lecture 22: intro to endocrine system

Question 1

8.1. Distinguish between exocrine and endocrine glands; localize the major endocrine glands and organs in the body

Answer 1

endocrine:
- hormone, blood stream, response

• autocrine: hormone, response (same cell type)
• paracrine: hormone, diff cell type response
• neurocrine: neuron, hormone, bloodstream, response

exocrine:
- use duct system
- sweat, sebaceous, glands

Question 2

8.2. Describe the different structural classes of hormones and justify the different mechanisms of action for water-soluble versus lipid-soluble hormones

Answer 2

3 main structural groups:

1) amino acids/peptide/proteins (water soluble)

• water soluble
• cannot cross plasma membrane
• bind to cell surface receptor
• activates membrane bound G protein.
• produces 2nd messenger (eg cyclic AMP)
• activate protein kinases to regulate activity of enzymes or open/close channels

2) steroid (derived from cholesterol- lipid soluble)
- found inside cell (cytoplasm or nucleus)
- can go into membrane
-can enter nucleus and activate gene transcription

3) eicosanoids

Question 3

8.3. Briefly summarize the three different mechanisms of hormonal regulation of body function

Answer 3

control of hormone release:
- mostly negative feedback (set point) sometimes positive feedback (goal)
- 3 types of stimuli: humoral:
- whole body
- secretion in response to change in blood level
- ex: PTH, blood calcium, insulin, blood glucose

neural:
- not as common
- sympathetic ns + epinephrine
- release by adrenal medulla, hypothalamic neurons, oxytocin

hormonal:
-3 tier system, involves hypothalamus, pituitary, and target endocrine gland
- concept of hypothalamic pituitary axis

Question 4

8.4. Describe the functional organization of the hypothalamic-pituitary axis

Answer 4

1. hypothalamic hormone (releasing)
2. anterior pituitary hormone (stimulating)
3. target gland

pituitary gland:
- size and shapee of pea
- connects to hypothalamus by pituitary gland

• posterior: hormone storage area

example:

• thyroid releasing hormone (TRH)
• thyroid stimulating hormone (TSH)
• thyroid gland
• corticotropin releasing hormone (CRH)
• adrenocorticotropic (ACTH)
• adrenal glands (cortisol)