MCAT hormones

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MCAT hormones
2013-04-12 07:08:34
MCAT Hormones

MCAT Hormones
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  1. ACTH

    stimulates adrenal cortex to release glucocorticoids via second messenger system using cAMP

    • Release stimulated by many types of stress
    • Stress hormones
  2. TSH
    • Thyroid Stimulating hormone
    • peptide
    • Stimulates thyroid to release T3 and T4 via second messenger system using cAMP
    • also increase thyroid cell size, number, and rate of secretion of T3 and T4. 
    • T3 and T4 concentrations have negative feedback effect on TSH release, both at the anterior pituitary and hypothalamus
  3. Prolactin
    • peptide
    • Promotes lactation by breasts
    • hypothalamus generally inhibits the release of prolactin
  4. Posterior Pituitary
    • composed mainly of support tissue for nerve endings extending from hypothalamus
    • oxytocin and ADH synthesized in the neural cell bodies of hypothalamus, transported down axons to the posterior pituitary where they are released into the blood
  5. Oxytocin
    • small peptide
    • increases uterine contractions during pregnancy and causes milk to be ejected from breasts
  6. ADH
    • Antidiuretic hormone (aka Vasopressin)
    • small peptide hormone
    • causes collecting ducts of the kidney to become permeable to water reducing the amount of urine and concentrating the urine
    • coffee and beer are ADH blockers-->increase urine volume
  7. Adrenal Cortex
    • outside portion of the adrenal glands, secretes only steroid hormones
    • mineral corticoids (affect the electrolyte balance in blood stream) and glucocordicoids (increase blood glucose concentration and have greater effect on fat and protein metabolism)
  8. Aldosterone
    • steroid, mineral corticoid
    • acts in the distal convoluted tubule and collecting duct to increase Na+ and Cl- reabsorption and K+ and H+ secretion
    • creates net gain in particles in plasma --> increase in BP
    • Same effect but to lesser extent on sweat glands, salivary glands, and intestines
  9. Cortisol
    • steroid, glucocorticoid
    • increases blood glucose levels by stimulating gluconeogenesis in the liver
    • also degrades adipose tissue to fatty acids to be used for cellular energy
    • causes moderate decrease in use of glucose
    • causes degradation of nonhepatic proteins, decrease of nonhepatic AA's and corresponding increase in liver and plasma proteins and AA's
  10. Catecholamines
    • tyrosine derivatives synthesized in the adrenal medulla
    • epinephrine and norepinephrine
    • vasoconstrictors of internal organs and skin, but vasodilators of skeletal muscle
    • Also considered stress hormones
  11. Thyroid
    T3 (triiodothyronine), T4 (thyroxine) and calcitonin released from thyroid
  12. T3 and T4
    • act the same for MCAT purposes
    • lipid soluble tyrosine derivatives
    • diffuse through lipid bilayer and act in nucleus of effector cells
    • in general, increase the basal metabolic rate
    • secretion regulated by TSH
  13. Calcitonin
    • large peptide hormone
    • released by thyroid gland
    • slightly decreased blood calcium by decreasing osteoclast activity and nubmer
    • Not essential to controlling calcium levels in humans
  14. Pancreas
    • endocrine and exocrine gland
    • secretes insulin and glucagon
  15. Insulin
    • peptide hormone
    • released by β-cells of the pancreas
    • associated with energy abundance in the form of high energy nutrients in the blood
    • released when blood levels of carbs or proteins are high
    • affects carb, fat, and protein metabolism
    • causes barbs to be stored as glycogen in the liver and muscles, fat stored in adipose tissue, and AA's are taken up by the cells of the body and made into proteins
    • NET EFFECT: lower blood glucose levels
  16. Insulin binding
    • binds to membrane receptor, begins cascade inside cell
    • cells become highly permeable to glucose (and AA's) upon binding of insulin
  17. Glucagon
    • peptide hormone
    • released by the α-cells of pancreas
    • nearly opposite to insulin
    • Stimulates glycogenolysis (breakdown of glycogen) and gluconeogenesis in the liver
    • acts via second messenger system of cAMP
    • in high concentrations, it breaks down adipose tissue, increasing FA levels in the blood
    • NET EFFECT: raises blood glucose levels
  18. Parathyroid
    • 4 small parathyroid glands attached to back of thyroid
    • release parathyroid hormone
  19. PTH
    • Parathyroid hormone
    • peptide
    • increases blood calcium and phosphate from bone and stimulates proliferation of osteoclasts
    • increases renal calcium reabsorption and renal phosphate excretion
    • increases calcium and phosphate uptake from gut by increasing renal production of the steroid 1,5 dihydroxycholecalciferol (DOHCC), derived from Vitamin D
    • Regulated by calcium ion plasma concentration and the parathyroid glands shrink or grow accordingly
  20. What does the adrenal medulla release? (general)
    catecholamines:  Epi, NE
  21. What are the tyrosine derivatives? 
    Where are they formed (inside cell)
    T3, T4, catecholamines (Epi and NE) 

    formed by enzymes in the cytosol or in the rough ER
  22. Name the three kinds of steroid hormones and what they do
    Where do they act?
    • Glucocorticoids: increase glucose concentration
    • Mineral corticoids: effect electrolyte balance in blood stream
    • Gonadal hormones: estrogen, progesterone, testosterone

    They are carried to the nucleus where they act at the transcription level
  23. Endocrine glands release enzymes _____
    Exocrine glands release enzymes _____
    • directly to body fluids
    • to external environment (via a duct)
  24. What are peptide hormones derived from?
    Where are they manufactured?
    Water/fat soluble?
    Describe their mechanism of action
    • derived from peptides
    • manufactured in Rough ER (then to golgi-->vessicle-->out)
    • water soluble
    • attach to membrane-bound receptor, activate second messenger cascade
  25. What are steroid hormones derived from? 
    Where are they manufactured?
    water/fat soluble?
    • derived from and similar to cholesterol
    • manufactured in smooth ER and mitochondria
    • fat soluble, need transport molecule