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2013-04-25 13:05:11
Physio t3

Endocrine system, physiology of domestic animals, test 3
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  1. Suckling reflex
    • Nerve response signals hormone. 
    • Suckling stimuli travels up spinal cord to hypothalamus
    • neurocrines secrete oxytocin
    • travels down axon, released in blood
    • contraction of smooth muscle of mammary gland
    • milk to teat
  2. Endocrine vs Neuro
    • NS fast, short duration
    • ES cellular metabolism, growth and reproduction.  Long term, slow-acting. 
    • Interact closely--dopamine, histamine, somatostatin are in endocrine and neuro.  Endocrine cells can be controlled by neurons. 
  3. Endocrine gland
    a cell or group of cells that secretes a chemical messenger (hormone) directly into the bloodstream. 
  4. endocrine hormone
    a chemical messenger that is produced by one or a group of cells, secreted directly into the bloodstream and transported to distant target cells, eliciting a response
  5. neurocrines
    • neurohormones.  Chemical messengers secreted by axonal terminal of neuron directly into bloodstream. 
    • can act on distant cell.  Oxytocin. 
  6. Paracrine hormone
    a chemical messenger secreted by a cell into ISF that acts on a DIFFERENT type of neighboring cell. 
  7. Autocrine hormone
    a chemical messenger secreted by a cell into ISF that acts on the cell of origin or an identical neighbor. 
  8. Endocrine hormone classification
    • 2 kinds:
    • Peptide hormone: peptides, polypeptides, proteins, produced by adrenal medulla, pituitary gland, hypothalamus, thyroid gland, parathyroid gland, pancreas, placenta, endometrium
    • Steroid hormone: derived from cholesterol.  Produced by gonads, adrenal cortex, fetal membranes (placenta). 
  9. Protein hormone synthesis
    synthesized as preprohormones, cleaved in rough ER to make prohormones, golgi apparatus to form active hormones, STORED in granules, released in response to stimuli
  10. steriod hormone synthesis
    • made from cholesterol in the liver
    • released AS SYNTHESIZED
  11. Transport of hormones in blood
    • Peptide/protein hormones are hydrophilic, dissolve in plasma
    • steroid and thyroid hormones are lipophilic carried in plasma bound to proteins.  Must unbind before it can penetrate a target cell. 
  12. Peptide hormone-cell interaction
    • receptors are on or next to membrane (outside). 
    • changes enzymatic activity in target cell if stimulated
    • effect occurs fast, lasts less than 1 hour
  13. steroid hormone-cell interaction
    • intracellular receptors
    • stimulated receptor changes synthesis of specific proteins
    • effect occurs slow, lasts hours to days
  14. Functions of the endocrine system
    • control of physiologic functions like
    • metabolism (energy and mineral)
    • growth
    • reproduction
  15. Hormones in energy metabolism
    • Insulin
    • glucagon
    • cortisol
    • epinephrine
    • thyroid hormone
    • growth hormone
  16. hormones in mineral metabolism
    • parathyroid hormone
    • calcitonin
    • angiotensin
    • renin
  17. hormones in growth
    • growth hormone
    • thyroid hormone
    • insulin
    • estrogen
    • androgen
    • growth factors
  18. hormones in reproduction
    • estrogen
    • androgens
    • progesterone
    • luteinizing hormone (LH)
    • Follicle stimulating hormone (FSH)
    • Prolactin (PRL)
    • Oxytocin
  19. Hormone amplification
    small amount of hormone produces significant effects due to gain of signal
  20. Negative feedback control
    when the released hormone can go back up to the hypothalamus and pituitary to stop production of the tropic hormone
  21. Adrenal axis negative feedback
    • Hypothalamus secretes CRH
    • CRH acts on anterior pituitary
    • anterior pituitary secretes ACTH
    • ACTH goes to adrenals
    • adrenals produce cortisol
    • cortisol tells hypothalamus and pituitary to stop producing
  22. Positive feedback
    • less common than negative feedback
    • when production of the final hormone stimulates more hormone to be produced. 
    • Seen in ovulation (estrogen makes more estrogen and progesterone)
  23. Circadian rhythms
    Hormone patterns change based on light rhythms as well as negative feedback
  24. Hypothalamus
    • Interface between ES and NS. 
    • Produces peptides and amines to influence pituitary
    • Part of diencephalon, floor of third ventricle, connected to hypophysis. 
  25. pituitary gland
    • made up of anterior (adenohypophysis) and posterior (neurohypophysis). 
    • anterior made from pouch of pharyngeal mucosa
    • posterior made from outgrowth of hypothalamus.  Remains connected by stalk. 
  26. Hypothalamic-neurohypophyseal relationship
    • direct axonal connection. 
    • Hormones secreted by posterior pituitary are synthesized by hypothalamus, carried by axon, posterior secretes into veins, then systemic.  Called neurocrines.  Vasopressin (ADH) and Oxytocin.  Peptide hormones.  Direct hormones. 
    • Secreted into blood, cause response not more hormone. 
  27. Oxytocin
    • released by posterior pituitary. 
    • contraction of smooth muscle (mammary gland and uterus)
  28. vasopressin
    • released by posterior pituitary. 
    • conservation of water, increased blood pressure. 
  29. Diabetes Insipidus
    • disorder of water metabolism characterized by polyuria, dilute urine and polydipsia. 
    • caused by defective secretion of ADH (Central) or renal lack of response to ADH (nephrogenic)
    • partial or complete
  30. Central diabetes insipidus
    lack of secretion of ADH causes water disorder with dilute urine and dehydration. 
  31. nephrogenic diabetes insipidus
    when kidneys don't respond to ADH, leads to dehydration and dilute urine
  32. Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
    • hypersecretion of vasopressin (ADH). 
    • often neoplastic or drug reaction
    • hyponatremia (low NA+) because body is SO dilute. 
    • concentrated urine, over-hydration
  33. Hypothalamic-adenohypophyseal relationship
    • portal system links anterior hypophysis with hypothalamus. 
    • hypothalamic releasing factors stimulate endocrine cells within anterior pituitary to secrete hormones into capillary system
    • capillary systems in hypothalamus and in anterior pituitary that coalesce and drain into systemic veins. 
  34. Hypothalamic releasing hormones (7)
    • released from hypothalamus into portal system, stimulate anterior pituitary to secrete hormones into capillaries
    • Thyrotropin-releasing hormone (TSH)
    • Gonadotropin releasing hormon (GnRH)
    • Growth hormone inhibiting hormone (GHIH)
    • Growth hormone releasing hormone (GHRH)
    • Corticotropin-releasing hormone (CRH)
    • Prolactin-releasing factor (PRF)
    • Prolactin-inhibiting hormone (dopamine) (PIH)
  35. Anterior pituitary hormones (6)
    • all are peptide hormones.  All are tropic except prolactin.
    • Growth hormone (somatotropin)
    • Thyroid stimulating hormone (TSH)
    • Follicle-stimulating hormone (FSH)
    • Lutenizing hormone (interstitial-cell-stimulating hormone) (LH or ICSH)
    • Prolactin (PRL) *only direct hormone
    • Corticotropin (adrenocorticotropic hormone) (ACTH)
  36. tropic hormone
    • Stimulate a target endocrine gland to secrete increased amounts of its own hormone
    • stimulated from anterior pituitary
    • feedback inhibition. 
    • FSH, LH, TSH, ACTH, GH
    • NOT prolactin
  37. Thyroid stimulating hormone (TSH)
    thyrotropin releasing hormone stimulates anterior pituitary to release TSH (tropic hormone) that travels to thyroid. 
  38. Thyroid follicles
    • thyroid gland is composed of follicles lined by epithelium filled with a fluid known as colloid
    • Thyroid hormones are stored extracellularly as part of thyroglobulin, main part of colloid
  39. principal cells
    most numerous cells in epithelium of thyroid follicle and secretes thyroid hormones and thyroglobulin (glycoprotein)
  40. Thyroglobulin
    • thyroid glycoprotein containing tyrosine
    • precurser to T4 and T3
    • Present in colloid of thyroid follicles
    • two tyrosines contain 3 or 4 iodines, making thyroid hormone
  41. parafollicular cell or C cell
    • located outside thyroid follicle
    • secretes calcitonin
  42. Thyroid hormones
    • Secreted in response to TSH
    • T4 - thyronine (4 iodines) (90%)
    • T3 - triiodothyronine (3 iodines) (10%, rest made from T4 in muscles/liver/kidneys)
    • thyroglobulin and enzymes synthesized in follicular cell, sent into colloid
    • iodine co-transported in with Na+, sent to colloid
    • Enzymes add iodine to thyroglobulin making T3 and T4
    • thyroglobulen returns to cell, enzymes separate T3 and T4
    • T3 and T4 enter circulation
    • negative feedback (thermostat)
    • T3 and T4
  43. iodine trapping
    • selective absorption of iodide from circulation by follicular cells in thyroid gland. 
    • Brought in by cotransport with Na+, sent to colloid
    • Iodine then used to synthesize T3 and T4
  44. reverse T3
    another type of T3, formed outside thyroid, few bio effects
  45. T3 and T4 travel
    • must combine with plasma proteins
    • T3 is less tightly bound, more is released to tissue cells
    • T3 is more potent but shorter-duration than T4
  46. Function of thyroid
    • Basal metabolism #1
    • O2 consumption = heat production
    • glucose absorption and uptake
    • glycogen storage or lysis
    • with GH for normal growth
    • lipid metabolism (lipolysis)
    • Enhances symp NS
    • CNS development
    • maintains cardiac contractility (nerves)
    • Increase heart rate/contraction
    • normal metabolic functions of all tissues
  47. goiter
    inability to secrete adequate amounts of thyroid hormone leading to enlargement of thyroid gland
  48. hypothyroid
    • decrease in thyroid hormone. 
    • Common in dog
    • lethargy, weight gain, symmetrical alopecia, cold sensitivity
  49. hyperthyroid
    • overproduction of thyroid hormone
    • common in cats
    • hyperactivity, tachycardia, aggression, polyphagia, weight loss, PUPD
  50. Growth hormone
    • AKA somatotropin and somatotrophic hormone
    • Stimulates liver to form somatomedins which promote bone growth, elongation and thickness
    • stimulates growth in all body cells that can grow
    • most important for controlling stature
    • conserves protein and breaks down fat to provide energy and increases blood glucose levels
    • milk production in cows
  51. somatomedins (insulin-like growth factors)
    • produced by liver in response to growth hormone from anterior pituitary. 
    • Somatomedin C (insulin-like growth factor 1) most important
    • stimulates systemic growth, growth in almost every cell in body
    • regulates cell growth/development (nerves, DNA synthesis)
  52. pituitary dwarfism
    • somatotropin deficiency in dog.  Destruction of pituitary gland. 
    • slow growth, dwarfism, mental retardation, others
  53. acromegaly
    • somatotropin excess in adult cat. 
    • uncontrolled diabetes melitus (insulin resistance), organomegaly (big organs), enlargement of extremities (body size, jaw, tongue, forehead)
  54. Adrenal glands
    • small paired structures immediatly cranial to kidneys
    • two glands wrapped around each other. 
    • Cortex and medulla
  55. Zones of adrenal cortex
    • Capsule
    • Zona glomerulosa (aldosterone)
    • Zona Fasciculata (cortisol and glucocorticoids)
    • Zona Reticularis (sex hormones and few glucocorticoids)
  56. two types of steroid hormones produced by adrenal cortex
    glucocorticoids and mineralcorticoids
  57. mineralcorticoids
    • steroid hormones produced by adrenal cortex. 
    • Electrolyte balance (blood pressure) (sodium reabsorption and potassium excretion)
    • aldosterone
    • zona glomerulosa
  58. regulation of aldosterone/mineralcorticoids
    • increased potassium ion concentration***
    • increased activity of renin-angiotensin system
    • increased sodium ion concentration (decrease aldosterone secretion)
    • ACTH from anterior pituitary is necessary for secretion of aldosterone--does not affect rate
  59. glucocorticoids
    • released mainly in zona fasciculata of adrenal cortex
    • secretion regulated by ACTH from anterior pituitary; negative feedback loop
    • Stimulated by stress
    • cortisol most important
  60. cortisol
    • glucocorticoid released by zona faciculata of adrenal cortex
    • essential for body's response to stress (sick, fear, etc)
    • increases blood glucose levels by increasing protein catabolism, increasing lipolysis and increasing gluconeogenesis
    • also anti-inflammatory, immunosuppressive
    • decreases ADH secretion, diluting urine
  61. cortisol and circadian rhythms
    • sleep and activity patterns are superimposed on negative feedback system
    • lowest at night and highest in early morning
  62. Adrenal axis
    • Stressors cause hypothalamus to secrete CRH
    • CRH makes anterior pituitary secrete ACTH
    • ACTH makes adrenal cortex secrete cortisol
    • cortisol goes to liver, fat, muscle, lymphocytes etc
    • cortisol goes to hypothalamus to stop CRH production
    • cortisol goes to anterior pituitary to stop ACTH production
  63. Hyperadrenocorticism
    • Cushing's disease
    • hypersecretion of adrenal cortex. 
    • Caused by pituitary tumor, adrenal tumor or iatrogenic (give too much cortisol, turns off system)
    • Signs are PUPD, polyphagia, lethargy, pot belly, panting, alopecia, thin skin
  64. hypoadrenocorticism
    • Addison's
    • hyposecretion of adrenal cortex
    • lack of mineralcorticoids and glucocorticoids
    • waxing and waning signs, vomiting, diarrhea, anorexia, weakness, bradycardia, electrolyte abnormalities
  65. Hyperaldosteronism
    • Conn's syndrome
    • adrenal glands produce excess aldosterone
    • results in hypertension or hypokalemia.  Uncommon
  66. Hormones of adrenal medulla
    • catecholamines (epinephrine and norepinephrine)
    • Flight or fight
    • metabolism, increase concentration of glucose
    • secretion initiated by ACH from preganglionic
  67. Pheochromocytoma
    • tumor of adrenal medulla, secretes epinephrine, norepinephrine or both. 
    • PU/PD, increased heart rate, restlessness, distended abdomen, sometimes hypertension.  Sometimes no signs. 
  68. Follicle stimulating hormone
    • protein hormone, stim by anterior pituitary.  Gonadotropin (with LH).  Dominant in growth of follicles.  Stimulates growth of oogenesis and spermatogenesis
    • controlled by GnRH (gonadotropin releasing hormone from hypothalamus)
    • Causes secretion of estrogen, progesterone and inhibin. 
  69. Luteinizing hormone
    • protein hormone stimulated by anterior pituitary.  Gonadotropin (with FSH).  Dominant during final follicular maturation and ovulation. 
    • Assists in ovulation and develops functional corpus luteum.  Simulates testosterone secretion in males. 
    • Controlled by GnRH (gonadotropin releasing hormone) from hypothalamus. 
    • Causes secretion of estrogen, progesterone and inhibin. 
  70. Lactation
    process by which mammary alveolar cells aquire ability to secrete milk. 
  71. Lactogenesis
    establishment of milk secretin--start
  72. galactogenesis
    continued production of milk by mammary glands. 
  73. prolactin
    • adenohypophysis hormone creates lactation (produce milk).  Stimulates and maintains milk production (sheep and non-ruminants).  Not so much needed to maintain in ruminants.
    • pulsatile (always releasing some)
    • inhibited by Dopamine (ventral hypothalamus)
    • stimulated by vasoactive intestinal peptides
    • Increases right before parturition (when progesterone drops)
  74. Process of teat stimulation
    • stimulation of nipple sends impuse to hypothalamus
    • Hypo blocks release of dopamine and stimulates vasoactive intestinal peptides
    • prolactin released from anterior pituitary
  75. Oxytocin
    • causes contraction of myoepithelial cells surrounding alveolus
    • milk enters ducts and cisterns (milk letdown)
    • Promotes contraction of uterus during parturition (if uterus has been exposed to adequate estrogen). 
    • Release stimulated by posterior pituitary.  NEUROCRINE, when tactile stimulation of nipple. 
  76. Parathyroid hormone
    • main organ involved in calcium and phosphorus metabolism (raises Ca to normal when low)
    • 4 pairs at base of thyroid
    • Chief cells secrete hormone. 
    • hormone secretion controlled by calcium concentrations in blood (less calcium turns on, too much turns off), epinephrine, magnesium and sleep.
  77. actions of parathyroid hormone
    • frees Ca2+ and phosphate from bone
    • increases production of active vitamin D by kidneys, promoting absorption of Ca and Phosphate from GI tract
    • causes kidneys to excrete P and keep Ca2+
    • works WITH Calcitriol and against calcitonin(action reaction pair with calcitonin)
  78. Calcitriol
    • activated vitamin D
    • important for absorption of Calcium from the gut. 
    • works with parathyroid hormone and against calcitonin
  79. Calcitonin
    • hormone of the thyroid gland that works against parathyroid hormone and calcitriol. 
    • Causes lowering of calcium levels in the blood. 
    • inhibits bone resorption and may increase excretion of Ca and phosphate in kidney
    • secreted by parafollicullar cells or C cells
    • stimulated by hypercalcemia and hypermagnesemia. 
  80. Hyperparathyroidism
    • excessive secretion of PTH by one or more abnormal glands
    • Primary (parathyroid adenoma usu.)
    • Secondary (renal disease or nutrition, takes from bones. "rubber jaw", can have normal blood levels)
    • signs are hypercalcemia, PUPD, weakness, vomiting, urinary incontinence
  81. hypoparathyroidism
    • absolute or relative deficiency in the secretion of PTH
    • usually we did it (when we took out thyroid), idiopathic
    • causes hypocalcemia and hyperphosphatemia
    • neuromuscular signs (nervousness, seizures, focal twitching, ataxia, weakness
  82. Four hormone-secreting cells of endocrine pancreas
    • cells in Islets of Langerhans
    • alpha cells secrete glucagon
    • beta cells secrete insulin
    • delta cells secrete somatostatin
    • F cells secrete pancreatic polypeptides
  83. Insulin function
    • lowers concentration of blood glucose, fatty acids and amino acids and converts to their storage forms (glycogen, triglycerides and protein) and decreases breakdown of storage. 
    • allows transport of glucose across cell membrane (out of blood)
  84. insulin inhibition
    • stimulated by LOTS of stuff
    • inhibited by somatostatin
    • also epinephrine, norepinephrine
  85. Diabetes mellitus
    • deficiency of insulin
    • high glucose in blood and urine
    • PUPD, anorexia or polyphagia, weight loss, vomiting, diarrhea, lethargy, weight loss, diabetic neuropathy
    • opposite of insulinoma
  86. insulinoma
    • increased production of insulin by islet cell tumors
    • Opposite of diabetes mellitus (causes low glucose in blood and urine, lots of storage). 
    • LOTS in ferrets
  87. Glucagon
    • produced by alpha cells in islets of langerhans
    • increases blood glucose levels.  (opposite of insulin.  Action/reaction pair)
    • decreases glycogen synthesis, increases glycogenolysis and increases gluconeogenesis. 
    • Stimulated by low glucose, Symp NS and Para NS,
  88. Glucagon and insulin
    work together to keep blood glucose levels steady.  After a meal, blood glucose is high, insulin released.  Hours later, glucagon released. 
  89. Glucagonoma
    • extremely rare tumor of alpha cell of islets of langerhans causing increased secretion of glucagon
    • superficial necrolytic dermatitis (on feet and hock area), hyperglycemia
  90. somatostatin
    • inhibitor of secretion of pancreatic hormones (insulin, glucagon, pancreatic polypeptide). inhibitor of growth hormone secretion, inhibitor of digestive process, decreasing absorption, secretion and motility. 
    • secreted by D cells of pancreas, brain and GI tract. 
    • Secretion stimulated by nutrients, neurotransmitters (ACH, epinephrine, norepinephrine)
  91. somatostatinoma
    • tumor of delta cells of endocrine pancreas
    • extremely rare (bearded dragons). 
    • anorexia, vomiting, hyperglycemia, anemia
  92. pancreatic polypeptide
    • secreted by F cells of endocrine pancreas. 
    • effects in GI tract (not exactly sure how--inhibits pancreatic/gallbladder secretions,increases gastric emptying and motility)
    • secretion stimulated by intestinal hormones (CCK, Secretin, Gastrin), vagus, and ingestion of protein. 
    • Inhibited by SOMATOSTATIN
  93. Pancreatic polypeptide disease
    pancreatic polypeptidomas are very rare.  Pancreatic tumors can cause multiple hormone problems
  94. acinus
    exocrine hormones of the pancreas.