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32 Cards in this Set
- Front
- Back
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Nervous System & Endocrine System |
2 major systems of internal communication. Endocrine system works closely with nervous system to maintain homeostasis. |
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Endocrine System Controls: |
Metabolism, growth, reproduction, blood glucose, Na+, K+, Ca++, water, and coping with stress |
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Endocrine Gland Exocrine Gland |
1) Ductless glands - The glands are highly vascularized so hormone is picked up by the blood vessels and transported by blood vessels 2) Ducts (tubes) - Includes salivary, oil, sweat glands, and most pancreas |
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Chemical Signal: Hormones |
(50 known hormones in humans) Secreted from the endocrine glands - targets cells for the hormones have receptors in their cell membranes or receptors are inside cells to respond to the hormones. Hormones secreted by neurons" epinephrine, ADH, Oxytocin, most invertebrate hormones (control regeneration in hydra, platyhelmenthes, annelids, insect molting, insect metamorphosis) (Neurosecretory cells release these hormones) |
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Chemical Signal: Local Regulators |
Chemical messengers from individual cells - Prostaglandins (Many different kinds of control, many different functions such as vasodilation, vasoconstriction, smooth muscle contraction, smooth muscle relaxation, bronchiodilation, bronchioconstriction, inhibit gastric secretion, increase/decrease BP, aid in blood clotting, stimulate contraction of uterus, cause fever, pain, inflammation) |
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Chemical Signal: Pheromones: |
Chemicals that produced that enable animals to communicate with animals of same species. (Produced by exocrine glands and not really hormones) -In humans, pheromones are probably responsible for the synchronizing menstral cycles (other examples include mate attractants, territory marking, alarm substances, trail marking in ants) |
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Nature of Hormones: Amino Acids |
Derived from hormones - (adrenaline, peptides, proteins) Includes most of the hormones especially those from the pituitary, parathyroid, thyroid, pancreas, adrenal medulla - these hormones - These hormones are polar molecules and soluble in water. |
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Nature of Hormones: Steroids |
(4 c rings, containing 17 C) synthesized from cholesterol - from adrenal cortex and gonads - are non polar and not soluble in water. (Lipid Soluble) |
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Nature of Hormones: Lipids - Prostaglandins |
(Synthesized from fatty acids in cells with damaged cell membranes; Fatty acids come from phospholipids) - All cells except RBC can produce this. They are nonpolar and not soluble in water. |
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Mechanism of Hormone Action |
Is on certain target cells |
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Direct gene Activation |
Since lipids (steroids) are soluble in cell membranes this is the mode of action for the adrenal cortex and sex steroid hormones (also thyroxine) -steroids and thyroxine pass directly through the membrane to receptors to the nucleus of target cells. Once hormone is inside the cell, the hormone binds to the receptor which then in turn activates DNA transcription and further RNA translation. Main effect of direct gene activation: synthesis of protein |
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Second Messenger System |
Virtually all aa-based hormones (water soluble hormone) exert effect through a second messenger system, most important of which is cAMP system (1st messenger = Hormone; 2nd messenger =cAMP) - Receptors on cell membrane When hormone binds to receptor in cell membrane, it activates adenyl cyclase (membrane bound enzyme) ATP> cAMP >Enzyme Activation & Cellular secretions main effect of 2nd messenger system: Enzyme activation & Cellular Secretion |
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Regulation of Hormone Secretion |
Generally by a negative feedback system; (definition is: the product (response) of hormone's action inhibits the production of more hormone (stimulus) the response is negative to stimulus. example: when Ca++ levels decrease, parathyroid hormone (PTH) is secreted; PTH causes Ca++ levels to increase; as Ca++ increases levels to increase, PTH is inhibited |
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Pituitary Gland: Anterior Pituitary |
Pituitary Gland is Controlled by hypothalamus (connected via infundibulum) Controlled via portal vein by releasing or release inhibiting hormones from the hypothalamus which travel through the portal vein to anterior pituitary. |
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Tropic hormones |
Hormones that regulate other endocrine glands TSH- Stimulates secretion of Thyroid Hormones (thyroxine) ACTH- Stimulates adrenal cortex, esp glucocorticoids (cortisol) Gonadotropic Hormones - FSH = Follicle Stimulating Hormone (ovaries & Testies) & LH= Luteinizing Hormone (stimulates Corpus Luteum in ovary & Testies) Prolactin- Stimulates milk production from mammary gland (nontropic hormone) GH- (Growth Hormone) major targets are bones and skeletal muscles (nontropic) GH stimulates growth by promoting protein synthesis by uptake of amino acids from the blood especially to synchronize growth in bones and skeletal Hyposecretion - Pituitary dwarf; Hyper Secretion - gigantism |
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Posterior Pituitary |
Hormones are produced by neurons in hypothalamus and merely stored in axon terminals (Actually an extension of the hypothalamus) |
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Posterior Pituitary: Oxytocin |
Stimulate smooth muscle in uterus to contract when cervix is dilated (positive feedback mechanism) Stimulates contractile cells around milk ducts to release milk when baby mammals nurse. |
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Posterior Pituitary: ADH (antiduretic hormone) |
1) Decreases urine by increasing water reabsorbtion from kidney tubules 2) Osmoreceptors in hypothalamus detects decreased water in blood and this stimulates release 3) Alcohol inhibits ADH and therefore alcohol increases urine output. |
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Thyroid Gland |
Butterfly shaped, just below larynx |
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Thyroid Gland: Thyroxine |
2 tyrosines (amino acid) + 4 Iodine atoms -- controlled by TSH -Controls normal growth and development (physical and mental) along with GH -Receptor for this is in nucleus of cells -increases metabolic rate by stimulating breakdown of carbohydrates and lipids and therefore raising body temperature (increases cell respiration) Goiter - any abnormal enlargement of thyroid associated with either hyposecretion or hypersecretion Cretinism - Hyposecretion in fetal life or infancy - results in severely compromised physical and mental development |
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Thyroid Gland: Calcitonin |
(30aa long) Decreases Ca++ levels in blood by increasing Ca++ absorption into bone (location of most Ca++ storage) |
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Parathyroid Gland (PTH) |
Not under pituitary control.Hormone increases Ca++ levels in body by increasing breakdown of bone matrix, reabsorbtion of Ca++ from kidney tubules, activates vitamin D so Ca++ is absorbed from gut. |
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Body Responds to Stress |
By signaling the adrenal cortex and adrenal medulla. (The Adrenal gland is like the pituitary gland in that it is a fused endocrine and neuroendocrine gland) |
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Adrenal Cortex |
Steroid hormones (synthesized from cholesterol) -is true endocrine gland -is controlled by hypothalamus -Hypothalamus is the director of the stress response |
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Adrenal Cortex: Outer Layer |
1) (smaller zone) - mineralocorticoids - aldosterone most important - overall effect: increases Na+ return to blood in kidney tubule. (water follows, therefore increases BP) and K+ to be excreted into urine. (regulates Na+ and K+ balance) -Has only a minor influence by ACTH |
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Adrenal Cortex: Middle Layer |
(Larger zone) Under control of ACTH -Releases glucocorticoids of which cortisol is most potent. Cortisone provides resistance to long term stress Glucocorticoids (augments glucagon from pancreas) a) Converts amino acids into glucose (gluconeogenesis) -can then be stored as glycogen in liver and skeletal muscle- mobilizes fats so fatty acids are available for cell respiration Cortisone at high levels: b) anti-inflammatory by inhibiting synthesis of prostaglandins c) By being anti-inflammatory, it decreases WBC so one is more prone to infection. |
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Adrenal Cortex: Inner Layer |
(smallest zone) Secretes sex hormones |
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Adrenal Medulla |
May be regarded as knot of nervous tissue of sympathetic NS. Is neuroendocrine gland -Involved in short term memory, immediate stress by secreting epinephrine and norepinephrine into the blood - prolongs and augments action of sympathetic response Tyrosine (aa)> DOPA> Dopamine> Norepinephrine> Epinephrine |
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Pancreas |
2% is endocrine and known as Islets of Langerhans while 98% is exocrine and excretes digestive enzymes. |
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Pancreas: Insulin |
(51 aa) decreases glucose in blood by enabling glucose to move into cells -is secreted from the B cells of islets of Langerhans. (increases # of glucose transporters (proteins) into cell membranes so glucose can move across the cell membrane by facilitated diffusion) -Brain does not need it to move glucose across membranes of neurons -mostly needed to move glucose into cells of skeletal muscle and adipose cells. Diabetes - symptoms: Increase in blood glucose. |
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Pancreas: Insulin: Diabetes |
1) Type 1 - Juvenile (before 20) =insulin dependent diabetes destruction of b cells by virus (coxsackie, rubella, mumps) directly or virus alters membrane so immune system produces Ab against B cells, therefore cannot produce enough insulin so need insulin injections (cannot be taken orally because insulin is a polypeptide that could be digested by digestive enzymes) (as glucose is excreted in urine, more water is also lost, therefore persistent thirst) diabetes = Copious urination 2) Type 2 - Adult Insulin independent diabetes (90% of diabetes) -due to problems with insulin receptors, frequently in obese -80% of type 2 are or have been overweight; with increased insulin in overweight people, the receptors down regulate (actually sink down into membrane because of bombardment by insulin) -Therapy= Weight loss, diet control, exercise might enable insulin receptors to return to cell membrane |
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Pancreas: Glucagon |
(29 aa) - Secreted from a cells of islets of Langerhans - Majority target is Liver -increases blood glucose levels by stimulating liver glycogenolysis -stimulates glucose from amino acids, glycerol & lactic acid (gluconeogenesis) |
