Cardiovascular anatomy & physiology 5

Question 1

The cardiac cycle influences

Answer 1

how and when blood flows through the coronary circulation

Question 2

Left ventricular contraction compresses the

Answer 2

endocardial vessels during systole

Question 3

The ________________ is most vulnerable to ischemia

Answer 3

LV subendocardium

Question 4

Flow through the __________ is relatively constant throughout the cardiac cycle

Answer 4

right ventricle

Question 5

Which condition increases myocardial oxygen consumption?
a. decreased diastolic filling time
b. decreased end-diastolic volume
c. decreased P50
d. decreased aortic diastolic blood pressure

Answer 5

a. decreased diastolic filling time

Question 6

Myocardial oxygen balance requires that oxygen delivery

Answer 6

meets or exceeds oxygen demand

Question 7

At rest, the myocardium consumes _____ of the oxygen delivered to it.

Answer 7

70%

Question 8

When oxygen demand increases, ________ and _____________ must increase to satisfy the demand

Answer 8

coronary blood flow and CaO2

Question 9

Determinants of oxygen delivery include

Answer 9

coronary blood flow
CaO2
oxygen extraction

Question 10

Determinants of oxygen demand include

Answer 10

preload
afterload
contractility
wall stress

Question 11

________________ is detrimental to the ischemic heart, because it simultaneously decreases oxygen supply while increasing oxygen demand

Answer 11

Tachycardia

Question 12

During ischemia, anaerobic metabolism leads to

Answer 12

lactic acid production

Question 13

Lactic acid contributes to

Answer 13

the perception of chest pain

Question 14

Most perioperative myocardial infarctions occur

Answer 14

24-48 hours following surgery

Question 15

Although increased afterload increases myocardial oxygen demand, the benefit of

Answer 15

increased coronary perfusion pressure typically outweighs the risk of increased wall tension

Question 16

What factors increase oxygen demand?

Answer 16

tachycardia
hypertension
SNS stimulation
increased wall tension
increased LVEDV
increased afterload
increased contractility

Question 17

What factors decrease oxygen delivery?

Answer 17

decreased CaO2- hypoxemia, anemia
decreased oxygen extraction- decreased P50 (aka left shift)
decreased coronary flow- tachycardia, decreased vessel diameter, increased LVEDP, decreased aortic pressure

Question 18

Inhaled nitric oxide: (select 2)
a. is inactivated by hemoglobin
b. reduces right ventricular afterload
c. stimulates cAMP production
d. causes hypotension

Answer 18

a. is inactivated by hemoglobin
b. reduces right ventricular afterload

Question 19

___________ plays a critical role in the regulation of peripheral vessel diameter

Answer 19

Calcium

Question 20

Increased calcium causes __________ and reduced intracellular Ca2+ leads to _____________

Answer 20

vasoconstriction; vasodilation

Question 21

Regulation of vascular smooth muscle tone is dependent on the successful integration of the

Answer 21

autonomic nervous system
renin-angiotensin-aldosterone system
local metabolism
myogenic response

Question 22

Describe 3 second messenger systems that modulate vascular tone by affecting calcium concentrations.

Answer 22

G-proteins cAMP pathway
Nitric oxide cGMP pathway
Phospholipase C Pathway

Question 23

How does the G-proteins cAMP pathway work.

Answer 23

increased cAMP–> vasodilation

Question 24

How does the nitric oxide cGMP pathway work?

Answer 24

increased cGMP–> vasodilation

Question 25

How does the phospholipase C pathway work?

Answer 25

increased IP3 & DAG–> vasoconstriction

Question 26

What 4 ways does protein kinase A affect excitation-contraction?

Answer 26

1. inhibits VGCa2+ channels in the sarcolemma
2. inhibits Ca2+ release from the SR
3. reduces the sensitivity of the myofilaments to Ca2+
4. facilitates Ca2+ reuptake into the SR via the SERCA2 pump

Question 27

Phenylephrine stimulates what effector to ultimately cause vasoconstriction?

Answer 27

phospholipase C