UNIT 2 ANS Flashcards
What are the 4 classifications of receptors?
- ion channel
- GPCR
- enzyme linked receptor
- intracellular receptor
Describe the general architecture of the GPCR second messenger system.
1st messenger: extracellular signaling
Receptor: responds
G protein: turns off/on an effector
Effector: activates/inhibits a 2nd messenger
2nd messenger: primary intracellular signal
Enzymatic cascade
Cellular response
What second messenger system is associated w/ alpha-1 receptor? What other receptors share the same pathway?
Gq –> phospholipase C –> IP3/DAG/Ca++
others:
- histamine 1
- muscarinic 1, 3, 5
- vasopressin 1
What second messenger is associated w/ alpha-2 receptor? What other receptors share a similar pathway?
G1 –> adenylate cyclase –> ATP to cAMP
others:
- muscarinic 2
- dopamine 2
What second messenger system is associated w/ beta1 & beta2 receptors? What other receptors share a similar pathway?
Gs –> adenylate cyclase –> ATP to cAMP
others:
- histamine 2
- vasopressin 2
- dopamine 1
describe the autonomic innervation of the heart
myocardium - B1 = increased contractility - M2 = decreased contractility conduction system - B1 = increased HR & conduction speed - M2 = decreased HR & depressed CV
SNS: cardiac accelerator fibers from T1-T4
PNS: vagus
describe the autonomic innervation of the vasculature
vasculature:
arteries a1>a2 –> vasoconstriction
veins a2>a1 –> vasoconstriction
specific vascular beds:
- myocardium B2 = vasodilation
- skeletal m B2 = vasodilation
- renal DA = vasodilation
- mesenteric DA = vasodilation
Describe the autonomic innervation of the bronchial tree
B2 = bronchodilation M3 = bronchoconstriction
B2 aren’t innervated, just respond to catecholamines in the systemic circulation or the airway (inhaled)
Describe the autonomic innervation of the kidney
renal tubules: a2 = diuresis via ADH inhibition
renin release: B1 = increased renin release
Describe the autonomic innervation of the eye
sphincter m (iris) = M = contraction (miosis)
radial muscle (iris) = a1 = contraction (mydiasis)
ciliary m =
B2 = relaxation (far vision)
M = contraction (near vision)
Describe the autonomic innervation of the GI tract
sphincters
a1 = contraction
M = relaxation
motility & tone
a1/a2/B1/B2 = decrease
M = increase
salivary glands
a2 = decrease
M = increase
gallbladder & ducts
B2 = relaxation
M = contraction
describe the autonomic innervation of the pancreas
islet (beta cells)
a2 = decrease insulin release
B2 = increase insulin release
describe the autonomic innervation of the liver
a1/B2 = increase serum glucose
describe the autonomic innervation of the uterus
a1 = contraction B2 = relaxation
describe the autonomic innervation of the bladder
trigone & sphincter
a1 = contraction
M = relaxation
destrusor m
B2 = relaxation
M = contraction
describe the autonomic innervation of the sweat glands
a1 = increase secretion M = increase secretion
list the steps of NE synthesis. What is the rate limiting step?
tyrosine
- -> DOPA (via tyrosine hydroxylase)
- -> dopamine (via DOPA decarboxylase)
- -> NE (via dopamine B-hydroxylase)
- -> Epi (via phenylethanolamine N-methyltransferase)
Tyrosine hydroxylase is the rate limiting step
All occurs in the adrenal medulla
What are the 3 ways in which NE can be removed from the synaptic cleft? Which is the most important?
- reuptake (80%)
- diffusion away
- reuptake by extraneural tissue
What enzymes metabolize NE & Epi? What is the final metabolic byproduct?
MAO
COMT
final byproduct = vanillylmandelic acid (VMA) aka 3-methoxy-4-hydroxymandelic acid
elevated VMA in urine aids in diagnosis of pheochromocytoma