diabetestalk.net

What Hormone Promotes Storage Of Glucose By The Liver

Regulation Of Glycolysis And Gluconeogenesis

Regulation Of Glycolysis And Gluconeogenesis

- [Instructor] At its most simplistic level, regulation of metabolic pathways inside of the body is really just a fancy word for a balancing act that's occurring in the body. So, to illustrate this, I have a seesaw and we've been learning about two metabolic pathways: glycolysis, which is the process of breaking down glucose into pyruvate; and gluconeogenesis, which is essentially the opposite in which we start out with pyruvate and through a little bit of a different route we end up back at glucose. And when we're talking about the regulation of these particular pathways, we're essentially asking ourself, "When is glycolysis the predominant pathway and when is gluconeogenesis the predominant pathway?" The body wants to make sure that we either have a net breakdown of glucose, in the case of glycolysis, or that we have a net production of glucose, in the case of gluconeogenesis. So now the next question is, "How does the body "accomplish this balancing act?" And to answer this question, the way I like to think about it is to think about it along a spectrum. There are very fast-acting forms of regulation that take place on the order of seconds, and there are very very slow forms of regulation that can take up to hours or even days to occur. So let's talk about each of these in a little bit more detail. The major principle that helps me understand fast-acting forms of regulation is a good old principle from general chemistry: Le Chatelier's Principle. So if you remember, Le Chatelier's Principle talks about anything that's in equilibrium and it says that if there's any change to this equilibrium, let's say more products are added or reactants are taken away, the equilibrium will adjust to essentially counter that change and return the system back to equilibrium. So what d Continue reading >>

Pancreatic Regulation Of Glucose Homeostasis

Pancreatic Regulation Of Glucose Homeostasis

Go to: The pancreas is an exocrine and endocrine organ The pancreas has key roles in the regulation of macronutrient digestion and hence metabolism/energy homeostasis by releasing various digestive enzymes and pancreatic hormones. It is located behind the stomach within the left upper abdominal cavity and is partitioned into head, body and tail. The majority of this secretory organ consists of acinar—or exocrine—cells that secrete the pancreatic juice containing digestive enzymes, such as amylase, pancreatic lipase and trypsinogen, into the ducts, that is, the main pancreatic and the accessory pancreatic duct. In contrast, pancreatic hormones are released in an endocrine manner, that is, direct secretion into the blood stream. The endocrine cells are clustered together, thereby forming the so-called islets of Langerhans, which are small, island-like structures within the exocrine pancreatic tissue that account for only 1–2% of the entire organ (Figure 1).1 There are five different cell types releasing various hormones from the endocrine system: glucagon-producing α-cells,2 which represent 15–20% of the total islet cells; amylin-, C-peptide- and insulin-producing β-cells,2 which account for 65–80% of the total cells; pancreatic polypeptide (PP)-producing γ-cells,3 which comprise 3–5% of the total islet cells; somatostatin-producing δ-cells,2 which constitute 3–10% of the total cells; and ghrelin-producing ɛ-cells,4 which comprise <1% of the total islet cells. Each of the hormones has distinct functions. Glucagon increases blood glucose levels, whereas insulin decreases them.5 Somatostatin inhibits both, glucagon and insulin release,6 whereas PP regulates the exocrine and endocrine secretion activity of the pancreas.3, 7 Altogether, these hormones regul Continue reading >>

Blood Glucose And Hormonal Control

Blood Glucose And Hormonal Control

The following metabolic processes serve to regulate the production, metabolism, and storage of carbohydrates within the body: Glycogenolysis: The breakdown or hydrolysis of glycogen in the liver (as well as kidneys, muscle and brain) into glucose which is released into the bloodstream. Glycolysis: The oxidative breakdown or metabolism of glucose to produce energy Glycogenesis: The conversion of excess glucose into glycogen as a cellular storage mechanism. Gluconeogenesis: The reversal of glycogenolysis whereby glucose is synthesized within the body from non-carbohydrate substances, such as pyruvate, lactate, glycerol, and certain amino acids. Several hormones are involved in carbohydrate metabolism. The following are the main hormones that affect carbohydrate metabolism: Pancreatic insulin: Insulin is the main regulatory hormone produced and secreted by the pancreatic beta cells. It stimulates the uptake of glucose and the movement of glucose from blood to cells for energy production. Insulin also stimulates glycogenesis, inhibits glycogenolysis, and regulates protein synthesis. Pancreatic glucagon: Glucagon is a hormone produced by the alpha cells of the pancreas and stimulates glycogenolysis and gluconeogenesis, causing an increase in blood glucose. It has the opposite effect as that of insulin. Adrenal gland cortisol: Cortisol is a steroid hormone produced by the adrenal gland and promotes gluconeogenesis. It is released in response to stress and low blood glucose levels. It functions to increase blood glucose through gluconeogenesis. Epinephrine: Epinephrine is a hormone produced by both the adrenal glands and certain neurons. It serves as a neurotransmitter that increases glycogenolysis. Continue reading >>

Hormone Effects + General Info

Hormone Effects + General Info

Sort Hormone levels in blood Blood concentration of hormone can change dramatically by --Changing rate of hormone synthesis --Changing rate hormone removed from blood or inactivated Protein and peptide hormones synthesized at a steady rate in an unstimulated cell Changing transcription rates increases or decreases the supply Reservoir of stored hormone in secretory vesicles Steroid hormones are made on demand with no significant storage Hypothalamus and pituitary gland --Hypothalamic nuclei make neurohormones --Infundibular stalk connects hypothalmus and pituitary Also connected by portal veins 2 capillary beds in series Allows for direct communication HT connected to anterior pituitary by portal veins Posterior pituitary is extension from HT by nerve axons. Axon terminals store ADH and oxytocin. Continue reading >>

Pancreatic Hormone

Pancreatic Hormone

Insulin Insulin is a pancreatic hormone that regulates blood glucose levels by stimulating the conversion of glucose to glycogen. In addition to this role in carbohydrate metabolism, insulin suppresses the appetite, as shown by the effect of direct insulin injections into the brain. Insulin receptors are distributed in the hypothalamus and NTS and are particularly concentrated on NPY and POMC neurons in the arcuate nucleus, where their distribution is similar to that of the leptin receptor. This additional role for insulin may be related to its function in lipid homeostasis since, as well as promoting the storage of carbohydrates, insulin promotes the storage of fats. Overall levels of insulin correlate with the degree of adiposity in a manner similar to the correlation shown by leptin. Physiology Insulin is a polypeptide pancreatic hormone secreted by the beta cells of the islets of Langerhans. Preproinsulin is produced by ribosomes of the beta cells and quickly cleaved to proinsulin and stored in secretory granules of the Golgi complex. Proinsulin is then cleaved to form insulin, C-peptide, and split peptides. Insulin's primary role in the body involves the metabolism of carbohydrates and the regulation of glucose levels in the blood, by promoting the uptake, utilization, or storage of glucose by hepatocytes, myocytes, and adipocytes. Insulin promotes glucose uptake into myocytes and adipocytes via the glucose transporter GLUT-4 but is not required for other carriers. Insulin secretion is stimulated by increasing blood concentrations of glucose, growth hormone, glucagon, or amino acids. The sequence of the insulin molecule is highly conserved between species. Equine insulin has one amino acid difference from porcine insulin, which has one amino acid difference from hu Continue reading >>

The Endocrine Pancreas

The Endocrine Pancreas

Cells and Secretions of the Pancreatic Islets The pancreatic islets each contain four varieties of cells: The alpha cell produces the hormone glucagon and makes up approximately 20 percent of each islet. Glucagon plays an important role in blood glucose regulation; low blood glucose levels stimulate its release. The beta cell produces the hormone insulin and makes up approximately 75 percent of each islet. Elevated blood glucose levels stimulate the release of insulin. The delta cell accounts for four percent of the islet cells and secretes the peptide hormone somatostatin. Recall that somatostatin is also released by the hypothalamus (as GHIH), and the stomach and intestines also secrete it. An inhibiting hormone, pancreatic somatostatin inhibits the release of both glucagon and insulin. The PP cell accounts for about one percent of islet cells and secretes the pancreatic polypeptide hormone. It is thought to play a role in appetite, as well as in the regulation of pancreatic exocrine and endocrine secretions. Pancreatic polypeptide released following a meal may reduce further food consumption; however, it is also released in response to fasting. Regulation of Blood Glucose Levels by Insulin and Glucagon Glucose is required for cellular respiration and is the preferred fuel for all body cells. The body derives glucose from the breakdown of the carbohydrate-containing foods and drinks we consume. Glucose not immediately taken up by cells for fuel can be stored by the liver and muscles as glycogen, or converted to triglycerides and stored in the adipose tissue. Hormones regulate both the storage and the utilization of glucose as required. Receptors located in the pancreas sense blood glucose levels, and subsequently the pancreatic cells secrete glucagon or insulin to mai Continue reading >>

Absorbing And Storing Energy: How The Body Controls Glucose

Absorbing And Storing Energy: How The Body Controls Glucose

Editor’s note: Physicians have a special place among the thinkers who have elaborated the argument for intelligent design. Perhaps that’s because, more than evolutionary biologists, they are familiar with the challenges of maintaining a functioning complex system, the human body. With that in mind, Evolution News is delighted to offer this series, “The Designed Body.” For the complete series, see here. Dr. Glicksman practices palliative medicine for a hospice organization. Just like a car needs the energy, in the form of gasoline, to run properly, the body needs the energy in glucose to survive. When we haven’t eaten for a while, our blood glucose level drops and our stomach is empty, causing the hunger center in our brain to tell us to eat or drink something with calories. As I have explained in my last couple of articles, the complex molecules that are in what we eat and drink enter the gastrointestinal system, where digestive enzymes break them down into simpler molecules so the body can absorb them. Carbohydrates are broken down into simple sugars, like glucose, which are then absorbed into the blood. Tissues, such as the brain and other organs, rapidly absorb some of this glucose, to be used for their immediate energy needs. However, the amount of glucose absorbed after a meal is usually much more than what the tissues can use right away, causing excess. The body is able to chemically link these excess glucose molecules together to form a carbohydrate called glycogen. Most of the glycogen in the body is made and stored in the liver, with smaller amounts in the muscles, kidneys, and other tissues. Once the liver and other tissues have filled up their glycogen stores, any excess glucose is stored as fat, apparently without limit. These tissues can use this Continue reading >>

Shared Flashcard Set

Shared Flashcard Set

Details Title Chapter 21 Description Endocrine System Total Cards 60 Subject Physiology Level Undergraduate 1 Created 04/28/2010 Click here to study/print these flashcards. Create your own flash cards! Sign up here. Additional Physiology Flashcards Cards Term Anabolism Definition or biosynthesis, is the process by which living organisms synthesize complex molecules of life from simpler ones together with catabolism, are the two series of chemical processes in cells that are, together, called metabolism requires input of energy "uphill process" Term Catabolism Definition produce smaller molecules used by the cell to synthesize larger molecules "downhill" process during which energy is released Term Describe Glucose Tranporters in the blood Definition Inside cells, glucose can be oxidized for energy which generates carbon dioxide as a waste product; provides substrates for other metabolic reactions or be converted to glycogen for storage if glucose levels in the cell decrease, glycogen can be broken down to glucose by glycogenolysis Term Describe amino acids in the blood Definition amino acids are used for the synthesis of proteins or catabolized for energy by proteolysis the proteins function as amino acid stores that can subsequently be broken down to amino acids which can then be catabolized for energy or released into the bloodstream for use by other cells Term What three metabolic pathways ar necessary for the handling of glucose Definition Glycolysis Krebs cycle Electron transport chain Term Triglycerides are transported in the bloodstream in Definition lipoproteins, small protein- and lipid- containing particles Term To facilitate entry into cells, triglycerides at the outer surface of lipoproteins are broken down by the enzyme Definition lipoprotein lipase which i Continue reading >>

Module 26 /hormonal Regulation Of Metabolism

Module 26 /hormonal Regulation Of Metabolism

Describe how endocrine function regulates the homeostasis of glucose and list the hormones involved in the process. Compare the roles of insulin and thyroid hormones. Blood glucose levels vary widely over the course of a day as periods of food consumption alternate with periods of fasting. Insulin and glucagon are the two hormones that are primarily responsible for maintaining homeostasis of blood glucose levels. Additional regulation is mediated by the thyroid hormones. Regulation of Blood Glucose Levels by Insulin and Glucagon Cells of the body require nutrients in order to function, and they obtain these nutrients through feeding. In order to manage nutrient intake, storing excess and utilizing stores when necessary, the body uses hormones to modulate energy metabolism. Insulin is produced by the beta cells of the pancreas, which are stimulated to release insulin as blood glucose levels rise, for example, after a meal is consumed. Insulin lowers blood glucose levels by enhancing glucose uptake by most body target cells, which utilize glucose for ATP production; muscle cells are a good example. It also stimulates the liver to convert glucose to glycogen, which is then stored by cells for later use. Increased glucose uptake occurs through an insulin-mediated increase in the number of glucose transporter proteins in cell membranes, which remove glucose from circulation by facilitated diffusion. As insulin binds to its target cell, it triggers the cell to incorporate transport proteins into its membrane. This allows glucose to enter the cell, where it can be used as an energy source. However, this does not always occur in all body cells, as some cells in the kidneys and brain have been shown to regularly access glucose without the use of insulin. Insulin also stimulates Continue reading >>

What Is Glucagon?

What Is Glucagon?

Blood sugar levels are an important part of overall health. When blood sugar levels drop, an individual may feel lethargic. If they drop too low, the individual may become disoriented, dizzy or even pass out. Blood sugar control involves a complex system of hormones, and one of those hormones is glucagon. Glucagon is a hormone that works with other hormones and bodily functions to control glucose levels in the blood. It comes from alpha cells found in the pancreas and is closely related to insulin-secreting beta cells, making it a crucial component that keeps the body’s blood glucose levels stable. What does glucagon do? Although secreted by the pancreas, glucagon directly impacts the liver as it works to control blood sugar levels. Specifically, glucagon prevents blood glucose levels from dropping to a dangerous point by stimulating the conversion of stored glycogen to glucose in the liver. This glucose can be released into the bloodstream, a process known as glycogenolysis. Secondly, glucagon stops the liver from consuming some glucose. This helps more glucose to enter the bloodstream, rather than being consumed by the liver, to keep levels stable. Finally, glucagon works in a process known as gluconeogenesis, which is the production of glucose in the amino acid molecules. In each of these processes, glucagon and insulin work together. Insulin will prevent glucose levels from increasing to a point that is too high, while glucagon prevents it from dropping too low. Glucagon production is stimulated when an individual eats a protein-rich meal, experiences a surge in adrenaline, or has a low blood sugar event. Potential problems with glucagon function Glucagon function is crucial to proper blood glucose levels, so problems with glucagon production will lead to problems Continue reading >>

How Insulin And Glucagon Work

How Insulin And Glucagon Work

Insulin and glucagon are hormones that help regulate the levels of blood glucose, or sugar, in your body. Glucose, which comes from the food you eat, moves through your bloodstream to help fuel your body. Insulin and glucagon work together to balance your blood sugar levels, keeping them in the narrow range that your body requires. These hormones are like the yin and yang of blood glucose maintenance. Read on to learn more about how they function and what can happen when they don’t work well. Insulin and glucagon work in what’s called a negative feedback loop. During this process, one event triggers another, which triggers another, and so on, to keep your blood sugar levels balanced. How insulin works During digestion, foods that contain carbohydrates are converted into glucose. Most of this glucose is sent into your bloodstream, causing a rise in blood glucose levels. This increase in blood glucose signals your pancreas to produce insulin. The insulin tells cells throughout your body to take in glucose from your bloodstream. As the glucose moves into your cells, your blood glucose levels go down. Some cells use the glucose as energy. Other cells, such as in your liver and muscles, store any excess glucose as a substance called glycogen. Your body uses glycogen for fuel between meals. Read more: Simple vs. complex carbs » How glucagon works Glucagon works to counterbalance the actions of insulin. About four to six hours after you eat, the glucose levels in your blood decrease, triggering your pancreas to produce glucagon. This hormone signals your liver and muscle cells to change the stored glycogen back into glucose. These cells then release the glucose into your bloodstream so your other cells can use it for energy. This whole feedback loop with insulin and gluca Continue reading >>

Introduction

Introduction

INTRODUCTION Glucose in the blood provides a source of fuel for all tissues of the body. Blood glucose levels are highest during the absorptive period after a meal, during which the stomach and small intestine are breaking down food and circulating glucose to the bloodstream. Blood glucose levels are the lowest during the postabsorptive period, when the stomach and small intestines are empty. Despite having food only periodically in the digestive tract, the body works to maintain relatively stable levels of circulatory glucose throughout the day. The body maintains blood glucose homeostasis mainly through the action of two hormones secreted by the pancreas. These hormones are insulin, which is released when glucose levels are high, and glucagon, which is released when glucose levels are low. The accompanying animation depicts the functions of these hormones in blood glucose regulation. CONCLUSION Throughout the day, the release of insulin and glucagon by the pancreas maintains relatively stable levels of glucose in the blood. During the absorptive period blood glucose levels tend to increase, and this increase stimulates the pancreas to release insulin into the bloodstream. Insulin promotes the uptake and utilization of glucose by most cells of the body. Thus, as long as the circulating glucose supply is high, cells preferentially use glucose as fuel and also use glucose to build energy storage molecules glycogen and fats. In the liver, insulin promotes conversion of glucose into glycogen and into fat. In muscle insulin promotes the use of glucose as fuel and its storage as glycogen. In fat cells insulin promotes the uptake of glucose and its conversion into fats. The nervous system does not require insulin to enable its cells to take up and utilize glucose. If glucose Continue reading >>

Medical Terminology For Cancer

Medical Terminology For Cancer

Contents Functions of the Endocrine System About Hormones The Pituitary Gland The Thyroid gland The Parathyroids The Pancreas The Adrenal Glands The Gonads Roots, suffixes, and prefixes Cancer Focus Related Abbreviations and Acronyms Further Resources The Endocrine system (along with the nervous system) controls and regulates the complex activities of the body. The Endocrine system regulates the activities of the body by secreting complex chemical substances (hormones) into the blood stream. These secretions come from a variety of glands which control various organs of the body. The key functions are: To regulate the metabolic functions of the body. To regulate the rate of chemical reactions in various cells. To influence the ability of substances to transport themselves through cell membranes. This is known as the "master gland" because it exerts control over all of the other glands of the endocrine system. Despite its importance the pituitary gland is no larger than a small pea. The Pituitary gland is made up of two separate glands: the Anterior lobe which is an outgrowth of the pharynx, and the Posterior lobe which is an outgrowth of the brain composed of neural (nerve) tissue. The Anterior Lobe of the pituitary plays the 'master' role secreting six major hormones that affect most of the body, including the other Endocrine glands: ACTH (Adrenocorticotrophic hormone) stimulates the adrenal glands to secrete its hormones. hGH (Human growth hormone) also known as somatotrophic hormone is responsible for the growth of long bones, muscles and viscera. TSH (Thyroid stimulating hormone) influences the structure of the thyroid and causes it to secrete thyroid hormone. FSH (Follicle stimulating hormone) stimulates female egg production or male sperm production. PRL (Prolactin Continue reading >>

Insulin And Glucose Regulation

Insulin And Glucose Regulation

INTRODUCTION Glucose in the blood provides a source of fuel for all tissues of the body. Blood glucose levels are highest during the absorptive period after a meal, during which the stomach and small intestine are breaking down food and circulating glucose to the bloodstream. Blood glucose levels are the lowest during the postabsorptive period, when the stomach and small intestines are empty. Despite having food only periodically in the digestive tract, the body works to maintain relatively stable levels of circulatory glucose throughout the day. The body maintains blood glucose homeostasis mainly through the action of two hormones secreted by the pancreas. These hormones are insulin, which is released when glucose levels are high, and glucagon, which is released when glucose levels are low. The accompanying animation depicts the functions of these hormones in blood glucose regulation. EFFECTS OF INSULIN 1 After a high carbohydrate lunch, like a plate of spaghetti, polysaccharides are digested into monosaccharides. Monosaccharides such as glucose are absorbed by the small intestine and released into the blood. 2 Increased levels of blood glucose signal the pancreas to secrete insulin into the bloodstream. 3 Insulin promotes the uptake of glucose by most cells of the body. Many cells, like muscle, burn glucose for their metabolic fuel. Fat cells in adipose tissue use glucose to make fat. Liver cells convert glucose to glycogen and fat. 4 As the afternoon passes, the cells continue to take up glucose, and blood glucose levels decrease. 5 By 6:00, all the glucose from the spaghetti lunch has been absorbed, and blood glucose levels have fallen further. 6 The low blood glucose puts a brake on insulin release from the pancreas. 7 Without a glucose supply, cells switch to usin Continue reading >>

Jakes Human Physiology 2

Jakes Human Physiology 2

A B When you haven't eaten for a couple of hours and your blood glucose levels drop (low), what happens within your body? If we haven't eaten for several hours, our blood glucose levels decline. This decrease in blood glucose stimulates the alpha cells of the pancreas to release the hormone glucagon. Glucagon stimulates glycogenolysis within the LIVER, the breakdown of glycogen, to yield glucose. The glucose is released from the LIVER into the bloodstream, raising the levels of glucose back to normal. What happens to glucose when it is not being used for energy? Glucose gets stored in muscle cells and the liver. When these storages are full, glucose then gets stored as fat. What is a special paracrine that is secreted by a neuron? A Neurotransmitter. Give an example of an Antagonistic Effect that occurs within the CNS? NE and ACh binding on the heart. What is Catabolism? The breaking down of larger molecules into smaller ones, with the aid of enzymes. What is Anabolism? (Give an example) The building of smaller molecules by enzymes into larger molecules./ (Amino acids-into- Proteins.) What branches does Metabolism consist of? Catabolism and Anabolism. Name the most important hormone associated with maintaining metabolism and body heat./ What organ Secretes it? And what is its "Target Tissue"? Thyroxine./ The Thyroid Gland/ Target= All body cells. Explain the process in which the body regulates metabolic rate... The Thyroid gland secretes Thyroxine, which increases metabolic rate. Also the Pituitary Gland secretes (TSH) Thyroid Stimulating Hormone which enters the blood stream to the Thyroid gland and stimulates it to "produce" more Thyroxine! What is the target tissue for Estrogen?/ What is its specific action? The Uterus./ It stimulates the endometrium of the Uterus to Continue reading >>

More in blood sugar