Physiology 11.28.12 ANS 1 Flashcards
What is NTS?
nuclues tractus soliatrius
major lower brainstem command center for control of peripheral organs
What is the role of hypothalamus
coordinates autonomic output and regulates feeding, body temp, circadian rhythm, emotion, exual drive, and other brain functions
Where are the cell bodies of preganglionic nueonrs of sympathetic division lovated?
intermediolateral horn of psinal cord
Where do axons of myelinated preganglionic neurons leave the spinal cord?
via VENTRAL ROOTS
at level T1-L3 (thoracolumbar)
Where do preganglionic neurons make synapse with postganglionic neurons??
in PARAVERTEBRAL sympathetic chain ganglia
upper chain ganglia merge into superior, middle and inferior cervical ganglia
or in the PREVERTEBRAL COLLATERAL ganglia (celiac, superior and inferior mesenteric ganglia)
Where do nonmyelintated axons of postganglionic neruosntravel ?
form these chaisnn and colaleratal ganglia to teh TISSUE THAT THEY INNERVATE
What is the exception to the 2-neuron rule for the sympathetic pathway?
Adrenal gland (medulla)!
What does adrenal gland (medulla) secrete?
90% Epinephrine
10% NE
What muscles are innervated by sympathetic system?
hair follicles
secretion of sweat glagnds
certain BV in skeletal muscles
This is via Sympathetic Cholinergic Pathway
What is the transmitter at the autonomic ganglia of sympathetic pathway
Ach
What combines together to make Ach
Chonline and acetylCoA combine to form ACh
Is the action of ACh short-lasting or long-lasting?
Short-lasting
What are the two ACh receptors
- Nicotinic - ion channel; multimer with several subunits
2. Muscarinic - one subunit, 7 TM, G protein 2nd messenger signaling
Which type of Ach receptors are predominant at sympathetic autonomic ganglia?
NICOTINIC!
Nicotinic is much faster than muscarinic in actino
Is the beta 2 adrenergic receptor closer to nicotinic or musscarinic receptor
it’s more similar to muscarinic
What is the predominant form of ACh receptor?
Nicotinic R are predominantly expressed!
keep in mind both are expressed though
What are the similarireis of nACH receptors in autonomic ganglia vs nACH R in skeletal? What type of Nicotinic R in each?
Same general structure
Different amino acid seqeunces
Sk muscle: N1 type Receptor
Autonomic neuron: N2 type receptor
What is the role of the muscarinic R
less abundantly expressed (compared to nictonici)
modulate strength of depolarization that is necessary for generation of repetitive AP firings
What is Decdamethonium?
stimulates N1
What is Tubocurare
Blocks N1
What is Teteramethylammonium
Stimulates N2
How many isoforms of MUSCARINIC R are tehre
M1-M5
will ony discuss M1-M3
What happens when Ach action on M1/M3
coupled to PLC –> IP3 & DAG by PIP2
What happens when M1/M3 recepetors decreases PIP2 in membrane
level of PIP2 in membrane ins reduced due to its degradation by PLC -> inhibits active K+ curren (M current) –> produces small membrane depolarization
Increases excitability of the membrane, and allows repetiive firing of the neuron
Whawt does Ach action on muscarinic receptors regualte
strength of innervatino of the organ
enchansces predominant Nicotinic effect) –> repetitive firing
What is the role of M2 receptor
coupled to AC and K+ channel
Which amino acids are precursors for the synthesis of Catecholiamines
Catacholamines = NE and Epi
Phe and Tyr are essential aa that are precursors for catecholaimnes
which catecholamines
NE
Epi
Dopamine (within CNS)
What are two major subtypes of adrenergic R
alpha
beta
Difference between the binding of NE and Epi with adrenergic recetpros
Epi binds to B2
NE doesn’t bind to B2
difference in receptor specificity
What are main receptors expressed in heart (myocytes)
beta 1
which receptors are predominantly expressed in SM of vasculature
alpha 1
Beta 2
What receptors woudl NE act on?
B1 receptors of heart
alpha 1 (not beta 2) R in BV SM
main effect of Alpha 1 R
contractile effecet on SM via IP3-Ca
Effect of Beta 1 and Beta 2
similar signaling pathway up to PKA
any difference in actions would be distal to PKA
Protien targets of PKA scould be different
Effect of alpha 2 receptor
effect is small when AC activity and [cAMP] levels low
not well expressed in vascular SM cells and not significantly invovled in BP regulation by sympathetic NS
What happens when NE is added to solution of perfusing heart
yes
Where are cell bodies of preganglionic neurons of Parasympathetic division ?
Cranial protion of brainstem and in Sacral sements of spinal cord
CRANIOSACRAL
Which cranial nerves supply parasympethic system
3 oculumotor
7 facial
9 glossopharyngeal
10 vagus
does preganglionic neuron long or short?
long! and terminates close to effector organ
What is the significance of the epinephrine effect
Various vascular beds react differently to epineprhine
REDISTRIBUTION OF BLOOD OCCURS
Decrease BF (hands, feet, skin alpha1> beta2)
Incraese skeletal muscle BF (Beta2»_space;alpha1 effect)
Beta2- also stimualtes glucose produciton–for energy
What is the effect of epinephrine for cutaneous blood flow (hands, feet, skin)
alpha1 R > beta2 R
therefore, Gi –> dcrease cutaneous BF
What is the effect of epinephrine on skeletal muscle blood flow
beta2 R»_space; alpha1 R
therefore Gs»_space; Gi
Increase sk. muscle BF
B2 also stimulates glucose production for energy
How does PS affect BV?
cholinergic innervation restricted to External genitalia and Certain cranila nerves
if ACh injected into blood, releaxation of SM in arteriorles adn fall in BP due to endothelial cells–NO
How do organic nitrates like nitroglycerin work in treatment of angina pectoris caused by ischemic heart disease
These agents lead to formation of NO when administered to the body.
Vasorelaxatino roduced by NO increases blood supply t ischemic myocardium an ecreases oxygen consumptino by musce ==> this reduces pain
How does viagra and cialis work?
inhibits PDE-5
inhibits the inhibitor of cGMP –> inhibits the terminatino of cGMP inot 5-GMP
