Lecture 7

Question 1

What regulates cerebral blood flow?

Answer 1

• solely PCO2
• not under the influence of the ANS
• More PCO2 = higher blood flow

Question 2

ECG anomalies due to hypokalemia:

Answer 2

• globally present (all leads)
• ST depression with flattened T waves

Question 3

Ischemia due to angina on ECG:

Answer 3

• ST depression
• usually accompanied by T wave inversion

Question 4

Renal circulation can accommodate about how much of CO?

Answer 4

20%

Question 5

Hepatic circulation can accommodate about how much of CO?

Answer 5

25%

Question 6

What is portal vein venous inflow set by?

Answer 6

splanchnic arteriolar tone (celiac trunk, SMA, IMA)

Question 7

What gives the splanchnic arterial system a relatively low threshold for VSM activation/vasoconstriction?

Answer 7

• large concentrations of α1 adrenoreceptors
• will vasoconstrict in response to low levels of SNS tone

Question 8

Pulse pressure equation:

Answer 8

PP = systolic BP - diastolic BP

Question 9

What determines pulse pressure (3)?

Answer 9

SV, arterial compliance, and ejection force

Question 10

As SV increases, arterial compliance must coordinately increase to maintain a normal pulse pressure. If arteries become less compliant, what occurs?

Answer 10

• turbulent flow
• systolic arterial BP elevates
• greater work load on LV

Question 11

Anticipatory phase of exercise:

Answer 11

1. SNS becomes activated solely by cognitive output.
2. HR increases via beta-1 activation, some inotropy as well.
3. Increased TPR due to alpha-1 mediated vasoconstriction.

Question 12

Cause of cardiac output increase during anticipatory and early stages of exercise:

Answer 12

• mostly increase HR via beta-1 activation; little inotropy

Question 13

What changes occur during the early phase of exercise?

Answer 13

1. SNS increase.
2. PSNS decrease.
3. HR increase = CO increase.
4. TPR increase (no vasodilation yet).
5. Skeletal muscle vasodilatory factors increase.
6. Skeletal muscle afferents reset high pressure baroreceptors and increase resipiratory drive.

Question 14

During exercise, skeletal mechanoreceptor afferents cause two changes in the medullary cardio/respiratory centers:

Answer 14

1. high pressure baroreceptors are reset so that the SNS can remain active.
2. respiration drive increased due to increased PCO2. Chemoreceptors.

Question 15

How does vasodilation due to vasodilatory metabolites increase heart efficiency during exercise?

Answer 15

• decreases afterload
• occurs in late phase of exercise

Question 16

Differences in systolic and diastolic blood pressures during exercise:

Answer 16

• systolic increases (dependent on CO) throughout.
• diastolic decreases due to vasodilatory factors (dependent on TPR) in late stage.

Question 17

What changes during the late stage of vigorous exercise?

Answer 17

• increased HR, EDV, EDP, CO (5X)
• decreased ESV
• increased systolic BP
• diastolic BP stable or drops

Question 18

What happens to arterial blood gases (ABGs) during the late exercise stage?

Answer 18

• PCO2 increases in the venous blood
• Mild acidemia drives ventilation

Question 19

Anaerobic threshold:

Answer 19

• level at which lactic acid production exceeds removal. Accumulates.
• Mild acidemia drives ventilation.

Question 20

Draw cardiac function curve during the initial phase of exercise:

Answer 20

• SNS tone increases.
• Vasoconstriction and inotropy.

Question 21

Draw cardiac function curve during the late stage of physical exercise:

Answer 21

Vasodilation occurs due to skeletal muscle work metabolites