Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Endocrine System Part 2: Glucose Regulation Glucose in Blood Glucose is an important fuel for cells Pancreas maintains blood glucose levels by secreting hormones Pancreas Exocrine system: secretion of hormones through ducts Exocrine cells: 98%-99% of pancreas by mass Produce digestive enzymes released into small intestine http://media-2.web.britannica.com/eb-media/17/74317-004-9B143D52.jpg Pancreas Endocrine cells: 1%-2% of pancreas by mass Scattered throughout the pancreas Islets of Langerhans http://media-2.web.britannica.com/eb-media/17/74317-004-9B143D52.jpg Islets of Langerhans Alpha cells: secrete glucagon Beta cells: secrete insulin Insulin and glucagon are antagonistic hormones http://www.rajeun.net/diabetes-pancreas.gif Insulin Insulin Stimulant: Blood glucose level rises above a set point Observed naturally after eating a meal Effect: Uptake of glucose by body cells through facilitated diffusion by activating glucose transporters Inhibits the liver's breakdown of glycogen Inhibits liver’s conversion of amino acids and glycerol to glucose Result: lowering blood glucose level decrease stimulus for insulin release Glucagon Stimulant: Lowered blood glucose Glucose cleared from the blood stream Effect: Liver to increase breakdown of glycogen Liver convert amino acids and glycerol to glucose Result: Higher blood glucose level Decrease stimulus for glucagon release Insulin Function beta cells hyperglycemia insulin release Increased glucose uptake by cells glycogen production in liver decreased blood sugar Glucagon Function hypoglycemia alpha cells glucagon release glucose released by liver from non-carb source glycogen breakdown in liver releasing glucose increased blood sugar Comparing Insulin & Glucagon Situation After a meal Hormone Insulin Stimulant: Blood glucose levels Effect: Glucose uptake Effect: Glycogen breakdown Between meals Glucagon Comparing Insulin & Glucagon Situation Hormone Stimulant: Blood glucose levels Effect: Glucose uptake Effect: Glycogen breakdown After a meal Insulin Increased Increase Decrease Between meals Glucagon Comparing Insulin & Glucagon Situation Hormone Stimulant: Blood glucose levels Effect: Glucose uptake Effect: Glycogen breakdown After a meal Insulin Increased Between meals Glucagon Decreased Increase Decrease Decrease Increase Diabetes Common symptoms: frequent urination Types of diabetes: Mellitus (related to insulin and glucose) Type 1 Type 2 Insipidus (related to reabsorption) Diabetes Mellitus Cause Type 1 diabetes Immune system attacks insulin producing cells Decreased insulin levels Type 2 diabetes Reasons not related to autoimmunity Decreased responsiveness of cells to insulin Inability of insulin to regulate blood glucose levels Impairment of ability to remove glucose from the bloodstream Diabetes Mellitus Type 2 Diabetes Mellitus Types Onset Type 1 (Insulin dependent) Childhood Type 2 (Non-insulin dependent) Adult (past age 40) Pregnancy Insulin resistance (unresponsive receptors) and deficiency Obesity Molecular Cause Insulin deficiency Cause Genetic Autoimmune disorder Treatment Daily insulin injections Exercise & dietary control drugs Diabetes Mellitus Effect Glucose unavailable to body cells Hyperglycemia: high glucose in blood Excessive hunger Fat used for cellular respiration Increased blood viscosity and decreased blood flow leads to blurry vision (poor blood flow in capillaries of retina) foot infections (gravity cause blood to pool in feet) Kidneys start to excrete glucose Glucosuria: glucose in urine, “sweet” urine Frequent urination Persistent thirst Canadian Connection Frederick Banting & Charles Best Nobel Prize – 1923 insulin isolation tied off ducts to digestive tract cell producing digestive enzymes shrivelled only islets of Langerhans remained Banting and Best Banting and Best began their experiments by removing the pancreas from a dog. This resulted in the following: It's blood sugar rose. It became thirsty, drank lots of water, and urinated more often. It became weaker and weaker. The dog had developed diabetes. They then isolated “insulin” and injected it back into the dogs and they seemed to be cured. Leonard Thompson January 1922 in Toronto, Canada 14-year-old boy was the first to be treated with insulin injections Stress Regulation What is Stress? The feeling of alarm or distress when reacting to particular event Can be physical, emotional, cognitive or mental Stress Response Natural response Prepares an individual to handle the stressor (an event that provokes stress) Types: Short term: responses are immediate Long term: responses are ongoing and can cause detrimental side effects on the individual Adrenal Gland Secretes stress response hormones Location: adjacent to kidneys Structure: Adrenal cortex : outer portion, involved with longterm stress response Adrenal medulla : inner portion, involved with short-term stress response Short Term Stress Response Short-term Stress Response Stress excites nerve cells to release a neurotransmitter: acetylcholine (ACh) Stimulates adrenal medulla to release catecholamines: epinephrine and norepinephrine Catecholamines Synthesized from tyrosine Secreted in response to positive or negative stress by the adrenal medulla Types: Epinephrine (adrenaline) Norepinephrine (noradrenaline) Catecholamines Tyrosine Effects Stimulates the “fight-or-flight” response Increase metabolism Cellular respiration produces ATP Need energy source (glucose) Need oxygen Effects: Energy Source Increased blood glucose levels Glycogen glucose more ATP readily available Stimulates the release of fatty acids from fat cells to supply the body with more energy Decreased kidney and digestive activity Effects: Oxygen Increased blood pressure and blood flow oxygen is distributed to cells faster Increased breathing rate Relaxes/contracts certain blood vessels overall effect of redirecting blood away from nonvital areas increasing blood flow to the heart, brain, and skeletal muscles Increased alertness Short-term Stress Response stress Adrenal medulla epinephrine Breakdown glucose Increase blood glucose Increased blood volume, pressure, breathing rate Increased energy source Increased oxygen Fight or flight in response to stress Application Epinephrine is present in epinephrine autoinjectors (EpiPens) Long Term Stress Response Long-Term Stress Response: Neuroendocrine pathway CRH ACTH Corticosteroid Glucocorticoid Mineralcorticoid Long-Term Stress Response: Neuroendocrine pathway Location Stimulus Hypothalamus Hormone Stress Corticotropin-releasing Hormone (CRH) Anterior Pituitary Adrenocorticotropic Hormone (ACTH) Adrenal Cortex Corticosteroids: Glucocorticoids (e.g. cortisol) Mineralocoritcoids (e.g. aldosterone) Effect Increase glucose production Increase oxygen delivery Corticotropin-Releasing Hormone (CRH) Neuropeptide hormone Released from hypothalamus Cause: stressful stimuli Stimulates anterior pituitary to synthesize ACTH Adrenocorticotropic Hormone (ACTH) Polypeptide hormone Tropic hormone Produced from anterior pituitary Stimulates adrenal cortex to synthesize corticosteroids Corticosteroids steroids produced and released from the adrenal cortex Type Example Glucocorticoid Cortisol Mineralcorticoid Aldoesterone Sex hormones testosterone Glucocorticoid (Cortisol) Effects: Energy source Affects glucose metabolism Raise blood glucose levels by synthesizing glucose from non-carbohydrate sources: Breakdown of fat to glucose Liver breaks down muscle protein in skeletal muscles to glucose Occurs when body needs more glucose than what the liver can produce from its storage of glycogen Other effects: Suppress immune system Natural anti-inflammatory (antihistamine) Mineralocorticoid (Aldosterone) Effects: Indirectly on oxygen Hormone that affects the body’s osmotic balance Stimulates reabsorption of salt and water by kidneys Cause increase in blood volume and pressure Increase oxygen delivery Long-term Stress Response stress Hypothalamus CRH Anterior pituitary ACTH Glucocorticoid (cortisol) Mineralcorticoid (aldosterone) Synthesize glucose from non-carbohydrate source Increased reabsorption, blood volume, pressure Increased energy and oxygen for cellular respiration Compare Short & Long Term Stress Management Stress Hormones Energy Oxygen Short term Epinephrine Norepinephrine Long term Glucocorticoid (cortisol) Mineralcorticoid (aldoesterone) Glucose from Glucose from nonglycogen stores carbohydrate source Increase heart Increase reabsorption rate, pressure, flow of salt and water, blood & resp rate, volume, pressure & regulate vessel size flow Stress Associated Disorders Hypersecretion: Cushing’s Disease Overproduction of glucocorticoid (cortisol) Mimic diabetes: Hyperglycemia (high blood glucose) Glucosuria (glucose in urine) Protein shortage (protein converted to glucose) Cause: pituitary tumour (excess ACTH) Treatment: surgery, radiation Cushing’s Disease Physical Effects Excess glucose deposited as body fat in abdomen, face, above shoulder blades Weight gain, “moon face” and “buffalo hump” Appendages remain thin Muscle weakness, prone to bruising Weak skeleton, prone to fractures Cushing’s Disease Physical Effects Effects also seen in people who take glucocorticoids for other reasons Anti-inflammatory: Asthma Arthritis, joint injuries Immune suppressant: Lupus (autoimmune disease) Karoshi “death from overwork” (Japan) Death from heart attack and stroke due to stress Chronic increase in cortisol Hyposecretion: Addison’s Disease Failure to produce adequate levels of glucocorticoid (cortisol) Cause: autoimmune / adrenal gland disorders immune system gradually destroys the adrenal cortex Treated with gluco/mineralocorticoids Addison’s Disease Symptoms Characterized by several non-specific symptoms: major weight loss dizziness, vomiting and nausea abdominal pain muscle weakness Notable case: US president John F. Kennedy