Exam1Lec7AutonomicNS Flashcards
What does the CNS consist of
Brain + spinal cord
What the PNS break down into
- Somatic: Voluntary control of skeletal muscle
- Autonomic: Involuntary control of viscera
* Sympathetic: ”Fight or flight”
* Parasympathetic: ”Rest, digest and repair”
Where is the distal synapse location for autonomic and somatic
Autonomic: Peripheral ganglia ->GPA
Somatic: cerebrospinal Axia-> CAS
Are the post synaptic nerve myelinated or not in autonomic and somatic
Automonic: non-myelinated
Somatic: myelinated
What happens when denervation happens in autonomic and somatic
Auto: Spontaneous activity
Somatic: paralysis, atrophy
For the Sympathetic division, where are the paravertebral ganglia located
Lay close to the spinal cord
lay close to CNS
For the Sympathetic division, what are the pre-ganglionic neurons and what do they innervate
Short cholinergic (ACh) projections leave CNS to innervate ganglia
For sympathetic division, what are the post-ganglionic neurons and where do they innervate
Long adrenergic (NE) projections leave ganglia to innervate effector
What is the exception of the post ganglionic neurons for sympathetic response
Exception: Kidney has dopaminergic innervation
What is the response to sympathetic stimulation?
Think of these reactions in term of “fight or flight.”
For the parasymapthetic, what are the pre-gang neurons and where do they inverate
Long cholinergic projections which innervate ganglia NEAR target organ.
For the parasymapthetic, what are the post-gang neurons and where do they inverate
Short cholinergic projections to target organ.
All projections of the parasympathetic division are _
cholinergic
What is the reponse to parasympathetic stimulation?
Think of these reactions in term of “Rest, digest, and repair.”
Most organs receive _ _
dual innervation (sympathetic + parasympathetic)
How does the human eye recieve dual innervation
- Sympathetic – Radial muscle contracts dilating the pupil
- Parasympathetic – Circular muscle contracts constricting the pupil
What does not recieve parasympathic innervation
Blood vessels, hair follicles, and sweat glands
When I sweat, my hair bleeds- not para
What is the precursor, enzyme of actylcholine and how is it terminated
- Precursors: choline + acetyl CoA
- Enzyme: choline acetyltransferase (ChAT)
- Terminated: hydrolysis by acetylcholinesterase (AChE)
What are the locations of cholinergic receptors
- ALL pre-ganglionic neurons (parasympathetic and sympathetic) are cholinergic
- ALL post-ganglionic neurons of the parasympathetic are cholinergic
- ALL somatic (skeletal muscle) neurons are cholinergic
What are the subtype of cholinergic receptor
- Nicotinic Receptors
* Ligand-gated (FAST)
* NM & NN - Muscarinic Receptors
* G Protein-Coupled (SLOW)
* M1, M2, M3, M4, M5
Where is nicotinic acetylcholine receptors found? What is the speed of transmission and via what?
- Found in the ganglia + skeletal muscle
- FAST transmission via ligand-gated ion channels
What are nicotinic agonists
Nicotine, DMPP, & Epibatidine
What are the subtypes of nicotinic acetylcholine receptors? Location and physiological response?
- Nm: in NMJ to have skeletal muscle contraction
- Nn: in Autonomic ganglia, brain to have ganglionic transmission
Muscarinic acetylcholine receptors are exclusively where?
post-ganglionic neurons of parasympathetic system
* Cardiac and smooth muscle, gland cells, nerve terminals
Some post-ganglionic neurons of the sympathetic nervous system
* Sweat glands, vascular smooth muscle
What are muscarinic agonists
Muscarine, Pilocarpine, & Oxotremorine
What is the conduction of ODD muscarinic acetylcholine receptors? what do they cause?
- Odd numbered Muscarinic receptors = EXCITATORY
- Elevate intracellular [Ca2+]
These receptors modulate a parasympathetic response
What is the conduction of EVEN muscarinic acetylcholine receptors? what do they cause?
- Even numbered Muscarinic receptors = INHIBITORY
- Inhibit Adenylyl Cyclase = Decrease cAMP
These receptors modulate a parasympathetic response
Explain NE metabolism
- Dopamine synthesized from tyrosine by enzyme tyrosine hydroxylase
- Dopamine transported into vesicle by VMAT2
- Dopamine β-hydroxylation (DßH) to Norepinephrine
How is NE action terminated
- Reuptake into pre-synaptic terminal
- . Catabolized by MAO-A and COMT
Where are the locations of adrenergic receptors
Post-ganglionic neurons of the sympathetic nervous system
* Cardiac and smooth muscle, gland cells, nerve terminals
What are the subtypes of adrenergic receptors
- Alpha Receptors (GPCR)
- Beta Receptors (GPCR)
What do the alpha one and two resemble
a1 resemble odd muscarinic ACh receptors
* Increase intracellular Ca2+
* in vascular smooth muscle, heart, liver
* Causes vasoconstriction, increase contractile force, glycogenolysis, gluconegenesis
a2 resemble even muscarinic ACh receptors
* Inhibit adenylyl cyclase
* In pancrease islets (b cells)
* Decrease insulin secretion
These receptors modulate a sympathetic response
What does beta adrenergic receptors do?
INCREASE cAMP via activation of Adenyl cyclase.
What is the role of cAMP
- INCREASES contraction of the heart (B1)
- DECREASES contraction (relaxes) vascular and bronchial smooth muscle (B2)
These receptors modulate a sympathetic response
What are the beta adrenergic receptor subtypes, their location and response
- B1: in heart, juxtaglomerular cells to cause increase force and rate of contraction, increase renin secretion
- B2: in Smooth muscle (vascular, bronchial, GI), bronchial glands, liver to cause relaxation (vasodilation, bronchodilation), increase bronchial secretions, glycogenolysis, glycoengoenesis, increase insulin secretion
- B3: in adipose tissue to cause lipolysis, no release
What is the nested loops
The function of the ANS is to preserve homeostasis. There are several “layers” that ensure if one fails, another can step in.
Why do we care about the amygdala complex
While the brainstem is the primary region of homeostasis, there are several “higher centers” of control such as the amygdala.
* Associates ANS responses to specific behaviors (i.e. shock)
* Example: loud sound triggers fight or flight reflex via emotional response in amygdala
What is the baroreceptor reflux
Sensory afferent neurons that help modulate control based on various internal stimuli. (i.e. chemo and mechano receptors)
Normally, the bladder distends and signals to the brain that we must void. But what if there is damage this higher center?
- Sensory neurons at the dorsal root ganglion send signal to the spinal cord (which innervates bladder) and trigger voiding.
- Spinal cord injury and MS may negatively affect this loop.
_ on the surface of organs can modulate function to some extent
Ganglia
* Ganglia on the heart contribute to rhythmicity.
* CHF and arrhythmias can be associated with failure of this loop.
What does the presense of heteroreceptors at the neuronal synapse allow
allows for regulation of synaptic signaling
What do heteroreceptors act as
terminal receptors for other transmitters that may act either to stimulate or inhibit release at that terminal(e.g., a cholinergic receptor on an adrenergic nerve terminal).
