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Animation: Pancreatic Hormones Regulate Blood Glucose Level

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Hi, this is Kelly Hogan from the University of North Carolina. In this visualizing the concept video we'll walk through how pancreatic hormones regulate blood glucose level. We'll also consider what happens when that regulation goes awry. Let's get started! Your cells need fuel to function and glucose is an important energy source for almost all cells. What would it look like if you graphed blood glucose level throughout the day, would it be a straight line? Would it rise and fall? Blood glucose level fluctuates throughout a day so we would see a wavy line like this one. Notice that as the glucose level rises and falls throughout a day it hovers around a set point. The regulation of glucose level around this set point demonstrates an example of homeostasis which is a state of equilibrium or steady state of body functioning. The blood glucose set point is maintained by two antagonistic hormones, insulin and glucagon. These two pancreatic hormones are said to be antagonistic because the effects of one oppose the effects of the other. Both hormones are always present but the level of each fluctuates depending on your diet, exercise and other factors. To begin, let's consider the effect of a meal such as a carbohydrate rich cereal breakfast at 7:00 in the morning. As breakfast is digested glucose monomers are readily absorbed into the bloodstream causing the sharp rise of blood glucose level on our graph. The sharply rising line we just observed on our graph corresponds to what we will now see represented in the blood vessels. After a carbohydrate rich breakfast at 7:00 AM we see an increase of glucose molecules in the bloodstream. The rising blood glucose level stimulates the pancreas. In response, beta cells of the pancreas secrete insulin that diffuses into the blood. The insulin secreted from the pancreas travels throughout the whole body through the circulatory system. When insulin diffuses out of the blood vessels it binds to receptors located on the surface of most cell types. Notice that insulin itself does not enter the cell. The binding of insulin to receptors on the outside of the cell initiates a signaling pathway inside the cell. As a result, cells are temporarily able to take up glucose when insulin is present. The glucose will be used as cellular fuel. Some cells like liver cells are like a bank. They store excess glucose and release it when it's needed. The binding of insulin to the receptors on liver cells causes them to take up as well as store glucose as a polysaccharide called glycogen. Muscle cells store glucose in the form of glycogen too. Actively contracting muscles require large amounts of energy. So storing glucose directly in muscle cells is efficient for when the muscle cells require immediate fuel. Once the various cells of the body have taken glucose in the once high blood glucose level decreases. We see that here represented by fewer glucose molecules in the bloodstream. As blood glucose level decreases the beta cells of the pancreas are no longer stimulated to secrete insulin. Insulin secretion slows. The blood glucose level is now nearing the set point again. Let's summarize what we have just learned with our graph. At 7:00 AM blood glucose level rises after a carbohydrate rich meal. Insulin is secreted and blood glucose level declines. Thus insulin production lowers blood glucose level. Let's now examine how the antagonistic hormone glucagon raises blood glucose level. What happens if we go too long without eating such as if we skip lunch on a busy day? When we go an extended time without food blood glucose level begins to decline. The declining line we just followed on our graph is represented in the blood vessel here. No food has been eaten since breakfast and it is now past 2:00 PM resulting in fewer glucose molecules in the blood stream. The declining blood glucose level stimulates the pancreas in response alpha cells of the pancreas release glucagon. As we saw with insulin, glucagon diffuses out of the blood. It binds the receptors located on the surface of living cells. The binding of glucagon to receptors on liver cells results in the breakdown of glycogen polymers into glucose monomers that are then secreted. The secretion of glucose from liver cells causes the blood level to rise, the glucose is now available for use by all cells of the body. With more glucose molecules in the blood the alpha cells of the pancreas are no longer stimulated to secrete glucagon; glucagon secretion slows. The blood glucose level is nearing the set point. We can now explain why the line on our graph declines and rises when a meal is skipped; going an extended time without eating causes blood glucose level to decline. Glucagon is secreted and blood glucose level increases. If beta cells of the pancreas were absent which hormone would an individual not be able to produce and as a result, what would this individual cells not be able to do? In the pancreas the beta cells are responsible for insulin secretion. Insulin's presence allows most cells to take up glucose. Thus, if beta cells of the pancreas are absent an individual would not make the hormone insulin and without insulin cells could not take up glucose. With less fuel they wouldn't be able to complete as much cellular work as normal. In the absence of insulin, what would you predict the blood glucose level to be? Lower than the set point? Higher than the set point? Or equal to the set point? The blood glucose level would be higher than the set point. Although glucose would be plentiful, without insulin many cells would not be able to take up glucose and they would starve. As more and more glucose remained in the blood and not inside cells, blood glucose level would stay elevated. It's normal for blood glucose level to fluctuate around the set point throughout the day but abnormally elevated blood glucose level is known as hyperglycemia. The serious hormonal disorder diabetes mellitus is characterized by hyperglycemia. Did you know that 1 in 12 American's has diabetes and by 2050 if current trends continue 4 out of 12 or 1 in 3 American's will be affected. Hyperglycemia associated with untreated diabetes can cause dehydration, blindness, cardiovascular and kidney disease. With statistics like these it's imperative we all understand homeostasis of blood glucose.
Hi, this is Kelly Hogan from the University of North Carolina. In this visualizing the concept video we'll walk through how pancreatic hormones regulate blood glucose level. We'll also consider what happens when that regulation goes awry. Let's get started! Your cells need fuel to function and glucose is an important energy source for almost all cells. What would it look like if you graphed blood glucose level throughout the day, would it be a straight line? Would it rise and fall? Blood glucose level fluctuates throughout a day so we would see a wavy line like this one. Notice that as the glucose level rises and falls throughout a day it hovers around a set point. The regulation of glucose level around this set point demonstrates an example of homeostasis which is a state of equilibrium or steady state of body functioning. The blood glucose set point is maintained by two antagonistic hormones, insulin and glucagon. These two pancreatic hormones are said to be antagonistic because the effects of one oppose the effects of the other. Both hormones are always present but the level of each fluctuates depending on your diet, exercise and other factors. To begin, let's consider the effect of a meal such as a carbohydrate rich cereal breakfast at 7:00 in the morning. As breakfast is digested glucose monomers are readily absorbed into the bloodstream causing the sharp rise of blood glucose level on our graph. The sharply rising line we just observed on our graph corresponds to what we will now see represented in the blood vessels. After a carbohydrate rich breakfast at 7:00 AM we see an increase of glucose molecules in the bloodstream. The rising blood glucose level stimulates the pancreas. In response, beta cells of the pancreas secrete insulin that diffuses into the blood. The insulin secreted from the pancreas travels throughout the whole body through the circulatory system. When insulin diffuses out of the blood vessels it binds to receptors located on the surface of most cell types. Notice that insulin itself does not enter the cell. The binding of insulin to receptors on the outside of the cell initiates a signaling pathway inside the cell. As a result, cells are temporarily able to take up glucose when insulin is present. The glucose will be used as cellular fuel. Some cells like liver cells are like a bank. They store excess glucose and release it when it's needed. The binding of insulin to the receptors on liver cells causes them to take up as well as store glucose as a polysaccharide called glycogen. Muscle cells store glucose in the form of glycogen too. Actively contracting muscles require large amounts of energy. So storing glucose directly in muscle cells is efficient for when the muscle cells require immediate fuel. Once the various cells of the body have taken glucose in the once high blood glucose level decreases. We see that here represented by fewer glucose molecules in the bloodstream. As blood glucose level decreases the beta cells of the pancreas are no longer stimulated to secrete insulin. Insulin secretion slows. The blood glucose level is now nearing the set point again. Let's summarize what we have just learned with our graph. At 7:00 AM blood glucose level rises after a carbohydrate rich meal. Insulin is secreted and blood glucose level declines. Thus insulin production lowers blood glucose level. Let's now examine how the antagonistic hormone glucagon raises blood glucose level. What happens if we go too long without eating such as if we skip lunch on a busy day? When we go an extended time without food blood glucose level begins to decline. The declining line we just followed on our graph is represented in the blood vessel here. No food has been eaten since breakfast and it is now past 2:00 PM resulting in fewer glucose molecules in the blood stream. The declining blood glucose level stimulates the pancreas in response alpha cells of the pancreas release glucagon. As we saw with insulin, glucagon diffuses out of the blood. It binds the receptors located on the surface of living cells. The binding of glucagon to receptors on liver cells results in the breakdown of glycogen polymers into glucose monomers that are then secreted. The secretion of glucose from liver cells causes the blood level to rise, the glucose is now available for use by all cells of the body. With more glucose molecules in the blood the alpha cells of the pancreas are no longer stimulated to secrete glucagon; glucagon secretion slows. The blood glucose level is nearing the set point. We can now explain why the line on our graph declines and rises when a meal is skipped; going an extended time without eating causes blood glucose level to decline. Glucagon is secreted and blood glucose level increases. If beta cells of the pancreas were absent which hormone would an individual not be able to produce and as a result, what would this individual cells not be able to do? In the pancreas the beta cells are responsible for insulin secretion. Insulin's presence allows most cells to take up glucose. Thus, if beta cells of the pancreas are absent an individual would not make the hormone insulin and without insulin cells could not take up glucose. With less fuel they wouldn't be able to complete as much cellular work as normal. In the absence of insulin, what would you predict the blood glucose level to be? Lower than the set point? Higher than the set point? Or equal to the set point? The blood glucose level would be higher than the set point. Although glucose would be plentiful, without insulin many cells would not be able to take up glucose and they would starve. As more and more glucose remained in the blood and not inside cells, blood glucose level would stay elevated. It's normal for blood glucose level to fluctuate around the set point throughout the day but abnormally elevated blood glucose level is known as hyperglycemia. The serious hormonal disorder diabetes mellitus is characterized by hyperglycemia. Did you know that 1 in 12 American's has diabetes and by 2050 if current trends continue 4 out of 12 or 1 in 3 American's will be affected. Hyperglycemia associated with untreated diabetes can cause dehydration, blindness, cardiovascular and kidney disease. With statistics like these it's imperative we all understand homeostasis of blood glucose.