Physio- CVS and ANS

Question 1

The cell bodies for the preganglionic vagal efferents innervating the heart are found in which region of the brain?

Answer 1

Medulla bc this region of the brainstem contains cell bodies for both sympathetic and parasympathetic neurons

Question 2

the nucleus tractus solitarius is the region in the medulla that?

Answer 2

receives afferent fibers from peripheral sensors (e.g., baroreceptors) and then sends excitatory or inhibitory fibers to sympathetic and parasympathetic neurons within the medulla.

Question 3

Increased sympathetic stimulation of the heart increases what?

Answer 3

heart rate, atrial contractility, and ventricular contractility and also increases NE release at the ventricular sympathetic nerve endings. it causes an increased sodium permeability of the A-V node, which increases the rate of upward drift of the membrane potential to the threshold level for self-excitation, thus increasing HR

Question 4

how does sympathetic stimulation affects the heart?

Answer 4

Permeability of the SA node to sodium increases, Permeability of the AV node to sodium increases, Theres an increased rate of upward drift of the resting membrane potential of the SA node, Permeability of the cardiac muscle to calcium increases (this is what causes inc. contractility)

Question 5

Contractility of heart caused by effects of EPN actually decreases preload because of?

Answer 5

the increased ejection fraction induced.

Question 6

Norepinephrine released by sympathetic nerves Binds preferentially to?

Answer 6

Constricts blood vessels by binding to α1-adrenoceptors- NE binds to α1-adrenoceptors located on vascular smooth muscle to stim vasoconstriction- NE preferentially binds to α-adrenoceptors in the heart over B-adrenoreceptors on cardiac myocytes

Question 7

norepinephrine stimulates renin release through?

Answer 7

β1-adrenoceptors.

Question 8

Which receptor mediates constriction of arteriolar smooth muscle?

Answer 8

α1 receptors

Question 9

Acetylcholine causes hyperpolarization of the S-A node and the A-V node by? This results in?

Answer 9

• increasing permeability to potassium ions.

- a decreased heart rate

Question 10

ACh causes slowing of the heart via which receptors?

Answer 10

muscarinic receptors (M2) in the SA (and AV) node(s). (Open K+ channel; hyperpolarizing the membrane potential, and reduce If and ICa

Question 11

Externally applied pressure and increased arterial blood pressure both stimulate the high-pressure baroreceptors. The afferent impulses from the carotid sinus are carried over the glossopharyngeal nerve, where they stimulate the cardioinhibitory and depressor centers, leading to what effects?

Answer 11

cardiac slowing and a decreased sympathetic tone to the vascular system. The result is decreased aortic blood pressure

Question 12

Atropine is what type of drug?

Answer 12

muscarinic antagonist (syncope is presumably produced by an abnormally slow heart rate due to increased release of ACh by the vagus nerve or by ACh agonists, (that’s why atropine was given)

Question 13

Parasympathetic or ACh do not affect contractility of the heart. Increasing PR interval decreases what?

Answer 13

heart rate, and that’s what ACh does and that’s what atropine is going to inhibit. So, PR interval will decrease upon atropine administration.

Question 14

Shortening of any components of ECG means?

Answer 14

increasing heart rate. By inhibiting parasympathetic, her heart rate should go up.

Question 15

Propranolol is what type of drug? How does it work and what are the effects?

Answer 15

nonselective β2 antagonist. By blocking β1 receptors in SA node, it reduces the heart rate, and in ventricles, it reduces contractility thus decrease the ejection fraction and stroke volume.

Question 16

Splanchnic and cutaneous vascular resistances are mediated by what type of receptors?

Answer 16

α1 receptors.

Question 17

cGMP is increased by what in blood vessels?

Answer 17

nitric oxide

Question 18

Infusion of a high dose of epinephrine following pharmacologic blockade of β-adrenoceptors will?

Answer 18

Increase systemic vascular resistance- systemic vasoconstriction will increase arterial pressure and cause a reflex decrease in heart rate

Question 19

Vascular smooth muscle contraction is enhanced by?

Answer 19

Activation of myosin light chain kinase- cuz myosin light chain kinase activation by calcium-calmodulin phosphorylates myosin light chains, which induces contraction (side note: there is no troponin C in vascular smooth muscle

Question 20

Which of the following structures are commonly seen in both skeletal and cardiac muscle?

Answer 20

Sarcoplasmic reticulum and Troponin- All mm has sarcoplasmic reticulum, therefore it is present in both skeletal and heart muscle. Troponin, which binds calcium, is also present in both muscle types.