How Insulin Works in the Body How Insulin Works in the Body Search the site By Elizabeth Woolley - Reviewed by a board-certified physician. Updated November 14, 2016 Insulin has a hand in several processes in your body: Not only does it assist with metabolizing carbohydrates and storing glucose for energy in cells, but it also helps utilize the fat, protein, and certain minerals you eat. Because this hormone is so important in helping your body use the foods you ingest, a problem with insulin can have widespread effects on all of your body's systems, tissues, and organs—either directly or indirectly. If you have type 2 diabetes, learning how insulin works can help you understand why so many other medical conditions are associated with diabetes, why certain lifestyle practices are beneficial, and how your body reacts to food. Where Insulin is Produced in the Body Insulin is a hormone made up of a small polypeptide protein that is secreted by the pancreas, which acts as both an endocrine and exocrine gland. Endocrine glands are the system of glands that secrete hormones to regulate body functions. Exocrine glands aid in digestion.

The pancreas sits behind the stomach, nestled in the curve of the duodenum (the first part of the small intestine), and contains clusters of cells called islets of Langerhans. Islets are made up of beta cells, which produce and release insulin into the bloodstream. Insulin is Part of a Balancing Act Insulin affects carbohydrate, protein, and fat metabolism. Your body breaks these nutrients down into sugar molecules, amino acid molecules, and lipid molecules, respectively. The body can also store and reassemble these molecules into more complex forms. Insulin causes the storage of these nutrients, while another pancreatic hormone called glucagon releases them from storage. Insulin is involved in your body's careful balancing act to keep your blood sugar levels within a normal range. In simple terms: If your blood sugar is high: The pancreas releases insulin to help cells absorb glucose from the bloodstream to lower blood sugar levels. If your blood sugar is low: The pancreas releases glucagon to help the liver release stored glucose into the bloodstream to raise blood sugar levels. Blood sugar levels rise when most foods are consumed, but they rise more rapidly and drastically with carbohydrates. The digestive system releases glucose from foods and the glucose molecules are absorbed into the bloodstream.

The rising glucose levels signal the pancreas to secrete insulin to clear out glucose from the bloodstream. Insulin binds with insulin receptors on cell surfaces and acts as a key to open up the cells to receive glucose. Insulin receptors are on almost all tissues, including muscle cells and fat cells. Insulin receptors have two main components—the exterior and interior portions. The exterior portion extends outside the cell and binds with insulin. When this happens, the interior part of the receptor sends out a signal inside the cell for glucose transporters to mobilize to the surface and receive glucose. As blood sugar and insulin levels decrease, the receptors empty and the glucose transporters go back into the cell. Insulin and Type 2 Diabetes In a perfect situation, glucose from carbohydrates gets cleared rapidly. However, when there is insulin resistance , this does not happen, and sustained high glucose levels become a problem. Insulin resistance can be due to a problem with the shape of the insulin (preventing receptor binding), not having enough insulin receptors, signaling problems, or glucose transporters not working properly. Whatever the specific cause, the function of insulin is impaired. Insulin resistance develops before type 2 diabetes is diagnosed.

To make up for less effective insulin, the pancreas works overtime to increase insulin output. Eventually, some of the insulin works and blood sugar levels remain normal for a while. As insulin resistance worsens and the pancreas cannot keep up with the demand, glucose levels begin to rise and diabetes is diagnosed when levels get too high. How Insulin Affects Fat Metabolism Carbohydrate and fat metabolism are closely connected and both influenced by insulin. If insulin is not working properly, problems can occur. For example, high levels of insulin can send the wrong signals to the brain. These signals tell the brain that there is excess insulin and that your cells are starving for glucose. So in response, your brain creates cravings for carbohydrates, signals your body to store fat, and orders carbs to be burned for energy rather than body fat. This is why weight loss can be difficult when you have type 2 diabetes. Insulin also plays a key role in the development of high triglyceride levels: In the Liver: Insulin stimulates the creation and storage of glycogen from glucose. High insulin levels cause the liver to get saturated with glycogen. When this happens, the liver resists further storage.

Glucose is used instead to create fatty acids that are converted into lipoproteins and released into the bloodstream. These break down into free fatty acids and are used in other tissues. Some tissues use these to create triglycerides. In Fat Cells: Insulin stops the breakdown of fat and prevents the breakdown of triglycerides into fatty acids. When glucose enters these cells, it can be used to create a compound called glycerol. Glycerol can be used along with the excess free fatty acids from the liver to make triglycerides. This can cause triglycerides to build up in the fat cells. How Insulin Affects Protein and Minerals Insulin helps amino acids from protein to enter cells. When this process is hindered, it can make it difficult to build muscle mass. Insulin also makes cells more receptive to potassium, magnesium, and phosphate. These substances are also known as electrolytes, which help conduct electricity within the body. They influence muscle function, blood pH, and the amount of water in your body. An electrolyte imbalance can be worsened by high blood sugar levels as this can cause excessive urination with water and electrolyte loss.

Normal and Impaired Insulin Function To break things down in an easy-to-remember format, this list illustrates what happens with normal and impaired insulin function. Normal function: Insulin transports glucose into cells to clear glucose from the bloodstream. Impaired function: Glucose is not cleared from the bloodstream. Normal function: Insulin helps convert glucose to glycogen (the storage form of glucose) in liver and muscle cells. Impaired function: Glucose is not easily stored as glycogen. Cells "starve," which can cause the body to behave as if there are starvation conditions and even cause cravings for sweet carbohydrates, although there are high levels of glucose in the body. Normal function: Insulin slows down the creation of glucose from non-carbohydrate sources, like protein in the liver. An example of this is when the liver releases glucose into the bloodstream when blood sugar levels are too low. Impaired function: The liver releases glucose into the bloodstream inappropriately even when blood sugar levels are high. Normal function: Insulin stops the breakdown of fat and stimulates the creation of fat under the right circumstances. Impaired function: High insulin levels can signal for less fat loss and more fat storage.

Normal function: Insulin regulates the formation of fat from simple sugars, which can eventually become triglycerides . Impaired function Triglycerides levels increase inappropriately. Normal function: Insulin stimulates protein synthesis (creation), which affects muscle growth. Impaired function: You may have difficulty building muscle. How to Help Insulin Work Better These strategies may help you increase insulin sensitivity and reduce insulin resistance: What is Insulin? - Important hormone allows your body to use sugar (glucose) What is Insulin? Written by Amy Hess-Fischl MS, RD, LDN, BC-ADM, CDE Insulin is a hormone made by the pancreas that allows your body to use sugar (glucose) from carbohydrates in the food that you eat for energy or to store glucose for future use. Insulin helps keeps your blood sugar level from getting too high ( hyperglycemia ) or too low (hypoglycemia). The cells in your body need sugar for energy. However, sugar cannot go into most of your cells directly. After you eat food and your blood sugar level rises, cells in your pancreas (known as beta cells) are signaled to release insulin into your bloodstream.

Insulin then attaches to and signals cells to absorb sugar from the bloodstream. Insulin is often described as a “key,” which unlocks the cell to allow sugar to enter the cell and be used for energy. After you eat, cells in your pancreas are signaled to release insulin into the bloodstream. If you have more sugar in your body than it needs, insulin helps store the sugar in your liver and releases it when your blood sugar level is low or if you need more sugar, such as in between meals or during physical activity. Therefore, insulin helps balance out blood sugar levels and keeps them in a normal range. As blood sugar levels rise, the pancreas secretes more insulin. If your body does not produce enough insulin or your cells are resistant to the effects of insulin, you may develop hyperglycemia (high blood sugar), which can cause long-term complications if the blood sugar levels stay elevated for long periods of time. Insulin Treatment for Diabetes People with type 1 diabetes cannot make insulin because the beta cells in their pancreas are damaged or destroyed. Therefore, these people will need insulin injections to allow their body to process glucose and avoid complications from hyperglycemia. People with type 2 diabetes do not respond well or are resistant to insulin.

They may need insulin shots to help them better process sugar and to prevent long-term complications from this disease. Persons with type 2 diabetes may first be treated with oral medications, along with diet and exercise. Since type 2 diabetes is a progressive condition, the longer someone has it, the more likely they will require insulin to maintain blood sugar levels. Various types of insulin are used to treat diabetes and include: Rapid-acting insulin: It starts working approximately 15 minutes after injection and peaks at approximately 1 hour but continues to work for two to four hours. This is usually taken before a meal and in addition to a long-acting insulin. Short-acting insulin: It starts working approximately 30 minutes after injection and peaks at approximately 2 to 3 hours but will continue to work for three to six hours. It is usually given before a meal and in addition to a long-acting insulin. Intermediate-acting insulin: It starts working approximately 2 to 4 hours after injection and peaks approximately 4 to 12 hours later and continues to work for 12-18 hours. It is usually taken twice a day and in addition to a rapid- or short-acting insulin.

Long-acting insulin: It starts working after several hours after injection and works for approximately 24 hours. If necessary, it is often used in combination with rapid- or short-acting insulin. Insulin can be given by a syringe, injection pen, or an insulin pump that delivers a continuous flow of insulin. Your doctor will work with you to figure out which type of insulin is best for you depending on whether you have type 1 or type 2 diabetes, your blood sugar levels,and your lifestyle. Endocrine System: Discover the Anatomy and Function of Glands Oxytocin Antidiuretic hormone (ADH) All of the releasing and inhibiting hormones affect the function of the anterior pituitary gland. TRH stimulates the anterior pituitary gland to release thyroid-stimulating hormone. GHRH and GHIH work to regulate the release of growth hormone—GHRH stimulates growth hormone release, GHIH inhibits its release. GnRH stimulates the release of follicle stimulating hormone and luteinizing hormone while CRH stimulates the release of adrenocorticotropic hormone.

The last two hormones—oxytocin and antidiuretic hormone—are produced by the hypothalamus and transported to the posterior pituitary, where they are stored and later released. Pituitary Gland The pituitary gland , also known as the hypophysis, is a small pea-sized lump of tissue connected to the inferior portion of the hypothalamus of the brain. Many blood vessels surround the pituitary gland to carry the hormones it releases throughout the body. Situated in a small depression in the sphenoid bone called the sella turcica, the pituitary gland is actually made of 2 completely separate structures: the posterior and anterior pituitary glands. Posterior Pituitary: The posterior pituitary gland is actually not glandular tissue at all, but nervous tissue instead. The posterior pituitary is a small extension of the hypothalamus through which the axons of some of the neurosecretory cells of the hypothalamus extend. These neurosecretory cells create 2 hormones in the hypothalamus that are stored and released by the posterior pituitary: Oxytocin triggers uterine contractions during childbirth and the release of milk during breastfeeding.

Antidiuretic hormone (ADH) prevents water loss in the body by increasing the re-uptake of water in the kidneys and reducing blood flow to sweat glands. Anterior Pituitary: The anterior pituitary gland is the true glandular part of the pituitary gland. The function of the anterior pituitary gland is controlled by the releasing and inhibiting hormones of the hypothalamus. The anterior pituitary produces 6 important hormones: Thyroid stimulating hormone (TSH), as its name suggests, is a tropic hormone responsible for the stimulation of the thyroid gland. Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex, the outer part of the adrenal gland, to produce its hormones. Follicle stimulating hormone (FSH) stimulates the follicle cells of the gonads to produce gametes—ova in females and sperm in males. Luteinizing hormone (LH) stimulates the gonads to produce the sex hormones—estrogens in females and testosterone in males. Human growth hormone (HGH) affects many target cells throughout the body by stimulating their growth, repair, and reproduction.

Prolactin (PRL) has many effects on the body, chief of which is that it stimulates the mammary glands of the breast to produce milk. Pineal Gland The pineal gland is a small pinecone-shaped mass of glandular tissue found just posterior to the thalamus of the brain. The pineal gland produces the hormone melatonin that helps to regulate the human sleep-wake cycle known as the circadian rhythm. The activity of the pineal gland is inhibited by stimulation from the photoreceptors of the retina. This light sensitivity causes melatonin to be produced only in low light or darkness. Increased melatonin production causes humans to feel drowsy at nighttime when the pineal gland is active. Thyroid Gland The thyroid gland is a butterfly-shaped gland located at the base of the neck and wrapped around the lateral sides of the trachea. The thyroid gland produces 3 major hormones: Calcitonin Triiodothyronine (T3) Thyroxine (T4) Calcitonin is released when calcium ion levels in the blood rise above a certain set point. Calcitonin functions to reduce the concentration of calcium ions in the blood by aiding the absorption of calcium into the matrix of bones.

The hormones T3 and T4 work together to regulate the body’s metabolic rate. Increased levels of T3 and T4 lead to increased cellular activity and energy usage in the body. Parathyroid Glands The parathyroid glands are 4 small masses of glandular tissue found on the posterior side of the thyroid gland. The parathyroid glands produce the hormone parathyroid hormone (PTH), which is involved in calcium ion homeostasis. PTH is released from the parathyroid glands when calcium ion levels in the blood drop below a set point. PTH stimulates the osteoclasts to break down the calcium containing bone matrix to release free calcium ions into the bloodstream. PTH also triggers the kidneys to return calcium ions filtered out of the blood back to the bloodstream so that it is conserved. Adrenal Glands The adrenal glands are a pair of roughly triangular glands found immediately superior to the kidneys. The adrenal glands are each made of 2 distinct layers, each with their own unique functions: the outer adrenal cortex and inner adrenal medulla. Adrenal cortex: The adrenal cortex produces many cortical hormones in 3 classes: glucocorticoids, mineralocorticoids, and androgens.

Glucocorticoids have many diverse functions, including the breakdown of proteins and lipids to produce glucose. Glucocorticoids also function to reduce inflammation and immune response. Mineralocorticoids, as their name suggests, are a group of hormones that help to regulate the concentration of mineral ions in the body. Androgens, such as testosterone, are produced at low levels in the adrenal cortex to regulate the growth and activity of cells that are receptive to male hormones. In adult males, the amount of androgens produced by the testes is many times greater than the amount produced by the adrenal cortex, leading to the appearance of male secondary sex characteristics. Adrenal medulla: The adrenal medulla produces the hormones epinephrine and norepinephrine under stimulation by the sympathetic division of the autonomic nervous system. Both of these hormones help to increase the flow of blood to the brain and muscles to improve the “fight-or-flight” response to stress. These hormones also work to increase heart rate, breathing rate, and blood pressure while decreasing the flow of blood to and function of organs that are not involved in responding to emergencies. Pancreas The pancreas is a large gland located in the abdominal cavity just inferior and posterior to the stomach .

The pancreas is considered to be a heterocrine gland as it contains both endocrine and exocrine tissue. The endocrine cells of the pancreas make up just about 1% of the total mass of the pancreas and are found in small groups throughout the pancreas called islets of Langerhans. Within these islets are 2 types of cells—alpha and beta cells. The alpha cells produce the hormone glucagon, which is responsible for raising blood glucose levels. Glucagon triggers muscle and liver cells to break down the polysaccharide glycogen to release glucose into the bloodstream. The beta cells produce the hormone insulin, which is responsible for lowering blood glucose levels after a meal. Insulin triggers the absorption of glucose from the blood into cells, where it is added to glycogen molecules for storage. Gonads The gonads—ovaries in females and testes in males—are responsible for producing the sex hormones of the body. These sex hormones determine the secondary sex characteristics of adult females and adult males. Testes: The testes are a pair of ellipsoid organs found in the scrotum of males that produce the androgen testosterone in males after the start of puberty.

Testosterone has effects on many parts of the body, including the muscles, bones, sex organs, and hair follicles. This hormone causes growth and increases in strength of the bones and muscles, including the accelerated growth of long bones during adolescence. During puberty, testosterone controls the growth and development of the sex organs and body hair of males, including pubic, chest, and facial hair. In men who have inherited genes for baldness testosterone triggers the onset of androgenic alopecia, commonly known as male pattern baldness. Ovaries: The ovaries are a pair of almond-shaped glands located in the pelvic body cavity lateral and superior to the uterus in females. The ovaries produce the female sex hormones progesterone and estrogens. Progesterone is most active in females during ovulation and pregnancy where it maintains appropriate conditions in the human body to support a developing fetus. Estrogens are a group of related hormones that function as the primary female sex hormones. The release of estrogen during puberty triggers the development of female secondary sex characteristics such as uterine development, breast development, and the growth of pubic hair. Estrogen also triggers the increased growth of bones during adolescence that lead to adult height and proportions.

Thymus The thymus is a soft, triangular-shaped organ found in the chest posterior to the sternum. The thymus produces hormones called thymosins that help to train and develop T-lymphocytes during fetal development and childhood. The T-lymphocytes produced in the thymus go on to protect the body from pathogens throughout a person’s entire life. The thymus becomes inactive during puberty and is slowly replaced by adipose tissue throughout a person’s life. Other Hormone Producing Organs In addition to the glands of the endocrine system, many other non-glandular organs and tissues in the body produce hormones as well. Heart: The cardiac muscle tissue of the heart is capable of producing the hormone atrial natriuretic peptide (ANP) in response to high blood pressure levels. ANP works to reduce blood pressure by triggering vasodilation to provide more space for the blood to travel through. ANP also reduces blood volume and pressure by causing water and salt to be excreted out of the blood by the kidneys. Kidneys: The kidneys produce the hormone erythropoietin (EPO) in response to low levels of oxygen in the blood.

EPO released by the kidneys travels to the red bone marrow where it stimulates an increased production of red blood cells. The number of red blood cells increases the oxygen carrying capacity of the blood, eventually ending the production of EPO. Digestive System: The hormones cholecystokinin (CCK), secretin, and gastrin are all produced by the organs of the gastrointestinal tract. CCK, secretin, and gastrin all help to regulate the secretion of pancreatic juice, bile, and gastric juice in response to the presence of food in the stomach. CCK is also instrumental in the sensation of satiety or “fullness” after eating a meal. Adipose: Adipose tissue produces the hormone leptin that is involved in the management of appetite and energy usage by the body. Leptin is produced at levels relative to the amount of adipose tissue in the body, allowing the brain to monitor the body’s energy storage condition. When the body contains a sufficient level of adipose for energy storage, the level of leptin in the blood tells the brain that the body is not starving and may work normally.

If the level of adipose or leptin decreases below a certain threshold, the body enters starvation mode and attempts to conserve energy through increased hunger and food intake and decreased energy usage. Adipose tissue also produces very low levels of estrogens in both men and women. In obese people the large volume of adipose tissue may lead to abnormal estrogen levels. Placenta: In pregnant women, the placenta produces several hormones that help to maintain pregnancy. Progesterone is produced to relax the uterus, protect the fetus from the mother’s immune system , and prevent premature delivery of the fetus. Human chorionic gonadotropin (HCG) assists progesterone by signaling the ovaries to maintain the production of estrogen and progesterone throughout pregnancy. Local Hormones: Prostaglandins and leukotrienes are produced by every tissue in the body (except for blood tissue) in response to damaging stimuli. These two hormones mainly affect the cells that are local to the source of damage, leaving the rest of the body free to function normally. Prostaglandins cause swelling, inflammation, increased pain sensitivity, and increased local body temperature to help block damaged regions of the body from infection or further damage.

They act as the body’s natural bandages to keep pathogens out and swell around damaged joints like a natural cast to limit movement. Leukotrienes help the body heal after prostaglandins have taken effect by reducing inflammation while helping white blood cells to move into the region to clean up pathogens and damaged tissues. Physiology of the Endocrine System Endocrine System vs. Nervous System Function The endocrine system works alongside of the nervous system to form the control systems of the body. The nervous system provides a very fast and narrowly targeted system to turn on specific glands and muscles throughout the body. The endocrine system, on the other hand, is much slower acting, but has very widespread, long lasting, and powerful effects. Hormones are distributed by glands through the bloodstream to the entire body, affecting any cell with a receptor for a particular hormone. Most hormones affect cells in several organs or throughout the entire body, leading to many diverse and powerful responses. Hormone Properties Once hormones have been produced by glands, they are distributed through the body via the bloodstream. As hormones travel through the body, they pass through cells or along the plasma membranes of cells until they encounter a receptor for that particular hormone.

Hormones can only affect target cells that have the appropriate receptors. This property of hormones is known as specificity. Hormone specificity explains how each hormone can have specific effects in widespread parts of the body. Many hormones produced by the endocrine system are classified as tropic hormones. A tropic hormone is a hormone that is able to trigger the release of another hormone in another gland. Tropic hormones provide a pathway of control for hormone production as well as a way for glands to be controlled in distant regions of the body. Many of the hormones produced by the pituitary gland, such as TSH, ACTH, and FSH are tropic hormones. Hormonal Regulation The levels of hormones in the body can be regulated by several factors. The nervous system can control hormone levels through the action of the hypothalamus and its releasing and inhibiting hormones. For example, TRH produced by the hypothalamus stimulates the anterior pituitary to produce TSH. Tropic hormones provide another level of control for the release of hormones. For example, TSH is a tropic hormone that stimulates the thyroid gland to produce T3 and T4. Nutrition can also control the levels of hormones in the body.

For example, the thyroid hormones T3 and T4 require 3 or 4 iodine atoms, respectively, to be produced. In people lacking iodine in their diet, they will fail to produce sufficient levels of thyroid hormones to maintain a healthy metabolic rate. Finally, the number of receptors present in cells can be varied by cells in response to hormones. Cells that are exposed to high levels of hormones for extended periods of time can begin to reduce the number of receptors that they produce, leading to reduced hormonal control of the cell. Classes of Hormones Hormones are classified into 2 categories depending on their chemical make-up and solubility: water-soluble and lipid-soluble hormones. Each of these classes of hormones has specific mechanisms for their function that dictate how they affect their target cells. Water-soluble hormones: Water-soluble hormones include the peptide and amino-acid hormones such as insulin, epinephrine, HGH, and oxytocin. As their name indicates, these hormones are soluble in water. Water-soluble hormones are unable to pass through the phospholipid bilayer of the plasma membrane and are therefore dependent upon receptor molecules on the surface of cells.

When a water-soluble hormone binds to a receptor molecule on the surface of a cell, it triggers a reaction inside of the cell. This reaction may change a factor inside of the cell such as the permeability of the membrane or the activation of another molecule. A common reaction is to cause molecules of cyclic adenosine monophosphate (cAMP) to be synthesized from adenosine triphosphate (ATP) present in the cell. cAMP acts as a second messenger within the cell where it binds to a second receptor to change the function of the cell’s physiology. Lipid-soluble hormones: Lipid-soluble hormones include the steroid hormones such as testosterone, estrogens, glucocorticoids, and mineralocorticoids. Because they are soluble in lipids, these hormones are able to pass directly through the phospholipid bilayer of the plasma membrane and bind directly to receptors inside the cell nucleus. Lipid-soluble hormones are able to directly control the function of a cell from these receptors, often triggering the transcription of particular genes in the DNA to produce "messenger RNAs (mRNAs)" that are used to make proteins that affect the cell’s growth and function.

Prepared by Tim Taylor, Anatomy and Physiology Instructor What organ produces insulin? | Reference.com What organ produces insulin? A: Quick Answer The pancreas is the organ responsible for producing insulin in the human body. The pancreas is located near the midsection of the body by the stomach. Full Answer Insulin is an important hormone that the body produces in order to remove glucose from the bloodstream and transport it to the muscles. When insulin levels are high, this also prevents the release of stored fat, while also promoting storage of the lipids in the bloodstream. If the pancreas cannot create insulin as needed, a person has a condition known as diabetes. This means that they can no longer regulate their blood sugar properly, which can lead to significant health issues like cardiovascular disease. Understanding Our Bodies: Insulin | Nutrition Wonderland Understanding Our Bodies Featured , Health & Disease , Understanding Our Bodies Almost everyone has heard of Insulin. You probably know that people with type 1 diabetes need to inject themselves with insulin to survive, and must constantly monitor the amount of sugar they eat. But what do you really know about insulin? What is its purpose in the body, and why do we need it? How does it relate to our diets? What happens when things go wrong with it?

And why should anyone who doesn’t have diabetes give a hoot? Insulin is one of the most important hormones in the human body, and yet most people don’t really understand why our bodies make it or how what we eat affects the levels of insulin we produce. More so than any other hormone, our diet is key in regulating insulin levels, and thus a number of biological processes. As you’ll soon see, everyone should think about how what they eat impacts their body’s insulin release to be at their happiest and healthiest. Why We Need Insulin Every living thing requires energy to survive. In cells, energy is stored and shuttled around using a molecule called Adenosine Tri-Phosphate, or ATP. Whenever the cell then has an energy-requiring reaction, enzymes can use the energy stored in ATP’s phosphate bonds to fuel it. Cells rely on ATP to survive, and to create ATP, they rely on glucose. ATP - the fuel for life All cells, from bacteria and fungi to us, take glucose and use it to generate ATP by a process called Oxidative Phosphorylation. First, glucose is converted to an intermediate molecule called pyruvate via a process called glycolosis.

As long as there is oxygen around, this pyruvate is further converted to Acetyl CoA, which enters a cycle of reactions called the Citric Acid Cycle. This takes the carbon to carbon bonds and uses them to create high energy electrons, which are then passed down a chain of enzymes which use the electron’s energy to create a proton gradient, the force of which fuels ATP synthase, the enzyme which creates ATP from ADP. Without glucose, cells cannot create ATP, and eventually die. In plants, a process called photosynthesis takes light energy from the sun and uses it to combine carbon dioxide (CO2) and water (H2O) to create glucose (C6H12O6). This means that to survive, all they need is light, air and water. Unlike plants, though, we cannot create our own glucose, so we rely on our diets to provide it for us. Just about everything we eat is able to be used to create glucose. Carbohydrates, by definition, are sugars, and all sugars are readily converted to glucose. The amino acids that make up proteins can be converted to glucose via an enzymatic process called gluconeogenesis.

Fats, too, are converted to glucose or its derivatives; glycerol, for example, can be converted to glucose via gluconeogenesis, and fatty acids can be converted to Acetyl CoA via beta oxidation. No matter where it comes from, the glucose from our meals then ends up in our blood to travel around our bodies to the tissues that need it. Obviously, having a blood glucose level that is too low would be bad – not enough glucose will get to our various tissues, and our cells won’t be able to generate enough ATP to function. This is a condition known as hypoglycemia, and the effects can range from mildly ‘feeling bad’ to seizures, unconsciousness, permanent brain damage or even death, all of which are due to a lack of ATP. But you can tip the scale too far in the other direction, too. You would think that since it’s so important, we would want a ton of glucose in our blood, but too much causes our blood to thicken, slowing it down and drawing fluid from our tissues to try and make it thin again.

Too high of a blood glucose level, called hyperglycemia, can result in blurred vision, fatigue, dry mouth and heart problems that can sometimes be fatal. So our bodies work very hard to maintain our blood glucose levels between 3.6 and 5.8 mM (mmols/liter). This is about enough glucose to provide energy to the body for 20-30 minutes, so as we use up the glucose in our blood, our bodies constantly release more (hopefully) without overdoing it. It’s particularly important for our bodies to maintain glucose levels every time we eat. Whenever we ingest food, our bodies have to quickly adjust to the sudden flood of glucose entering our systems as our meals are digested. Take something as small as a roll of Smarties, for example. One roll of Smarties contains 6 grams of sugar. At around 125 lbs, my body contains an average of 4 liters of blood. This means that if all the sugar from a single roll of those delicious candies were to enter my bloodstream at once and remain unchecked, it would raise by blood sugar by 8 mM! Four smarties packs, and my blood sugar levels would be fatal.

So why, then, when I enjoy a sugary treat, do I not go into severe hyperglycemia? The answer is insulin. Our bodies release insulin right before and during eating, and that insulin tells our bodies to start taking glucose out of the blood, thus lowering our blood glucose levels. It does this by both promoting uptake of glucose by cells and the storage of glucose within our cells. Without insulin, we would all go into hyperglycemic shock and die from something as common as a hamburger. What is Insulin? Insulin is a relatively small peptide hormone produced by β-cells in the pancreas. It’s main job is to signal the liver, muscle and fat tissues to take up glucose from the blood and store it as glycogen. As the glucose level in the blood drops to normal, insulin release slows or stops. If it drops too low, an antagonistic hormone, called glucagon, is released which does the opposite of insulin, stimulating cells to break down glycogen and release glucose. The insulin and glucose process illustrated But insulin does much more than just control blood glucose levels. Its effects depend on the cell type that receives its signal. Fat cells, for example, don’t take up or store glucose.

Instead, they respond to insulin by taking the fats that enter the blood stream and turning them into fatty acids, which they store in large vacuoles. Thus insulin promotes the uptake and storage of fat in our adipose tissues. While insulin levels are high, our bodies don’t digest or use fats for fuel. Instead, we rely on the glucose in our blood and tissues. This is key to keep in mind when trying to lose weight – you body simply won’t break down and use your fat reserves with insulin around. Furthermore, insulin stimulates the body to absorb most amino acids. However, it doesn’t lead to intake of tryptophan by cells. This creates an effective rise in tryptophan concentration in the blood, allowing it to pass through the blood brain barrier. In the brain, tryptophan is converted to serotonin, a neurotransmitter whose primary purpose, in this case, is to reduce appetite. But serotonin has a lot of other effects, as those of you who have read the previous Understanding Our Bodies on Serotonin know well. In general, increased serotonin leads to a feeling of happiness and calm, which is why we get such satisfaction when we eat.

Thus insulin is important not just when it comes to dealing with fats and sugars but in regulating our emotions, too! It turns out insulin in the brain has a lot of functions, very few of which we understand well. Mice that lack insulin and leptin receptors in their brains, however, exhibit insulin resistance that is characteristic of diabetes . Strangely, though, they have a lot of reproductive deficiencies, too – the females have poor fertility, high testosterone levels and deformed ovaries, for example. Why insulin has these effects on reproduction is unknown, but it just goes to show that insulin does a lot more than regulate blood sugar levels, and is far more important in our bodies than we once thought. Regulating Insulin While insulin levels are mostly regulated by the amount of glucose in our blood, other things can stimulate its release. Other molecules from digestion, like certain amino acids, proteins and lipids, can similarly stimulate insulin release. But most incredibly, our bodies begin releasing insulin before we even take a single bite of food. When we think about, smell, or slightly taste foods, our brains trigger what is called Cephalic Phase Insulin Release.

A food’s color, appearance, flavor, aroma, and texture can all impact how our brains respond to the idea of eating it. The goal is to prepare the body for what the brain thinks will be a sudden flood of glucose. The sweeter and sugarier the brain thinks the meal will be, the more insulin it stimulates the pancreas to release before the food even enters the mouth. Merely waiting in line for food can ramp up the body's insulin system - credit, flickr -Eleets121 Once we start to eat, our bodies ramp up insulin secretion, in what is often called first phase insulin release. Insulin that was kept in storage while our blood glucose levels were normal is released all at once, leading to a dramatic increase in insulin levels. The amount of insulin secreted in the first phase response to a meal is determined by the amount of glucose encountered in the previous meal – the more you needed last time, the more is released in this first phase. In a healthy person, this first phase response peaks a few minutes after you’ve started your a meal. The β-cells then take a quick pause. If the first pulse was enough, then they slowly take up the insulin they released, and store it for the next meal.

If the blood glucose levels stay high, though, the β-cells begin producing and releasing insulin in pulses every ten to twenty minutes. They continue this until the body’s blood glucose gets back to normal levels. The blood sugar rise caused by the meal peaks about half an hour after eating, and this, in turn, leads to a decrease in insulin production and release. There are other regulators of release of insulin, too. Stress hormones like noradrenaline inhibit insulin release. This makes sense when you think about it evolutionarily. The purpose of stress hormones is to prepare our bodies for a sudden need to act. If we see a tiger, for example, our stress hormones spike so we can be prepared to fight if it attacks or run like hell to get away. Either way, we’ll need extra energy on hand to deal with the stressful situation, so stress hormones stop insulin from being released to ensure that a little extra glucose is in the bloodstream and able to reach whatever body parts need it most. Not all insulin is produced in the pancreas, though. The brain also produces its own supply of insulin. The brain is a complex organ and needs lots of fuel to run properly. Insulin in the brain enhances learning and memory.

Meanwhile, reduced levels of insulin and its related proteins are linked to Alzheimer’s disease and other degenerative disorders. Insulin and Disease Insulin is at the heart of many diseases. As I just explained, insulin in the brain is particularly key, and can lead to neurological disorders. But too much or too little insulin in the body is a big problem, too. There is a special name for the series of diseases caused by impaired insulin signaling in the body. You might have heard of it: Diabetes Mellitus. When your body stops producing insulin, injections are all that is left - credit, i5a, flickr Diabetes occurs when the body does not have the insulin signaling it should. There are two major types: type 1 and type 2. People with type 1 diabetes tend to realize their condition early in life, and must deal with it throughout their lifetime, while those with type 2 tend to develop symptoms later on. What’s the difference? While both conditions involve problems with the insulin pathway, type 1 diabetes is caused by a lack of insulin, while type 2 is caused by chronically high levels. People with type 1 diabetes have innately low levels of insulin due to genetic mutations.

Without the ability to produce enough of this vital hormone, they usually have consistently high blood glucose levels. While this is a problem, there are many forms of treatment, including insulin injections. By carefully controlling their sugar intake and taking insulin when they need it, people with type 1 diabetes can regulate their blood glucose levels to being almost normal. Type 2 diabetes is different. Type 2 diabetes results from the body having high insulin levels for too long. Insulin is meant to be a fast acting hormone – you release it when glucose levels are high, so that they drop. Then the signal stops. If you constantly eat too much or have a very sugary diet, you can end up with high insulin levels all the time. This leads to the body becoming desensitized to insulin. It’s kind of like trying to listen to a radio with static. If you only get a little static every once in a while, you can hear the song fine, and understand what the artist is saying. But start having high static all the time and you can’t tell what song is playing anymore. Your body, in effect, can’t tell what signal it’s supposed to be getting, and instead stops listening all together.

Type 2 diabetes is that much more dangerous because the body will rarely respond to insulin treatment, meaning that drastic diet changes and exercise are the only ways to fight back. Sadly, more than 90% of diabetes cases are type 2. Prevalence rates of type 2 diabetes doubled between 1990 and 2005, causing the CDC to declare it an epidemic . Insulin is also a key player in Metabolic Syndrome. Metabolic syndrome, often called prediabetes, is poorly characterized, and even more poorly understood. Symptoms include elevated blood pressure, high blood cholesterol, and increased waist circumference. The main cause appears to be decreased response to insulin in certain tissues, specifically muscle and fat. The thing is, we’re not sure if it’s treatable or an irreversible first step in Type 2 diabetes. Often, people with metabolic syndrome are overweight, and at higher risk for other, even more life threatening conditions like heart disease. While some drugs can be prescribed to treat the symptoms like high blood pressure, the only long-term solution is to lower chronic blood glucose levels and restore insulin sensitivity, if, indeed, it can be restored at that point.

Nutrition and Insulin: Glycemic Indexes, Glycemic Loads and Beyond Everyone should think about insulin and blood glucose levels, not just people with diabetes or metabolic syndrome. What we eat, how much of it, and when can impact our insulin release, which in turn can have a big impact on our bodies and how we feel. Refined carbohydrates like spaghetti can exacerbate blood sugar issues - credit, flickr, Bxl06 The major dietary players in insulin regulation are carbohydrates. While fats, proteins and everything else can increase blood glucose levels, carbohydrates do it much faster for two simple reasons: firstly, they’re one of the first things we break down in digestion. There are enzymes in our saliva that begin carbohydrate breakdown before the foods even reach our stomachs! But more importantly, carbohydrates lead to immediate rises in blood glucose because they contain glucose. Other molecules must first be converted to glucose, but carbohydrates, which include sugars, just need to be hacked into pieces by our digestive enzymes. Different carbohydrates contain different amounts of the monosaccharides, like glucose or fructose. Thus they each have different impacts on immediate rises in blood glucose levels.

This difference in effect on blood sugar level is the basis of the Glycemic Index, or GI. The glycemic index rates foods based on how much of an immediate impact they have on blood glucose per 50 grams of carbohydrate. If you picture the rise in blood glucose levels in response to a food on a graph over time, the glycemic index is a number that is related directly the area under a two-hour curve. The higher the spike in blood glucose levels, the larger the area under the curve is, and thus the higher the glycemic index, which is somewhere on a scale of 1 (low) to 100 (high). Most foods that have a low GI induce lower spikes in insulin, but not all of them. There is another index, called the Insulin Index, that looks directly at rises in insulin levels. While the glucose and insulin scores of most foods are related, high-protein foods and baked goods that are rich in fat and refined carbohydrates usually elicit much higher insulin responses than their glycemic index values would suggest. Research into the glycemic index have found strong support of the idea that low GI foods are better for us.

People who eat less high GI foods have lower risks of developing both type 2 diabetes and heart disease. It’s uncertain if this is due to overall lower blood sugar levels or reduced glycemic “spikes.” When glucose levels increase dramatically, our bodies ramp up the release of insulin and the processing of glucose from the blood, including ATP generation. While ATP is great, the process by which we make it – oxidative phosphorylation – has side effects. Mainly, the faster it’s churning, the more likely the machinery is to leak reactive oxygen species (ROS). These oxygen radicals are highly reactive and tend to transform whatever they come in contact with, which can cause damage to proteins, membranes, or even our DNA. By eating foods that increase glucose levels more slowly, we limit ROS bursts that can damage our cells. The glycemic impact of foods can be strikingly different for your body However, the glycemic index isn’t perfect. Glycemic indices aren’t the whole story since they are based on a per-carbohydrate basis. Two foods that have the same GI can have dramatically different effects on blood glucose per serving if one has significantly higher carbohydrate content than the other.

The affect a serving of food has on blood glucose is referred instead to its Glycemic Load. Glycemic load is calculated by multiplying the weight (in grams) of carboydrate in a serving by the food’s overall GI and divided by 100. A GL of 10 or less is considered low, while 20 or more is considered high. Let’s say you want to eat a baguette, for example. Both whole gain and French baguettes have similar GIs (roughly 73). But there’s a lot less carbohydrates per serving in the whole gain loaf, and thus its GL is only 9 while the GL of the french baguette is 27! The GI or GL of a food isn’t the only thing you should consider when it comes to insulin and your diet. When you eat matters a lot, too. Our bodies react to the same foods differently at different times of day. Morning is a special time for your body because you’ve just spent a while in a comatose state. The changes your body undergoes while you sleep can have a dramatic impact on how it responds to food.

Insulin levels tend to be low in the early morning, for example, because your body releases stress hormones just before you wake up. Once you’re awake, though, your body ramps up insulin secretion to metabolize the high glucose levels and give your cells a little fuel to start the day with. These alterations have a big impact on how our diets affect us. When different foods were tested for their GI values at different times of the day, for example, researchers found that the same food eaten for lunch instead of breakfast induced a lower glucose response . This is why it may be particularly important to eat a protein-rich breakfast, like eggs, instead of high glycemic foods like white bread toast. Time of day has been found to have a larger effect on insulin responses in women than in men, though no one understands why. Furthermore, studies have shown that the quality of sleep you get affects how strongly your body reacts to food. A restless night can lead to higher glucose responses and larger spikes in insulin in response to food in the morning . So getting a good night’s sleep is also important in preventing the kinds of spikes which may be a major factor in type 2 diabetes. Also, foods can interact with each other to lower or raise the GI values of a meal.

For example, foods that contain fiber, protein, or fat will generally reduce the GI of the meal as a whole. Recent studies have even shown that having a small volume of alcohol (one drink) prior to a meal reduces the GI of the meal by 16-37% – which, as far as I’m concerned, is fantastic news. Furthermore, many cultures eat high GI foods like potatoes or rices but have low occurrences of diabetes and obesity. The truth is we have yet to tease out all the factors that lead to these conditions, and the GI level of our diets is likely only one of many related factors. The Even Bigger Picture Clearly, what we eat, with what and when matters a lot when it comes to insulin levels. This is important in keeping healthy and reducing the risk of metabolic syndrome and type 2 diabetes. But insulin affects so many other things in our bodies, from amino acid uptake to fat storage. We need to consider insulin whether we’re worried about type 2 diabetes or not! Thinking about how our diet affects insulin is especially key when trying to lose weight or maintain a healthy weight. Insulin actually triggers the storage of fats in adipose tissues, so sustained high levels of insulin promote weight gain!

Furthermore, recall that our bodies don’t break down fat while insulin is circulating. This means that if we eat foods with high GIs that produce sustained insulin levels, we’re shooting ourselves in the foot, even if we eat less calories overall. Understanding how our bodies regulate insulin release also explains why certain foods are worse for us than we’d expect. Sugary drinks are particularly bad for us, for example, even when we take into account their calorie and sugar content. This is because our brains don’t judge their sugar content well in advance. Thousands of years of evolution led our brains to believe that drinks, overall, were low-cal things that mostly contain water. Our brains aren’t wired to think that fluids contain a lot of sugar. Thus when we look at a soda or even begin to sip one, we don’t have the same level of cephalic phase insulin release or first phase insulin release that we would for a solid treat. The end result of this is that our bodies are unprepared for the sudden sugar rush, and have to instead release a massive amount of insulin all at once to deal with what it considers an inexplicable rise in blood glucose.

High spikes in insulin lead to dramatic drops in blood glucose, which can cause your body to feel hungry sooner. Eating low GI and GL foods can help you lose weight by making you feeling fuller longer. Low GI foods don’t cause dramatic drops in glucose levels, thus you tend eat less throughout the day. It’s thought that this effect, on top of the high-sensitivity of our bodies to high GI foods in the AM, is why eating eggs, a low GI food, instead of cereal or toast in the morning has been found to reduce overall food intake for the day by as much as 18% . You can create lower spikes in insulin not only by avoiding sugary drinks and eating lower GL foods but also by eating smaller meals. This is because the amount of first phase insulin release is dependent on the amount of insulin needed for the previous meal. The bigger meals are, the larger the spike at the beginning of every meal, and the bigger the drop in glucose afterward. But you shouldn’t just cut out everything that leads to insulin release! Insulin is important, and too little is just as bad as too much. Even small drops in daily insulin levels can affect us negatively.

For example, dieters often experience depression around 2 weeks after they begin cutting high-glycemic foods like carbohydrates out of their diet. Why? Because they have much lower levels of insulin than they did before. Decreased insulin means decreased amino acid uptake, and because the level of other amino acids affects how well tryptophan crosses the blood brain barrier, decreased insulin means less serotonin which leads to, in layman’s terms, feeling like crap. While you should monitor the GI of your meals to reduce insulin spikes, you shouldn’t go for rock bottom either. At least you shouldn’t if you want to be happy about it! Previous posts in the Understanding Our Bodies series: BBC Science & Nature - Human Body and Mind - Organ Layer Location: Behind the stomach and level with the top of the small intestine Physical description: Pistol-shaped Function: Secreting digestive enzymes and hormones that control blood sugar levels Digestion When you eat, your pancreas releases digestive juices through a duct into your duodenum - the first part of your small intestine. This fluid is rich in enzymes that break down fats, proteins and carbohydrates. It also contains sodium bicarbonate which neutralises acid in your stomach.

Blood sugar levels Your pancreas produces insulin and glucagon, two hormones that regulate sugar levels in your blood. Insulin and glucagon are secreted from your pancreas directly into your blood. When the concentration of glucose (a sugar) rises in your blood, insulin is released. Insulin lowers blood glucose levels by stimulating cells throughout your body to use and store glucose. Glucagon has the opposite effect of insulin. It triggers the release of stored sugars, increasing the concentration of glucose in your blood. Glucagon acts as a control mechanism whenever your body produces too much insulin. Can you live without your pancreas? It is possible to live without your pancreas provided you take insulin to regulate blood sugar concentration and pancreatic enzyme supplements to aid digestion. 11 Effects of Insulin on the Body insulin on the Body Insulin is a hormone produced by the pancreas. Its function is to allow other cells to transform glucose into energy throughout your body. Without insulin, cells are starved for energy and must seek an alternate source. This can lead to life-threatening complications. People with diabetes can inject insulin into the abdomen, upper arms, thighs, or buttocks. Read more. An insulin pump placed under the skin of the abdomen can take the place of frequent injections.

Read more. Your pancreas produces insulin and releases it into the bloodstream when you eat. Insulin therapy can step in for a nonfunctioning pancreas. Read more. Insulin is vital to your body’s ability to create energy from glucose and to distribute it to cells throughout your body. Read more. Insulin tells the liver to take excess glucose from the bloodstream and store it for later use. Read more. Insulin directs muscles and fat cells to store extra glucose so it won’t overload your bloodstream. Read more. Too much or too little glucose in your bloodstream is dangerous. It can even be life threatening. Insulin helps keep glucose within a healthy range. Read more. Insulin helps to distribute energy to cells throughout your body, including your central nervous system and cardiovascular system, so they can function properly. Read more. Cells in every part of your body need energy to function and to remain healthy. Without insulin, cells become starved for energy and seek it elsewhere, which can lead to dangerous complications. Read more. Insulin uses your bloodstream as a transportation route to cells all around your body. A blood test can reveal blood sugar levels that are too high or too low. Read more. Insulin helps you use glucose for energy.

Without it, your body begins to burn fat, which may cause high levels of toxic ketones. High levels of ketones can be detected in urine. Read more. Insulin Injection Sites In the Bloodstream The Effects of Insulin on the Body Insulin is a natural hormone produced in the pancreas. When you eat, your pancreas releases insulin to help your body make energy out of sugars (glucose). It also helps you store energy. Insulin is a vital part of metabolism. Without it, your body would cease to function. In type 1 diabetes, the pancreas is no longer able to produce insulin. In Type 2 diabetes, the pancreas initially produces insulin, but the cells of your body are unable to make good use of the insulin (insulin resistance). Uncontrolled diabetes allows glucose to build up in the blood rather than being distributed to cells or stored. This can wreak havoc with virtually every part of your body. Complications of diabetes include kidney disease, nerve damage, eye problems, and stomach problems. People with Type 1 diabetes need insulin therapy to live. Some people with Type 2 diabetes must also take insulin therapy to control blood sugar levels and avoid complications.

Insulin is usually injected into the abdomen, but it can also be injected into the upper arms, thighs, or buttocks. Injection sites should be rotated within the same general location. Frequent injections in the same spot can cause fatty deposits that make delivery of insulin more difficult. Some people use a pump, which delivers insulin through a catheter placed underneath the skin of the abdomen. Endocrine, Excretory, and Digestive Systems When you eat, food travels to your stomach and small intestines where it is broken down into nutrients. The nutrients are absorbed and distributed via your bloodstream. The pancreas is an organ located in your abdomen between your stomach and your spine. This integral component of your digestive system produces insulin and releases it into the bloodstream when you eat. Insulin is an important part of metabolism and necessary for turning glucose into energy and distributing it to cells all throughout your body. Insulin helps the liver, muscle, and fat cells to store the glucose you don’t need right away, so it can be used for energy later. In turn, the liver produces less glucose on its own. This keeps your blood glucose levels in check. The liver releases small amounts of glucose into your bloodstream between meals to keep your blood sugars within that healthy range.

Circulatory System When insulin enters your bloodstream, it helps cells throughout your body — including in your central nervous system and cardiovascular system — to absorb glucose. It’s the circulatory system’s job to deliver insulin. As long as the pancreas produces enough insulin and your body can use it properly, blood sugar levels will be kept within a healthy range. A buildup of glucose in the blood (hyperglycemia) can cause complications like nerve damage (neuropathy), kidney damage, and eye problems. Symptoms of high blood glucose include excessive thirst and frequent urination. Too little glucose in the blood (hypoglycemia) can make you feel irritable, tired, or confused. Low blood sugar can lead to loss of consciousness. When you don’t have enough insulin, your body’s cells begin to starve. Because the cells can’t use the glucose, they begin to break down fat for energy. In addition to a buildup of glucose in your blood, this process creates a dangerous buildup of chemicals called ketones. Symptoms include sweet-smelling breath, dry mouth, nausea, and vomiting. Your body tries to get rid of the ketones through your urine, but sometimes it can’t keep up.

This causes a life-threatening condition called ketoacidosis. If you have diabetes, insulin therapy can do the job your pancreas can’t. Rapid-acting insulin reaches the bloodstream within 15 minutes and keeps working for up to four hours. Short-acting insulin enters the bloodstream within 30 minutes and works for up to six hours. Intermediate-acting insulin finds its way into your bloodstream within two to four hours and is effective for about 18 hours. Long-acting insulin starts working within a few hours and keeps glucose levels even for about 24 hours. Blood tests can quickly indicate whether your glucose levels are too high or too low. Recommended for You Insulin 101: Everything You Need to Know From its natural role in the body to types of insulin therapy, we give you the facts you need. Insulin's role in the human body Insulin's role in the human body By Yolanda Smith , BPharm Insulin is a hormone produced by the pancreas that has a number of important functions in the human body, particularly in the control of blood glucose levels and preventing hyperglycemia.

It also has an effect on several other areas of the body, including the synthesis of lipids and regulation of enzymatic activity. Image Copyright: Designua, Image ID: 283557914 via Shutterstock.com Insulin and Metabolic Processes The most important role of insulin in the human body is its interaction with glucose to allow the cells of the body to use glucose as energy. The pancreas usually produces more insulin in response to a spike in blood sugar level, for example after eating a meal high in energy. This is because the insulin acts as a “key” to open up the cells in the body and allows the glucose to be used as an energy source. Additionally, when there is excess glucose in the bloodstream, known as hyperglycemia, insulin encourages the storage of glucose as glycogen in the liver, muscle and fat cells. These stores can then be used at a later date when energy requirements are higher. As a result of this, there is less insulin in the bloodstream, and normal blood glucose levels are restored. Insulin stimulates the synthesis of glycogen in the liver, but when the liver is saturated with glycogen, an alternative pathway takes over.

This involves the uptake of additional glucose into adipose tissue, leading to the synthesis of lipoproteins. Image Copyright: Alila Medical Media, Image ID:114645271 via Shutterstock.com Results Without Insulin Researchers developing novel formulation to improve longevity of insulin infusion implants In the absence of insulin, the body is not able to utilize the glucose as energy in the cells. As a result, the glucose remains in the bloodstream and can lead to high blood sugar , known as hyperglycemia. Chronic hyperglycemia is characteristic of diabetes mellitus and, if untreated, is associated with severe complications, such as damage to the nervous system, eyes, kidneys and extremities. In severe cases, lack of insulin and reduced ability to use glucose as a source of energy can lead to a reliance of fat stores as the sole source of energy. The breakdown of these fats can release ketones into the bloodstream, which can lead to a serious condition called ketoacidosis. Other Functions of Insulin In addition to the regulation of glucose, insulin also plays a role in other areas of the body. It may be involved in all of the following functions to: Modify the activity of enzymes and the resulting reactions in the body.

Build muscle following sickness or injury via the transportation of amino acids to the muscle tissue, which is required to repair muscular damage and increase size and strength. It helps to regulate the uptake of amino acids, DNA replication and the synthesis of proteins. Manage synthesis of lipids by uptake into fat cells, which are converted to triglycerides. Manage breakdown or protein and lipids due to changes in fat cells. Uptake of amino acids and potassium into the cells that cannot take place in the absence of insulin. Manage excretion of sodium and fluid volume in the urine. Enhance learning and memory of the brain functions. It is evident that insulin plays a number of essential roles in the body, including the management of sugar levels in the blood and many other areas.

Question: Which organ of the human body produces insulin?
Answer: Pancreas