12. Autonomics Flashcards
sympathetic vs parasympathetic:
where do they leave the CNS
s: thoracolumbar regions
ps: cranial and sacral regions
sympathetic vs parasympathetic:
where do they synapse on postganglion fibers
s: sympathetic chain ganglia
ps: ganglia on or near target organ
sympathetic vs parasympathetic:
preganglionic fibers release what NT onto what receptors
both Ach to nicotinic receptors
sympathetic vs parasympathetic:
postganglionic fibers release what NT onto what receptors
s: NE onto alpha or beta adrenergic receptors
ps: Ach onto muscarinic cholinergic receptors
preganglionic fibers of the sympathetic system that do not synapse at the sympathetic trunk do what
- → chromaffin cells of adrenal medulla
- release ACH onto nicotinic receptors
- influx of Na causes release of NE
where are alpha 1 receptors found and what does their activation cause?
alpha 2?
Alpha 1: smooth muscle, causes contraction
Alpha 2: vascular smooth muscle, causes vasodilation
where are beta 1 receptors found and what does their activation cause?
beta 2?
Beta 1: on cardiac myocytes
Beta 2: smooth muscle, cause relaxation
what does activation of M1 ,M3, and M5 receptors cause?
M2, M4?
M1, M3, M5: IP3/DAG production and release of intracellular Ca
M2, M4: Gi proteins that lead to reduction in cAMP
parasympathetic stimulation: SA node
- innervation via:
- receptors:
- effect:
- vagus
- muscarinic
- decreases rate of depolarization of pacemaker potential → slows HR
sympathetic stimulation: SA node
- innervation via:
- receptors:
- effect:
- T1-5
- beta 1
- increases rate of depolarization of pacemaker potential → increases HR
parasympathetic stimulation: AV Node and Ventricular Conducting Pathways (Bundle of His, Purkinjes)
- innervation via:
- receptors:
- effect:
- vagus
- muscarinic
- decreases slope of pacemaker potential; decreases depolarization rate during phase 0 of slow AP → decreased conduction velocity through AV node and ventricles
sympathetic stimulation: AV Node and Ventricular Conducting Pathways (Bundle of His, Purkinjes)
- innervation via:
- receptors:
- effect:
- T1-5
- beta 1
- increases rate of depolarization during phase 0 and pacemaker potential
→ increased conduction velocity through AV node; increased ventricular rate if AV node is pacemaker
parasympathetic stimulation: Cardiac Myocytes
- innervation via:
- receptors:
- effect:
- vagus (atria), debated for ventricles
- muscarinic
- decreased Ca entry into myocyte
→ decrease in atrial contractility, possible decrease in ventricular
sympathetic stimulation: Cardiac Myocytes
- innervation via:
- receptors:
- effect:
- T1-5
- beta 1, beta 2 sometimes
- increases Ca conduction into myocytes
→ increase in contractility (muscle pumps stronger)
sympathetic stimulation: Cerebral Vasculature
- innervation via:
- receptors:
- effect:
- local control (neuronal activity produces metabolites that vasodilate the local blood vessels in proportion to the metabolic need)
- alpha 1
- vasoconstriction
***only when systemic blood pressure becomes high enough that it might damage the cerebral capillaries; small arteries constrict to protect capillaries
parasympathetic stimulation: Coronary Arteries
- innervation via:
- receptors:
- effect:
- vagus
- muscarinic
- vasodilation
sympathetic stimulation: Coronary Arteries
- innervation via:
- receptors:
- effect:
- T1-T5
- alpha 1
- vasoconstriction
sympathetic stimulation: Cutaneous Vasculature
- innervation via:
- receptors:
- effect:
- multiple sources
- alpha 1
- vasoconstriction
***except sweat glands, muscarinic receptors causing vasodilation
parasympathetic stimulation: Skeletal Muscle Vasculature
- innervation via:
- receptors:
- effect:
- vagus
- muscarinic
- vasodilation
sympathetic stimulation: Skeletal Muscle Vasculature
- innervation via:
- receptors: alpha 1 vs beta 2
- effect:
- multiple
- alpha 1: vasoconstriction
- beta 2: vasodilation
sympathetic stimulation: Splanchnic Vessels
- innervation via:
- receptors:
- effect:
- T5-L2 (celiac, superior and inferior mesenteric ganglion)
- alpha 1
- vasoconstriction
***vasodilation occurs when sympathetic input stops
sympathetic stimulation: Veins
- innervation via:
- receptors: alpha 1 vs alpha2/ beta2
- effect:
- alpha 1: contraction → increases blood return to heart
- alpha 2/ beta 2: relaxation → slowing blood return to heart
parasympathetic stimulation: Pulmonary Vasculature
- innervation via:
- receptors:
- effect:
- vagus
- muscarinic
- vasodilation (via NO production and release)
sympathetic stimulation: Pulmonary Vasculature
- innervation via:
- receptors: alpha 1 vs beta 1/2
- effect:
- first five thoracic ganglia
- alpha 1: vasoconstiction of large vessels
- beta 1/2: vasodilation of large vessels
parasympathetic stimulation: Upper Airways
- innervation via:
- receptors:
- effect:
- PS branches of trigeminal and sphenopalatine ganglion
- muscarinic
- vasodilation and increased mucus secretion
sympathetic stimulation: Upper Airways
- innervation via:
- receptors:
- effect:
- superior cervical ganglia (CN7)
- alpha 1
- vasoconstriction and reduced mucus secretion
parasympathetic stimulation: Lower Airways
- innervation via:
- receptors:
- effect:
- vagus
- muscarinic
- bronchoconstriction and increased mucus synthesis/ secretion
sympathetic stimulation: Lower Airways
- innervation via:
- receptors:
- effect:
- T1-T5
- beta 2
- bronchodilation
sympathetic stimulation: Renal Vasculature
- receptors:
- effect:
- alpha
- vasoconstriction of renal artery and all arteries in kidney, afferent and efferent arteriole
→ decreased blood flow into kidney, decreased urine production, preservation of BP
sympathetic stimulation: Juxtaglomerular Apparatus
- innervation via:
- receptors:
- beta 1 (granule cells of afferent arteriole)
- increased release of renin → increased production of ANG → ANG2 → aldosterone → reabsorption of Na; release of ADH → water reabsorption → increase blood volume
alpha 1 receptors are found where (5) and cause what
- cerebral, cutaneous, skeletal m, pulmonary vasculature
- coronary a
- splanchnic vessels
- veins
- upper airways
CONSTRICTION
alpha 2 receptors are found where and cause what
veins
DILATION
beta 1 receptors are found where (5) and cause what
- SA node (increase HR)
- AV node (increase conduction)
- cardiac myocytes (increase contractility via Ca)
- pulmonary vasculature (dilation)
- juxtaglomerular apparatus (increase blood volume via renin release)
overall increases
beta 2 receptors are found where and do what
- cardiac myocytes (increase contractility via Ca)
- skeletal m vasculature (dilation)
- veins (relaxation, decreased venous return)
- pulmonary vasculature (dilation)
- lower airways- dilation
mostly dilation