ANS - Lecture 2 Flashcards
cranial nerve X also called ____ ____ carries 75% of
- vagus nerve
- all parasympathetic fibers innervating various organs
cranial nerve that innervates heart, lungs and various parts of the intestinal tract
vagus nerve or cranial nerve X
the PSNS ganglia are found
close to the organ or within the walls of the organ
The functions of the parasympathetic system dominate during the
rest/digest response
T/F adrenal medulla is innervated by parasympathetic fibers
False - no parasympathetic innervation
T/F smooth muscles of most blood vessels in the body receive parasympathetic innervation
False; exception is penis and clitoris
what is meant by dual autonomic innervation?
innervation of organ/tissues from both the SNS and PSNS
Tone in DAI is
a background level of activity maintained by both SNS and PSNS
The SNS and PSNS are activated reciprocally meaning
the increase in activity of one system will decrease the activity of the other system
one division turns up its activity and the other turns down its acitivity; this is to
give more control over body responses
what are the exceptions of dual innervation
adrenal medulla, most blood vessels and sweat glands; receive parasympathetic innervation only
T/F the sympathetic system is always excitatory and the parasympathetic system is always inhibitory
False - depends on target tissue, neurotransmitter and receptor to which it binds
chemical transmitters of the ANS and what they release
- cholinergic: releases ACh
- adrenergic: releases NE
Preganglionic neurons release ____ in both he SNS and PSNS
ACh
The major transmitter at all ganglia in the ANS
acetylcholine
PS postganglionic fibers release
ACh at target tissues
S postganglionic fibers innervating MOST of the target tissues release
NE at target tissues
ACh is released by S postganglionic fibers at
SOME of the innervated target tissues
** see slides for events at a cholinergic nerve terminal
ACh is synthesized from
acetyl CoA and choline in the nerve terminal
what enzyme catalyzes events at the cholinergic nerve terminal?
choline acetyltransferase
Ach binds to receptors on the membrane of the _________ neuron called
- postsynaptic
- cholinergic receptors
enzyme that breaks down ACh to choline and acetate
acetylcholinesterase
What is varicosity, what type of neuron does it occur on?
- swellings along the axon branches
- both S and PS postganglionic neurons
site where the neurotransmitters are made and stored in vesicles
varicosities
what function do varicosities have in neurotransmitter release?
- releases neurotransmitters along a significant length of the axon and therefore over a large surface area of the effector tissue
NE is synthesized from
the amino acid tyrosine
tyrosine is converted to
dopa and dopamine
How is norepinephrine recycled?
a special transport system that can take the whole molecules of norepinephrine back up into the varicosity
ACh is released at
- all autonomic ganglia
- parasympathetic postganglionic fibers
- sympathetic preganglionic fibers innervating sweat glands and blood vessels in skeletal muscles
NE is released at
- most sympathetic postganglionic fibers
- adrenal medulla (along with E)
Cholinergic receptors bind to ____ and the two types are:
- ACh
- nicotinic, muscarinic
Nicotinic receptors found in skeletal muscles (Nm) are responsible for ______ _______ in what nervous system?
muscle contraction
somatic nervous system
Nicotinic receptors found on the cell bodies of the postganglionic neurons (Nn) are responsible for: in what nervous system?
- the production of an EPSP
- PSNS and SNS
what contains the Nn type of nicotinic receptor?
cell bodies of all postganglionic neurons (SNS and PSNS) and adrenal medulla
Adrenergic receptors bind
NE or E
2 types of adrenergic receptors
alpha (2 subtypes)
bets (3 subtypes)
Adrenergic receptors are ____________ receptors meaning the binding of NE/E to the receptor causes excitation/inhibition of the target tissue through a ___________ coupled mechanism
- metabotrophic
- G-protein
membrane-bound receptor proteins that respond to ligand binding by opening an ion channel and allowing ions to flow through
ionotropic
see the document for structures and mechanisms of nicotinic, muscarinic and adrenergic receptors
convergence in the ANS is when
numerous preganglionic neurons form synapses with a single postsynaptic neuron
divergence is when
a small number of presynaptic neurons form synapses with a larger number of postsynaptic neurons
in the ANS, divergence exists at the
ganglia
______ nervous system exhibits a greater degree of divergence than the ______ nervous system
sympathetic
parasympathetic
in the PSNS, the ratio of preganglionic neuron synapsing with postganglionic neuron is between ____ and ____ meaning more specific/localized
1, 3
In the SNS the ratio of preganglionic neuron to postganglionic neuron can be anywhere between ___ and ____ meaning a more diffuse response
1, 20
