BBC Science & Nature - Human Body and Mind - Muscles Layer Skeletal muscle: Produces movement, maintains posture, stabilises joints and generates heat Smooth muscle: Found in the walls of hollow organs Cardiac muscle: Exists only in your heart Three types of muscle You've got around 650 muscles in your body, and they make up roughly half of your bodyweight. These muscles can be divided into three different groups: skeletal, smooth and cardiac. All of these muscles can stretch and contract, but they perform very different functions. Skeletal muscle The tissue most commonly thought of as muscle is skeletal muscle. Skeletal muscles cover your skeleton, giving your body its shape. They are attached to your skeleton by strong, springy tendons or are directly connected to rough patches of bone. Skeletal muscles are under voluntary control, which means you consciously control what they do. Just about all body movement, from walking to nodding your head, is caused by skeletal muscle contraction. Your skeletal muscles function almost continuously to maintain your posture, making one tiny adjustment after another to keep your body upright. Skeletal muscle is also important for holding your bones in the correct position and prevents your joints from dislocating.

Some skeletal muscles in your face are directly attached to your skin. The slightest contraction of one of these muscles changes your facial expression. Skeletal muscle generates heat as a by-product of muscle activity. This heat is vital for maintaining your normal body temperature. Smooth Muscle Smooth muscle is found in the walls of hollow organs like your intestines and stomach. They work automatically without you being aware of them. Smooth muscles are involved in many 'housekeeping' functions of the body. The muscular walls of your intestines contract to push food through your body. Muscles in your bladder wall contract to expel urine from your body. Smooth muscles in a woman's uterus (or womb) help to push babies out of the body during childbirth. The pupillary sphincter muscle in your eye is a smooth muscle that shrinks the size of your pupil. Cardiac Muscle Your heart is made of cardiac muscle. This type of muscle only exists in your heart. Unlike other types of muscle, cardiac muscle never gets tired. It works automatically and constantly without ever pausing to rest. Cardiac muscle contracts to squeeze blood out of your heart, and relaxes to fill your heart with blood.

Types of Muscle | Muscles Theory | Muscles | Anatomy & Physiology Anatomy & Physiology There are three types of muscle found in the human body: Skeletal Muscle Cardiac Muscle (heart muscle) Skeletal muscle Skeletal Muscles are those which attach to bones and have the main function of contracting to facilitate movement of our skeletons. They are also sometimes known as striated muscles due to their appearance. The cause of this 'stripy' appearance is the bands of Actin and Myosin which form the Sarcomere, found within the Myofibrils. Skeletal muscles are also sometimes called voluntary muscles, because we have direct control over them through nervous impulses from our brains sending messages to the muscle. Contractions can vary to produce powerful, fast movements or small precision actions. Skeletal muscles also have the ability to stretch or contract and still return to their original shape. Skeletal muscle fibre type Not all fibres within Skeletal muscles are the same. Different fibre types contract at different speeds, are suited to different types of activity and vary in colour depending on their Myoglobin (an oxygen carrying protein) content.

Smooth muscle Smooth muscle is also sometimes known as Involuntary muscle due to our inability to control its movements, or Unstriated as it does not have the stripy appearance of Skeletal muscle. Smooth muscle is found in the walls of hollow organs such as the Stomach, Oesophagus, Bronchi and in the walls of blood vessels. This muscle type is stimulated by involuntary neurogenic impulses and has slow, rhythmical contractions used in controlling internal organs, for example, moving food along the Oesophagus or contricting blood vessels during Vasoconstriction. Cardiac muscle (heart muscle) This type of muscle is found solely in the walls of the heart. It has similarities with skeletal muscles in that it is striated and with smooth muscles in that its contractions are not under conscious control. However this type of muscle is highly specialised. It is under the control of the autonomic nervous system, however, even without a nervous imput contractions can occur due to cells called pacemaker cells. Cardiac muscle is highly resistant to fatigue due to the presence of a large number of mitochondria, myoglobin and a good blood supply allowing continuous aerobic metabolism.

The Differences Between Skeletal, Smooth & Cardiac Muscles | Healdove The Differences Between Skeletal, Smooth & Cardiac Muscles The Differences Between Skeletal, Smooth & Cardiac Muscles Updated on December 04, 2015 Joined: 5 years agoFollowers: 205Articles: 82 Descriptions and examples of the three types of muscles in the human body. Advertisement Three Types of Muscles Found in the Human Body • Skeletal (muscles that move voluntarily) • Smooth (involuntary muscles in organs) • Cardiac (only found in the heart) The Function of Muscles To help us move and maintain posture. Create heat (the calories burned for energy tend to have an output of 75% heat, therefore on a cold day running is an effective way to warm up). Regulate organs. Move substances around the body (blood from the heart and food through the digestive system. Skeletal muscles, viewed under a microscope, appear striated. Advertisement • Are directly attached to the skeleton by tendons. • Aid in movement and locomotion. • Are voluntarily activated. • Appear striped under a microscope. Also called "striated" muscle.

• Fatigue more quickly than smooth or cardiac muscles. • Are able to stretch and resume original shape. • Striated appearance comes from formation of actin and myosin muscle fibres. • Are capable of powerful contractions and, just as adequately, small contractions for delicate movement requiring precision. • Stimulated by the nervous system's motor neurons. • Well-supplied with nerves and blood vessels. Smooth muscles are found in the walls of hollow structures, including veins and blood vessels. Advertisement • Get their name from their smooth appearance under a microscope. • Arranged in bundles of muscle fibre sheets. • Contract involuntarily. Regulated by autonomic part of nervous system. • Found in walls of hollow structures, including veins, arteries, and intestines. • Maintain flow of fluid and food along hollow structures. • Found in hair erectors, pupils, gland ducts, esophagus, bronchi, intestines, stomach, and blood vessels. • Contract slowly and rhythmically. Cardiac muscles appear striped or striated when viewed under a microscope. Advertisement • Found only in heart and at cardiac ends of main blood vessels. • Contract involuntarily. • Striated when viewed under a microscope. • Do not fatigue.

• Controlled by central nervous system, but can contract without signals due to "pacemaker" cells. • Contain high count of mitochondria and myoglobin. • Have good blood supply. Muscle Fatigue Skeletal muscle tissue fatigues much more quickly than cardiac or smooth muscles, perhaps because skeletal movement is not essential to homeostasis and survival. It is theoretically quite possible to survive without having to use some skeletal muscles at all. At the opposite extreme, cardiac muscle tissue is under permanent tension to lesser or greater extents to deliver blood, other fluids, oxygen, nutrients, and other substances vital to survival. Cardiac muscles have great blood supply and are designed specifically to avoid becoming fatigued. Since asphyxiation can lead to death within minutes, cardiac muscles must be able to fulfill their duty transporting oxygen in blood hemoglobin. Cardiac muscle mitochondria help with energy production rhythmic capacity, even at high force when needed. Research has shown that skeletal muscle mass grows in correlation to the force exerted. These muscles are bigger than smooth and cardiac muscles as a result. Advertisement Conscious or Subconscious Contraction (also known as voluntary or involuntary contraction) Cardiac and smooth muscles operate on a subconscious, or involuntary, basis.

Given the frequency of contractions this is just as well. Not only would it be nearly impossible to make a conscious decision to activate our heart and smooth muscles, but the responsibility would be too much. It is important that the heart maintains a rhythm. A heartbeat that is too fast would lead to high blood pressure. Too slow, and low blood pressure would result, resulting in low energy. Only skeletal muscles require voluntary contraction, although sometimes movement can be a reflex action (i.e. hitting the patella region with a rubber hammer can cause flexion of the knee). Generally it must be a voluntary action, or else we would have no control over the locomotion of our body to do everyday tasks. Advertisement by Natalie Lamb 0 What are examples of muscle tissue? | Reference.com What are examples of muscle tissue? A: Quick Answer There are three different types of muscle tissues found in the human body: skeletal, smooth and cardiac. All three tissue types are found in different areas of the body and perform similar functions. Full Answer Skeletal muscle surrounds the bone and cartilage in the body. It is voluntarily controlled and is highly striated. Smooth muscles are located in the linings of internal organs.

They are not voluntarily controlled, and instead, are controlled by the nervous system. Cardiac muscle is found in the walls of the heart and is also not voluntarily controlled. Cardiac muscle movement is also controlled by the nervous system. Muscles and their types Muscles and their types Human Anatomy » Basic Anatomy » Muscles and their types Muscle: The term “muscle” is derived from Latin word “Musculus” diminutive of “mus” meaning mouse. They were named so because their belly resembles body of the mouse and their tendons resemble mouse’s tail. Muscles are contractile tissues that bring about movements of different body parts. They can be regarded as motors of human body because they provide all the force necessary to perform different types of movements. Whether it is the locomotion of body as a whole or just motion of its parts, its all because of muscles. Types of muscles: Muscles are of three types; skeletal, smooth and cardiac. Characteristic features of each of them are described below. Types Of Muscles Link to Image Source: Earth Physiology Skeletal Muscles: They are also known as striped, striated, somatic and voluntary muscles They are the most abundant type and are found attached to the skeleton.

For this reason they are called skeletal muscles. They are innervated by somatic nervous system and are therefore under voluntary control. They obey the will of human beings. They respond quickly to stimuli and are capable of rapid contractions. They get fatigued easily because of their rapidity Each muscle fiber is multinucleated cylindrical cell containing groups of myofibrils. The myofibrils are in turn made up of myofilaments of three types namely actin, myosin, and tropomyosin. Thus the skeletal muscles have three structural levels namely muscle fibers, myofibrils and myofilaments. Examples of skeletal muscles include all muscles of body wall. Smooth muscles: They are also known as plain, unstriped, visceral and involuntary muscles. Unlike skeletal muscles, they do not exhibit cross striations under the microscope and thus they got the name “smooth”. They are supplied by autonomic nervous system and therefore they are involuntary in their action. They do not obey the will of human being. They respond slowly to stimuli but are capable of long time sustained contractions. They do not get fatigued easily because of their slowness of response.

They provide motor power for regulating internal environment related to digestion, circulation, secretion and excretion. Each smooth muscle fiber is an elongated spindle shaped cell with a single nucleus placed at the center. They also possess actin and myosin filaments but the structural arrangement of these filaments is very different as compared to the skeletal muscles. Examples of smooth muscles include muscles of blood vessels, and muscles of the gut etc. Cardiac muscles: They form the myocardium of human heart. Cardiac muscle is intermediate in structure lying between the skeletal and smooth muscles. They are striated like skeletal muscles but at the same time they are involuntary and have uninuclear cells like smooth muscles. They are meant for automatic rhythmic contractions for long period of time. Each muscle fiber has a single centrally placed nucleus. The fibers branch and anastomoses with each other to form a syncitium. Neighboring cells are joined by intercalated discs which provide conductive pathways from one cell to another. Share this page: Muscle Home Page Revision aids Introduction: All the muscles in the human body show biochemical specialisation which allows them to perform their particular physiological functions.

The eyeballs are steered by extra-ocular muscles when reading: they must contract quickly and precisely, but the muscles in your back and buttocks evolved for continuous heavy lifting where fuel economy is important. The hollow viscera often require a slow steady squeeze to function properly. We normally recognise three basic types of vertebrate muscle: 1) Voluntary skeletal muscle is under conscious control. Each fibre is an enormous, multi-nucleate cell, formed by fusing hundreds of myoblasts end-to-end. They show a striated pattern, reflecting the regular arrangement of sarcomeres within each cell. 2) Cardiac muscle is similar to skeletal muscle, but is not under conscious control. These mono-nucleate cells are much smaller, but still show a striated pattern. 3) Smooth muscle is closer to non-muscle cells. No regular striations are visible and the contractions are much slower. Smooth muscle is found in the blood vessels, gut, skin, eye pupils, urinary and reproductive tracts. Skeletal muscle fibre types Voluntary muscles contain a variety of fibre types which are specialised for particular tasks. Most muscles contain a mixture of fibre types although one type may predominate.

The pattern of gene expression within each voluntary muscle cell is governed by the firing pattern of its single motor neurone. Motor neurones branch within their target muscle and thereby control several muscle fibres, called a motor unit. The high precision eye muscles have only a few fibres in each motor unit, but the muscles in your back have thousands. All the cells in a motor unit contract in unison and they all belong to the same fibre type: Type 1 or slow oxidative fibres have a slow contraction speed and a low myosin ATPase activity. These cells are specialised for steady, continuous activity and are highly resistant to fatigue. Their motor neurones are often active, with a low firing frequency. These cells are thin (high surface to volume ratio) with a good capillary supply for efficient gas exchange. They are rich in mitochondria and myoglobin which gives them a red colour. They are built for aerobic metabolism and prefer to use fat as a source of energy. These are the marathon runner's muscle fibres. Type 2A or fast oxidative-glycolytic fibres have a fast contraction speed and a high myosin ATPase activity. They are progressively recruited when additional effort is required, but are still very resistant to fatigue.

Their motor neurones show bursts of intermittent activity. These cells are thin (high surface to volume ratio) with a good capillary supply for efficient gas exchange. They are rich in mitochondria and myoglobin which gives them a red colour. They are built for aerobic metabolism and can use either glucose or fats as a source of energy. These are general purpose muscle fibres which give the edge in athletic performance, but they are more expensive to operate than type 1. Type 2B or fast glycolytic fibres have a fast contraction speed and a high myosin ATPase activity. They are only recruited for brief maximal efforts and are easily fatigued. Their motor neurones transmit occasional bursts of very high frequency impulses. These are large cells with a poor surface to volume ratio and their limited capillary supply slows the delivery of oxygen and removal of waste products. They have few mitochondria and little myoglobin, resulting in a white colour (e.g. chicken breast). They generate ATP by the anaerobic fermentation of glucose to lactic acid. These are sprinter's muscle fibres, no use for sustained performance.

These differences are nicely illustrated by the serial sections from rat diaphragm published by Gauthier and Lowey (1979) J. Cell Biology 81, 10-25. In the figure above, the left hand section was stained for the mitochondrial enzyme succinate dehydrogenase, the centre panel shows direct immunofluorescence against "fast" type myosin, and the right hand section was stained for alkali-stable ATPase activity (i.e. "fast" type myosin). Notice the differences in the fibre diameters, which correlates with their requirements for efficient gas and substrate exchange. Notice also how the mitochondria tend to cluster near the outside of the cells. Voluntary muscle cells are electrically isolated from each other, and respond only to direct instructions from a particular motor neurone via the motor end plate. They have nicotinic acetylcholine receptors, which are ligand-gated sodium channels concentrated in a specialised region of the muscle sarcolemma beneath the axon terminus. These ion channels respond to acetylcholine (secreted from the nerve) by depolarising the muscle sarcolemma near the motor end plate.

The depolarisation triggers voltage-gated sodium channels which spread the excitation over the remainder of the cell. Cardiac muscle In cardiac muscle and some types of smooth muscle the cells are in electrical contact through communicating gap junctions. These are important for the orderly spread of excitation through the heart. This starts with the spontaneous depolarisation of the specialised pacemaker cells in the sino-atrial node, spreads via the atria to the atrio-ventricular node and thence to the conducting fibres in the Bundle of His (in the intraventricular septum) and the Purkinje system. These cells finally activate the bulk of the ventricular muscle in the chamber walls, in each case through direct electrical contacts. Catecholamine hormones such as adrenalin are released during frightening or stressful situations. They increase the force and frequency of cardiac contractions by binding to Beta-1 receptors, which are protein molecules protruding from the outer face of the cardiac sarcolemma. These activate G-proteins within the membrane, which in turn activate the enzyme adenyl cyclase on the inner face of the sarcolemma.

Adenyl cyclase produces 3'5' cyclic AMP, which is an important second messenger controlling numerous intra-cellular activities. Cyclic AMP activates protein kinase A which phosphorylates many intracellular enzymes, temporarily modifying their properties. Cardiac muscle contains muscarinic acetylcholine receptors. These are also linked to adenyl cyclase (via inhibitory G proteins) and to a potassium ion channel in the cardiac sarcolemma. Acetylcholine reduces the levels of cyclic AMP and increases potassium currents, promoting slower, less forceful beats. Many types of smooth muscle also contain gap junctions and muscarinic acetylcholine receptors, but here acetylcholine normally leads to contraction. Depending on the type of smooth muscle, catecholamines may produce either contraction (alpha receptors linked to intracellular calcium stores), or relaxation (beta receptors linked to adenyl cyclase). This relaxation is apparently mediated by the cyclic AMP-dependent phosphorylation and inactivation of the enzyme myosin light chain kinase, which plays a central role in smooth muscle contraction. Vascular smooth muscle redistributes the blood supply during exercise, and visceral smooth muscle empties the gut in stressful or frightening situations.

In contrast to all this, the force of contraction in voluntary muscle is unaffected by circulating hormones. Control of cardiac contraction The diagram above shows the control of cardiac muscle contraction in greater detail. The Na/K ATPase or sodium pump (1) works continuously, using the energy from ATP to maintain a high K+ concentration inside the cells and a high Na+ concentration in the extracellular fluid (ECF). The cell membrane (sarcolemma) is usually more permeable to potassium ions than to sodium ions, and this gives rise to a membrane potential of about 80mV (inside negative) in relaxed muscle. Calcium ions are also removed from the cytosol into the ECF by an ATP-driven calcium pump (2) in all tissues. Cardiac muscle possesses an additional sodium/calcium exchange protein (3). This export system is driven by the pre-existing sodium ion gradient. The calcium concentration inside resting cells is low, but rises sharply during contractions. The sarcolemma is very thin (about 6 nm) so the 80mV membrane potential equates to a voltage gradient of about 13,000,000 volts per metre!

All membrane components are subject to intense electric fields, and protein conformations are greatly influenced by the membrane potential. "Voltage gated" ion channels will only conduct over a narrow range of membrane potentials, whereas "ligand gated" ion channels (such as the acetylcholine receptor in voluntary muscle) require specific chemical activators. Contraction in cardiac muscle is triggered by a wave of membrane depolarisation which spreads from neighbouring cells. The change in electric field activates voltage gated sodium channels (4) in the sarcolemma, each of which allows a few hundred positively charged sodium ions to enter the negatively charged cytosol, further reducing the cardiac membrane potential until the whole sarcolemma is depolarised. The sodium channel undergoes a second conformational change, as a result of which these channels close spontaneously after a few milliseconds in all excitable tissues. In cardiac muscle, but NOT skeletal muscle, slower voltage-gated calcium channels, probably identical with dihydropyridine receptors (5) take over and maintain a positive inward current for several hundred milliseconds (in human ventricle) during the plateau phase of the cardiac action potential.

As in nerves and skeletal muscle, the membrane potential in cardiac muscle is eventually restored to its resting value by a delayed efflux of positive potassium ions from the cells. Dihydropyridine drugs (e.g. verapamil & nifedipine) inhibit calcium entry into heart and reduce blood pressure. About 10% of the calcium needed to activate cardiac contraction enters during each beat from the ECF. This is often described as "trigger calcium". The remainder is released from the sarcoplasmic reticulum through a channel known as the ryanodine receptor (6). Ryanodine receptors are widely distributed in the body, and are present in non-muscle tissues such as brain. The genes coding for this enormous protein (5037 amino acids) have been sequenced. Different tissues have their own specific isoenzymes. The operation of the ryanodine receptor depends in a mysterious way on the flow of calcium ions through the dihydropyridine receptors in cardiac muscle, but not in other muscle types. Calcium ions from both sources bind to the regulatory protein troponin-C located in the thin filaments (7), leading to a change in filament shape.

This allows flexible head groups from the protein myosin in the thick filaments (8) to interact with the protein actin in the thin filaments. A change in myosin conformation causes the thick and thin filaments to slide against each other and hydrolyse ATP, which provides the energy for contraction. Movement and ATP hydrolysis continue until the calcium ions are removed from the cytosol at the end of each contraction. Most of the calcium ions are returned to the sarcoplasmic reticulum by a calcium pump (9) but about 10% leave the cell via proteins (2) and (3) described above. Calcium ions are stored within the sarcoplasmic reticulum loosely bound to a protein, calsequestrin (10). In cardiac muscle circulating hormones like catecholamines and glucagon bind to specific receptors (11) on the outer surface of the sarcolemma, changing their shape. This change is communicated via G-proteins (12) within the sarcolemma to adenyl cyclase (13) bound to the internal face of the sarcolemma. Several G-proteins are known, some activatory, others inhibitory.

They all slowly hydrolyse GTP while working, although it is not clear what advantage this confers on the cell. Adenyl cyclase manufactures 3'5' cyclic AMP, which is continuously destroyed by a phosphodiesterase enzyme. The steady-state concentration of cyclic AMP depends on the balance between synthesis and degradation. Cyclic AMP in turn controls the activity of cyclic AMP-dependent protein kinase. This enzyme phosphorylates several of the proteins involved in the contraction process, and temporarily alters their properties until a protein phosphatase restores the status quo ante by removing the phosphate group. The sodium pump (1) is activated by phosphorylation, which allows it to handle the increased ion traffic across the sarcolemma when cardiac work output rises. The dihydropyridine receptor (5) is activated by phosphorylation, increasing calcium entry into the cells. The ryanodine receptor (6) is also activated, increasing the rate of calcium release from the sarcoplasmic reticulum. The troponin-I component in the thin filaments (7) is phosphorylated and this reduces calcium binding to the neighbouring troponin-C.

(This may be a defence mechanism preventing tetany in cardiac muscle, which would be rapidly fatal.) A small protein called phospholamban associated with the sarcoplasmic reticulum calcium pump (9) is phosphorylated, and this accelerates calcium uptake by the S.R. pump. (A fast heart rate requires quick relaxation as well as rapid contraction.) The enzymes triglyceride lipase (14) and glycogen phosphorylase (15) are activated by phosphorylation. These enzymes catalyse the first steps in the mobilisation of food reserves. They eventually increase the supply of ATP and provide the energy for the anticipated extra work. These changes take place in a coordinated sequence over many seconds, so that the initial response to adrenalin may be a pounding heart, but both the rate and the force of contraction tend to return to normal when the stimulation is prolonged. Skeletal muscle can contract in the absence of extracellular calcium, and skeletal S.R, shows depolarisation-induced calcium release In contrast to this, cardiac S.R needs external "trigger calcium" to enter the cells via the dihydropyridine receptors during the plateau phase of each action potential to initiate calcium-induced calcium release (CICR).

Cardiac and skeletal ryanodine receptors probably differ in their precise intracellular location. The two genes are on separate chromosomes and show substantial differences. They are also expressed in brain, egg cells and many other tissues, where they regulate calcium release from the smooth endoplasmic reticulum. Dihydropyridine receptors are also present in some smooth muscles. They are blocked by the important drugs verapamil and nifedipine, which reduce the force of cardiac contraction, while maintaining an adequate cardiac output by relaxing vascular smooth muscle and reducing the peripheral vascular resistance. The system(s) which terminate CICR are far from clear, There must be some mechanism, since otherwise rising cytosolic calcium would lock the S.R. Ca++ release channels in the open state. Perhaps the ryanodine receptor has a built in relaxation time (like the voltage gated sodium channels in the sarcolemma) or perhaps there is a mechanism to sense the emptying of the S.R. The transmembrane protein triadin might provide a link to either measure or modulate calcium binding to the low-affinity binding protein calsequestrin in the lumen of the S.R.

The repeated entry of external calcium ions during the plateau phase of each cardiac action potential requires a cardio-specific calcium export system to stabilise the internal calcium concentration. This is achieved by the electrical exchange of one intracellular Ca++ ion for three extracellular Na+ ions in cardiac muscle. The exchange is assisted by the resting membrane potential. Cardiac glycosides such as ouabain and digitalis (from foxgloves) inhibit the Na/K ATPase, reducing the Na+ gradient across the plasmalemma in all tissues. This specifically increases the force of cardiac (but not skeletal muscle) contraction by interfering with the cardiac Ca++ export system. Back to the table of contents Smooth Muscle Smooth muscles form a very heterogenous group of tissues, and the properties of vascular smooth muscles differ greatly from those in the airway, gut or reproductive tract. Many of these differences arise from tissue-specific expression of cell surface receptors, but even among the intracellular proteins, the variation between different smooth muscles is at least as great as that between the different types of striated muscle.

Smooth muscle has only about half the myosin found in striated muscles, and lacks their sarcomere organisation [actin:myosin = 7:1 in striated muscle, 15:1 in smooth muscle, very large ratio in non-muscle cells]. Smooth muscle myosins do not self-associate into the thick filaments seen in striated muscles. Smooth muscle contraction speeds are very slow when compared with voluntary muscle, but it can achieve a much greater degree of shortening, and it is very economical to operate. In contrast to the "all or none" reactions associated with nerves and striated muscles, smooth muscles often show a graded response to membrane depolarisation. Cell to cell transmission via communicating gap junctions may be very important in smooth muscles, as in the heart. The resting potential in smooth muscles is generally lower than in striated muscles, and fast voltage-gated sodium channels are not significant. Chloride ion circulation (electroneutral uptake of NaCl plus electrical export of chloride ions) may be important in setting the resting potential in the 40mV range.

Spike depolarisations associated with calcium ion entry are seen in some types of smooth muscle, but the fast action potentials associated with nerves and striated muscles are not observed. Receptors are distributed fairly evenly over the surface of smooth muscle cells, and are not organised in synapses or motor end plates seen in nerves and voluntary muscles. Many types of smooth muscle require external calcium in order to contract, and have nifedipine-sensitive calcium channels very similar to the dihydropyridine receptors observed in cardiac muscle. Troponin is absent from smooth muscles, and their actin regulatory system (where present) differs considerably from the thin filament regulatory system found in striated muscles. Caldesmon is a smooth muscle protein that binds reversibly to the actin / tropomyosin filaments and blocks the actomyosin ATPase activity. Caldesmon can be sequestered away from the actin by two separate, calcium-dependent methods: (a) by phosphorylation using protein kinase C, or (b) by binding calcium and calmodulin to form a caldesmon-calcium-calmodulin complex that is unable to bind to actin.

In contrast to this, troponin is a permanent feature of striated muscle thin filaments, and never dissociates from the actin. The myosin regulatory system is much more important in smooth muscles than in striated muscle. The enzyme myosin light chain kinase is activated by calcium + calmodulin, and phosphorylates the DTNB "regulatory" light chains in the myosin S1 head groups. This increases the inherent myosin calcium sensitivity, and brings it into the physiological range, allowing contraction to proceed. This system also operates in striated muscle, where it seems to play a subordinate role. Phosphorylation of myosin light chains on a second site by protein kinase C interferes with this process and leads to smooth muscle relaxation. Isolated vascular smooth muscle contracts in response to acetyl choline, but this compound relaxes intact blood vessels as a result of nitric oxide generated by endothelial cells. Nitric oxide relaxes vascular smooth muscle via cyclic GMP. Both vascular and airway smooth muscles relax in response to beta adrenergic agonists via cyclic AMP. These effects are of considerable medical significance in the treatment of hypertension and asthma.

Gene knockout experiments [ Pfeifer et al (1998) ] have established that cAMP and cGMP transduce independent signalling pathways, but the detailed mechanisms underlying these effects remain to be elucidated. Back to the table of contents Muscle Metabolism Muscle tissue accounts for most of an individual's mass and daily energy consumption. Fuel economy is very important, not only for minimising food requirements, but also for reducing unwanted heat production. The different skeletal muscle fibre types are described above: in general the routine tasks are handled by slowly contracting, economical fibres with an fat-based aerobic metabolism, and the more expensive high-speed fibres using carbohydrate fuels are only recruited when the occasion demands. Smooth muscle is particularly economical because it has a low myosin: actin ratio, a low ATPase activity and a much lower contraction speed. It is ideal for sphincters and slow squeezes, and is used for these tasks in preference to striated fibres. Cardiac muscle contracts quite slowly, but it is used continuously and the total energy consumption is high. It is totally specialised for energy production, and achieves the highest sustained metabolic rates (and the highest arterio-venous oxygen extractions) of any tissue in the body.

Mitochondria represent 30-40% of the ventricular mass. This high metabolic rate creates serious diffusion problems within cardiac muscle. There is a high capillary density and the cells are small, with a high surface to volume ratio. The tissue is rich in myoglobin (for oxygen transport) and creatine + creatine phosphate (for energy transport). The organ shows a distinct preference for free fatty acids, ketone bodies and lactate; but requires insulin for efficient glucose uptake and utilisation. Nucleotide metabolism Linear 5' AMP (not 3'5' cyclic AMP) is a major allosteric activator for glycogen phosphorylase and phosphofructokinase, and is also the immediate precursor for the local hormone adenosine, a powerful vasodilator which increases blood flow to rapidly metabolising tissues. Adenine nucleotide (AMP, ADP & ATP) concentrations are related by the enzyme myokinase, which catalyses the freely reversible reaction: ATP + AMP = ADP + ADP The myokinase equilibrium means that [AMP] = [ADP]*[ADP]/[ATP] (approximately).

The free cytosolic ADP concentration is normally very low, because it is actively taken up by mitochondria in exchange for ATP. This makes 5' AMP an exquisitely sensitive indicator of the cellular energy supply in all types of muscle, and indeed in all other tissues. Linear 5' AMP is an activator for AMP-activated protein kinase [AMPK] which stimulates glucose uptake by skeletal muscle during exercise and under conditions of metabolic stress. It appears to play a major role in type 2 diabetes. Try not to confuse AMPK with protein kinase A (which responds to 3'5' cyclic AMP) since their functions are entirely different. AMPK protects cells from stresses that cause ATP depletion by switching off ATP-consuming biosynthetic pathways, whereas PKA is part of the hormonal second messenger system. The purine nucleotide cycle is an unusual feature of skeletal muscle, which serves to replenish TCA cycle and glycolytic intermediates when the energy demand is high. AMP is deaminated to yield inosine monophosphate (IMP) which is converted to adenylosuccinate and then back to AMP.

The net effect is an AMP-dependent conversion of aspartate to fumarate and ammonia whenever the mechanical work load increases. The process can be used repeatedly because the aspartate pool is many times larger than the pool of TCA intermediates and is constantly replenished from the blood or the internal muscle protein stores. Amino acid metabolism Skeletal muscle is the body's major store of amino acids during fasting. These tissues are degraded in an orderly fashion, and release mainly alanine and glutamine into the blood. These amino acids help to maintain blood glucose during fasting through gluconeogenesis in liver, kidney and gut. Skeletal muscles lack a urea cycle, but they are able to transaminate most amino acids and degrade their carbon skeletons as far as Krebs cycle intermediates, such as succinyl-CoA and fumarate. Surplus cycle intermediates are converted via an allosteric NAD-linked "malic" enzyme into pyruvate, which is transaminated to yield alanine. Some amino acids such as serine are deaminated to pyruvate and ammonia, which is de-toxified yielding glutamine.

In this way surplus nitrogen is exported from the muscles to the liver, kidney and gut for further processing. respiratory defects, abnormal morphology, lactic acidosis and stroke (MELAS) selective loss of Krebs cycle enzymes or other respiratory components There is very much more information on the OMIM database. Back to the table of contents Some Skeletal Muscle Proteins Please do not attempt to learn all the information in this table! It has been included to show the complexity of the systems controlling gene expression in muscle tissues, and to provide a quick method for locating reviews and original papers on particular aspects of muscle biochemistry. Use OMIM to identify one or two important papers in your area of interest, and then use the citation search option in BIDS to see who has subsequently quoted them. Component Your Body's Systems Your Body's Systems Circulatory System The circulatory system is the body's transport system. It is made up of a group of organs that transport blood throughout the body. The heart pumps the blood and the arteries and veins transport it. Oxygen-rich blood leaves the left side of the heart and enters the biggest artery, called the aorta. The aorta branches into smaller arteries, which then branch into even smaller vessels that travel all over the body.

When blood enters the smallest blood vessels, which are called capillaries, and are found in body tissue, it gives nutrients and oxygen to the cells and takes in carbon dioxide, water, and waste. The blood, which no longer contains oxygen and nutrients, then goes back to the heart through veins. Veins carry waste products away from cells and bring blood back to the heart , which pumps it to the lungs to pick up oxygen and eliminate waste carbon dioxide. Digestive System The digestive system is made up of organs that break down food into protein, vitamins, minerals, carbohydrates, and fats, which the body needs for energy, growth, and repair. After food is chewed and swallowed, it goes down the esophagus and enters the stomach, where it is further broken down by powerful stomach acids. From the stomach the food travels into the small intestine. This is where your food is broken down into nutrients that can enter the bloodstream through tiny hair-like projections. The excess food that the body doesn't need or can't digest is turned into waste and is eliminated from the body. Endocrine System The endocrine system is made up of a group of glands that produce the body's long-distance messengers, or hormones.

Hormones are chemicals that control body functions, such as metabolism, growth, and sexual development. The glands, which include the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, thymus gland, pineal body, pancreas, ovaries, and testes, release hormones directly into the bloodstream, which transports the hormones to organs and tissues throughout the body. Immune System The immune system is our body's defense system against infections and diseases. Organs, tissues, cells, and cell products work together to respond to dangerous organisms (like viruses or bacteria) and substances that may enter the body from the environment. There are three types of response systems in the immune system: the anatomic response, the inflammatory response, and the immune response. The anatomic response physically prevents threatening substances from entering your body. Examples of the anatomic system include the mucous membranes and the skin. If substances do get by, the inflammatory response goes on attack. The inflammatory system works by excreting the invaders from your body. Sneezing, runny noses, and fever are examples of the inflammatory system at work. Sometimes, even though you don't feel well while it's happening, your body is fighting illness.

When the inflammatory response fails, the immune response goes to work. This is the central part of the immune system and is made up of white blood cells, which fight infection by gobbling up antigens . About a quarter of white blood cells, called the lymphocytes, migrate to the lymph nodes and produce antibodies, which fight disease. Lymphatic System The lymphatic system is also a defense system for the body. It filters out organisms that cause disease, produces white blood cells, and generates disease-fighting antibodies. It also distributes fluids and nutrients in the body and drains excess fluids and protein so that tissues do not swell. The lymphatic system is made up of a network of vessels that help circulate body fluids. These vessels carry excess fluid away from the spaces between tissues and organs and return it to the bloodstream. Muscular System The muscular system is made up of tissues that work with the skeletal system to control movement of the body. Some muscles—like the ones in your arms and legs—are voluntary, meaning that you decide when to move them. Other muscles, like the ones in your stomach, heart, intestines and other organs, are involuntary.

This means that they are controlled automatically by the nervous system and hormones—you often don't even realize they're at work. The body is made up of three types of muscle tissue: skeletal, smooth and cardiac. Each of these has the ability to contract and expand, which allows the body to move and function. . Skeletal muscles help the body move. Smooth muscles, which are involuntary, are located inside organs, such as the stomach and intestines. Cardiac muscle is found only in the heart. Its motion is involuntary Nervous System The nervous system is made up of the brain, the spinal cord, and nerves. One of the most important systems in your body, the nervous system is your body's control system. It sends, receives, and processes nerve impulses throughout the body. These nerve impulses tell your muscles and organs what to do and how to respond to the environment. There are three parts of your nervous system that work together: the central nervous system, the peripheral nervous system, and the autonomic nervous system. The central nervous system consists of the brain and spinal cord. It sends out nerve impulses and analyzes information from the sense organs, which tell your brain about things you see, hear, smell, taste and feel.

The peripheral nervous system includes the craniospinal nerves that branch off from the brain and the spinal cord. It carries the nerve impulses from the central nervous system to the muscles and glands. The autonomic nervous system regulates involuntary action, such as heart beat and digestion. Reproductive System The reproductive system allows humans to produce children. Sperm from the male fertilizes the female's egg, or ovum, in the fallopian tube. The fertilized egg travels from the fallopian tube to the uterus, where the fetus develops over a period of nine months. Respiratory System The respiratory system brings air into the body and removes carbon dioxide. It includes the nose, trachea, and lungs. When you breathe in, air enters your nose or mouth and goes down a long tube called the trachea. The trachea branches into two bronchial tubes, or primary bronchi, which go to the lungs. The primary bronchi branch off into even smaller bronchial tubes, or bronchioles. The bronchioles end in the alveoli, or air sacs. Oxygen follows this path and passes through the walls of the air sacs and blood vessels and enters the blood stream.

At the same time, carbon dioxide passes into the lungs and is exhaled. Skeletal System The skeletal system is made up of bones, ligaments and tendons. It shapes the body and protects organs. The skeletal system works with the muscular system to help the body move. Marrow, which is soft, fatty tissue that produces red blood cells, many white blood cells, and other immune system cells, is found inside bones. Urinary System The urinary system eliminates waste from the body, in the form of urine. The kidneys remove waste from the blood. The waste combines with water to form urine. From the kidneys, urine travels down two thin tubes called ureters to the bladder. When the bladder is full, urine is discharged through the urethra. Types of Muscle: Skeletal Muscle vs Smooth Muscle vs Cardiac Muscle - YouTube Types of Muscle: Skeletal Muscle vs Smooth Muscle vs Cardiac Muscle Want to watch this again later? Sign in to add this video to a playlist. Need to report the video? Sign in to report inappropriate content. The interactive transcript could not be loaded. Loading... Rating is available when the video has been rented. This feature is not available right now. Please try again later.

Published on Aug 4, 2016 Muscle Types | Learn Muscular Anatomy Tweet 3 Types of Muscle Tissue: The Function of Skeletal, Cardiac, and Smooth Muscle About half of your body’s weight is muscle. In the muscular system, muscle tissue is categorized into three distinct types: skeletal, cardiac, and smooth. Each type of muscle tissue in the human body has a unique structure and a specific role. Skeletal muscle moves bones and other structures. Cardiac muscle contracts the heart to pump blood. The smooth muscle tissue that forms organs like the stomach and bladder changes shape to facilitate bodily functions. Here are more details about the structure and function of each type of muscle tissue in the human muscular system. 1. The Human Body Has Over 600 Skeletal Muscles That Move Bones and Other Structures Skeletal muscles attach to and move bones by contracting and relaxing in response to voluntary messages from the nervous system. Skeletal muscle tissue is composed of long cells called muscle fibers that have a striated appearance. Muscle fibers are organized into bundles supplied by blood vessels and innervated by motor neurons. 2. The Walls of Many Human Organs Contract and Relax Automatically Smooth muscle is found in the walls of hollow organs throughout the body.

Smooth muscle contractions are involuntary movements triggered by impulses that travel through the autonomic nervous system to the smooth muscle tissue. The arrangement of cells within smooth muscle tissue allows for contraction and relaxation with great elasticity. The smooth muscle in the walls of organs like the urinary bladder and the uterus allow those organs to expand and relax as needed. The smooth muscle of the alimentary canal (the digestive tract) facilitates the peristaltic waves that move swallowed food and nutrients. In the eye smooth muscle changes the shape of the lens to bring objects into focus. Artery walls include smooth muscle that relaxes and contracts to move blood through the body 3. Cardiac Muscle Contracts in Response to Signals from the Cardiac Conduction System The heart wall is composed of three layers. The middle layer, the myocardium, is responsible for the heart’s pumping action. Cardiac muscle, found only in the myocardium, contracts in response to signals from the cardiac conduction system to make the heart beat. Cardiac muscle is made from cells called cardiocytes. Like skeletal muscle cells cardiocytes have a striated appearance, but their overall structure is shorter and thicker. Cardiocytes are branched, allowing them to connect with several other cardiocytes, forming a network that facilitates coordinated contraction.

Muscular Tissue - Structure and Functions of Human Tissue Types. 05 April 2016 - FDA Regulation for Food Safety during Transportation (USA) Structure and Functions of Muscular Tissue Note: This page is part of the section about the structure and function of different Tissue Types, which is related to the section about Histology and Cells (incl. structure of animal cells , cell division , mitosis , meiosis ). This "Tissue Types" section is included to complete description of the knowledge of "Histology - The Cell" required by some courses in First-Level Anatomy and Physiology. To read about other tissue types see the list of on the left. There are 3 types of muscle tissue: Skeletal muscle tissue, Cardiac muscle tissue, and Smooth muscle tissue. The structure of these muscle tissues can be described from the level of detail of the muscle fibres ( muscle cells ) through all the other muscle structures and parts of structures that bind muscle cells together enabling them to perform their functions. The functions of muscle tissues depend on the type of muscle tissues and their locations in the body. Here is an overview of the 3 types of muscle tissues: (a) Skeletal Muscle Tissue

Question: In the human body, Skeletal, Smooth and Cardiac are all types of what?
Answer: Muscle