ANS Flashcards
What second messenger system is associated with the alpha-1 receptor?
Gq = Phosopholipase C = IP3/DAG
-other receptors that share this pathway are Histamine1 and Muscarinic 1, 3, 5
-Vasopressin 1
What second messenger system is associated with the alpha 2 receptor? Name other receptors.
Gi = decreased AC = decreased cAMP
M2
DA2
What second messenger system is associated with beta 1 and beta 2 receptor? Other receptors?
Gs = increased Ac = increased cAMP
DA-1
VA- 2 (renal)
Histamine 2
Describe PSNS heart innervation
M2 decreased contractility and heart rate
Describe the autonomic innervation of vasculature
v/c ARTERIES = a1 > a2
v/c VEINS = a2 > a1
myocardium, sk. muscle B2 vasodilation
renal & mesenteric DA vasodilation
describe the autonomic innervation of the bronchial tree
B2 = bronchodilation respond to catechols in the systemic circulation b/c not innervated
M3 = bronchoconstriction
Autonomic innervation of the kideny
renal tubules = a2 (diuresis)
renin release = b1
a1/a2 = vasoconstriction
b2/da1 = vasodilation
describe autonomic innervation of the eye
SPHINCTER MUSCLE (IRIS) = M = contraction = miosis
RADIAL MUSCLE (IRIS) = A1 = contraction (mydriasis)
CILIARY MUSCLE =
B2 = relaxation (far vision)
Muscarinic = contraction (near vision)
Describe autonomic innervation of pancreas
alpha 2 = decreased insulin release
beta 2 = increased insulin release
Bladder autonomic innervation
sphincter = a1 contraction
detrusor = b2 relaxation
List the steps of NE synthesis. What is the rate-limiting step?
Tyrosine
via Tyrosine hydroxylase –> L-dopa
via Dopa decarboxylase –> Dopamine
via Dopamine B-hydroxylase –> NE
via Phenylethanolamine N methytransferase in the adrenal medulla –> EPI
**rate limiting is tyrosine hydroxylase
Three ways that NE can be removed from synaptic cleft?
- Reuptake (80%)
- Diffusion into bloodstream
- Reuptake by extraneural tissue
What enzymes metabolism NE and epi? Final metabolic byproduct?
MAO and COMT (monoamine oxidase and catechol-O-methyltransferase)
VMA (VANILLYLMANDELIC ACID = 2-4-methoxy-4hydroxymandelic acid)
Describe synthesis of Ach
Choline is transferred into neuron.
Mitochondria produces Acetyl CoA.
ChAT converts Choline + Acetyl CoA into Ach
Where is Ach released for SNS postganglionic
Sweat glands, piloerector muscles, some vessels
Where is the origin of the efferent SNS pathways?
T1 - L3 (THORACOLUMBAR)
via intermediolateral region of the spinal cord and axons exit via ventral nerve roots.
22 paired sympathetic ganglia**
What is ShyDrager
-Multiple system atrophy (aka)
-causes autonomic dysfunction and degeneration at the locus coeruleus, intermediolateral column of spinal cord, and peripheral autonomic nerves.
s/s reflect autonomic dysfunction - orthoHoTn, urinary retention, bowel dysfunction, cerebral hypoperfusion
HD instability!! use direct acting sympathomimetics
What is the ratio of epi to NE from chromaffin cells?
80% and 20%
Describe the HD management of a patient with pheochromocytoma?
ALPHA block before BETA (A before B)
alpha antagonist: phenoxybenzamine, phentolamine (non-selective) or doxazosin and prazosin (selective)
Name four things that shift K+ intracellularly
alkalosis
beta 2 agonism
theophylline
insulin
Name 4 things that shift K+ out
-acidosis
-cell lysis
-hyperosmolar
-sux
What are the sensors in the baroreceptor reflex?
Carotid body = GPN
Aortic arch = Vagus N.
Describe the reflex arc of Bainbridge
-Sensor = SA node, RV, pulmonary veins
-Afferent = Vagus
CONTROL = VASOMOTOR CENTER IN MEDULLA
-Efferent: Vagus
-Effector: SA node increases HR
*only reflex still present in denervated heart
*ex = autotransfusion during childbirth
Describe the reflex arc of the Bezold-Jarisch reflex
sensor = cardiac mechanoreceptors and chemoreceptors
afferent = vagus
control center = vasomotor center in medulla
efferent = vagus
effector = SA node decreases HR and AV node decreases conduction velocity
Describe the reflex arc of the OCR
afferent = long & short ciliary n. > ciliary ganglion > ophthalmic division V1 of CN 5 > gasserion ganglion
control = vasomotor center in medulla
efferent = vagus
Primary concerns for glomus tumor removal
-VAE (grow close to carotid artery, aorta, middle ear)
-Aspiration (d/t GPN involvement, vagus, hypoglossal)
-Serotonin & Kallikrein release (bronchoconstriction, HTN, diarrhea)
-Histamine & Bradykinin (Bronchoconstriction & hOTN)
Low, Intermediate, High dose Epi
Low = 0.01 - 0.03 mcg/kg/m - B1 & B2 (increased CO, decreased SVR, increased pulse pressure)
Intermediate = 0.03 - 0.15 mcg/kg/m - beta & alpha
High dose = > 0.15 mcg/kg/m (alpha)
Isoproteronol
Synthetic catecholamine that stimulates B1&B2
-may reduce CPP by reducing DBP
-clinical indications: pacemaker, heart transplant, bronchoconstriction, cor pulmonale
When should ephedrine NOT be used to treat hypotension
-Patient on MAOIs, cocaine
-Denervated heart
-Sepsis
6 drugs selective for beta-1
Betaxolol
Bisoprolol
Atenolol
Acebutolol
Esmolol
Metoprolol
6 drugs non-selective for beta blockers
-Carvedilol
-Labetalol (has ISA)
-Nadolol
-Pindolol
-Propanolol (MSA)
-Timolol
What is the primary site of metabolism of the commonly used beta blockers?
-Liver
-The two exceptions are atenolol (kidneys) and esmolol (nonspecific plasma esterases)
Which beta blockers have local anesthetic properties? What is another name for this?
Membrane stabilizing properties (MSA)
-Propanolol and Acebutolol
What is intrinsic sympathomimetic activity? Which drugs exert this effect?
-BB that exert a partial agonist effect while simultaneously blocking other agnoistss that have a higher affinity for beta receptors
-Labetalol
-Pimolol
-Acebutolol
List 3 alpha antagonists. What is the MOA for each?
- Phenoxybenzamine (noncompetitive) & Phentolamine (short acting) - alpha 1&2
- Yohimbe - alpha 2
- Prazosin - alpha 1
