Neuroscience Autonomic Nervous System I and II Mary Lou Vallano Flashcards
The sympathetic nervous system is also known as the:
thorocolumbar system
The PNS is aka:
Craniosacral system
Is survival without ANS activity possible?
Yes, but physiological function is severely imparied.
Stimulation of heart rate at the SA node:
- -What ANS branch?
- -What kind of effect?
Sympathetic
Positive chronotropic effect
Stimulation of AV nodal conduction:
- -What ANS branch?
- -What kind of effect?
Sympathetic
Positive dromotropic effect
Stimulation of myocardial contractility:
- -What ANS branch?
- -What kind of effect?
Sympathetic
Positive inotropic effect
Inhibition of heart rate at SA node:
- -What ANS branch?
- -What kind of effect?
Parasympathetic
Negative chronotropic effect
Inhibition of AV nodal conduction:
- -What ANS branch?
- -What kind of effect?
PS
Negative dromotropic effect
Inhibition of atrial contractility:
- -What ANS branch?
- -What kind of effect?
PS
Negative inotropic effect (mild)
What kind of receptor antagonists are used to treat hypertension and tachycardias?
B1
Propranolol
What is divergence?
The avg preganglionic axon in the SNS contacts an estimated 100 postganglionic neurons by collateral branching, enables widespread responses. Not a thing in the PNS (1:15-20)
En passant synapses are aka
varicosities, show divergence
Are ANS preganglionic axons myelinated?
No
smaller diameter than skeletal axons
slower-conducting
B-fibers
Are ANS postganglionis axons myelinated?
No
smaller diameter than skeletal axons
slower-conducting
C-fibers
What is the main player NT in the PNS?
Acetylcholine, in both ganglion and target tissue
What kind of receptor is the main PNS receptoron target tissue?
Muscarinic
What is the main player NT in the somatic nervous system?
Acetylcholine, N1 receptors (nicotinic cholinergic)
Where are N2 receptors found?
- PNS at the 1st synapse (peripheral ganglion)
2. Peripheral ganglia of SNS
What kind of receptor is a muscarinic cholinergic receptor?
GPCR:
- PLC –> generation of IP3 and DAG, OR
- Inhibition of adenylate cyclase –> cAMP down
In most postganglionic SNS synapses, the NT is:
norepinephrine
When is the postganglionic SNS NT epinephrine?
Adrenal medulla, synapse on chromaffin cell instead of ganglion
T or F: The adrenal medulla secretes enough epi (and norepi) to maintain a near normal blood pressure if sympathetic innervation to the heart is interrupted.
True
What are the common ANS co-transmitters, being released with norepi and ACh?
ATP
Neuropeptide Y
(others)
What kind of innervation do sweat glands received?
Sympathetic cholinergic innervation (MUSCARINIC receptor, ACh NT)
What are the common themes of the MOA’s of a1, b1 and b2 adrenoreceptors?
Norepi binds to receptor
GDP –> GTP and subunit comes off
Subunit (a-q or a-s) activated other pathways leading to either Ca2+ influx, or physiological changes in the cell
What is the major adrenergic receptor in the heart
B1
What is the major receptor for the vasculature/arterioles?
A1
How many subunits does a nicotinic receptor have?
5, 2 alpha, 1 beta, 1 gamma and 1 delta
What kind of receptor is a nicotinic cholinergic receptor?
Ligand-gated ion channel
ligand - ACh (x2)
ions - Na+ and K+
d-Tubocurarine is an antagonist of what receptor?
N1 nicotinic
What are the N1 agonists?
ACh
Nicotine
ACh and nicotine are agonists for what receptor?
N1 and N2
What are the agonists for muscarinic cholinergic receptors?
ACh
muscarine
What is the antagonist for muscarinic cholinergic receptors?
atropine
Hexamethonium is an antagonist of what receptor?
N2
Name two B1 antagonists
Propranolol
Metoprolol
A1, B1 and B2 are all what kind of receptors?
adrenergic
Both B1 and B2 have the same agonists. What are they?
Epi > NE - Epi has greater affinity for B adrenergic receptors than Norepi.
A1 adrenergic agonists are:
NE > Epi - Norepi has greater affinity for B adrenergic receptors than epi.
A1 has what kind of receptor?
GPCR, Ga-q (same as muscarinic)
B1 and B2 have what kind of receptors?
Ga-s GPCR
Skeletal muscle can constrict and dilate via SNS innervation. Which skeletal muscle constricts, and which receptor does it use?
Brionchioles, B2
Where in the SNS can B1 receptors be found and what is their effect?
Heart - SA node - increase contractions
- -AV node - increase nodal conduction
- -increase contracility
Saliva - secretion
Where in the SNS can B2 receptors be found?
Bronchioles - dilate
Bladder wall - relaxes
Smooth muscle - relaxes
Skeletal muscle - dilates
__1__ effects are more prominent in targets where B-adrenergic receptors prodominate, such as the heart, lungs and liver, whereas __2__ effects predominate in the vasculature where alpha-adrenergic receptors are expressed.
- EPI
2. NOREPI
What is a pheochromocytoma?
A tumor of the adrenal medulla that causes norepinephrine and/or epinephrin surges. Excessive cyclic hypertension
What is enopthalmus?
Sunken eyeball
The major prevertebral ganglia are:
Celiac
Superior mesenteric
Inferior mesenteric
The celiac ganglion innervates:
the stomach, liver, pancreas, gallbladder, small intestine, spleen, kidneys
The superior mesenteric ganglion innervates:
the small and large intestine
The inferior mesenteric ganglion innervates:
the lower colon and rectum, urinary bladder, reproductive organs
The pteryopalatine and submandibular ganglia come from what nerve and serve what areas?
- CN VII
- Pterygopalatine serves nasal mucosa and lacrimal gland
- Submandibular serves salivary glands
What are the main cranial nuclei of the vagus nerve?
Nucleus ambiguous
Dorsal motor nucleus
More than 75% of the PNS is controlled by:
the two vagus nerves
The myenteric plexus is aka:
Auerbach’s plexus
In the myenteric plexus, PNS activation does what?
It is depolarizing and generates action potentials leading to contractions of the smooth muscle of the gut.
What is ileus?
Strong SNS stimulation can inhibit motility so greatly that food movement is blocked.
During bladder filling, sympathetic control predominates, causing:
relaxation of the detrusor muscle
contraction of the internal sphincter
During micturition, parasympathetic control predominates, causing:
contraction of the detrusor muscle
relaxation of the sphincter muscle
What receptors relax the detrusor muscle, and what receptors contract the muscle?
B2 - sympathetic - relaxes
A1 - sympathetic - contracts
Transection of the brain stem just below the medulla results in a decrease in:
arterial blood pressure to less than half the normal value
Transection above the mid-pontine level preserves:
basal control of arterial pressure, but eliminates modulation by higher structures
What part of the brain is most responsible for influencing cardiac function?
Nucleus of the solitary tract
What is vasovagal syncope?
Begins with disturbing thoughts in the cortex, this leads to activation of vasodilator centers in the hypothalamus, and to the heart through the vagus nerves, rapidly slowing the heart. There are also signals through the spinal cord to the SNS vasodilator nerves of the muscles (rapidly increasing flow to muscles). The resultant fall in arterial pressure reduces blood flow to the brain and causes the person to lose consciousness.
What are examples in which visceral afferents overwhelm cortical functions (where nothing seems to matter):
Hunger Nausea Dyspnea Visceral pain Bladder and bowel distention Hypothermia/hyperthermia
