Intro to Endocrinology

Question 1

difference btw endo and exocrine

Answer 1

exocrine: have ducts
- i.e. exocrine pancreas, salivary, sweat, mammary glands

endocrine: well vascularized, ductless
- i.e. pituitary, thyroid, adrenal, parathyrdoid

Question 2

list, describe chemical classes of hormones

Answer 2

1. protein: most common, water soluble
   - stored in vescile until stimulus-induced release
   - main source: anterior pituitary, HTh, endocrine pancreas
2. steroid: lipid soluble, synthesized from cholesterol
   - synthesis requires specific enzymes only in steroidogenic organs such as gonads, adrenal glands, placenta
   - diffuse to ECF/blood immediately after synthesis, not stored
3. amines: small molecules dervied from Tyr or Trypt
   Tyr: in adrenal medulla, precursor to NE and EP
   in thyroid, 2 tyr = thyroid hormones
   Trypt: in gut/brain, precurosr to 5-ht
   in brain (pineal) 5-ht is precuros of melatonin
4. eicosanoids: small, synthesized from lipids, phospholipids
   - most derived from arachidonic acid
   - local chemical mediators, inc. prostaglandins

Question 3

what is negative FB. why is positive FB rare?

Answer 3

biological action of hormone reduces/inhibits additional secretion of that hormone.

+FB- hormone induce additional release. can result in vicious cycle incompatible with homeostasis –> disease/death

Question 4

modes of hormone delivery to target

Answer 4

1. endocrine
   - endocrine cell -> blood -> target
2. neuroendocrine
   - endocrine cell->blood->target
3. paracrine
   - endocrine cell -> EC space –> target
4. autocrine
   - endocrine cell -> EC space -> target (same cell)
5. intracrine hormones- act within cell

Question 5

location of receptors, important of hormone-receptor complex

Answer 5

needed for hormone to exert biological function
locations:
1. PM: protein hormones, catecholamine receptors
2. cytoplasm: some steroid receptors (i.e. T)
3. nucleus: some steroid/thyroid receptors