Peyer’s patches of small intestine and appendix. The increased power and duration of the secondary immune response explain why immunization (method of providing immunity artificially, it is called vaccination) is usually accomplished by injecting antigen in multiple doses. Innate Immunity | Tutorvista.com Top Innate (Non - specific) Immunity The human body continuously attempts to maintain homeostasis by counteracting harmful stimuli in the environment. These stimuli are mostly disease - causing organisms called Pathogens or their toxins. Innate immunity consists of all those defense elements with which an individual is born and which always protects the body. One aspect of innate immunity is the various types of barriers that prevent entry of pathogens and any foreign substances into the body. Even if the pathogens enter into the body, they are quickly killed and their multiplication is rapidly controlled by some other components of this system. This is called the first line of defence. The barriers are of four types:- 1) Anatomical 2) Physiological 3) Phagocytic and 4) Inflammatory barriers. Sub Topics Back to Top These block the entry of organisms into the body.

The skin and mucous membranes of the body possess certain mechanical factors and chemical factors that are involved in combating the initial attempt of a microbe to cause a disease. Mucous secreted by the membranes being slightly viscous, entraps foreign micro organisms and dust and prevents their entry into the body. For e.g., the mucous secreted in the nasal passage. Cilia of the wind pipe and upper respiratory tract drive away the bacteria and dust trapped in mucous and prevent them from entering into lungs. But some pathogens can thrive on the secretions of the mucous membrane, and they penetrate the membrane, if present in large numbers. The intact skin provides a formidable physical barrier to the entrance of microbes. It is rarely penetrated by bacteria. But when the epithetical surface is broken, a subcutaneous infection often develops. There are several other mechanical factors that help to protect epithetical surfaces of the skin and mucous membranes. One such mechanism that protects the eye is the lacrimal apparatus. The continuous washing action of tears produced by the lacrimal glands, helps to keep microbes from settling on the surface of the eye. If an irritating substance or large number of microbes make contact with the eye, the lacrimal glands start to oversecrete.

This is also a protective mechanism to dilute and wash away the irritating substance or microbes. Saliva Back to Top means the ingestion and destruction of microbes or any foreign particulate matter by certain cells called phagocytes. The most important phagocytes are the macrophages and microphages. Microphages are mostly Neutrophils. When an infection occurs monocytes migrate to the infected area, enlarge and develop into phagocytic cells called macrophages. Since these cells migrate to infected areas, they are called wandering phagocytes. Some macrophages called fixed macrophages enter certain tissues and organs and remain there. For e.g., in Liver, lungs, brain etc. During phagocytosis adherence or attachment is the first phase, when the firm contact between the cell membrane of the phagocyte and the microbe is established. In the next phase, ingestion occurs, when by means of pseudopodia the phagocyte engulfs the microbe and kills it with the help of lysosome. Inflammatory Barriers Back to Top Whenever there is an infection or tissue injury, it results in redness, swelling, pain and production of heat and may result in fever.

Such a manifestation is localised and is known as inflammatory response. Inflammation is characterised by 4 fundamental symptoms: redness, pain, heat and swelling. A fifth symptom can be the loss of function of the injured area. The inflammatory response serves a protective and defensive role. It is an attempt to neutralize and destroy toxic agents at the site of injury and to prevent their spread to other organs. The inflammatory response occurs in the following ways: 1) Vasodilation and increased permeability of blood vessels Back to Top Vasodilation increases blood supply to the damaged area which will help to remove toxic products and dead cells. Increased permeability of blood vessels permits white blood cells and serum proteins to enter into the injured area. These changes occur due to release of chemical alarm signals, mainly histamine and prostaglandins by the damaged mast cells. (2) Further, the phagocytes appear in the affected area soon and destroy the invading micro-organisms. (3) The leakage of serum proteins like fibrinogen to the tissues, forms a thick network of fibrin which localises and traps the invading germs and prevents their spread. This eventually forms a clot and isolates the infected area.

(4) Besides phagocytes, natural killer cells kill virus - infected cells and some tumour cells of the body by creating perforin - lined pores in the plasma membrane of the target cells. These pores allow entry of water into the target cells, which then swells and bursts. 5) Another antimicrobial substance which is very important to non-specific immunity is complement system. It consists of over 30 proteins that act in various ways to protect the individual from foreign invaders. These proteins are found in normal blood serum. Some complement proteins initiate a series of reactions leading to cell lysis caused by holes or pores in the plasma - membrane of the microbe. Some complements coat the invading microbes. This coating enables phagocytes to attach to the microbes and destroy them. Some complements contribute to the release of histamine from mast cells. Some complements serve to attract leucocytes to the area. 6) Fever is also a response, which inhibits growth of many pathogens. Frequent cause of fever, an abnormally high body temperature, is infection from bacteria and viruses. The high body temperature inhibits some microbial growth and speeds up body reactions that aid repair.

Question: What is the main component of blood besides cells and clotting/glycoprotein factors? Serum; Water; Mucus; or Sweat?
Answer: Serum