BIOL 1203 Week 1 Endocrine System PDF

BIOL 1203 – Week 1 Endocrine System Endocrine Lab Learning Outcomes Endocrine glands Hormones Disorders from the hyposecretion or hypersecretion of hormones Homeostasis (roles of the nervous system and endocrine system together) Brief discussion of “Test Anxiety” ...

BIOL 1203 – Week 1 Endocrine System Endocrine Lab Learning Outcomes Endocrine glands Hormones Disorders from the hyposecretion or hypersecretion of hormones Homeostasis (roles of the nervous system and endocrine system together) Brief discussion of “Test Anxiety”  Gland: Organ that releases a secretion (hormone, enzyme, etc) Exocrine Glands Endocrine Glands Secretion is discharged onto the Secretion (hormone) is discharged into surface of an epithelium (e.g. skin, the interstitial fluid and enters the digestive tract) bloodstream Examples: Examples: Sudoriferous (sweat) glands Pituitary gland Mammary glands Thyroid Salivary glands Adrenal glands Pancreas (acinar cells) Pancreas (Islets of Langerhans) Hormones = get moving, exciting A molecule (chemical messenger) that is released in one part of the body and regulates the activity of another part of the body Each hormone has its own receptor in the target organs Different hormone structures: Steroid hormones (testosterone, estrogen, progesterone) Amine hormones (epinephrine, thyroxine), peptides hormones (ADH, oxytocin), protein hormones (insulin, growth hormone) Functions of hormones 1. Stimulate secretions by exocrine glands (E.g. Prolactin from pituitary gland stimulates milk secretion from mammary glands) 2. Stimulate secretion of hormones from other endocrine glands (E.g. TSH from pituitary stimulates secretion of thyroid hormones) 3. Regulate metabolic reactions and changes in body’s biochemistry (E.g. Insulin from pancreas stimulates glycogenesis, parathyroid hormone increases calcium in blood) 4. Regulate muscle contraction and nervous stimulation (E.g. Epinephrine from adrenal gland increases heart rate) 5. Regulate growth and development (E.g. Thyroid hormone accelerate body growth and development) 6. Regulate reproduction (E.g. Estrogen from the ovaries regulate the menstrual cycle) Hormones Consider for each hormone: 1. What stimulates it? 2. What organ does it affect? 3. What is the overall effect? Hypothalamus and Pituitary Gland The hypothalamus is the control centre that targets the pituitary gland (e.g., blood osmotic pressure, glucose level, some hormone concentrations, temperature) The pituitary gland is divided into the anterior and posterior glands Hypothalamus works differently on each Eight hormones from the hypothalamus Five “releasing” hormones stimulates the anterior pituitary One “inhibitory” hormone inhibits release of a hormone from the anterior pituitary Two are produced in the hypothalamus secreted by the posterior pituitary Hypothalamus and Anterior Pituitary Hypothalamus secretes five releasing hormones which tells the anterior pituitary to “release” the corresponding hormone (“stimulating hormone”) from different organs The hypophyseal portal system refers to blood vessels at the base of the brain connecting the hypothalamus with the anterior pituitary Releasing hormones of the hypothalamus 1. Adrenocorticotropic hormone releasing hormone 2. Thyroid stimulating hormone releasing hormone 3. Gonadotropin releasing hormone 4. Growth hormone releasing hormone 5. Prolactin releasing hormone (pregnancy only) 1. Adrenocorticotropic hormone Hypothalamus releasing hormone Anterior Pituitary Adrenocorticotropic hormone Adrenal Cortex Cortisol 2. Thyroid stimulating hormone Hypothalamus releasing hormone Anterior Pituitary Thyroid stimulating hormone Thyroid Thyroxine 3. Hypothalamus Gonadotropin releasing hormone Anterior Pituitary Luteinizing hormone Follicle-stimulating hormone Ovaries and Eggs Testes Growth of organs, eggs Growth of organs, sperm Estrogen, Progesterone Testosterone 4. Growth hormone Hypothalamus releasing hormone Anterior Pituitary Growth hormone Various tissues 5. and 6. 5. Prolactin releasing hormone (PRH) – in pregnancy, stimulates prolactin release from the anterior pituitary to act on mammary glands to produce milk (lactation) 6. Prolactin inhibiting hormone (PIH) – inhibits the levels of prolactin released from the anterior pituitary (normal conditions) Hypothalamus and Posterior Pituitary Produced by the hypothalamus, released by the posterior pituitary Hypothalamus and posterior pituitary connected by a stalk (infundibulum) that contains both nerve cells and blood vessels Hormones secreted from the Posterior Pituitary 7. Oxytocin: causes contraction of the uterus which is important during childbirth and the release of milk (milk ejection reflex) during breastfeeding 8. Antidiuretic hormone: increases water absorption in the kidney When things go wrong… Over or under activity of endocrine glands can lead to increased or decreased amounts, respectively, of hormone secreted Anterior Pituitary Growth hormone Leads to physical growth Increased metabolism, cell size, bone and muscle growth In adults, needed for maintenance of bone and muscle mass, also to promote healing and tissue repair Growth hormone Hyposecretion Hypersecretion Childhood Pituitary dwarfism Gigantism -epiphyseal plates -abnormally large person close before normal growth completes -can be prevented by administering growth hormone before the plates close Adult Simmond’s disease Acromegaly -weakness, weight -thickening of bones and loss, body tissue various other tissues wasting away Posterior Pituitary Hyposecretion of ADH leads to diabetes insipidus Can be caused by damage of posterior pituitary or hypothalamus Symptoms include polyuria and extreme thirst (polydipsia) Hormones of the Thyroid 1. Thyroid hormone (thyroxine) Stimulated by thyroid stimulating hormone (anterior pituitary) Effects: increased basal metabolic rate, increased breakdown of fats and carbohydrates, affects protein metabolism, synthesis of sodium potassium pumps, involved in the development of nervous and skeletal systems  Either the anterior pituitary or thyroid gland is affected that changes levels of thyroxine… Hyposecretion Hypersecretion Childhood Cretinism Grave’s disease (increased -poor growth, lethargy, metabolic rate, nervous, easy weight gain, irritable, protruding eyes) mental delay -same for children and Adult Myxedema adults -decreased body Goiter (increased thyroid metabolism, body gland size) can be caused tissue swelling, easy by lack of iodine in diet weight gain -controlled by surgery or drugs Hormones of the Thyroid 2. Calcitonin Regulated by negative feedback of calcium ion levels in the blood Reduces blood calcium and phosphate levels Hormones of the Parathyroid Parathyroid hormone Also regulated by negative feedback of calcium ion levels in the blood Increases blood calcium levels Adrenal glands 2 structural areas - each producing their own set of hormones Adrenal cortex Outer zone: produces mineralocorticoids Aldosterone: reabsorption of Na+, leading to increased water reabsorption and excretion K+, H+ from kidney Middle zone: produces glucocorticoids Cortisol: stimulated by anterior pituitary; responds to stress, increases muscle metabolism, increases sugar storage via gluconeogenesis, other effects Inner zone: produces androgens in male and female is primary source until puberty when sex glands take over; involved in the development of secondary sex characteristics  Cortisol Abnormal secretions of cortisol from the adrenal cortex (either the adrenal gland not working, or is overstimulated by the anterior pituitary) Hyposecretion Hypersecretion Addison’s disease Cushing’s syndrome Hypoglycemia Redistribution of body fat (legs become thin, Muscle weakness face swells, hump on back) Mental lethargy Flushed facial skin Weight loss Bruising and poor wound healing Hyperglycemia, hypertension Polyuria and increased thirst Adrenal medulla Produces: Epinephrine (adrenaline) Norepinephrine (noradrenaline) Both are also neurotransmitters that respond to fear, excitement and danger Both hormones increase blood pressure Epinephrine increases blood flow to heart and muscles (and increases bronchial dilation) Norepinephrine decreases blood flow to the intestines and skin Hormones of the Pancreas Produced by the islets of Langerhans Alpha cells produce glucagon Several targets Main effect is to increase blood glucose levels Beta cells produce insulin Several targets Main effect is to decrease blood glucose levels (cells take in glucose) Ovaries Stimulated by follicle-stimulating hormone and luteinizing hormone Produces estrogen and progesterone Progesterone also produced by the corpus luteum and involved in ovulation and pregnancy Leads to the development of primary (growth of uterus and vagina) and secondary (body hair, breasts, pelvis) sex characteristics Testes Also stimulated by follicle stimulating hormone and luteinizing hormone Produces testosterone Leads to the development of primary (penis and accessory glands) and secondary (body hair, voice changes) sex characteristics Undercover endocrine organs Hormonal secretions are not their main job 1. Placenta: human chorionic gonadotropin (hCG), estrogen, progesterone 2. Stomach: gastrin to produce gastric juice 3. Duodenum: secretin and cholecystokinin Less understood endocrine organs 1. Thymus gland Secretes thymosins – involved in the development of immune system Larger as a baby, decreases in size as age increases 2. Pineal gland Secretes melatonin – acts on the hypothalamus to change levels of luteinizing hormone Also responds to light and may be related to daily rhythms Homeostasis When the body gets stressed Homeostasis The condition where the internal environment is relatively constant Internal environment is the extracellular compartment (in the body, outside of cells) A constant balance of gases and nutrients, temperature and pressure Stress = any stimulus that leads to an imbalance to homeostasis External: eg. heat, cold, loud noise Internal: eg. pain, emotion, increased blood pressure Adaptation In order to survive, the body must adapt and regain homeostasis, usually done through negative feedback Done through two systems: autonomic nervous system and endocrine system Both are controlled and monitored by the hypothalamus Endocrine vs. Nervous Nervous system: releases neurotransmitters, which act locally (on nerve, muscles, glands), fast-acting Endocrine system: releases hormones, which act at distant locations around body, slow-acting, long-lasting Both directed by the hypothalamus Function together to coordinate and regulate activities of all the other body systems Dealing with stress 1. Alarm phase Nervous system stimulated first Fast acting but short-lived 2. Resistance phase Endocrine system kicks in Long lasting, but needs time to get started 3. Exhaustion phase Endocrine system breaks down Hormones no longer work Organ failure= stress-related diseases e.g. IBS, migraine, hypertension, depression Control of blood glucose levels Insulin and glucagon counter each other in terms of their effects Insulin Glucagon Produced by beta cells of the Produced by alpha cells of the pancreas after eating pancreas when fasting Lowers blood glucose levels to Increases blood glucose levels to physiological conditions by: physiological conditions by: Increasing cellular glucose uptake Stimulating gluconeogenesis Stimulating glycogen synthesis Stimulating glycogen breakdown Stimulating fatty acid synthesis Stimulating triglyceride Stimulating triglyceride synthesis breakdown Role of insulin in glucose homeostasis Role of glucagon in glucose homeostasis Other hormones Other hormones have the same main effect as glucagon, which is to increase blood glucose levels: Epinephrine – breakdown of glycogen Growth hormone – increase fat breakdown, decrease sugar usage Adrenocorticotropic hormone – produces glucocorticoids (cortisol) to increase gluconeogenesis Thyroid hormone has complicated effects and can decrease or increase blood glucose levels Loss of blood glucose level control Diabetes mellitus Loss of insulin No uptake of glucose (leading to hyperglycemia) Leads to ketoacidosis Two types: Type I – juvenile – beta cells are destroyed by immune system Type 2 (90% of cases) – mature onset – cells do not respond to insulin; pancreas responds by making more insulin and eventually beta cells become “exhausted” Hyperinsulinemia Leads to hypoglycemia Symptoms: anxiety, sweating, tremors, increased heart rate Leads to unconsciousness, coma Blood calcium levels Most of the calcium in the body is stored in the bone Needs some circulating calcium for: Blood clotting Release of neurotransmitters Muscle contraction Normal heartbeat For normal functioning, need a constant blood calcium level Control of blood calcium levels Calcitonin Parathyroid hormone Released from thyroid gland when Released from parathyroid gland when blood calcium levels increase blood calcium levels decrease Works to decrease blood calcium levels Works to increase blood calcium levels to physiological conditions by: to physiological conditions by: Stimulating osteoblasts to absorb Inhibiting osteoblasts calcium to make bone Stimulating osteoclasts to Reducing osteoclast activity breakdown bone release calcium and phosphorus (phosphorus is excreted from the kidneys) Increasing calcium absorption in the GI tract Loss of blood calcium level control Hyperparathyroidism: Too much parathyroid hormone Over breakdown of bone Bone become weak, deform and fracture easily Hypoparathyroidism: Too little parathyroid hormone Insufficient extracellular calcium Depolarization in the absence of stimuli (unable to maintain resting state of neurons) Leads to tetany (twitches, spasms, convulsions) Checklist of glands and hormones 1. Hypothalmus: GnRH, ACTHRH, TSHRH, PRH, PIH, GHRH, not secreted: oxytocin, ADH 2. Ant Pituitary: FSH, LH, ACTH, TSH, Prolactin, GH 3. Post Pituitary - not produced only secreted: oxytocin, ADH 4. Thyroid: thyroid hormone, calcitonin 5. Parathyroid: parathyroid hormone (PTH) 6. Adrenal cortex: cortisol, aldosterone, androgens 7. Adrenal medulla: epinephrine, norepinephrine 8. Pancreas: insulin, glucagon 9. Ovaries: estrogen, progesterone 10. Testes: testosterone 11. Pineal: melatonin 12. Thymus: thymosins 1. Stomach (gastrin) 2. Small intestine (secretin, CCK) 3. Placenta (hCG, estrogen, progesterone) 4. Prostaglandins Test Anxiety What is it? How can we manage it? What is test anxiety? Cycle that occurs in three stages: Before the test (eg. fearful anticipation leading up to test which can impact study habits and lead to procrastination) During the test (eg. physiological symptoms such as mind going blank, rapid heartbeat, sweating, shortness of breath, negative thoughts) After the test (eg. fear and disappointment, getting a lower score than you expected might “confirm” your worries, which then increases the likelihood of higher test anxiety and lower test performance on the next exam) Some ways to deal with test anxiety In the days/weeks leading up to the exam: 1. Study a little bit at a time with lots of breaks– don’t cram the night before because cramming reinforces anxiety 2. Do practice exams in a low pressure environment Right before and during the exam: 1. Positive self-talk can change your mindset (eg. “I can do this”) 2. Take deep breaths 3. Stay grounded (eg. when your mind starts racing, take a sip of water or feel your feet resting on the floor)