ANS Flashcards
Where are the integration centers for the ANS?
Brain stem, hypothalamus, spinal cord
Sympathetic ANS nerves
Spinal nerves - thoracic and lumbar
Exit here
Sympathetic preganglionic
- Short
- Cell body in spinal cord
- Axon through anterior horn of spinal cord and to spinal nerve and sympathetic ganglia
Where does the sympathetic preganglionic synapse?
- Postganglionic neuron
- Other ganglions in sympathetic chain
- Prevertebral ganglion (Celiac, hypogastric)
Sympathetic postganglionic
Long
Target organs
Adipose tissue
receptor
Beta 1 - Sympathetic effect - lipolysis
Uterus
Receptor
Beta 2 - Sympathetic - Relaxation
Alpha 1 - Sympathetic - Contraction
Pancreas
Receptor
Beta 2 -
Sympathetic - decreased insulin
Para - increased insulin
Alpha 1 -
Sympathetic - decreased glucagon
Para - increased glucagon
Bladder
Receptor
Alpha 1 -
Sympathetic - relaxation
Parasympathetic - contraction
Upper GI
Alpha 1 - Sympathetic - relaxation
Alpha 1 - Parasympathetic - increased motility
Gallbladder
Beta 2
Sympathetic - relaxation
Para - contraction
Liver
Beta 2
Sympathetic - glycogenolysis, gluconeogenesis
Kidney
Beta 2
Sympathetic - renin release
Para - none
Spleen
Alpha 1
Symp - release RBC
Para - none
Bronchioles
Beta 2
Symp - dilation
Para - constriction
Secretions
Beta 2
Symp - none
Para - increased
skeletal vessel
Beta 2
Symp - dilation
Para - none directly
blood vessels
Alpha 1
Symp - vasoconstriction
Para - none directly
myocardium
Beta 1
Symp - increased contractility
Para - none directly
A.V node
Beta 1
Symp - increased conduction
Para - decreased conduction
S.A. node
Beta 1
Symp - increased HR
Para - decreased HR
Salivary glands
Unknown receptor
Symp - decreased secretions
Para - increased secretions
Pupil
Alpha 1
Symp - dilation
Para - constriction
what is the concept of sympathetic and parasympathetic “tone”
Vessels - sympathetic
Heart rate - Parasympathetic
what is the concept of sympathetic and parasympathetic “tone”
Vagus regulated heart rate at rest = vagal tone
Sympathetic regulate vascular tone all the time = sympathetic tone
Vessels - sympathetic
Heart rate - Parasympathetic
What population of pts in vulnerable to autonomic hyperreflexia?
T5-T7 transection
What changes occur in the spinal cords/NS of these pts?
New synapses formed below the transection, which causes a lot of activity below the lesion
What kinds of stimuli initiate the mass reflex?
Pain
Full bladder
Bowel movement
Stretching of the organ sends a bunch of AP to the spinal cord, activate sympathetic output, causing increase BP
Above the lesion - parasympathetic. B/c BP is high, so baroreceptors are stretched that activate PNS and the person will get bradycardia, nasal congestion, flushing.
Compare the actions of the sympathetic and parasympathetic in Autonomic hyperreflexia above and below the level of a lesion in a pt with a mass reflex episode?
Sympathetic reflex below lesion
Parasympathetic reflex above lesion
What is the greatest clinical concern during a mass reflex episode?
Severe Hypertension
cranial nerves III, VII, IX, X
- III - oculomotor, pupils (constriction)
- VII - facial, salivary glands
- IX glossopharangeal, pharynx (swallowing), carotid baroreceptors
- X - vagus, aortic baroreceptors, ANS motor
Where to the Parasympathetic cell bodies live?
Spinal - Sacral (exit here) 1. colon 2. bladder 3. external genitalia Cranial nerves
What NTx is released by the preganglionic cell?
Sympathetic
ACH
What NTx is released by the preganglionic cell?
Parasympathetic
ACH
Where are the receptors for the NTx released by the preganglionic cell?
Sympathetic
Ganglion (located near the spinal cord)
Where are the receptors for the NTx released by the preganglionic cell?
Parasympathetic
Ganglion (located near target organs)
What kind of subtype of receptor are they?
Sympathetic
Nicotinic
What kind of subtype of receptor are they?
Parasympathetic
Nicotinic
Give an example of an agonist and an antagonist for this receptor?
Sympathetic
agonist - nicotine
antagonist - NMB
Give an example of an agonist and an antagonist for this receptor?
Parasympathetic
agonist - nicotine
antagonist - NMB
Where are the receptors for the NTx released by the postganglionic cell?
Sympathetic
At the periphery (target organ)
Where are the receptors for the NTx released by the postganglionic cell?
Parasympathetic
At the periphery - at target organ
What kind of subtype(s) of receptor are they?
Sympathetic
Adrenergic (alpha or beta)
What kind of subtype(s) of receptor are they?
Parasympathetic
Muscarinic
What neurotransmitter stimulates the medulla?
ACH
What kind of receptors are located at the adrenal medulla?
Nicotinic receptors
what does the medulla produce?
catecholamines
80% epi
20% dopamine, norepi
Give an example of an agonist and an antagonist for this receptor?
Parasympathetic
agonist - Muscarine
antagonist - atropine, scopolamine
What are the major actions of the parasympathetic nervous system?
s one of three divisions of the autonomic nervous system. Sometimes called the rest and digest system, the parasympathetic system conserves energy as it slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles in the gastrointestinal tract.
What are the major actions of the sympathetic nervous system? How do these actions support an organism in an emergency situation?
The sympathetic nervous system is responsible for up- and down-regulating many homeostatic mechanisms in living organisms. Fibers from the SNS innervate tissues in almost every organ system, providing at least some regulation of functions as diverse as pupil diameter, gut motility, and urinary system output and function.
the fight-or-flight response - priming the body for action, particularly in situations threatening survival.
One example of this priming is in the moments before waking, in which sympathetic outflow spontaneously increases in preparation for action.
What is the role of the adrenal medulla in the autonomic nervous system?
the preganglionic sympathetic fibers that end in the adrenal medulla (but also all other sympathetic fibers) secrete acetylcholine, which activates the great secretion of adrenaline (epinephrine) and to a lesser extent noradrenaline (norepinephrine) from it. Therefore, this response that acts primarily on the cardiovascular system is mediated directly via impulses transmitted through the sympathetic nervous system and indirectly via catecholamines secreted from the adrenal medulla.
where is the synapse in the adrenal medulla?
pre-ganglionic neurons synapse with chromaffin cells, triggering the release of two transmitters: a small proportion of norepinephrine, and more substantially, epinephrine. The synthesis and release of epinephrine as opposed to norepinephrine is another distinguishing feature of chromaffin cells compared to postganglionic sympathetic neurons.
Postganglionic sympathetic nerves terminating in the kidney release dopamine, which acts on dopamine D1 receptors of blood vessels to control how much blood the kidney filters. Dopamine is the immediate metabolic precursor to norepinephrine, but is nonetheless a distinct signaling molecule.[7]
where do these substances produced by the adrenal medulla have their effects?
cardiovascular system
What neurotransmitter stimulates the medulla?
ACH
Cholinergic, preganglionic sympathetic neurons from the splanchnic sympathetic nerves release acetylcholine
What kind of receptors are located at the adrenal medulla?
Nicotinic receptors
Nicotinic acetylcholine receptors on Chromaffin cells
- Receptor stimulates Gs
- Activates adenylate cyclase
- Increases production of cAMP
- Activates A kinase
- Activates tyr hydroxylase
Stimulated by sympathetic input.
Acetylcholine binds ion-channel nicotinic receptor.
Depolarizes chromaffin cells.
Increases calcium influx.
Stimulates exocytosis of chromaffin granules.
what does the medulla produce?
stimulates both synthesis and secretion of catecholamines
80% epi
20% dopamine, norepi
Compare the time scale of sympathetic neuronal versus adrenal medulla effects.
catecholamine release and impact takes approximately 2 minutes
