Lecture 6: Autonomic and Somatic Nervous Systems Flashcards
the nervous system is divided into ___ and ___ branches
central and peripheral
the peripheral nervous system is divided into the sensory systems of ___ and ___
autonomic and somatic
the autonomic nervous system is divided into ___ and ___ branches
sympathetic and parasympathetic
movement, respiration, posture and voluntary movements are controlled by what branch of the peripheral nervous system?
somatic
cardiac output, blood flow, digestion etc and involuntary control are controlled by what branch of the peripheral nervous system?
autonomic
the ___ nervous system regulates processes in the fight/flight response
sympathetic
the ___ nervous system regulates processes in the rest/digest response
parasympathetic
in the sympathetic system, the ganglia cluster together in a structure called the ___
sympathetic chain
location of parasympathetic ganglia
close to or within their target organs
in both sympathetic and parasympathetic systems, the preganglionic neurons release ___ into the synapse with the post ganglionic cell
acetylcholine
___- receptors on the post-ganglionic cells receive the signal and propagate ___ along to the target tissue
nicotinic Ach; action potentials
the post-ganglionic cells of the parasympathetic nervous system release ___ and the target tissue typically express ___ type Ach receptors
Ach; muscarinic
in most tissues of the sympathetic system, ___ type receptors are expressed and respond to ___ (NT)
adrenergic; NE
___ are endogenous agonists
neurotransmitters
controlled release of ___ transmits signals to the specific tissue that is to be activated
NT
___ trigger the release of neurotransmitter
AP
___ are the primary mediators of signals in many systems
NT
the propagation of action potentials between neurons is carried out by ___
neurotransmitters
influx of ___ion causes NT release at the synapse
Ca
a ____ will be created if a stimulus / amount of NT is not great enough to trigger an AP
EPSP
what are the 3 structurally related catecholamine NT?
NE , E , and dopamine
epinephrine is released by the ___ in response to ___
adrenal gland; sympathetic activation
t/f E and NE act on similar receptors
true
which NT is the key mediator in the CNS?
ach
t/f there are multiple receptor types involved in Ach signalling to generate specific responses in different tissues
true
what are the 2 main classes of cholinergic receptors?
nicotinic and muscarinic
what are the 2 types of nicotinic receptors? where is each type found?
- Neuronal (NN): found in CNS & ANS
2. Muscular (NM): found in neuromuscular junction
what are the 2 families of muscarinic receptors? where is each found?
- Odd (M1,3,5): found in CNS & smooth muscle
2. Even (M2&4): found in heart & CNS
what receptors type are nicotinic ach receptors?
ligand-gated ion channels
what type of nicotinic receptors are present in the pre and ganglionic neurons of the parasympathetic nervous system?
neuronal
describe the 4 steps involved in action of nicotinic receptors
- ach binds, resulting in conformational change
- influx of Na
- change in membrane excitability (depolarization)
- action potential or muscle contraction
what type of receptors are muscarinic receptors?
GPCR
even muscarinic receptors have ___ effects
excitatory
odd muscarinic receptors have ___ effects
inhibitory
M1,3,5 are ___ coupled GPCRs
gQ
M2&4 are ___ coupled GPCRs
Gi
the primary effects of most GI GPCRs is the decrease the cellular levels of ____, which reduces cell activities
cAMP
binding of agonist to GPCR causes a ____ change and the ___ of the G-alpa and G-beta subunits
conformational change; dissociation
the dissociation of the G-alpha and G-beta subunits results in the initiation of ____
signalling cascaded
activation of a GQ coupled pathway in a neuronal cell would be expected to cause what result?
increased NT release
activation of a GQ coupled pathway in a muscle cell would be expected to cause what result?
muscle contraction
what are the 4 steps in activation of muscarinic receptors?
- agonist binds to extracellular surface of receptor
- conformational change causing the exchange of GDP for GTP on the G protein
- Ga and Gb dissociate from the receptor and initiate intracellular signalling cascades
- 2nd messenger molecule amplify the signal and initiate cellular response
responses initiated by Ach are regulated by the rapid ___ in the synapse
Ach breakdown
____ is a membrane-bound enzyme that cleaves Ach into inactive products, quickly terminating neuronal response
Ache
Ach is made and stored in the ___ within structures called ___
nerve terminal; vessicless
Ach is released in response to ___
AP
in addition to binding to postsynaptic receptors, Ach also defuses back to the presynaptic cell and binds to ____ receptors that act to achieve ___
autoreceptors; decrease NT release to prevent overstimulation and down-regulation of postsynaptic receptor
NE is made and stored in ___
sympathetic neurons
VMAT (vesicular monoamine transporter) is required for packaging and storage of ___ in nerve terminals
NE
NE is made from what amino acid? what is the intermediate product?
tyrosine; dopamine
differential expression of ___ within a cell determines which catecholamine is present in highest concentration
enzyme
t/f increasing the amount of one catecholamine may increase the amount of another because they are made by the same pathway
true
adding dopamine to manage Parkinson’s can have the unintended effect of increasing ___
NE
preventing metabolism of one catecholamine may result in the increased production of other metabolites, such ___ which can have cardiovascular effects
tyramine
many things about NE release are similar to that of Ach, but one key difference is that NE can be taken back up into the pre-synaptic cell by ___
NETs, NE transporters
the reuptake of NE to the presynaptic cell ___ the stimulatory response
terminates
NE is metabolized by 2 enzymes: ___ and ___ that produce inactive metabolites
COMT and MAO
what is COMT?
catechol-o-methyltransferase
what is MAO
monoamine oxidase
what are the 2 isoforms of MAO?
MAO-A and MAO-B
COMT is one of the enzymes that metabolizes ___ in the central and peripheral nervous systems
catecholamines
MOA metabolizes ___
catecholamines
COMT and MAO are targets for treating ____ conditions
central nervous sytem
what are the 2 main types of adrenergic receptors?
- Alpha
2. Beta
alpha receptors have multiple ___ within each subtype
isoforms
A1 receptors are primarily found in the ___ and some in the ___
smooth muscle; heart
A1 receptors are coupled to ___ G proteins and what type of cellular responses?
GQ; increased Ca and muscle contraction
A2 receptors are found in the ___ and ___
central nervous system and sympathetic nervous system
A2 receptors are coupled to ___ G protein which regulates the ____ from presynaptic neurons
Gi; amount of NT release
B1 receptors are found in the ___
heart
B2 receptors are found in the ___ , ___ and ___
lungs, smooth muscle /blood vessels and liver
both b1 and b2 receptors couple to ____ G protein and result in increase in __
Gs; cAMP
in the heart, increased levels of cAMP results in __
increased contractility
in the lungs and other smooth muscles, cAMO results ___
relaxation
what are the 2 families of dopamine receptors?
D1 and D2
what dopamine receptors are in the D1 family? what is their main role and what G protein are the coupled to?
D1 & 5; excitatory ; Gs
where are D1 family receptors found?
smooth muscle and renal vasculature
what dopamine receptors are in the D2 family? what is their main role, and what G protein are they coupled to?
D2, D3, & D4; inhibitory; Gi
where are D2 family receptors found?
smooth muscle and presynaptic neurons
D2 receptors in presynaptic neurons act as ___
autoreceptors
the eye is an example of a tissue that can be influenced by what branch of the ANS?
both parasympathetic and sympathetic
Ach cause pupil ___
constriction
NE causes pupil ___
dilation
ach causes the lens to accommodate for ___ vision by becoming more ___ in shape
near ; round
NE cause lens to accommodate for ___ vision by becoming more ___ in shape
far; flat
intraocular pressure is determined by the balance between __ and __
aqueous humour secretion into the eye and aqueous outflow
___ (NT) stimulates the secretion of aqueous humour into the eye
NE
____ (NT) stimulates aqueous outflow, having a net effect of lowering intraocular pressure
Ach
the dynamic sliding back and forth between sympathetic and parasympathetic is called
autonomic tone
