BIOL 1030 – TOPIC 18 LECTURE NOTESTopic 18: Hormones and the Endocrine System (Ch. 45)I. function A. coordination and regulation of body functionsB. via regulatory molecules (chemical signals are easy to send in the bloodstream and can have target specificity)II. types of regulatory moleculesA. neurotransmitters (wait for nervous system)B. hormones – secreted by endocrine glands, carried in blood, only target cells respondC. autocrine regulators – not transported in blood, acts within an organ on cells similar to the secretory cellsD. paracrine regulators – same as autocrine, but acts on cells of a different tissue type from secretory cellsE. pheromones affect other individuals of the same species; often used for sexual attraction or signaling, but also for control; typically produced by exocrine glandsF. there is some overlap; definition based on how transported and used, not chemical identityIII. autocrine and paracrine regulationA. many typesB. common autocrine: cytokines in immune system (actually travel in the blood)C. paracrine examples1. growth factors (stimulate cell division and proliferation)2. prostaglandins-modified lipids-many functions, including promoting pain and fever in inflammation and stimulating smooth muscle contraction-NSAIDS inhibit (includes aspirin) by inhibiting making of prostaglandinsIV. how hormones workA. lipid-soluble hormones enter target cells1. includes steroid hormones and thyroxine2. travel in blood attached to protein carriers3. steroids-derived from cholesterol-bind to receptor proteins in the cytoplasm or nucleus of the target cell-complex binds to specific DNA region, activating or enhancing gene transcription-examples: cortisone, testosterone, estrogen, progesterone4. thyroxine – the thyroid hormone-modified form of tyrosine produced by the thyroid gland-contains 4 or 3 iodine atoms (most made with 4)-within target cells, all converted to 3-iodine form-bind with receptors in the nucleus-initiates growth-promoting mRNA synthesis-stimulates oxidative respirationB. water-soluble hormones do not enter target cells1. peptide, glycoprotein, and catecholamine hormones2. bind to receptors in the target cell plasma membrane (example: G proteins)3. binding often brief and reversible (one hormone molecule can affect many cells)4. second messengers needed to transmit signal inside-examples are cyclic AMP (cAMP), inositol trisphosphate (IP3), Ca++-different cells may respond differently to the same second messenger-many intermediate messengers may be involved (signaling pathways)-may or may not involve transcriptional activationV. major endocrine glands and their hormones (focus on humans)A. pituitary gland1. two-part gland below hypothalamus of brain: anterior and posterior2. controlled by hypothalamus3. produces 9 major hormones4. many of these hormones affect other hormone-producing glands; thus, pituitary often called the "master gland"5. posterior pituitary-actually formed from neural tissue-hormones actually made in hypothalamus but secreted by pituitary-antidiuretic hormone (ADH, or vasopressin) stimulates water retention in kidneys damage or alcohol inhibition leads to excessive urination1 of 3BIOL 1030 – TOPIC 18 LECTURE NOTES-oxytocin stimulates uterine contraction during childbirth initiates mild release with nipple stimulation major signaling molecule in female orgasm6. anterior pituitary-develops from epithelial cells from roof of mouth-makes its own hormones-many stimulate growth (tropic hormones) growth hormone (GH) or somatotropin – stimulates growth of muscle, bone, some other tissues adrenocoritcotropic hormone (ACTH) or corticotropin – stimulates production of corticosteriods in adrenal cortex thyroid-stimulating hormone (TSH) or thyrotropin – stimulates production of thyroxine in thyroid luteinizing hormone (LH) – stimulates testosterone production, ovulation, and corpus luteum formation; a gonadotropin follicle-stimulating hormone (FSH) – another gonadotropin; required for spermatogenesis and development of ovarian follicles prolactin (PRL) – stimulates breasts to produce milk melanocyte-stimulating hormone (MSH) – stimulates synthesis and dispersion of melanin; no known functionin mammalsB. thyroid – a metabolic thermostat1. located in front of the neck2. produces-thyroxine: increases metabolic rate, promotes growth; promotes metamorphosis in amphibians-calcitonin: stimulates Ca++ uptake into bones3. goiter: enlarged thyroid due to insufficient iodine in dietC. parathyroid: builders of bones1. four small glands attached to the thyroid2. produces parathyroid hormone (PTH)-one of only two hormones absolutely essential for survival-stimulates osteoclasts to dissolve calcium phosphate in bone, leading to increase in blood Ca++ level-stimulates reabsorption of Ca++ in kidneys-activates vitamin D to absorb Ca++ from food in intestineD. adrenal glands1. two glands, one above each kidney2. inner and outer portions3. inner – adrenal medulla: emergency warning siren-activate "fight or flight" response to stressors-releases epinephrine (adrenalin) and norepinephrine-stimulates rapid deployment of body fuel: faster heartbeat, increased blood pressure, increased blood sugar (in pancreas, inhibited insulin production and stimulated glucagon production), dilated blood vessels, dilated bronchioles, increased blood flow to the heart and lungs, decreased blood flow to the skin and digestive organs4. outer – adrenal cortex: mineral and glucose balance-make steroid hormones-produces aldosterone a mineralocorticoid (regulates mineral balance) second hormone absolutely essential for survival stimulates kidneys to reabsorb Na+ – essential for normal blood volume maintenance (remember how most water is reabsorbed from the kidneys) stimulates kidneys to secrete K+ into the urine-produces cortisol (hydrocortisone) a glucocorticoid (regulates glucose balance) stimulates conversion of protein from muscles to glucose in liver also anti-inflammatory; used to treat rheumatoid arthritisE. pancreas: the body's dietician1. located behind the stomach2. also an exocrine gland that secretes digestive enzymes3. two antagonistic hormones, insulin and glucagon, produced in cell clusters called islets of Langerhans4. insulin lowers blood glucose level by activating uptake of glucose by cells and conversion of glucose to glycogen or fat2 of 3BIOL 1030 – TOPIC 18 LECTURE NOTES5.