Cardiac Exam Physiology & Neural Control

Question 1

when SA node in charge of myogenic rhythm what is the average HR?

Answer 1

60-100 bpm

Question 2

when AV node is in charge of myogenic rhythm what is the HR?

Answer 2

40-60 bpm

Question 3

when Purkinje system is in charge of myogenic rhythm what is the HR?

Answer 3

20-40 bpm

Question 4

what is a (+) inotropic effect?

Answer 4

• occur in SNS
• increase strength of the contraction

Question 5

what is a (+) chronotropic effect?

Answer 5

• occur in SNS
• increase HR

Question 6

what does the SNS have the most influence on?

Answer 6

speed & response to exercise and maximum output

Question 7

where are beta 1, 2 & 3 receptors found? what system are the involved in?

Answer 7

• beta 1: cardiac & renal tissue
• beta 2: Smooth muscles of vascular beds
• beta 3: adipocytes
• involved in SNS

Question 8

what is the purpose of vagal nerve?

Answer 8

• keep HR lower at rest
• speed up recovery after exercise

Question 9

what is a (-) inotropic effect?

Answer 9

• occurs in PNS
• decrease strength of atrial contraction

Question 10

what is a (-) chronotropic effect?

Answer 10

• occurs in PNS
• decrease HR

Question 11

where are alpha 1 & 2 receptors found? what system are they apart of?

Answer 11

• alpha 1: smooth muscles
• alpha 2: adrenergic synapses to regulate release of norepinephrine
• involved in PNS

Question 12

what are the circulating catecholamines?

Answer 12

• epinephrine
• norepinephrine

Question 13

what does free floating catecholamines do?

Answer 13

bind to beta receptors to trigger sympathetic response

Question 14

where is epinephrine & norepinephrine produced?

Answer 14

adrenal gland

Question 15

what pressure are baroreceptors stimulated at? when stimulated what response is induced?

Answer 15

• stimulated at arterial pressures > 60mmHg
• stretch receptor in large arteries induce vagal response

Question 16

when baroreceptors are stimulated, a vagal response is induced, what does this cause?

Answer 16

• vasodilation or decreased HR
• decreased strength of contraction

Question 17

what is the starling effect and what is it secondary to?

Answer 17

• increase strength of contraction
• secondary to venous return (preload)

Question 18

what is the anrep effect and what is it secondary to?

Answer 18

• increase strength of contraction
• secondary to increase in aortic pressure (after load)

Question 19

what is bowdich effect and what is it secondary to?

Answer 19

• increase in HR
• secondary to either starling or anrep effect

Question 20

is the resting potential for myocardial cells slightly positive or negative?

Answer 20

negative

Question 21

cardiac muscle physiology is balanced between (BLANK & BLANK) ions that line up on either side of the cell membrane

Answer 21

interstitial & intracellular ions

Question 22

at rest NA+ has difficulty crossing the cell membrane. what is the function of the sodium - potassium pump?

Answer 22

• keeps heart calm
• potassium moves into the cell to keep sodium out

Question 23

at rest NA+ has difficulty crossing the cell membrane. what is the function of the sodium - calcium pump?

Answer 23

• gets heart excited
• calcium moves out of cell to let sodium into the cell

Question 24

permeability of sodium changes within phases. is there greater or less permeability during depolarization? repolarization?

Answer 24

• depolarization: greater permeability to sodium
• repolarization: less permeability to sodium

Question 25

will high concentration of calcium increase or decrease the strength of a contraction? why?

Answer 25

- high concentration of calcium influence actin myosin attraction - increases the strength of contraction

Question 26

will higher calcium increase or decrease permeability of cell wall to sodium?

Answer 26

increase