Adrenal Medulla Hormones and Catecholamines

Question 1

what are the three zones of the adrenal cortex

Answer 1

Layer 1: zona glomerulosa
Layer 2: zona fasiculata
Layer 3: zona reticularis

Question 2

what are medullar chromaffin cells (aka Pheochromocytes)

Answer 2

•many secretory vesicles containing epinephrine or norepinephrine

Question 3

what does chromaffin cell mean

Answer 3

modified neuron

Question 4

epinepherine and norepinephereine are stimulated by what neurotransmitter

Answer 4

E/NE secretion stimulated by acetylcholine (uses nicotinic receptor)

Question 5

what is the adrenal gland

Answer 5

• Two distinct endocrine organs (cortex and medulla) organized into single gland (not true for some species – amphibians and fish)

Question 6

is the enteric nervous system independant of CNS input

Answer 6

Enteric nervous system which controls the digestive organs is mostly independent of CNS input. Communicates via sympathetic and parasympathetic pathways

Question 7

chatecholamine synthesis (5 steps)

Answer 7

1. Acting on tyrosine; tyrosine hydroxylase adds a hydroxyl group to make DOPA (rate-limiting step) – LDOPA is a treatment for Parkinson’s disease (those individuals have decrease functionality in their renal medulla)
2. Dopa to dopamine: enzyme in all tissues removes carboxyl; drugs that block can cause production of “false transmitters”
3. Dopamine enters storage vesicles – hydroxyl added to make norepinephrine – diffuses to cytoplasm
4. Norepinephrine: methyl added by Phenylethanolamine N-methyltransferase (PNMT) epinephrine – most occurs in adrenal medulla chromaffin cell
5. PNMT, gene induced by cortisol

Question 8

what are all catecholamines derived from

Answer 8

tyrosine

Question 9

functions of epinepherine and norepinephereine

1. Brain (1)
2. cardiovascular (3)
3. respiratory (2)
4. liver
5. adipose
6. muscle

Answer 9

1. Brain – increase alertness due to increased blood flow and glucose metabolism
2. Cardiovascular
   - Increased rate and force of heart contraction
   - Increased peripheral vasoconstriction
   - Decrease blood flow to non-essential tissues (GI and skin)
3. Respiratory
   - Increased ventilation
   - Increased oxygen supply by bronchiolar dilation
4. Liver – increased glucose production by glycogenolysis and gluconeogenesis
5. Adipose – increased lipolysis
6. Muscle – increased glycogenolysis

Question 10

Alpha 1 - Adrenergic receptor Signalling

Answer 10

• Increase alpha Q which will increase amount and activity of PLCs, DAGs and IP3 which increases activation of PKC and generally increases activation of whatever tissue
• BARKs stimulate Adenylyl Cyclase