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HOMEOSTASIS, FEEDBACK, AND REGULATION Pg. 468 – Read about EPO. Starting Points; Read and Notes on pages 470-474 HOMEOSTASIS How do these chemicals called hormones help to maintain a steady state in our bodies? And what happens if they don’t?? Negative Feedback The mechanism by which homeostasis works is negative feedback…..when a deviation is offset by a corrective action in the opposite direction. Negative Feedback -substances produced by a response to changes will go back and turn off the system when HOMEOSTASIS is achieved. NEGATIVE = OPPOSITE Hormone produced by Pituitary Activates target to produce hormone Response by target organ Feedback to TURN OFF production of the pituitary hormone if negative feedback does not function properly, disorders can result (ie. gigantism - growth hormone production not turned off Endocrine glands An endocrine gland is a ductless gland whose secretions (hormones) are released directly into the blood stream where the hormone will travel to its target tissue or organ……. this contrasts exocrine glands whose secretions (e.g.enzymes)are released via ducts to their required location. Comparing the Nervous System and Endocrine system Nervous Characteristic Endocrine electrical and 2 chemical very5 fast Type of 1 message Speed of 4 message Duration of 7 message Target of the 10 effect chemical 3 short 8 muscles/glands 11 slower and 6 variable long 9 many tissues 12 and variable Chemical Signals 2 Types of Hormones: 1) Steroid hormones: made from cholesterol (lipid) and are fat soluble eg. sex hormones, cortisol - these leave the blood, ENTER the target cell, bind to receptors, go to nucleus and cause specific proteins to be produced Chemical Signals 2 Types of Hormones: 2) Protein hormones: are chains of amino acids and are water soluble eg. insulin, growth hormone, epinepherine - do NOT enter target cells but “land” on receptors on the cell surface - this causes chemical changes that activates other enzymes in the cell to carry out their functions Actions of Steroid vs. Peptide Hormones What are the common endocrine glands?? GLANDS There are many glands that regulate the body through production and release of hormones. Most of these glands are under control of hormones from the pituitary. PITUITARY -located close to the hypothalamus in the brain 2 Lobes: Anterior Lobe Posterior Lobe Hypothalamus/Pituitary Complex ANTERIOR LOBE hypothalamus sends releasing or inhibiting factors that regulate the anterior pituitary these factors travel via the bloodstream to the anterior lobe of the pituitary POSTERIOR LOBE hypothalamus makes ADH and oxytocin which are stored in the posterior pituitary these 2 hormones travel via nerve fibers to the posterior lobe of the pituitary Pituitary hormones of the posterior lobe Hormone Target Primary Function Oxytocin -Uterus, -mammary glands -uterine contractions -milk letdown ADH Kidney Increases water reabsorption from kidney ADH feedback loop Pituitary hormones of the anterior lobe HORMONE TARGET PRIMARY FUNCTION TSH Thyroid gland Stimulates thyroxin release ACTH Adrenal Cortex Stimulates release of “stress hormones” hGH (Somatotropin ) All body cells; long bones Promotes growth of bones and other tissue LH Ovaries Testes Stimulates ovulation & corpus luteum Stimulates testosterone prod. FSH Ovaries Testes Promotes follicle development Promotes sperm development Prolactin Mammary glands Stimulates milk production in females ANTERIOR PITUITARY Growth Hormone (somatotropin) -affects most cells of the body but mostly the cartilage and bone cells. HYPERPRODUCTION: gigantism and acromegaly HYPOPRODUCTION: dwarfism Acromegaly CUTTHROAT: - ONE “Asker” - TWO “Answerers” - Asker gives a hormone action; First Answerer to give the correct hormone gets a point and remains an Answerer. - Loser becomes Asker; Asker becomes Answerer. - Keep score. THYROID Located at the base of the neck in front of the trachea. Produce THYROXINE and triiodothyronine used in metabolism. People who produce a lot of THYROXINE have high metabolic rates - they oxidize food (glucose) faster, produce more heat, and have low weight. People with hypothyroidism will be subject to cold and may gain weight as glucose is first stored as glycogen then as fat. Thyroid animation THYROID THYROID Disorders: Thyroid hormones require iodine. Without iodine the thyroid enlarges and GOITER results. (negative feedback is displayed here in that low thyroxine causes TSH to continue to stimulate the thyroid causing swelling. THYROID Also makes CALCITONIN which helps regulate calcium in the blood. Causes blood calcium to DROP by ADDING calcium to bone and by causing urination of Ca2+. Parathyroid glands - behind the thyroid. Produce PTH (ParaThyroid Hormone) also used in calcium regulation (with calcitonin from thyroid). Causes blood calcium to RISE by LEACHING calcium from bone, INCREASING absorption of calcium from small intestine, and DECREASING loss of Ca2+ in the urine. THYROID REGULATION PANCREAS The pancreas produces digestive enzymes AND hormones. Hormones are produced in structures called the ISLETS OF LANGERHANS. These have TWO types of cells: alpha and beta cells. ISLETS OF LANGERHANS - Produce two hormones: 1) INSULIN - produced by beta cells of IOL. Released when blood sugar is high. Makes many cells of the body (especially liver and muscles) permeable to glucose. Muscles use the glucose for energy and liver cells store the glucose as glycogen. PANCREAS PANCREAS The pancreas produces digestive enzymes AND hormones. Hormones are produced in structures called the ISLETS OF LANGERHANS. ISLETS OF LANGERHANS - Produce two hormones: 2) GLUCAGON - produced by alpha cells of IOL. Released when blood sugar is low. Converts glycogen to glucose. PANCREAS PANCREAS Diabetes Mellitus: inefficient insulin production (perhaps due to destruction of beta Islet cells) or inefficient use of insulin in system (cells don’t respond to it). Leads to high blood glucose which can be excreted in the urine along with large volumes of water. Diabetes Mellitus Symptoms: Body cells have low energy. Lipids and Proteins may be metabolized leading to acetone build up and lower blood pH. If untreated, it may lead to blindness, kidney failure, nerve damage and limb amputation. Much research being done on cures including Islet cell transplants. Blood Glucose Levels After Ingestion of 100g of Glucose 500 450 400 350 300 Blood Glucose 250 (mg/100mL) 200 150 100 50 0 0 1 2 3 4 5 Time (h) Plasma Insulin Levels After Ingestion of 100g of Glucose 60 50 40 Plasma Insulin 30 (mU/mL) 20 10 0 0 1 2 3 Time (h) 4 5 6 Diabetes mellitus (3 types) Type I (juvenile onset) Diagnosed in childhood 10% of people with diabetes have this form Beta cells are unable to produce insulin Lots of glucose in blood, but body cells can’t access it for cellular respiration. Must take insulin injections to survive. Diabetes mellitus (3 types) Type II (adult onset) 90% of people with diabetes have this form Due to decreased production of insulin OR ineffective use of the insulin that is produced Control with diet, exercise and oral drugs Diabetes mellitus (3 types) Gestational Diabetes Temporary condition that occurs in 2% to 4% of pregnancies Increases the risk of type 2 diabetes in mother and child Lab Ex 15A p. 483 (due) ADRENAL GLAND -located above each kidney. - is two glands in one. The adrenal medulla (inside) is regulated by nervous control. The adrenal cortex (outside) is regulated by hormonal control. ADRENAL GLAND 1) Adrenal Medulla - makes two hormones: a) epinephrine and b) norepinephrine which are stimulated by the sympathetic nervous system in times of stress. Both cause glycogen----> glucose, increase heart rate and breathing rate, dilate blood vessels (more O2), dilate iris of eye to allow more light in. ADRENAL GLAND 2) Adrenal Cortex makes three different hormones: a) GLUCOCORTICOIDS - regulate blood glucose levels. ex) CORTISOL increase blood amino acids. AA’s are converted to glucose in liver. Excess aa’s can be used to synthesize proteins needed for cell repair. FEEDBACK: ADRENAL GLAND 2) Adrenal Cortex makes three different hormones: b) MINERALOCORTICOIDS - regulate mineral absorption. ex. ALDOSTERONE increase sodium retention and water reabsorption from the kidneys. c) some SEX HORMONES very small amounts . QUESTION QUESTION Use the following information to answer the next question. Q. A logical interpretation of the graph is that the A. secretion of cortisol is inhibited by increased ACTH B. secretion of cortisol is doubled if the secretion of ACTH is doubled C. adrenal glands respond more quickly to small amounts of ACTH than to large amounts of ACTH D. adrenal glands respond to large amounts of ACTH by having a maximum cortisol secretion rate CH 15 REVIEW: PG 501-503 - #1-11 – MULT CH & NUM RESP - GOOD TO READ AND REFLECT ON #12-30 HOMEOSTASIS REVIEW: P. 504-505 -#1-9 – MC &NR - READ AND REFLECT ON #10-38