Apex-ANS

All of the following are examples of second messengers except:

a. Calcium

b. inositol triphosphate

c. cyclic adenosine monophosphate

d. glutamate

d. glutamate

Glutamate is the FIRST messenger for the NMDA receptor

Stimulation of which receptors activates phospholipase C (select 2):

a. Beta 1

b. M-2

c. Alpha 1

d. Vasopressin 1

C & D

alpha 1

vasopressin 1

Voltage gated Na+ channels in neurons are an example of what type of cellular communication?

ion-channels open or close to allows ions down a concentration gradient

What is an enzyme-linked receptor?

the receptor is also an enzyme

signal binging actiate the catalytic domain

ex. insulin receptor in skeletal muscle linked to tyrosine kinase

What is the first messenger?

the ligand that binds to a G-protein coupled receptor

can be a neurotransmitter, hormone, or drug

How does the G-protein coupled receptor activate the effector?

alpha dissociates from beta and gamma

After an effector activates the second messenger, what is the next step?

2nd messenger starts an enzymatic cascade to lead to a cellular response

The intracellular response to the 2nd messenger is _________________ _________________.

tissue specific

What are some examples of effectors that can be activated by a G-protein coupled receptor?

adenylate cyclase

phospholipase C

GABA

M2

How many second messengers are there and what are they?

FIVE

1. cAMP

2. cGMP

3. IP3

4. DAG

5. Ca++

Beta 1 stimulation in the SNS causes .....

increased contractility, increased HR, and increased conduction speed

Which alpha receptor is predominantly stimulated in the SNS in the arteries?

alpha 1

Which alpha receptors is predominantly stimulated in the SNS in the veins?

alpha 2

Which receptor causes vasodilation by SNS stimulation in the myocardium and skeletal muscle?

beta 2

Which receptor causes vasodilation by SNS stimulation in the renal and mesenteric vascular beds?

dopamine

Stimulation of the M2 receptors by the PNS causes.....

decreased contractility

decreased HR

decreased conduction speed

Which receptor in the bronchial tree cauess bronchoconstriction by PNS stimulation?

M3

Which receptor in the kidneys, when stimulated by the SNS, causes diuresis via ADH inhibition? Where in the kidneys are they located?

alpha 2

renal tubules

Which receptor in the kidneys, when stimulated by the SNS causes increased renin release?

Beta 1

Stimulation of the alpha 2 receptor reduces (select two):

a. sympathetic tone

b. platelet aggregation

c. serum glucose

d. shivering

A & D

a. sympathetic tone

d. shivering

Which enzyme metabolizes cAMP?

a. protein kinase A

b. adenylate cyclase

c. phospholipase C

d. phosphodiesterase III

d. phosphodiesterase III

Select the true statements regrding norepinephrine synthesis and release (select 2).

a. Norepinephrine in the synaptic cleft inhibits its release

b. Norepinephrine is converted to epinephrine in sympathetic post-ganglion nerves

c. Tyrosine hyroxylase catalyzes the rate limiting step in norepinephrine synthesis.

d. The adrenal medulla releases 80% norepinephrine and 20% epinephrine.

A & C

a. Norepinephrine in the synaptic cleft inhibits its release

c. Tyrosine hydroxylase catalyzes the rate limiting step in norepinephrine synthesis

What is the PRIMARY mechanism for termination of action of norepinephrine in the synaptic cleft

a. catechol-O-methyltransferase

b. reuptake

c. diffusion

d. monoamine oxidase

b. reuptake

What is the end product of norepinephrine metabolism?

a. tyrosine

b. vanillylmandelic acid

c. metanephrine

d. normetanephrine

b. vanillylmandelic acid

What are the 3 areas for the mechanism of action of alpha-2 receptors?

1. presynaptic

2. postsynaptic

3. nonsynaptic (platelets)

Why does rapid infusion of Precedex cause a transient increase in hypertension?

postsynaptic alpha 2 receptors in arterial and venous circultions cause vasoconstriction and HTN

the CNS effect of vasodilation lags slightly behind

How does Milrinone increase intracellular Ca and cardiac contractility?

PDE 3 inhibition-->increased cAMP

How does PDE 3 inhibition impact vascular smooth muscle?

cAMP inhibits MLCK causing vasodilation and decreased SVR

What is the primary neurotransmitter in the SNS?

Norepinephrine

What is the rate-limiting factor in the production of norepinephrine?

tyrosine hydroxylase

The adrenal medulla releases _______ epinephrine and ______norepinephrine.

80% epi, 20% norepi

Norepinephrine stimulation of alpha 2 in the synaptic cleft causes.......

inhibition of its own release

Norepinephrine augments its own release by stimulating _____________.

Beta 2

Norepinephrine release from the presynaptic neuron into the synaptic cleft is dependent on ____________.

Ca++

Reuptake is responsible for how much of norepinephrine's removal from the synaptic cleft?

80%

Norepinephrine's reuptake into the nerve terminal can be blocked by _______________________ and ________________________.

tricyclic antidepressants and cocaine

Norepinephrine that is diffused away from the synaptic cleft is metabolized by ________________________.

MAO and COMT in the liver and kidneys

Increased vanillylmandelic acid in the urine indicates......

pheochromocytoma

Preganglionic nerve fibers in the SNS are

a. unmyelinated C fibers

b. myelinated C fibers

c. myelinated B fibers

d. unmyelinated B fibers

c. myelinated B fibers

Sympathetic nerves that directly innervate the adrenal medulla are:

a. C fibers that release acetylcholine

b. C fibers that release norepinephrine

c. B fibers that release norepinephrine

d. B fibers that release acetylcholine

d. B fibers that release acetylcholine

Stimulation of which receptor causes a transcellular potassium shift?

a. alpha 1

b. alpha 2

c. beta 1

d. beta 2

d. beta 2

Which surgical procedures are most likely to activate the baroreceptor reflex (select 2):

a. C section

b. mediastinoscopy

c. carotid endarterectomy

d. strabismus repair

B & C

b. mediastinoscopy

c. carotid endarterectomy

What drugs are MOST likely to impair the intergrity of the baroreceptor reflex (select 3):

a. norepinephrine

b. labetolol

c. hydralazine

d. Sevoflurane

e. propofol

f. thiopental

B, D, E

b. labetolol

d. Sevoflurane

e. propofol

These drugs can lower both HR and BP, inhibiting the baroreceptor reflex from compensating.

Activation of the Bezold-Jarish reflex manifests as (select 3):

a. coronary atery vasoconstriction

b. bradycardia

c. tachycardia

d. coronary artery vasodilation

e. hypotension

f. hypertension

B, D, E

b. bradycardia

d. coronary artery vasodilation

e. hypotension

occurs with profound hypovolemia, heart is trying to acheive more time to fill

Risk factors that contribute to the manifestation of the oculocardiac reflex include all of the following EXCEPT:

a. hypercarbia

b. retrobulbar block

c. old age

d. strabismus surgery

c. old age

Identify the BEST agents to augment the HR in patients with a heart transplant (select 2):

a. isoproterenol

b. atropine

c. epinephrine

d. phenyleprhine

A & C

a. isoproterenol

c. epinephrine

Have to use DIRECT-agents

What is the primary neurotransmitter in the PNS?

acetylcholine

How is acetylcholine removed from the synaptic cleft?

acetylcholinesterase hydrolyzes ACh into choline and acetate

choline is recycled and acetate is diffused away

How and where is acetylcholine created?

Choline acetyltransferase (ChAT) joins choline and acetyl CoA to make acetylcholine in the cytoplasm of the nerve terminal

Where does Acetyl CoA come from?

mitochondria of the nerve cell body

How is acetylcholine released into the synpatic cleft?

ACh is packaged into vesicles after production. Ca++ influx into the nerve releases the packages of ACh into the synaptic cleft

How does magnesium cause muscle weakness and prolongation of neuromuscular blockers?

magnesium is an antagonist of Ca++ in the nerve terminal, decreasing Ca++ influx into the nerve ending to release ACh

What are the 3 control centers of autonomic reflexes?

hypothalamus, brainstem, and spinal cord

What is a ganglion?

site where a preganglionic nerve and postganglionic nerve synpase

Cholinergic PNS postganglionic fibers release _______________.

ACh

Adrenergic SNS postganglionic fibers release _______________.

norepinephrine

What division of the ANS has short preganglionic fibers and long postganglionic fibers?

SNS

What division of the ANS has long preganglionic fibers and short postganglionic fibers?

PNS

What is the origin of the SNS division of the ANS?

known as the thoracolumbar division

T1-L3

What are the origins of the PNS division of the ANS?

known as the craniosacral division

CN 3, 7, 9, 10 (occulomotor, facial, glossopharyngeal, vagus)

S2-S4

Where are the ganglia located in the SNS?

near the spinal cord

Where are the ganglia located in the PNS?

near or inside the effector organ

What part of the SNS does NOT have postglanglionic fibers?

adrenal medulla

Chromaffin cells release epi and norepi directly into the bloodstream

What is the difference between the gray and white rami?

White rami are myelinated

What are the 3 paths preganglionic fibers can take in the spinal cord?

1. synapse with postganglionic fiber at the same spinal level

2. ascend or descend spinal levels before synapsing with postganglionic fiber and exiting the spinal cord

3. they can bypass the sympathetic chain entirely and synapse in a collateral ganglion

What are examples of collateral ganglions?

superior cervical

middle cervical

stellate

celiac

superior mesenteric

inferior mesenteric

What does the stellate ganglion innervate?

upper extremity, some of head and neck

In what circumstances would the stellate ganglion be purposefully blocked?

upper extremity sympathetic dystrophy, complex regional pain syndrome, to increase blood flow to an extremity

When is the stellate ganglion most commonly blocked?

unintentionally via a brachial nerve plexus block

What is the consequence of blocking the stellate ganglion?

Horner's syndrome: vasodilation, ptosis, anhidrosis, enopthalmos, miosis

What are the two parts of the adrenal medulla and what are their purposes?

1. medulla-->secretes catecholamines

2. cortex-->secretes glucocorticoids, mineralocorticoids, and androgens

At rest, the adrenal medulla secretes how much epi and norepi?

epi 0.2 mcg/kg/min

norepi 0.05 mcg/kg/min

Do catecholamines prefer to stay in the bloodstream or synaptic cleft?

stay 5-10x longer in the bloodstream

Pheochromoctomas release mainly which catecholamine?

norepinephrine

Symptoms of a pheochromocytoma

SNS activation leads to HA, diaphoresis, tachycardia

What is the gold standard for diagnosing a pheochromocytoma?

VMA in urine

What is the most important thing to remember with drug administration for the patient with a pheochromocytoma?

BLOCK alpha before beta for the love of all that is holy

What are the non-selective alpha blockers?

Phentolamine and phenoxybenzamine

What are the alpha 1 selective blockers?

doxasozin and prazosin

What happens if you block beta before alpha with a pheochromocytoma?

inhibition of skeletal muscle vasodilation, increased SVR, decreased inotropy can precipitate CHF

What should you prepare for once the pheochromocytoma is out?

hypotension and hypoglycemia

What does SNS stimulation cause increased insulin output?

Cells have to have insulin to utilize glucose

What drugs cause an intracellular shift in K+?

Beta 2 agonists, insulin, methylxanthines

How do volatile anesthetics impact the baroreceptor reflex?

dose-dependent decrease

Iso impacts the reflex the least

How do vasodilators impact the baroreceptor reflex?

preserve it

How do beta blockers impact the baroreceptor reflex?

prevent increased HR in setting of low BP

When is the Bezold-Jarisch reflex activated?

when the heart is empty from decreased preload or myocardial ischemia, decreased HR and BP

What is the purpose of the Bezold-Jarisch reflex?

give the heart more time to fill

What sensor activates the Bezold-Jarisch reflex?

the left ventricle

What is the Bezold-Jarisch triad?

bradycardia

hypotension

coronary vasodilation

When is the Bainbridge reflex activated?

when the heart is full from too much preload, tachycardia

What is the purpose of the Bainbridge reflex?

minimize venous congestion and promote forward flow

What are the sensors of the Bainbridge reflex?

SA node

RV

pulmonary veins

What is the body's response to the Bainbridge reflex?

tachycardia

decreased ADH release to decrease water retention

increased ANP release to cause diuresis

What stimlulates the oculocardiac reflex?

traction to extraocular muscles

strabismus surgery

pressure on globe or conjunctiva

ocular trauma

pressure on orbital tissue after enucleation

retrobulbar block

True or False. A retrobulbar block can prevent the oculocardiac reflex.

TRUE. It can cause OR prevent it.

Describe the afferent nerve stimulation process leading to the oculocardiac reflex.

Long and short ciliary nerve--> ciliary ganglion--> ophthalmic V1 branch of trigeminal nerve--> Gasserion ganglion-->M2 receptor on SA and AV nodes

How does the oculocardiac reflex present?

bradycardia

hypotension

junctional rhythm

AV block

asystole

What factors can worsen the severity of the oculocardiac reflex?

hypoxemia

hypercarbia

light anesthesia

True or False. The oculocardiac reflex fatigues with subsequent stimulation.

True