Adrenal Medulla Hormones Flashcards
What is the adrenal gland?
- two distinct endocrine organs (cortex and medulla) organized into single gland
What do medulla chromaffin cells or pheochromocytes have? What are they?
- many secretory vesicles containing epi or norepi
- “modified neuron”
What is layer 1 to 3 of the adrenal cortex?
- zona glomerulose
- zona fasiculata
- zona reticularis
What is the job of the autonomic nervous system?
- homeostasis of organs and basic physiological functions
What is the autonomic nervous system divided into?
- parasympathetic ns: digestion and energy conservation
- sympathetic ns: energy expenditure
- enteric nervous system: controls digestive organs
What is the system of interconnected neurons in the sympathetic ns?
- brain – preganglia –> postganglia – secrete NE as NT –> stim innervated tissues
- innervate adrenal medulla – secrete E into blood
What is E/NE secretion stimulated by?
NT acetylocholine (uses nicotinic R)
Why are there serum NE concentrations?
- due to sympathetic nerve leakage
What are the steps in catecholamine synthesis?
- tyrosine: tyrosine hydroxylase adds a hydroxyl group
- Dopa to dopamine: enzyme in all tissues removes carboxyl
- dopamine enters storage vesicles (hydroxyl added to make norepinephrine and diffuses to cytoplasm)
- norephinephrine: methyl added to give epinephrine by PNMT
What results if drugs block dopa to dopamine by DOPA decarboxylase?
- production of “false transmitters”
What is the rate limiting step in catecholamine synthesis?
- the first step from tyrosine to DOPA by addition of hydroxyl group
Where does the process of converting norepinephrine to epinephrine by adding a methyl occur?
- mostly in adrenal medulla chromaffin cell
What is the PNMT gene induced by?
cortisol
Epinephrine that circulates in the blood to tissues that have what receptors?
- alpha or beta - adrenergic receptors
