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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 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
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)
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
Local regulators • Paracrine • Messages between neighboring cells • 1. Cytokines • Regulate immune system • 2. Growth factors • Regulate cell growth • 3. NO • Vasodilation (local blood vessels)
Local regulators • 4. Prostaglandins • 20-carbon fatty acid • Derived from lipids in plasma membrane • Found in many organs • Released into interstitial fluid
Local regulators • 4. Prostaglandins • A. Immune system • inflammation • B. Reproductive system • Labor • Semen • C. Digestive system • Inhibit gastric secretions • Increase gut motility
Local regulators • D. Respiratory system • Some cause dilation • Some cause constriction • E. Circulatory system • Platelets • F. Urinary system • Renal vasodilation • Increased excretion
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)
Hormone types • 4. Steroids • Lipids from cholesterol • Testosterone • Estradiol, progesterone • Aldosterone, cortisol
Mechanism of regulation • 1. Enter the cell • Lipophilic • Lipid soluble • 2. Do not enter the cell • Lipophobic • Water soluble
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
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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
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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
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
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
Ovaries • Abdomen • Estrogen • Secondary female characteristics • Menstruation • Progesterone • Prepares/maintains pregnancy
Testes • Inguinal region • Testosterone • Maintain male characteristics
Adrenal glands • Small glands on top of kidneys • 1. Adrenal cortex • Outer layer • 2. Adrenal medulla • Inner layer
Adrenal glands • Adrenal cortex • A. Corticosteriods • Cortisol (glucocorticoid) • Increases serum levels of glucose • Gluconeogenesis • Converts aa to glucose • Exercise or fasting
Adrenal glands • B. Mineralcorticoids • Aldosterone • Stimulates kidneys to reabsorb Na+1 • Stimulates kidneys to eliminate K+1 • C. Gonadocorticoids • Androgens • Sex characteristics
Adrenal glands • Adrenal medulla • Catacholamines • Epinephrine/norepinephrine • Increased heart rate, BP, glucose blood levels, • Dilation of bronchioles • Decreased blood flow to skin and gut
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
Anterior pituitary gland • All hormones stimulate growth in target organs • Tropins • A. GH (growth hormone) • Somatotropin • Stimulates muscle growth (bone)
Anterior pituitary gland • B. ACTH • Adrenocorticotropic hormone • Corticotropin • Stimulates adrenal cortex (cortisol) • C. TSH • Thyroid-stimulating hormone • Thyrotropin • Stimulates thryroid to produce thyroxine
Anterior pituitary gland • D. LH • Luteinizing hormone • Stimulates ovulation & lining of uterus • Stimulates testes to produce testosterone
Anterior pituitary gland • E. FSH • Follicle stimulating hormone • Stimulates the egg development • Development of sperm • F. Prolactin • Stimulates mammary glands to produce milk
Anterior pituitary gland • G. MSH • Melanocyte-stimulating hormone • Causes darkening of skin in some fish, amphibians & reptiles
Posterior pituitary gland • A. ADH • Antidiuretic hormone (vasopressin) • Stimulates water retention in the kidneys • B. Oxytocin • Milk ejection from mammary glands • Stimulates uterine contractions in labor
Pineal gland • Small mass of tissue located near center of brain • Synthesizes & secretes melatonin (modified aa) • Regulates functions related to day and night • Seasons