Overview Of CNS And Baroreceptor Reflex

Question 1

Sympathetic agents

Answer 1

Norepinephrine (sympathetic neurotransmitter)
- acts at effectors only

Epinephrine (sympathetic hormone)

Acetylcholine (sympathetic/parasympathetic neurotransmitter)
- acts at effectors and ganglia

Dopamine (sympathetic hormone)
-acts at effectors only

Question 2

Parasympathetic agents

Answer 2

Acetylcholine (sympathetic/parasympathetic neurotransmitter)

Question 3

What is the only location in the body that receives acetylcholine on its tissue receptors after the neuron has crossed the sympathetic trunk?
(Receives signals via the sympathetic route, but its actually acetylcholine)

Answer 3

Sweat glands

Question 4

Biosynthesis of catecholamines in the body

Answer 4

Catecholamines are dopamine, norepinephrine and epinephrine.

Begins with tyrosine substrate -> DOPA -> Dopamine -> norepinephrine-> epinephrine
- note if the body needs dopamine of norepinephrine, it will stop the conversion there .

Question 5

What receptor is consisted an autoreceptor?

Answer 5

A2
- while it also has immediate direct vasoconstriction effects, its primary purpose when activated is to block norepinephrine release. This overtime causes parasympathetic effects.

Question 6

Receptor Selectivity of catecholamines

Answer 6

NE = equal for alpha receptors, however (B1»>B2)
- therefore its clinical use is when you want a heart response, but little lung response

Epinephrine = Equal for all alpha and beta receptors

Dopamine = D»>B»>a
- causes increased renal filtration rates and a positive inotropic effect on the heart in large doses.

Question 7

Baroreflex sympathetic responses

Answer 7

In the presence of lowered blood pressure (MAP), the baroreflex will induce the following:

• increases heart rate
• increase inotropic effects
• increase venous tone
• increase preload
• increase stroke volume
• increase cardiac output
• increases peripheral vascular resistance (vasoconstriction)

All of these factors work together to increase Blood pressure (MAP)

Question 8

Baroreflex parasympathetic response

Answer 8

If the blood pressure is really high, the baroreflex will stimulate a parasympathetic response which is to decrease heart rate and cardiac output

Both of these two decreases work to decrease Blood pressure (MAP)

Question 9

A1 agonist effects

Answer 9

Peripheral vasoconstriction

Increased SVR

Increases venous return

Increased Blood pressure

Modest positive inotropic effect

will induce a baro-receptor mediated reflex bradycardia

Question 10

A2 agonist effects

Answer 10

Different effects based on local vs systemic (systemic is more common)

Local = vasoconstriction of arteries and veins

Systemic = decreases sympathetic outflow due to blocking the release of NE systemically
- causes vasodilation

Question 11

B1 agonist effects

Answer 11

Increases inotropic, dromotropic and chronotropic effects

Increases renin production (increases BP)
- done via retaining volume/sodium

Question 12

B2 agonist effects

Answer 12

Vasodilation and bronchodilation

Question 13

Albuterol

Answer 13

B2 selective agonist used in the treatment of asthma and COPD
- NOT used for heart stuff or HTN

Question 14

B receptor antagonists

Answer 14

Negative chronotropic and inotropic effects

Lowers blood pressure in HTN patients
- done via decreasing cardiac output due to decreased heart rate and stroke volume

• will acutely increase BP in non-HTN patients*
• this is because B2 blockade results in unopposed a1 vasoconstriction

Bronchoconstriction (DONT use w/ asthmatics of COPD patients)

Inhibts lipolysis and inhibits glycogenolysis
(DONT use w/ diabetics)

Increases VLDL and decreases HDL

Question 15

What BBs have local anesthetic effects

Answer 15

Labetalol

Propranolol

Pindolol

Metoprolol

Acebutolol

Question 16

Why is sotalol a special BB?

Answer 16

It blocks B1 and B2 receptor as well as K+ channels

Question 17

Why is esmolol special?

Answer 17

Shortest half life for a BB

- 10 min

Question 18

Clinical action against HTN for BBs

Answer 18

Induces a hypotensive action

- decreases cardiac output by suppressing renin release from the kidney

Question 19

Clinical action against ischemic heart disease w/ BBs

Answer 19

Reduces angina frequency and induces a negative inotropic/chronotropic effect on the heart
- this decreases cardiac work load and oxygen demand, allow for the damaged heart to compensate

Question 20

Clinical action against cardiac Arrhythmias w/ BBs

Answer 20

Antiarrhythmic properties surround slowing and regularizing the heart rate
- BBs give a negative chronotropic effect

Note: sotalol has additional antiarrhythmic effects since it also blocks K+ channels

Question 21

A-receptor antagonist broad effects

Answer 21

Hypotension

• mediates vasoconstriction in arteries and veins
• this is opposed by the baroreceptors reflex and usually results in reflex tachycardia

Orthostatic hypotension