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Endo Part 3

Endo Part 3. Can Males Lactate?. Yes, In humans, some men can breastfeed In rats, some males breastfeed their young. Receptors for both are similar Hormones are similar in size and chemical makeup Have similar functions ___________ can induce both to be secreted.

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Endo Part 3

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  1. Endo Part 3

  2. Can Males Lactate? • Yes, • In humans, some men can breastfeed • In rats, some males breastfeed their young. • Receptors for both are similar • Hormones are similar in size and chemical makeup • Have similar functions • ___________ can induce both to be secreted

  3. Feedback Control of the Anterior Pituitary • Anterior pituitary and hypothalamic secretions are controlled by the ______________organs they regulate. • Secretions are controlled by ___________ feedback inhibition by target gland hormones. • ______________ feedback at 2 levels: • The target gland hormone can act on the hypothalamus and inhibit secretion of ____________ hormones. • The target gland hormone can act on the anterior pituitary and inhibit __________ to the releasing hormone.

  4. Feedback Control of the Anterior Pituitary(continued) • Short feedback loop: • Retrograde transport of blood from anterior pituitary to the hypothalamus. • Hormone released by anterior pituitary ___________secretion of releasing hormone. • _______________ feedback effect: • During estrus, ______________ stimulates “___________ surge.”

  5. Higher Brain Function and Pituitary Secretion • Axis: • Relationship between _________ pituitary and a particular target gland. • Pituitary-gonad axis. • Hypothalamus receives input from higher brain centers. • Psychological stress affects: • _______________ rhythms. • ________________ cycle.

  6. ADRENAL GLANDS ______ adrenal glands:Location:Immediately anterior to the kidneys, encased in a _________tissue capsule The exact location relative to the kidney and the shape of the adrenal gland vary among species.

  7. Adrenal Glands • History – • Brown-Sequard (1856) adrenalectomy – fatal to dog • Cannon (1929) – fight or flight – adrenomedulla • Paired organs that cap the kidneys. • Each gland consists of an outer _____________ and inner ________________. • In ____________ – no distinct cortex or medulla

  8. Adrenal Glands (continued) • Adrenal cortex: • Does not receive ________ innervation. • Must be stimulated ______________ (ACTH). • Consists of 3 zones: • Zona __________ • Zona fasciculata. • Zona reticularis. • Secretes ________________

  9. Immune system: suppressed Stress Circadian rhythm Hypothalamus Muscle: Net loss of amino Acids (glucose) CRH Posterior Pituitary Gland Anterior Pituitary Gland Liver: Deamination of proteins into amino acids, gluconeogenesis (glucose) (-) ACTH Adrenals Glucocorticoids, Catecholamines, etc.. Glucocorticoids, Catecholamines, etc.. Fat Cells: Free fatty acid mobilization Kidney Heart rate: Increased Hypothalamopituitary adrenal axis

  10. The adrenal gland has two distinct regions: • An inner medulla: - _______________epinephrine (E) - norepinephrine (NE). - richly innervated by preganglionic sympathetic fibers and is, in essence, an extension of the sympathetic nervous system (involved in the “fight or flight” reaction). • An outer cortex: - Secretes several classes of _________hormone - three concentric zones of cells that differ in the major steroid hormones they secrete.

  11. Adrenal CORTEX Zona Glomerulosa Mineralocorticoids (Aldosterone) Na+, K+ and water homeostasis Zona Fasciculata Glucocorticoids (Cortisol) Glucose homeostasis and many others Zona Reticularis sex steroids (androgens) Medulla: Catecholamines

  12. Functions of the Adrenal Cortex • Zona glomerulosa: Mineralcorticoids • __________________ • Stimulate kidneys to reabsorb Na+ and secrete K+. • Deoxycorticosterone • Zona fasciculata: Glucocorticoids • __________________ • Inhibit glucose utilization and stimulate gluconeogenesis. • Zona reticularis (DHEA): _______ steroids: • Androgens – significant amounts • Estrogens – insignificant amounts

  13. Functions of the Adrenal Cortex (continued)

  14. Functions of the Adrenal Cortex (continued) • Carried by plasma specific – binding globulins • Mechanism of action • Enters cell, ___________receptor, enters nucleus, increases mRNA, increases __________ formation

  15. Adrenal Glands • Adrenal medulla: • Derived from _______________ neural crest ectoderm (same tissue that produces the sympathetic ganglia). • Synthesizes and secretes: • ____________________ (mainly Epi but some NE).

  16. Functions of the Adrenal Medulla • Actions • _____________ respiratory rate. • Increase HR and cardiac output. • __________________ blood vessels, thus increasing venous return. • Stimulate glycogenolysis. • Stimulate ____________________ • Increases BMR • Stimulates spleen contraction – increased RBC’s in blood

  17. Functions of the Adrenal Medulla • Stimuli • Hypoglycemia • Emergency situation

  18. Stress and the Adrenal Gland • Non-specific response to stress produces the general adaptation syndrome (GAS). • Alarm phase: • Adrenal glands activated. • Stage of resistance: • Stage of readjustment. • Stage of exhaustion: • Sickness and/or death if readjustment is not complete.

  19. Thyroid Hormones • Thyroid gland is located just below the larynx. • Thyroid is the _____________ of the pure endocrine glands. • Follicular cells secrete ___________. • Parafollicular cells secrete ___________.

  20. Thyroid Hormones • Different activity in different animals • Fish – no specific organs, follicles scattered • Birds – 2 lobes – widely separated, no isthmus • Snakes – 1 gland, anterior to heart

  21. Production of Thyroid Hormones • ___________ (I-) actively transported into the follicle and secreted into the colloid. • Oxidized to iodine (Io). • Iodine attached to tyrosine within thyroglobulin chain. • Attachment of 1 iodine produces monoiodotyrosine (MIT). • Attachment of 2 iodines produces diiodotyrosine (DIT).

  22. Production of Thyroid Hormones (continued) • _______ and ________ produced. • TSH stimulates pinocytosis into the follicular cell. • Enzymes hydrolyze T3 and T4 from thyroglobulin. • Attached to TBG and released into blood.

  23. Production of Thyroid Hormones (continued)

  24. Actions of T3 • Stimulates ________synthesis. • Promotes maturation of nervous system. • Stimulates rate of cellular respiration by: • Production of uncoupling proteins. • ____________ active transport by Na+/K+ pumps. • Lower cellular [ATP]. • Increases ____________ heat. • Increases ______________ rate. • Stimulates increased consumption of glucose, fatty acids and other molecules.

  25. Mechanism of Thyroid Hormone Action • Thyroxine (tetraiodothyronine) T4 • Travels attached to _______________ (thyroxine-binding globulin) • Small amount of T3 • Carrier proteins have a ___affinity for T4 • Free T3 is what is physiologically active • So, why do we have T4??? • T4 passes into cytoplasm and is converted to T3. • Receptor proteins located in nucleus.

  26. Diseases of the Thyroid • Iodine-deficiency (endemic) goiter: • Abnormal growth of the thyroid gland. • In the absence of sufficient iodine, cannot produce adequate amounts of T4 and T3.

  27. Diseases of the Thyroid (continued) • Adult myxedema: • Symptoms: • Decreased metabolic rate. • Weight gain. • Decreased ability to adapt to cold. • Lethargy. • Grave’s disease: • Autoimmune disorder: • Cretinism: • Hypothyroid from end of 1st trimester to 6 months postnatally. • Severe mental retardation.

  28. Parathyroid Glands • Embedded in the lateral lobes of the thyroid gland. • Parathyroid hormone (PTH): • Only hormone secreted by the parathyroid glands. • Single most important hormone in the control of blood [___________]. • Stimulated by ___________blood [Ca2+]. • Promotes ________ in blood [Ca2+] by acting on bones, kidney and intestines.

  29. Actions of Calcitonin • Secreted by __________ cells • Works with parathyroid cells to regulate Ca levels • Stimulates secretion of ________ in urine • Actions work to lower blood Ca levels

  30. Pancreatic Islets (Islets of Langerhans) • Alpha cells secrete ________. • Stimulus is decrease in blood [glucose]. • Stimulates glycogenolysis and lipolysis. • Stimulates conversion of fatty acids to ketones. • Beta cells secrete ________. • Stimulus is increase in blood [glucose]. • Promotes entry of glucose into cells. • Converts glucose to glycogen and fat. • Aids entry of amino acids into cells.

  31. Pineal Gland • Secretes __________________: • Production stimulated by the suprachiasmatic nucleus (SCN) in hypothalamus. • SCN is primary center for circadian rhythms. • Light/dark changes required to synchronize. • Melatonin secretion increases with darkness and peaks in middle of night. • May inhibit _________________. • May function in the __________ of puberty (controversial). • Controls estrus in sheep, goats, and horses

  32. Pineal Gland (continued)

  33. Thymus • Site of production of ____ cells (thymus-dependent cells), which are lymphocytes. • Lymphocytes are involved in cell-mediated immunity. • Secretes hormones that are believed to stimulate T cells after leave thymus. • Thymus gland size is large in newborns and children. • _____________ after puberty and becomes infiltrated with strands of fibrous tissue.

  34. Gonads and Placenta • Gonads (testes and ovaries): • Secrete sex hormones. • Testosterone. • Estradiol 17-b. • Progesterone. • Placenta: • Secretes large amounts of _____________, progesterone

  35. Autocrine and Paracrine Regulation • Autocrine: • Produced and act within the same tissue of an organ. • All autocrine regulators control gene expression in target cells. • Paracrine: • Produced within one tissue and regulate a different tissue of the same organ. • Cytokines (lymphokines): • Regulate different cells (interleukins) . • Growth factors: • Promote growth and cell division in any organ. • Neutrophins: • Guide regenerating peripheral neurons.

  36. Prostaglandins • Most diverse group of ________ regulators. • Produced in almost every organ. • Wide variety of functions. • Different prostaglandins may exert antagonistic effects in some tissues. • Immune system: • ___________________________________. • Reproductive system: • ________________________________. • Digestive system: • ______________________________

  37. Lipid Hormones - Prostaglandins Fatty Acids Prostaglandins 1. Produced by all tissues of body 2. Can have a local effect on tissues (same tissue which produced it) 3. Rapidly degraded in lungs Phospholipids - Rate limiting (Phospholipase A2) - Precursor to Prostaglandins Arachidonic Acid Aspirin inhibits Cyclo-oxygenase PGF2a PGE2 Causes vasoconstriction of Blood vessels Causes vasodilatation of blood vessels

  38. Prostaglandins (continued)

  39. Prostaglandins (continued) • Respiratory system: • May _____________________________. • Circulatory system: • _____________________________. • Urinary system: • Vasodilation. • See pg 318 • Inhibitors of prostaglandin synthesis: • Non-steroidal anti-inflammatory drugs (NSAIDS). • Aspirin, indomethacin, ibuprofen: inhibit COX1. • Celecoxib and rofecoxib: inhibit COX2.

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