Autonomic Nervous System

ANS controls important ___ functions

visceral (automatic)

the nervous system consists of the ___ and ___

CNS (central nervous system, brain and spinal cord) and PNS (peripheral nervous system, cranial nerves and spinal nerves)

the peripheral nervous system consists of ___ and ___

ANS (autonomic nervous system) and SNS (somatic nervous system)

the ANS system is autonomic (not under direct conscious control); it innervates ___

internal organs, glands, smooth and cardiac mucles

the SNS is the motor portion concerned with conscious functions; it innervates ___

SKM

sensory or ___ neurons transmit info about external and internal environments from ___ to ___

afferent, PNS, CNS

motor or ___ neurons transmit instructions from ___ to ___

efferent, CNS, PNS

ANS consists of ___ neurons

visceral sensory and motor

SNS consists of ___ neurons

somatic sensory and motor

__ receive input from adjacent neurons → __

dendrites, soma (cell body)

info transmitted from soma along __ in form of an __

axon, action potential

__ synthesizes a neurotransmitter (NT) and stores it in __

nerve terminal, vesicles

when action potential arrives at nerve terminal, NT is released by __

exocytosis

ANS motor neuron is a mostly __ neuron system, from __ → __

2, CNS, effector cell

describe neurotransmission in ANS

collection of somas in PNS =

ganglia

SMS motor neuron is __ neuron system

1

describe SNS

the ANS controls __

cardiac muscle, smooth muscle, secretory glands

ANS consists of ___ and ___

sympathetic, parasympathetic

sympathetic is ___

fight or flight

parasympathetic is ___

rest and digest

most organs are innervated by BOTH divisions but at rest are controlled predominantly by ___

parasympathetic division

only sympathetic innervates and controls:

blood vessels, sweat gland, adrenal medulla, ventricles

___ is required under circumstances of stress, and isn’t required for life in a controlled environment

sympathetic

___ is required for life, even in a controlled environment

parasympathetic

collection of somas in CNS =

nuclei

collection of somas in spinal cord =

column

collection of somas in PNS =

ganglia

somas of the sympathetic preganglionic neurons are in the __

thoracolumbar (thoracic and lumbar spinal cord)

fibers of the sympathetic preganglionic neurons are in the __

spinal nerves T1-L2/L3 (branch extensively)

somas of the sympathetic postganglionic neurons are in the __

peripheral ganglia near spinal cord (paravertebral and prevertebral ganglia)

fibers of the sympathetic postganglionic neurons are usually ___ than preganglionic fibers

longer

somas of the parasympathetic preganglionic neurons are in the __

craniosacral (brain stem and sacral spinal cord)

fibers of the parasympathetic preganglionic neurons are in the __

cranial nerves III, VII, IX, X, and spinal nerves S2-S4 (has limited branching → localized responses)

somas of the parasympathetic postganglionic neurons are in the __

peripheral ganglia near innervated structures (terminal and intramural ganglia)

fibers of the parasympathetic postganglionic neurons are usually ___ than preganglionic fibers

shorter (they innervate adjacent effector organs)

the autonomic NTs are __ and __

acetylcholine (ACh) and norepinephrine (NE)

acetylcholine (ACh) is ___ transmission

cholinergic

norepinephrine (NE) is ___ transmission

adrenergic

the NT in all synapses in peripheral ganglia is __

ACh

the NT at NEJ for parasympathetic is

ACh

the NT at NEJ for sympathetic is

NE (except sweat glands is ACh)

parasympathetic is always ___ transmission, while sympathetic is mostly ___ transmission

cholinergic, adrenergic (except for sweat glands)

adrenal medulla is a ___ that secretes ___

specialized peripheral ganglion, EPI and small amounts of NE (neurohormones)

SNS releases ___ (NT) onto ___

ACh, SKM

neurotransmission steps:

1. __ and __ of NT

2. __ of NT by __

3. __ of NT to post synapatic cell

4. __ of NT to __ on postsynaptic cell, initiating a response

synthesis, storage

release, exocytosis

diffusion

binding, receptors

ways to terminate action of NT are

enzymatic inactivation of NT, reuptake of NT by presynaptic fiber

the main way to terminate ACh is rapid hydrolysis by ___ aka enzymatic inactivation

AChE (acetylcholine esterase)

the main way to terminate NE is transport back into nerve terminal by ___ → reuptake allows for ___ of NE

NET, recycling

enzymatic inactivation of ACh is ___ than reuptake of NE

faster

sympathetic produces ___ responses while parasympathetic produces ___ responses

sustained, short duration

cholinergic receptors are stimulated by ___

ACh

adrenergic receptors are stimulated by ___

NE and/or EPI

cholinergic receptors that are ligand gated ion channels

nicotinic ACh receptors (Nm, Nn)

cholinergic receptors that are GPCRs

muscarinic ACh receptors (M2, M3)

when ACh binds to nAChR → ___ ion channel, ___ influx → ___ of postsynaptic membrane

opens (nAChR is a ligand-gated ion channel), Na+, depolarization

location of Nn

somas of postganglionic neurons in ANS ganglia

effect of Nn

stimulation of postganglionic neuron (depolarization)

location of Nm

SKM cells at NMJs in SNS

effect of Nm

SKM contraction

M2 location

effector cells at parasympathetic NEJs

M2 is what kind of GPCR

Gi

M2 causes ___

inhibition of heart

M3 is what GPCR

Gq

M3 location

effector cells at parasympathetic and sympathetic cholinergic NEJs

M3 causes __

smooth muscle contraction and glandular secretion at parasympathetic NEJs, sweating at sympathetic cholinergic NEJs

adrenergic receptors include

alpha-1, alpha-2, beta-1, beta-2

alpha-1 is which GPCR

Gq

alpha-2 is which GPCR

Gi

beta-1 is which GPCR

Gs

beta-2 is which GPCR

Gs

adrenergic receptors location

effector cells at sympathetic NEJs

alpha-1 activation causes

SM contraction

alpha-2 activation causes

modulatory functions (presynaptic receptor)

beta-1 activation causes

stimulation of heart, increased renin secretion

beta-2 activation causes

SM relaxation, metabolic effects (stimulated primarily by EPI from adrenal medulla)

presynaptic alpha-2 receptors are found on many sympathetic and parasympathetic ___ → ___ NT release

postganglionic nerve terminals, decreases

sympathetic and parasympathetic divisions are ___ active (even at rest)

continually

__ allows precise control of effector organ function

resting tone

for most organs, dominant tone at rest if ___

parasympathetic

__ are exclusively under sympathetic control

blood vessels, sweat glands, ventricles, adrenal medulla

__ are important for regulation of BP, involves both __ and __

baroreceptors, visceral sensory neurons, visceral motor neurons

location of baroreceptors

carotid sinus, aortic arch

baroreceptors respond to ___

stretch

__ sends signals to areas of medulla that control ANS regulation of the cardiovascular system; __ control of the heart and vessels; __ control of the heart

NTS (nucleus of the tractus solitarius), sympathetic, parasympathetic