PNS (Exam 2) Flashcards by Veronica Robinson

T/F
Most drugs either have a direct effect on the central nervous system or a side effect on the system.

False
peripheral

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T/F
Any PNS alteration in normal function could be life-threatening to the individual.

True

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PNS broken down into two major components

Somatic (skeletal muscle)
Autonomic (SNS and PNS)

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Somatic nervous system controls..

skeletal muscles

Somatic Skeletal

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Autonomic nervous system

controls other bodily functions required for life

subdivided into:
Sympathetic nervous system
Parasympathetic nervous system

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T/F
the peripheral nervous system is a subdivision of the autonomic system.

False

Peripheral NS:
Autonomic (sympathetic & parasymp)
Somatic

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Somatic Nervous System

Provides CNS and reflexive control of skeletal muscles.

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Gap junctions

Na ions flow between fibers here to allow stimulation

contraction of all linked fibers (motor unit)

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T/F
There is a nerve for every muscle fiber.

False
That is too much work
body clumps fibers together as motor unit
one nerve innervates the unit

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T/F
large muscle groups (glutes, biceps, triceps, calves) have less fibers per motor unit.

False
small muscles (fingers) = fewer muscle fibers per unit (finer control)

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Nerve fibers leave spinal cord from ___.

all levels

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Motor nerves synapse at ….

only at their final destination (the muscle)

the motor end plate

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T/F
There are no motor unit synapses in the SC.

True

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T/F
The Autonomic NS provides reflexive control of skeletal muscles

False
Somatic NS

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NMB affect which part of the nervous system?

Somatic

Suxx Somatic

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motor units

groups of muscle fibers

innervated by a single nerve fiber with axonal branches going to individual muscle fibers

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T/F
All motor nerves are myelinated

True

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Somatic NS

NT at motor end plate
receptor type

acetylcholine

nicotinic (N1 type [old term], neuromuscular nAChR)

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Transmission down motor axonal link occurs how quickly

~1/10 of a second
<2/10 sec

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⭐️
NACHr (nicotinic) receptor

nicotonic = ionophore
pentameric
2 Ach bind to open
Na+ influx
raises internal voltage
depolarization

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Autonomic Nervous System
controls…

body homeostasis

BP, RR, Temp
internal/smooth muscles (not skeletal)

Regulates hormonal secretions

tone & motility of smooth muscles

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Most tissues (except _____) are innervated by at least one branch of the ___.

skeletal muscles
Autonomic NS

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serves as a positive and negative control system

Many tissues innervated (or serviced) by both branches (sympathetic and parasympathetic)

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T/F
Most tissues are innervated by only one branch of the autonomic NS.

False
most are innervated by both branches of the ANS (parasymp & symp)

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"override"

Blocking one system (parasymp or symp) allows other to take over

Predominant control system of the heart

Parasympathetic

Ganglion

collection of nerves that synapse signals travel towards destination tissue

ganglia location sympath vs parasymp

sympathetic: close to SC (**paravertebral chain**) parsymp: closer to innervated tissue some exceptions exist sometimes ganglia can be used by both symp & parasymp

ganglionic receptors of symp & and parasymp are

nicotinic "ganglionic nicotinic" "nAChR" "neuronal"

neuronal refers to

ganglionic nicotinic receptors

the preganglionic neurons of both symp & parasymp use which NT?

ACh both cholinergic

T/F the N2 receptor is the only receptor that can control Autonomic output and transmission to post-ganglionic fibers.

False they are the single most important but not the only one

post-ganglionic fibers

exit ganglion and travel to tissue they innervate

Sympathetic Post Ganglionic/end organ tissue receptor

adrenergic (norepi)

Sympathetic Post Ganglionic/end organ tissue NT

Norepi

Parasymp Postganglionic fiber/end organ

cholinergic muscarinic (primarily G-protein)

T/F Post-ganglionic receptors of the parasympathetic nervous system are ionophores.

False muscarinic (G-protein)

Mainly controls sedentary functions.

Parasympathetic Nervous System

Parasympathetic Nervous System actions

Stimulates: Digestion peristalsis HCL acid production salivation lacrimation Miosis (smaller pupils)

T/F Controlling the lens allows us to alter pupil diameter.

False Use iris to control pupil diameter

mydriasis vs miosis

mydriasis: dilation miosis: constriction my**D**riasis = **D**ilate

ciliary muscle

controls lens; focusing

Parasympathetic control shifts the eye's focus ____

closer

accomodation

focusing in on shorter distance Ie: reading

Parasympathetic Nervous System Exits spinal column from ....

cranio-sacral regions (upper and lower regions).

Synapses at ganglia close to innervated tissue.

Parasympathetic

Parasympathetic ratio of incoming to outgoing fibers

1:1 provides fine control

Parasympathetic NT @ pre-ganglionic (N2, neuronal nAChR) & post-ganglionic (muscarinic)

ACh

N2 receptor

Preganglionic receptor nicotinic "nAChR" "neuronal"

Sympathetic Exits spinal column from...

thoraco-lumbar regions

Synapses at ganglia (paravertebral chain) that lies close spinal cord

Sympathetic

Sympathetic NS ratio of incoming to outgoing fibers

1:10 to 1:100 wider control 1 pre-gang fiber exits spinal column → 100 fibers exiting ganglia (vs Parasympathetic 1:1 ratio; finer control)

Sympathetic NT @ pre & post-ganglionic synapse

pre-ganglionic: ACh post-ganglionic: Norepi (mostly)

T/F Norepi is the sole post-ganglionic NT in Sympathetic nervous system.

False Dopamine and epi are also present (catecholamines)

paravertebral chain

series of ganglia that lies close to spinal column normal ganglia of sympathetic NS they synapse here

Which has more precise control? Sympathetic Parasympathetic

Parasympathetic (1:1 ratio incoming:outgoing fibers) (Sympathetic = 1:10 to 1:100) "**P**arasym = **P**recise"

Adrenal Medulla

acts as a giant ganglion pre-gang fibers can go straight here instead of paraverteb. chain mechanism for affecting wide-ranging tissues

Adrenal Medulla vs normal ganglion

Adrenal Medulla: **NTs in cell body** & its cells release NTs **directly into bloodstream** -no axon stimulation -does not use synapse -secretes epinephrine : norepinephrine in an 80:20 ratio (vs post-gang receptor that secretes mostly norepi)

The adrenal medulla is stimulated by...

preganglionic Ach release from Sympathetic system

Adrenal Medulla secretion

epi : norepi 80:20 ratio directly into bloodstream

Epi vs Norepi

Epi: more constriction of BV lasts longer in bloodstream both are quickly metabolized in blood

Anticholinergics override which system?

Parasympathetic sympathetic will take over

Primary tone of GI tract what would an anticholinergic do?

parasympathetic decreases GI output