Chapter 13 Endocrine System PDF

Chapter 13: Hormonal Regulation of Homeostasis How do Your Hormones work? Glands in your Body Endocrine glands: glands that release hormones directly into the blood or lymph FYI: Exocrine glands: glands that release secretions through ducts into a body cavity outside the body e.g., swe...

Chapter 13: Hormonal Regulation of Homeostasis How do Your Hormones work? Glands in your Body Endocrine glands: glands that release hormones directly into the blood or lymph FYI: Exocrine glands: glands that release secretions through ducts into a body cavity outside the body e.g., sweat glands, mucous glands and digestive glands  Hormones Hormone: “chemical messenger” for endocrine system; regulates activities of organs/tissues Mechanism of action 1. Endocrine cells in a gland release hormone into blood stream 2. Hormone travels through body to target tissue 3. Hormone binds to receptor sites on target tissue & causes effect General Model of Endocrine Gland  A model of a Q: How does a hormone hormone (A) bound to its protein receptor know which is its target (B). Each hormone of the endocrine system tissue?? has a unique molecular shape, which fits into a A: It binds to its receptor! specific receptor protein on its target cells. Q: How does a hormone know which is its target tissue?? A: It binds to its receptor!  1 Endocrine cells release hormone. 2 Hormone enters capillary and is carried throughout the body in the blood. interstitial 3 Hormone leaves fluid capillaries and diffuses capillary to all cells through interstitial fluid. 4 Hormone only influences target cells with matching receptors. Hormone does not affect tissues that lack receptors for it. Figure 37-2 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. Main Hormone Effects 1. control reproduction, growth, and development 2. regulate stress response 3. maintain nutrient, electrolyte (salt), and water balance General hormones: affect many organs or tissues Specific hormones: affect only 1 specific tissue The Endocrine System works in cooperation with the nervous system to control body functions many connections between both systems e.g., epinephrine functions as both a neurotransmitter and hormone General hormones: affect many organs or tissues Specific hormones: affect only 1 specific tissue The Endocrine System Goal: maintain homeostasis a stable state within the body despite changes in the external environment works in cooperation with the nervous system to control body functions many connections between both systems e.g., epinephrine functions as both a neurotransmitter and hormone Comparison of Nervous and Endocrine Systems Nervous System Endocrine System Messenger neurotransmitters hormones molecules Cells affected muscles, glands, virtually all cells neurons Speed and fast acting…but long lasting…but duration of doesn’t last as slower to start response long  Set Condition (optimal) Effector Stimulus change in conditions/ (muscle or gland) environment Control Centre Change compared to Receptor set point Feedback Loops Many hormones are regulated by negative feedback mechanisms: when a certain blood concentration of a hormone is reached, or when the targeted cells have responded to a hormone, the endocrine gland releasing that hormone is inhibited (stops releasing the hormone). Feedback Loops: How your body regulates the regulators  Inhibition of Hormone Secretion Negative Feedback: high hormone concentration or its effects inhibit further production of the hormone prevents over secretion and promotes homeostasis  Promotion of Hormone Secretion POSITIVE FEEDBACK – high hormone concentration or its effects promotes even more production of a hormone Specific examples such as Oxytocin  signals from the nervous system (nerve impulses) Hormones are released chemical changes in the blood because of: tropic hormones – stimulate other other hormones endocrine glands to release hormones Endocrine Disorders Disorders of the endocrine system involve: HYPERSECRETIO HYPOSECRETION N Not enough Faulty or missing Too much hormone hormone hormone secretion receptors secretion  Understand that the nervous and Endocrine systems work together to maintain homeostasis. Explain the difference in HOW the endocrine system works (compared to the nervous system) Describe HOW hormones work – what is their "mechanism of action"? Explain how a negative feedback loop works Understand how a positive feedback loop works Understand & Apply (in the future) how a hypersecretion or hyposecretion of a hormone can result in a homeostatic imbalance 3.2 - Hormones of the Hypothalamus & Pituitary Textbook p. 435-445 Now it’s time to learn some hormones and their effects! The body secretes over 200 known hormones You will only have to know a few of them including: ADH Prolactin Growth hormone Tropic hormones: TSH, ACTH, FSH, LH Hormones of the Thyroid & Parathyroid Hypothalamus: Main link between the nervous & endocrine systems Has specialized neural cells that secrete hormones Directly controls the release of hormones from the pituitary gland  Called the “master gland” because it makes many hormones, including hormones that cause other hormones to be released The Pituitary Gland Divided into two lobes controlled by the hypothalamus: Posterior pituitary: Anterior pituitary: controlled controlled by nerve impulses by tropic hormones from from hypothalamus hypothalamus  Oxytocin Neurotransmitter & hormone Involved in labour process (stimulates Start with the uterine contractions) & milk release from mammary glands (breast Hypothalamus/Post. feeding) Pituitary Anti-Diuretic Hormone Helps the body regulate blood pressure & water (osmotic) balance  Gland: Produced by hypothalamus, released by the posterior pituitary Target tissue: kidneys Antidiuretic Effect: elevates blood pressure by Hormone - ADH causing (also called kidneys to reabsorb water from urine back into “vasopressin”) blood (p. 308) blood vessels to constrict  Antidiuretic Hormone (ADH) Regulation Stimulated by: low blood pressure detected by hypothalamus Inhibited by: negative feedback exerted by increased blood pressure Alcohol = anti-anti-diuretic = diuretic NOTE: Actually covered in Section 13.1 – p. 441! (it inhibits ADH!) FYI: Alcohol inhibits ADH! Alcohol = anti-anti-diuretic = diuretic http://cache.gizmodo.com/assets/images/4/2009/03/5a64459e854ceb76_Have2p-iPhone-App.jpg  Diabetes insipidus: FYI: Diabetes derives from ADH production of large ancient Greek words meaning “siphon” and Disorder: volumes of urine “passing through” Caused by Diabetes hyposecretion of “Diabetes” therefore Insipidus ADH means to make lots of Results in urine dehydration & loss of ions from blood Corrected by administering ADH Hormones of the Anterior Pituitary Prolactin (PRL) Gland: Anterior pituitary Target: mammary glands Effect: stimulates production of milk FYI: “Milk men” Men produce oxytocin & prolactin 🡪 some are able to lactate! http://4.bp.blogspot.com/_Di1HzTLtBlM/RreOA_vv4UI/AAAAAAAABdk/X7l7gt31uiE/s400/lactating+man.jpg  Human Growth Hormone - hGH (also called “somatotropin hormone”) Gland: Anterior pituitary Target: nearly all cells (e.g., muscles, connective tissue, bones and other tissues) Effects: promotes growth by: stimulating protein synthesis, Stimulating stimulating cell division and growth, fat breakdown Most active during puberty Growth Hormone (hGH) Hyposecretion 🡪 Pituitary Dwarfism (children) Hypersecretion 🡪 Gigantism (children) http://commons.wikimedia.org/wiki/File:Gustaf_Edman.jpg  Growth Hormone (hGH) Hypersecretion🡪 Acromegaly (adults) Thickening of jaw, feet, hands FYI: Hard to diagnose at first Often accompanied by arthritis, heart and kidney failure, blindness Andre the Giant http://passionweiss.com/wp-content/uploads/2009/02/anybody-want-a-peanut-the-princess-bride-53263_365_788.jpg http://commons.wikimedia.org/wiki/Category:Andr%C3%A9_the_Giant#mediaviewer/File:Andre_in_the_late_%2780s.jpg  FYI: the Human Growth Hormone Feedback Loop is really complicated! SMS = somatostatin GHRH = growth hormone releasing hormone IGFs = Insulin-like growth factors IGFBPs = Insulin-like growth factor binding proteins The Anterior Pituitary also releases many tropic hormones TSH – Thyroid Stimulates the thyroid gland to stimulating hormone release thyroxine ACTH – Adrenocorticotropic Stimulates the adrenal cortex to hormone release cortisol FSH & LH – Follicle-stimulating Stimulate the gonads to release sex hormone & luteinizing hormones hormone Let’s Review  The body secretes over 200 known hormones Which hormones and glands do I need to For each of the hormones we cover in class, know? know What happens if there is too Which gland releases the What is the target tissue? little (hypo) or too much hormone and when? What is the effect? (hyper) secretion? **Only for some hormones***  Use a diagram to learn the location of glands. Make a small cue card for each hormone with the gland, target organ, and effect. A Suggested Make a large cue card for each feedback loop Plan of that shows how the hormones work together Action Each day (including weekends) learn 3 new hormones, and review previous hormones. You can learn all the glands and hormones and still have a few days review! ☺ The Thyroid and Parathyroid http://www.cartoonstock.com/lowres/for0436l.jpg  Thyroid Gland (in neck) Regulates metabolic rate: thyroxine lowers blood calcium levels by another hormone called calcitonin  Thyroxine (T4): Major metabolic hormone Target: most cells Effect: speeds up cellular respiration by speeding up metabolism of fats, proteins, & carbohydrates for energy. Requires 4 iodine atoms per molecule of thyroxine FYI, thyroglobulin + 4 iodine molecules 🡪 thyroxine Q: Where do we get dietary iodine from? http://www.diamondcrystalsalt.com/Images/culinary/restaurant_large.jpg Thyroxine Secretion Stimulated by: TSH from anterior pituitary Inhibited by: negative feedback from thyroxine & its effects anterior Disorders of the Thyroid Gland Hyposecretion (low levels of thyroxine) a. Childhood Hypothyroidism (previously called Cretinism) Irreversible mental and physical delays b. Adulthood Hypothyroidism Gain weight easily, feel cold, tired, and sluggish Slow mental responses Treated with synthetic thyroxine Disorders of the Thyroid Gland Hyperthyroidism (excess thyroxine) Graves Disease (severe hyperthyroidism) Weight loss, higher body temperature Insomnia, nervousness, and irritability Eyes protrude http://commons.wikimedia.org/wiki/File:Proptosis_and_lid_retraction_from_Graves%27_Disease.jpg Disorders of the Thyroid Gland Goitre (hypo thyroxine & hyper TSH) Hyposecretion of thyroxine due to damage or a lack of dietary iodine lack of negative feedback 🡪 TRH ↑ 🡪 TSH ↑ causes thyroid gland to swell http://commons.wikimedia.org/wiki/File:Goitre.jpg http://www.diamondcrystalsalt.com/Images/culinary/restaurant_large.jpg Calcitonin – Lowers Blood Calcium levels Target: bone cells Effect: Stimulates uptake of calcium INTO bones when the concentration of calcium in blood is too high Stimulated by: high levels of [Ca2+] in blood Inhibited by: low levels of calcium in blood OR Parathyroid Hormone  Parathyroid Gland - PTH Four Small glands attached to thyroid Releases parathyroid hormone Target: bone cells & kidneys Effect: breaks down bone to release calcium INTO blood; tells kidneys to reabsorb calcium from urine Stimulated by: low blood calcium levels Inhibited by: “High” blood calcium levels or calcitonin  What you need to know Hypothalamus & pituitary ADH, GH, PRL, tropic hormones Thyroid: thyroxine & calcitonin Disorders of the thyroid gland Parathyroid: PTH 13.3: The Adrenal Glands & the Stress Response Short term stress response: adrenal medulla hormones Long term stress response: adrenal cortex hormones Addison’s disease Textbook p. 451-455 http://smartmarketingguide.com/reviews/wp-content/uploads/2008/10/stress-cartoon.gif  Adrenal Glands: 2 layers 1. Adrenal Medulla: middle layer 2. Adrenal Cortex: outer layer (80-90%) Both layers produce hormones that help us respond to stress !  The Science Of Stress National Geographic Video Clip (3 min) http://video.nationalgeographic.com/video/science-stress-sci?source=relatedvideo http://www.kalavati.org/images/how-does-stress-affect-health01.gif Different types of stress; different adrenal response Short term stress response 🡪 adrenal medulla (epinephrine/norepinephrine) Long term stress response 🡪 adrenal cortex (cortisol & aldosterone) Adrenal Medulla (Inner layer) 🡪 Short Term Stress Response Prepares body for flight-or-fight controlled by the sympathetic nervous system (neurons rather than hormones cause release of adrenaline/noradrenaline) effects short-lived (inactive within 3min) http://commons.wikimedia.org/wiki/File:Hondius_Fight_between_a_dog_and_a_heron.jpg Short term stress response: Epinepherine (adrenaline) & norepinephrine (noradrenaline) Target: adrenaline 🡪 many cells noradrenaline 🡪 brain Effects: breakdown of glycogen in liver to glucose increases heart & breathing rate, blood pressure decreases digestive activity; blood re-routed to heart & muscles constricts blood vessels in skin, improves blood coagulation dilates pupils Epinephrine (Adrenaline) and Norepinephrine (Noradrenaline) Regulation Stimulated by sympathetic nerves coming from hypothalamus Inhibited by parasympathetic nerves FYI: The “Epi” Pen! shot of epinephrine Given during anaphylactic shock (nut allergy, bee venom, other chemicals) stimulates heart muscle contraction and opening of airways! Effects can wear off before allergic reaction is finished http://z.about.com/d/firstaid/1/0/R/A/-/-/EpiPen29.jpg Adrenal Cortex: Long-Term Stress Response controlled by hormones (not nerves) stimulated by ACTH from anterior pituitary inhibited by: negative feedback o cortisol in blood inhibits RH production in hypothalamus & ACTH production in anterior pituitary effects are long-lived (hours, days, etc.) Adrenal Cortex: Long-Term Stress Response Produces steroid hormones called corticoids 1. Glucocorticoids (cortisol): increase blood sugar 2. Mineralocorticoids (aldosterone): increase blood pressure 3. gonadocorticoids (small amounts of testosterone) 🡪 supplement sex hormones 1. Glucocorticoids (Cortisol) Targets: muscle and fat cells Effects: Overall: Increases blood glucose level 🡪 provides energy breaks down muscle protein and fats 🡪 liver uses these to make glucose suppresses immune system (FYI: one reason why long term stress is unhealthy!) Can Stress Kill you? (ASAP Science) https://www.youtube.com/watch?v=vzrjEP 5MOT4 Cortisol/ACTH Feedback Loop 2. Mineralocorticoids (Aldosterone) Helps regulate balance of Na+, K+, and water (blood pressure) in blood Target: kidney Effects: 🡪 Na+ and blood pressure, 🡪 K+ in blood o Na+ and water are reabsorbed into the blood o K+ is secreted from the blood back into the forming urine 3. Gonadocorticoids (Testosterone) Normally insignificant effects in adults. But... can lead to female masculinization if hypersecreted! http://commons.wikimedia.org/wiki/Bearded_Lady#mediaviewer/File:Annie_Jones.jpg Adrenal Gland Disorder: Hyposecretion: Addison’s Disease Caused by: damage to adrenal cortex Symptoms: low blood sugar (hypoglycemia) Na+/K+ imbalances low blood pressure weight loss fatigue and weakness Treatment: cortisol and aldosterone injections  Adrenal medulla hormones (epinephrine) & the short term stress response Adrenal cortex hormones (cortisol, testosterone) & the long term stress response: Addison’s disease IT’S TIME FOR ANOTHER POP QUIZ! ☺ 1. Name 5 endocrine glands 2. How does the hypothalamus control the anterior pituitary? 3. Name 2 hormones that are released in response to nerve impulses 4. Name 1 releasing hormone from the hypothalamus 5. Name 6 anterior pituitary hormones 6. What is the target tissue of TSH? 7. Name three hormones associated with increasing your body’s temperature. 8. What disorder is caused by hyposecretion of ADH? 1. Name 5 endocrine glands: Hypothalamus, anterior/posterior pituitary, thyroid, adrenals, pancreas (also: kidney, pineal), ovaries, testes, parathyroid 2. How does the hypothalamus control the anterior pituitary? RHs and IHs 3. Name 2 hormones that are released in response to nerve impulses. ADH, oxytocin, epinphrine/norepinephrine 4. Name 1 releasing hormone from the hypothalamus. GnRH 5. Name 6 anterior pituitary hormones: hGH, FSH, LH, ACTH, PRL, TSH 6. What is the target tissue of TSH? Thyroid 7. Name three hormones associated with increasing your body’s temperature. (T)RH, TSH, thyroxine 8. What disorder is caused by hyposecretion of ADH? Diabetes insipidus 13.4 Hormonal Regulation of Blood Sugar Blood glucose levels Glucagon Insulin Diabetes mellitus Textbook p. 456-459 http://www.cartoonstock.com/newscartoons/cartoonists/jlv/lowres/jlvn1365l.jpg Pancreas (behind stomach) both an exocrine and endocrine gland Exocrine Gland Function secretes pancreatic juice through a duct to small intestine to aid digestion Endocrine Gland Function areas called Islets of Langerhans with clusters of specialized cells that secrete antagonistic hormones to control blood sugar levels Pancreas  Today’s lecture is brought to you by the letter “G” http://1.bp.blogspot.com/_P6Kg5C9CX2A/SH5EDRazfmI/AAAAAAAAA1o/4P5Pkv3YgEY/s400/sesamestreet2.jpg http://comcastchd.vo.llnwd.net/o15/resized/008f7afb-95ce-41b0-bd5e-9c2a00bdf0ee.jpg Important G-words Blood Glucose Levels (BGLs): free glucose in the blood; available energy Glycogen: chains of stored glucose in liver and muscles; not available as energy Glucagon: pancreatic hormone that increases BGLs Alpha cells 🡪 produce glucagon Targets: liver and adipose tissue Effects: increases blood glucose levels Initiates breakdown of glycogen into glucose Stimulates production of glucose from fat Alpha cells 🡪 produce glucagon Regulation Stimulated by: low blood sugar Inhibited by: negative feedback o Once BGLs have increased, glucagon secretion is inhibited Hormones that increase BGLs Hormone Gland Effect 1. Epinephrine Adrenal medulla Fat/protein breakdown Norepinephrine 🡪 releases sugar 2. Cortisol Adrenal cortex Fat/protein breakdown 🡪 releases sugar 3. Glucagon Alpha cells of pancreas Conversion of glycogen to glucose in liver & fat breakdown Beta cells 🡪 produce insulin Target: all cells Effect: lowers blood glucose levels Body cells take up & use glucose for E Stimulates conversion of glucose 🡪 glycogen in liver Stimulates fat storage and protein synthesis Beta cells 🡪 produce insulin Regulation: Stimulated by: high blood glucose Inhibited by: negative feedback once BGLs have decreased, insulin secretion is inhibited Note: blood glucose levels are also decreased by thyroxine!  Hormones that decrease BGLs Hormone Gland Effect 1. hGH Anterior pituitary Boosts metabolism 🡪 glucose is utilized 2. Thyroxine Thyroid Boosts metabolism 🡪 glucose is utilized 3. Insulin Beta cells of pancreas Body cells take up glucose, conversion of glucose to glycogen in liver, fat storage/protein synthesis) Putting it all together! Diabetes Mellitus: Insulin hyposecretion Type I: not enough insulin Type II: body cells cannot respond Gestational: body cells cannot respond Result: hyperglycemia because cells can’t take up or store glucose; protein /fat metabolized for energy (“acetone breath”). Q: Why are untreated diabetics starving (to death) for glucose? A: Without insulin, the cells of the body cannot take up and use glucose for energy Effects of diabetes mellitus BGLs rise after a meal & remain high kidneys can’t reabsorb glucose >10 mmol/L 🡪 glucose is found in the urine. Blindness, kidney failure, nerve damage, gangrene Risk factors: http://www.diabetes.org/diabetes-basics/prevention/diabetes-risk- test/ Graphic Image Alert! Diabetic Foot FYI: “Diabetic Foot” high BGLs damage arteries/veins poor circulation to lower extremities delayed wound healing, ulcers, gangrene http://www.health-mania.com/wp-content/uploads/2009/06/diabetic-foot.jpg http://www.unchealthcare.org/site/woundmanagement/images/DM990730.JPG  FYI: Maggot Debridement Therapy (MDT) “biotherapy” (has been used for centuries!!!) disinfected fly larvae placed on damaged tissue: o selectively eat necrotic (dead) tissue o disinfect the damaged tissue (kill bacteria) o promote wound healing http://3.bp.blogspot.com/_vaqCjVyoA_c/SQICdzv3f9I/AAAAAAAABjs/c84jsDpwIKI/s320/Maggot-Therapy-in-a-Small-Wound.jpg 1. Type I Diabetes Mellitus (5-10%) AKA: “Juvenile”, “insulin-dependent” autoimmune disease: attacks beta cells 🡪 produce little to no insulin usually develops in youth but can appear at any age risk factors: mainly genetic symptoms: sudden onset of o ↑ thirst & urination (glucose in urine) o constant hunger o weight loss o extreme fatigue 1. Type I Diabetes Mellitus (5-10%) Treatment: o daily insulin injections (Why not orally?) o Islet cell transplantation: “The Edmonton Protocol” ❖ more permanent (but not 100%) ❖ Problems: source of cells? (xenotransplants, stem cells) immunosuppression? ❖ http://www.youtube.com/watch?v=fFnnYGDmTWY  2. Type II Diabetes Mellitus (90-95%) AKA: “adult-onset”, “insulin-independent” pancreas makes insulin but receptors on body cells don’t respond; eventually insulin production ↓ (can lead to Type I) o insulin not used effectively by body o high body fat🡪 insulin cannot get to tissues Develops: ages 40+, but becoming more common in youth Risk factors: being overweight (80%) o body fat 🡪 insulin cannot get to tissues o ↑ blood pressure & lipids 2. Type II Diabetes Mellitus (90-95%) Symptoms: gradual onset of o ↑ thirst & urination (glucose in urine) o constant hunger o weight loss o extreme fatigue Treatment: o meal planning for blood sugar control o weight loss & exercise o oral meds to manage symptoms Q: Why can’t most Type II diabetics treat their disorder with insulin injections? A: Because their body does not respond to insulin and it will have little to no effect 3. Gestational Diabetes temporary Type II diabetes triggered by high levels of pregnancy hormones chance of developing Type II after pregnancy is doubled Indonesian woman gives birth to 19 lb baby!  Type 2 Diabetes Animation http://ca.youtube.com/watch?v=VLiTbb6MaEU&feature=rela ted What you need to know How glucagon & insulin work together to regulate blood sugar levels The different types of Diabetes Mellitus Chapter 13 Concept Organizer