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Endocrine system

Endocrine system. Chapter 45. Endocrine system. Regulation & communication Blood system Glands (ductless) Hormones (chemicals) Target tissues. (a) Endocrine signaling. Blood vessel. Response. Nervous system. Regulation & communication Nerves Axon Neurotransmitters Synapse.

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Endocrine system

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  1. Endocrine system Chapter 45

  2. Endocrine system • Regulation & communication • Blood system • Glands (ductless) • Hormones (chemicals) • Target tissues

  3. (a) Endocrine signaling Blood vessel Response

  4. Nervous system • Regulation & communication • Nerves • Axon • Neurotransmitters • Synapse

  5. Both systems (overlap) • Neurohormone • Released by the nervous system • Into blood stream (ADH) • Norepinephrine • Chemical involved in both • Nervous system (cleft) • Endocrine system (adrenal gland)

  6. Both systems • Neural control of endocrine system • Hypothalamus • Regulates hormonal secretion of the anterior pituitary • Glands derived from nervous tissue • Adrenal medulla, posterior pituitary & pineal gland

  7. Local regulators • Paracrine • Messages between neighboring cells • 1. Cytokines • Regulate immune system • 2. Growth factors • Regulate cell growth • 3. NO • Vasodilation (local blood vessels)

  8. Local regulators • 4. Prostaglandins • 20-carbon fatty acid • Derived from lipids in plasma membrane • Found in many organs • Released into interstitial fluid

  9. Local regulators • 4. Prostaglandins • A. Immune system • inflammation • B. Reproductive system • Labor • Semen • C. Digestive system • Inhibit gastric secretions • Increase gut motility

  10. Local regulators • D. Respiratory system • Some cause dilation • Some cause constriction • E. Circulatory system • Platelets • F. Urinary system • Renal vasodilation • Increased excretion

  11. Figure 45.2 Blood vessel RESPONSE (a) Endocrine signaling Synapse Neuron RESPONSE RESPONSE (d) Synaptic signaling (b) Paracrine signaling Neurosecretory cell Blood vessel RESPONSE RESPONSE (e) Neuroendocrine signaling (c) Autocrine signaling

  12. Hormone types • 1. Polypeptide • Short, <100 aa, insulin, ADH • 2. Glycoprotein • >100 aa, carbohydrate attached, FSH, LH • 3. Amines • Tyrosine & tryptophan • Adrenal medulla (NE, Epinephrine) • Thyroid (T3 & T4 • Pineal (Melatonin)

  13. Hormone types • 4. Steroids • Lipids from cholesterol • Testosterone • Estradiol, progesterone • Aldosterone, cortisol

  14. Water-soluble (hydrophilic) Lipid-soluble (hydrophobic) Figure 45.4 Polypeptides Steroids 0.8 nm Cortisol Insulin Amines Epinephrine Thyroxine

  15. Mechanism of regulation • 1. Enter the cell • Lipophilic • Lipid soluble • 2. Do not enter the cell • Lipophobic • Water soluble

  16. (a) (b) Water-soluble hormone; receptor in plasma membrane Lipid-soluble hormone; receptor in nucleus or cytoplasm SECRETORY CELL SECRETORY CELL Lipid- soluble hormone Water- soluble hormone Blood vessel Blood vessel Transport protein Receptor protein TARGET CELL OR TARGET CELL Receptor protein Cytoplasmic response Gene regulation Cytoplasmic response Gene regulation NUCLEUS NUCLEUS

  17. Mechanism of regulation • 1. Lipophilic (Steroids, thyroxine) • Not water soluble • Plasma attached to protein carriers • Target cell-release carrier • Cross plasma membrane • Bind receptor protein (+/- nucleus) • Hormone receptor binds DNA • Protein synthesis

  18. Lipid-Soluble Hormone

  19. Mechanism of regulation • 2. Lipophobic or too large • Bind receptors on target cell membrane • A. Triggers second-messenger system • cAMP • IP3/Ca+2 • B. Causes change in an ion channel

  20. Water-Soluble Hormone

  21. Mechanism of regulation

  22. Mechanism of regulation

  23. Mechanism of regulation

  24. Mechanism of Regulation • Different effects on different target cells • Target cells have different • Receptors • Signal transduction pathways • Epinephrine

  25. Liver cell (b) (a) (c) Smooth muscle cell in wall of blood vessel that supplies skeletal muscle Smooth muscle cell in wall of blood vessel that supplies intestines Epinephrine Epinephrine Epinephrine β receptor β receptor α receptor Glycogen deposits Glucose Cell relaxes. Glycogen breaks down and glucose is released from cell. Cell contracts. Blood vessel constricts, decreasing flow to intestines. Blood vessel dilates, increasing flow to skeletal muscle. Blood glucose level increases.

  26. Thyroid • Neck • 2 lobes/isthmus • T4 (tetraiodothyronine) thyroxine • T3 (triiodothyronine) • Regulates metabolism in the body • Calcitonin • Stimulates Ca2+ uptake into bones • Decreases serum Ca+2

  27. Thyroid

  28. Parathyroid glands • Neck • 4 small glands on top of thyroid • PTH (parathyroid hormone) • Increase in blood calcium levels • Stimulates osteoclasts • Break down calcium phosphate crystals • Stimulates kidneys to reabsorb Ca2+ • Activates Vitamin D

  29. Parathyroid glands

  30. Pancreas • Abdomen behind stomach • Islets of Langerhans • Insulin ( cells) • Decreases blood glucose levels • Stores in glycogen (liver/muscle) & fat (adipose cells) • Glucagon ( cells) • Increases glucose blood levels

  31. Pancreas

  32. Ovaries • Abdomen • Estrogen • Secondary female characteristics • Menstruation • Progesterone • Prepares/maintains pregnancy

  33. Testes • Inguinal region • Testosterone • Maintain male characteristics

  34. Ovaries and Testes

  35. Steroids

  36. Adrenal glands • Small glands on top of kidneys • 1. Adrenal cortex • Outer layer • 2. Adrenal medulla • Inner layer

  37. Adrenal glands • Adrenal cortex • A. Corticosteriods • Cortisol (glucocorticoid) • Increases serum levels of glucose • Gluconeogenesis • Converts aa to glucose • Exercise or fasting

  38. Adrenal glands • B. Mineralcorticoids • Aldosterone • Stimulates kidneys to reabsorb Na+1 • Stimulates kidneys to eliminate K+1 • C. Gonadocorticoids • Androgens • Sex characteristics

  39. Adrenal glands • Adrenal medulla • Catacholamines • Epinephrine/norepinephrine • Increased heart rate, BP, glucose blood levels, • Dilation of bronchioles • Decreased blood flow to skin and gut

  40. Adrenal glands

  41. Pituitary gland (hypophysis) • In the brain • Hangs by a stalk from hypothalamus • 1.Anterior • Adenohypophysis • Developed from epithelial tissue • 2. Posterior • Neurohypophysis • Developed from the neural tissue • Nerve axons from hypothalamus end here

  42. Pituitary gland

  43. Anterior pituitary gland • All hormones stimulate growth in target organs • Tropins • A. GH (growth hormone) • Somatotropin • Stimulates muscle growth (bone)

  44. Anterior pituitary gland • B. ACTH • Adrenocorticotropic hormone • Corticotropin • Stimulates adrenal cortex (cortisol) • C. TSH • Thyroid-stimulating hormone • Thyrotropin • Stimulates thryroid to produce thyroxine

  45. Anterior pituitary gland • D. LH • Luteinizing hormone • Stimulates ovulation & lining of uterus • Stimulates testes to produce testosterone

  46. Anterior pituitary gland • E. FSH • Follicle stimulating hormone • Stimulates the egg development • Development of sperm • F. Prolactin • Stimulates mammary glands to produce milk

  47. LH, FSH

  48. Anterior pituitary gland • G. MSH • Melanocyte-stimulating hormone • Regulates skin color in some fish, amphibians & reptiles • Regulates pigment distribution in melanocytes • Mammals: hunger & pigment

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