Chapter 45 ppt


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Chapter 45 ppt

  1. 1. Chapter 45 Hormones & the Endocrine System Roohi Ramachandran
  2. 2. Vocab. <ul><li>Endocrine glands: ductless gland that secretes hormones directly into interstitial fluid, from which they diffuse into the bloodstream </li></ul><ul><li>Exocrine glands: have ducts that carry secreted substances onto body surfaces or into body cavities, e.g. salivary glands </li></ul><ul><li>Hormones: one of many types of secreted chemicals that are formed in specialized cells, travel in body fluids and act on specific target cells in other parts of the body to change their functioning </li></ul><ul><li>Target cells: cells that have receptors for a particular hormone </li></ul><ul><li>Neurosecretory cells: specialized neurons found in the brain that secrete molecules that diffuse from nerve cell endings into the bloodstream </li></ul><ul><li>Neurotransmitters: molecules released from the synaptic terminal of a neuron at a chemical synapse, diffuses across the synaptic cleft and binds to the postsynaptic cell, triggering a response </li></ul>
  3. 3. Nervous & Endocrine Systems <ul><li>Work together to maintain homeostasis, development and reproduction </li></ul><ul><li>Hypothalamus: receives information from nerves throughout body and brain and initiates endocrine signalling according to environmental conditions </li></ul>
  4. 4. Insect Development <ul><li>Neurosecretory cells produce PTTH </li></ul><ul><li>PTTH signals ecdysone release </li></ul><ul><li>Each ecdysone release stimulates molting </li></ul><ul><li>Juveline hormone determines effect of ecdysone; high concentration suppresses metamorphosis </li></ul>
  5. 5. Types of Signalling Molecules <ul><li>Local regulators: secreted molecules that act over short distances and reach their target cells solely by diffusion </li></ul><ul><li>Hormones: molecule secreted into extracellular fluid, circulates in blood/hemolymph and communicates regulatory messages throughout body </li></ul><ul><li>Pheromones: small molecule released into environment that functions in communication between same species; acts like hormone in animals </li></ul>
  6. 6. Inflammation <ul><li>Interleukins: regulate lymphocytes, other immune cells </li></ul><ul><li>Prostaglandins: promote inflammation & fever, intensify pain, regulate platelet aggregation (blood clotting) </li></ul><ul><li>Histamines: blood vessel dilation – more permeable to inflammatory response </li></ul>
  7. 7. Local Regulators <ul><li>Have varied effects because of differences in target cells’ reception, transduction and/or response </li></ul><ul><li>Prostaglandins: </li></ul><ul><ul><li>Childbirth: excite muscles, induce labor </li></ul></ul><ul><ul><li>Immune: fever, inflammation, intensify pain </li></ul></ul><ul><li>Nitric Oxide (NO) </li></ul><ul><ul><li>Neurons: neurotransmitter </li></ul></ul><ul><ul><li>White blood cells: kills bacteria and cancer cells </li></ul></ul><ul><ul><li>Endothelial cells: dilates the walls of blood vessels </li></ul></ul>
  8. 8. Regulation & Communication Hormones are signalling molecules. Their receptors can be affected by (non)competitive inhibitors. Negative feedback loops (feedback inhibition) regulate them.
  9. 9. Hypothalamus & Pituitary <ul><li>Hypothalamus: maintains homeostasis, coordinates endocrine & nervous systems </li></ul><ul><li>Anterior pituitary: synthesize/secrete several tropic/nontropic hormones; regulated by hypothalamus </li></ul><ul><li>Posterior pituitary: extension of hypothalamus; stores/secretes oxytocin & ADH </li></ul>
  10. 10. Pineal, Thyroid, Parathyroid <ul><li>Pineal gland: in center of brain; synthesizes/secretes melatonin </li></ul><ul><li>Thyroid gland: two lobes on ventral side of trachea; secretes iodine-containing T 3 and T 4 , which control metabolism & development; regulated by TSH (thyroid stimulating hormone) </li></ul><ul><li>Parathyroid gland: four small structures embedded in back of thyroid; regulate Ca 2+ levels (PTH decomposes bone, stimulates reabsorption in kidneys, activates Vitamin D to stimulate intestines to absorb) </li></ul>
  11. 11. Pancreas <ul><li>Islets of Langerhans: endocrine cells w/i pancreas; secrete into interstitial fluid & circulate </li></ul><ul><ul><li>Alpha cells: glucagon </li></ul></ul><ul><ul><li>Beta cells: insulin </li></ul></ul><ul><li>Insulin lowers blood glucose by stimulating glucose uptake in body cells </li></ul><ul><li>Glucagon signals liver to increase glycogen hydrolysis, convert aminos & glycerol to glucose & release glucose into bloodstream </li></ul>
  12. 12. Adrenal Glands <ul><li>Adrenal glands: near kidneys </li></ul><ul><li>Adrenal medulla: secretes epinephrine/norepinephrin in response to stress; regulates metabolism, blood pressure, etc. </li></ul><ul><li>Adrenal cortex: secrete glucocorticoids (promote glucose synthesis) and mineralocorticoids (maintain salt/water balance) </li></ul>
  13. 13. Gonads <ul><li>Gonads produce following hormones: </li></ul><ul><li>Androgen: any steroid that stimulates development of male reproductive system </li></ul><ul><li>Testosterone: major mammalian androgen </li></ul><ul><li>Estrogen: any steroid that stimulates development of female reproductive system </li></ul><ul><li>Estradiol: major mammalian estrogen </li></ul><ul><li>Progestin: any steroid w/ progesterone-like activity </li></ul><ul><li>Progesterone: steroid that prepares uterus for pregnancy; major mammalian progestin </li></ul><ul><li>All are produced in both genders – proportions differ </li></ul>