ANS A&P Flashcards
how many spinal nerves are there
31
A1 and V1 stimulation increases
PLC activity (Gq)
B1, 2, and 3 stimulation increases
adenylate cyclase activity (Gs)
A2, M2, M4, D2 receptor decreases
adenylate cyclase activity (Gi)
heart SNS and PSNS receptors and effects
SNS: B1–> positive inotropic, chronotropic, and dromotropic effects
PSNS: M2–> negative inotropic, chronotropic, and dromotropic effects
lung SNS and PSNS receptors and effects
SNS: B2–> bronchodilation
PSNS: M3–> bronchoconstriciton, gland secretions
GI tract SNS and PSNS receptors and effects
SNS: a1 –> vasoconstriction, sphincter contraction
PSNS: M3 –> increased Gi motility, sphincter relaxation, increased gland secretion
glands SNS and PSNS receptors and effects
SNS: a1 –> increased sweating and decreased pancreatic activity
PSNS: M1, M3 –>increased salivation, increased lacrimation, increased pancreatic activity
urinary tract SNS and PSNS receptors and effects
SNS: a1, b2 –>bladder sphincter contraction, increased renin secretion
PSNS: M3 –> bladder sphincter relaxation
skin SNS and PSNS receptors and effects
SNS: a1 –> vasoconstriction
PSNS: —–
skeletal muscle SNS and PSNS receptors and effects
SNS: B2 –> vasodilation
PSNS: ——-
pupils SNS and PSNS receptors and effects
SNS: a1–> dilation (mydriasis)
PSNS: M3 –> constriction (miosis)
intrinsic muscles of the eye (smooth muscles) include (3)
ciliary muscle, sphincter pupillae, dilator pupillae
A2 stimulation can produce these effects (3)
produce anti shivering effect
inhibit insulin release (which creates hyperglycemia)
promotes platelet aggregation
physiologic effect of A2 receptor stimulation for the following organs/effector sites
vasculature
renal tubules
pancreas
platelets
salivary glands
Gi tract
vasculature: constricts
renal tubules: inhibit ADH (diuresis)
pancreas: decreases insulin release
platelets: increases aggregation
salivary glands: dry mouth
Gi tract: decreased gut motility
in VSMC, cAMP inhibits ___________ which produces these two effects
inhibits myosin light chain kinase
vasodilation and decreased SVR result
PDE3 inhibitors are useful in the following clinical situations (4)
BB induced myocardial depression
acute HF
unresponsiveness to IV catecholamines
any time increased inotropy with reduced after load would be desirable.
how many molecules of ATP can be produced from 1 mole of glucose
38
rate limiting step in catecholamine synthesis
tyrosine hydroxylase
stimulation of which presynaptic adrenergic receptor augments NE release? stops it?
augments: B2
stops: A2
catecholamines are removed from synaptic cleft via what 3 mechanisms?
- reuptake into presynaptic nerve
- reuptake into extra neural tissue
- diffusion away from synaptic cleft
what 2 enzymes metabolize NE in the liver and kidney
MAO and COMT
major metabolite of dopamine
homovanillic acid (HVA)
Ach synthesis in presynaptic nerve terminal
- acetyl coenzyme A is produced in mitochondria and released into the cytoplasm
- choline is transported from the blood to the cytoplasm of the nerve terminal
- in the presence of choline aminotransferase, choline and acetyl coa are combined to form acetylcholine, which is then packaged into vescicles
byproducts of Ach metabolism
choline, which diffuses into circulation
acetate, acetate, which diffuses away from synaptic cleft
what is another name for true cholinesterase
acetylcholinesterase (AchE)
compare and contrast SNS and PSNS:
preganglionic fiber length
postganglionic receptor types
target organs
anatomical origin of SNS fibers
(origin, location on SC, where cell bodies arise from)
thoracolumbar region, mainly T1-L3
cell bodies arise from interomediolateral horn of SC and axons exit via ventral roots, aka lateral horn/rexeds lamina 7
anatomical origin of PSNS fibers
craniosacral
CN 3, 7, 9, 10
S2-S4
SNS ganglia compared to PSNS ganglia location
SNS ganglia are near SC (sympathetic chain) while PSNS ganglia are near or inside tissue effector/organ
SNS pre to post ganglionic ratio versus PSNS
SNS: 30:1, post synaptic amplification contributes to mass response
PSNS: 1:1 or 3:1, precise control of each effector organ
SNS versus PSNS preganglionic and postganglionic fibers comparison
(short, long? myelinated, unmyelinated?)
SNS: short, myelinated preganglionic B* fiber. long, myelinated postganglionic B fiber
PSNS: long, UNmyelinated preganglionic C* fiber. short, UNmyelinated postganglionic C fiber
NT and receptor at SNS and PSNS ganglia
both NT’s are Ach and both receptors are NnAchR
NT from postganglionic fiber: SNS v PSNS
SNS: NE (Ach at sweat glands, piloerector muscles, some blood vessels. there are no post ganglionic fibers at adrenal medulla. chromaffin cells release NE and epi directly into systemic circulation
PSNS: Ach
receptor at effector organ: SNS v PSNS
SNS: adrenergic (a, b, dopa) or muscarinic
PSNS: muscarinic
how many paired sympathetic ganglia are in the sympathetic chain
22
3 paths for preganglionic sympathetic fibers in sympathetic chain
- synapse at the same level where they enter sympathetic chain
- synapse at a different level than where they enter
- synapse outside of the sympathetic chain
synapse of preganglionic sympathetic fibers in sympathetic chain at same level of where they enter
synapse in sympathetic trunk ganglion. nonmyelinated axon (C fiber) rejoins spinal nerve via grey ramus
preganglionic sympathetic fibers synapsing at a different level than where they enter the sympathetic chain
ascending preganglionic fibers travel to cervical region where they synapse on postganglionic sympathetic fibers in the 3 cervical ganglia (superior, middle, inferior).
-must pass through stellate ganglion
preganglionic sympathetic fibers synapsing outside of sympathetic chain
pass through paravertebral ganglia (sympathetic chain or trunk) then synapse in unpaired prevertebral ganglia located near abdominal or pelvic visceral targets they elevate
preganglionic c fibers traverse through the sympathetic trunk associate to form splanchnic nerves
postganglionic fibers pass into the plexuses that surround the main branch of the aorta and are distributed with the arterial network
horner syndrome is characterized by (6)
ipsilateral ptosis, miosis, anhydrosis, flushing of the skin, nasal congestion, enopthalmos
Very Homely PAM vasodilation horner ptosis miosis anhydrosis
stellate ganglion (aka cervicothoracic ganglion) provides SNS innervation to
ipsilateral head, neck, and upper extremity
2 areas of adrenal gland and what they secrete
medulla: catecholamines
cortex: glucocorticoids, mineralocorticoids, androgens
triad of pheochromocytoma sx
HA, diaphoresis, tachycardia
anesthetic considerations for pheochromocytoma: anticipate (3)
HTN, tachycardia, hyperglycemia
if a pheochromocytoma patient experiences HoTN, which vasopressor is the best choice?
neo (because it is direct acting)
drugs to avoid during pheo surgery (3 categories)
histamine releasing agents (succ, atracurium, mivacurium, morphine)
indirect acting sympathomimetic agents: ephedrine
SNS activators: desflurane, ketamine, pancuronium, naloxone
describe the sympathetic innervation of the adrenal medulla (where the sympathetic fibers arise from, myelination, receptor ant NT type)
preganglionic sympathetic B fibers arise from T5-T9 and directly go to adrenal medulla (where Ach interacts with NnAchR’s
why does SNS activation eventually cause a decrease in potassium
when epinephrine binds to B2 receptors on skeletal muscles and erythrocytes, it activates Na/K pump and shifts K into cells which decreases serum K concentration
factors that cause K shift in/out include
what 2 molecules are released r/t SNS stimulation of hepatocytes?
K/glucose
surgical procedures that may elicit the baroreceptor reflex include
CEA, mediastonoscopy
function of baroreceptor reflex (aka carotid sinus reflex)
attempts to preserve CO during acute blood loss and shock. venous return too high
6 steps of baroreceptor reflex
which 2 vascular locations contain high pressure baroreceptors
carotid sinus
aortic arch
drugs that can likely impair baroreceptor reflex include (7)
propofol
sevoflurane
labetalol (B1 blockers)
thiopental
CCB
ACEI
PDE inhibitors
function of bezold jerisch reflex
slows HR in the setting of profound hypervolemia. venous return too low
activation of bezold jerisch reflex manifests as (3)
bradycardia
HoTN
coronary artery vasodilation
bainbridge reflex pathway
sensor
afferent
control
efferent
tachycardia caused by an increase in venous return
sensor: increased firing of low pressure stretch receptors during atrial filling
afferent: vagus
control center: NTS
efferent: SNS/PSNS to SA node
bezold jarisch reflex pathway
sensor
afferent
control
efferent
sensor: chemo and mechanoreceptors in LV wall
afferent: nonmyelinated C fibers in vagus to NTS
control center: NTS and medullary CV nuclei
efferent: vagus.
bradycardia and HoTN during spinal or epidural block are attributed to which reflex?
bezold jarisch
chemoreceptor reflex explanation (afferent, efferent, effects)
hypoxia elicits afferent impulses from carotid/aortic bodies through nerve of hering (branch of CN9) and vagus to NTS.
increased RR and MV ensues.
drugs that attenuate chemoreceptor reflex (3)
volatile anesthetics at subtherapeutic doses
opioids
NO
triggers of vasovagal reflex
peritoneal stretching or distention
stress
sx of vasovagal reflex
profound PSNS activation and cease of any SNS activation
afferent and efferent limbs of oculocardiac reflex
5 (trigeminal) afferent
10 vagus efferent
oculocardiac reflex
sensor
afferent pathway (more detail)
control center
efferent pathway (more detail)
effector and response
sensor: mechanoreceptors in ocular tissues
afferent: long and short ciliary nerves–>ciliary ganglion –>ophthalmic division (V1) of CN5 (trigeminal ganglion)
control center: NTS and medullary CV nuclei centers
efferent: CN10
effector and response: decreased activity of SA and AV nodes
clinical presentation of oculocardiac reflex (4 rhythm possibilities, 1 other sx)
bradycardia
HoTN
junctional rhythm
AVB
asystole
factors that worsen severity of oculocardiac reflex (3)
hypoxemia
hypercarbia
light anesthesia
what kind of heat loss occurs via sweating
evaporation
sx of cushings triad
HTN (SNS mediated increase in BP to restore CPP)
bradycardia (baroreceptor reflex)
irregular respirations (brainstem compression)
which component of the SNS forms the white rami?
preganglionic neuron
remember, preganglionic fibers exit via ventral nerve roots and enter sympathetic chain (T1-L2) via white rami. theyre white because theyre myelinated.
which reflex is associated with child birth?
bainbridge
which reflex is associated with pneumoperitoneum?
celiac. mediated by vagus nerve from traction and causes bradycardia/HoTN
which cranial nerves arise from the brain stem
vagus, facial, spinal accessory
10, 7, 11
which cranial nerves arise from midbrain
3, 4
which cranial nerves arise from the pons
5, 6, 7, 8
which cranial nerves arise from the medulla
9, 10, 11, 12
