autonomic nervous system (theory) Flashcards
what is the function of the ANS?
- to control our organ systems involuntarily
what does the ANS regulate and coordinate?
- body temp
- cardio
- respiratory
- digestive
- excretory
- reproductive
does the ANS have pre and post ganglionic fibers?
yes, unlike the somatic nervous system which innervates SKM
what is the thoracolumbar division?
the sympathetic nervous system
it originates from T1-T12 and L1-L2
this is the fight or flight part of the ANS
what is the craniosacral division
the parasympathetic nervous system
it originates from CN’s 3, 7, 9 and 10
it has sacral origins from S2-S4
this relaxes the body’s systems
sympathetic vs parasympathetic (prof’s notes)
basically, one opposes the other
what are the lengths of the pre and post ganglionic fibers of the sympathetic NS?
pre= short
post = long
the opposite is observed in the parasympathetic NS
where do the pre ganglionic fibers originate from in the thoracolumbar division?
lateral grey horn
what are the NTs of the pre and post ganglionic fibers of the thoracolumbar division
pre = cholinergic
post = adrenergic
ex… ACh = cholinergic
ex… adrenaline (epinephrine) = adrenergic
what are the NTs of the craniosacral division?
both pre and post ganglionic fibers are cholinergic
which has intraneural ganglia? the sympathetic or parasympathetic NS?
the parasympathetic bc some post ganglionic fibers are so short that some ganglia are inside organs
which is faster? thoracolumbar or craniosacral? (prof’s notes)
the parasympathetic NS is faster bc there’s only one NT (ACh) which can be acted on by AChE
does the parasympathetic NS originate from the lateral horn like the sympathetic NS?
no, this is bc it originates from CN’s 3, 7, 9, 10 and S2-S4
what are the 3 types of ganglia of the sympathetic NS?
- sympathetic chain ganglia (paired)
- collateral ganglia (unpaired)
- suprarenal medullae (special)
what is another name for the sympathetic chain ganglia?
paravertebral ganglia or lateral ganglia
what does the sympathetic chain ganglia act on?
- body wall
- head
- neck
- limbs
- thoracic cavity
what is another name for collateral ganglia?
prevertebral ganglia
what does the collateral ganglia act on? (think white ramus)
the collateral ganglia has neurons that innervate the organs of the abdominopelvic cavity
why is the suprarenal medullae considered special?
because it has a preganglionic fiber BUT once activated, it directly secretes hormones into circulation
what actions is the sympathetic chain ganglia responsible for (think fight or flight)
- decreases blood flow to the skin
- increases blood flow to SKM
- increases heart rate
- increases energy production in SKM
- release stored lipids
- dilates pupils
- dilates respiratory tubes
examples of blood redirection under sympathetic chain ganglia
redirecting blood from the skin to the skeletal muscle
ex… looking pale when nervous
ex… not sweating
how many ganglia does each sympathetic chain consists of ?
most of the chain ganglia are from the thoracic and lumbar region
3x cervical
11-12x thoracic
2-5x lumbar
4-5x sacral
1 coccygeal
an example of cervical ganglia control in the sympathetic chain
control of iris dilation
we have dilator and constrictor muscles in our iris that open and close our pupils
the dilator muscles widen the pupil
the constrictor muscles close the pupil
what are the notable nerves of the sympathetic chain ganglia
- lesser splanchnic nerve
- lumbar splanchnic nerve
of the cervical, thoracic, lumbar, sacral, and coccygeal chains in the sympathetic chain ganglia which has both pre and post ganglionic neurons?
the thoracic chain has both pre and post ganglionic neurons
all other chains have only post ganglionic neurons
cervical –> post
thoracic –> pre + post
lumbar –> post
sacral –> post
coccygeal –> post
what are the splanchnic nerves?
splanchnic nerves are part of the collateral ganglia
they are bundles of pre ganglionic fibers that converge on the collateral ganglia
what are the notable nerves of the collateral ganglia?
- celiac ganglion
- superior mesenteric ganglion
- inferior mesenteric ganglion
what actions is the collateral ganglia responsible for?
- reduce blood flow to visceral organs
- decrease activity of digestive glands
- stimulate glycogenolysis
- release lipids from adipose tissue
- relax smooth muscle of bladder
- reduce filtration rate of the kidneys
- control ejaculation in males
what action is the suprarenal medullae responsible for?
they are responsible for the release of NTs that act as hormones into the blood stream
- epinephrine
- norepinephrine
what are two cholinergic receptors?
- muscarinic
- nicotinic
what is ACh released onto in cholinergic synapses?
ganglionic neurons
what do ganglionic neurons release when stimulated?
adrenergic NTs
- epinephrine
- norepinephrine
can some ganglionic neurons in the sympathetic NS release ACh?
yes, at NMJs of skeletal muscles
are post ganglionic fibers myelinated?
no, they do end in varicosities that surround smooth muscle which carry vesicles of adrenergic NTs
what are the two classes of plasma receptors?
- alpha receptors (1,2)
- beta receptors (1,2)
what does alpha 1 do?
alpha 1 constricts the smooth muscle of blood vessels if stimulated
what does alpha 2 do?
alpha 2 decreases blood pressure in the brain (central receptor)
what does beta 1 do?
beta 1 increases HR if stimulated which by extension increases BP
we have drugs called beta blockers that counteract these effects
what does beta 2 do?
beta 2 dilates the bronchial tubes if stimulated
ex… albuterol is a drug for asthmatics that acts to stimulate beta 2 receptors
which is more divergent the sympathetic NS or the parasympathetic NS?
the sympathetic NS has more divergence (1:32) vs (1:4)
the parasympathetic NS is more localized
what does the parasympathetic NS have in place of the splanchnic nerves of the sympathetic NS?
pelvic nerves that innervate visceral organs in the inferior portion of the abdominoplevic cavity
what are the notable ganglia of the parasympathetic NS?
- ciliary ganglion
- pterygopalatine
- submandibular
- otic
- intramural
aside from AChE, what breaks down diffused ACh?
cholinesterase
what are characteristics of nicotinic receptors
- named bc of their response to nicotine
- found at para- and symp- ganglionic neurons
- ACh exposure causes excitation of the ganglionic neurons or the muscle fiber
ex… SKM contraction
ex… NMJ
what are characteristics of the muscarinic receptors
- named bc of their response to muscarine
- found on parasympathetic cholinergic neuroeffector junctions
- this can be excitatory or inhibitory
ex… excitatory = peristaltic movements
ex… inhibitory = decreasing HR
what is dual innervation?
most vital organs are innervated by both parasympathetic and sympathetic nerves
what are visceral reflexes?
reflexes of visceral organs
all visceral reflexes are polysynaptic
what are the two visceral reflex types?
- long reflexes
- short reflexes
differences between long and short reflexes
long reflexes have an interneuron that transmits the signal to the CNS to be interpreted
whereas short reflexes go to the ganglionic neurons and motor commands are distributed by the post ganglionic fibers
short reflexes bypass the CNS
thoracolumbar on pupils
dilation
thoracolumbar on gland secretion
decrease secretion
thoracolumbar on HR
increase HR
thoracolumbar on lungs
increase bronchial tube diameter to increase O2 intake
thoracolumbar on the liver
increase glycogenolysis to release glucose
increase glycolysis to produce energy
thoracolumbar on digestion
slows down digestion and relaxes smooth muscle
thoracolumbar on bladder and urination
relaxes the bladder and constricts the sphincter
relaxes the detrusor muscle
thoracolumbar on kidney filtration
decreases kidney filtration
thoracolumbar on the vagina and uterus
contracts
thoracolumbar on the penis
relaxation
craniosacral on pupils
constrict
craniosacral on gland secretion
increases secretion
craniosacral on HR
slows down HR
craniosacral on lungs
decreases bronchial tube diameter
craniosacral on liver
decreases glycogenolysis and increases energy storage
craniosacral on digestion
increases digestion and smooth muscle movement
craniosacral on bladder and urination
tenses bladder and relaxes sphincter –> peeing
craniosacral on kidney filtration
increases filtration to fill bladder
craniosacral on penis
causes erection
