EXAM 3 Kirk L3: Systemic Circulation 2

Question 1

Blood pressure is measured with a spyngonomater using Kortokoff sounds

1. When pressure generated by cuff is higher than systolic blood pressure:
2. As pressure is slowly released, BP drops below systolic blood pressure and blood begins to flow in a ____ manner
3. When cuff pressure falls below the diastolic pressure then….

Answer 1

1. When pressure in cuff is higher than systolic pressure: no pulse, no sound
2. As pressure is released from the cuff, BP drops below systolic and turbulant blood flow happens, allowing us to hear sounds
3. When cuff pressure falls below diastolic pressure flow is laminar so we hear no sounds

Question 2

Explain the following via sounds

The systolic pressure corresponds to _____

The diastolic pressure corresponds to _____

Answer 2

Systolic pressure corresponds to first tapping sound

Diastolic pressure corresponds to the muffling of sounds

Question 3

Explain the following determinants of arterial BP:

Pressure:

Transmural Pressure

Pressure Gradient

Hydrostatic Pressure

Answer 3

Pressure: force per unit area

Transmural pressure: pressure tending to distend or collapse a vessel

Pressure gradient: pressure differential between inflow and outflow

Hydrostatic Pressure: pressure caused by the height of a fluid column

Question 4

Define Mean Arterial Pressure

Define pulse pressure

Answer 4

Mean Arterial Pressure: average pressure existing in the aorta and the proximal arterial system during one cardiac cycle

Mean Arterial Pressure = Diastolic Pressure + 1/3 Pulse Pressure

Pulse pressure is the difference between systolic and diastolic pressure, represents the force of contraction of the heart

Question 5

Describe the various physiological factors regarding arterial pressure:

Cardiac Output

Total Peripheral Resistance

Answer 5

Cardiac Output: (stroke volume x HR) primarily affects systolic pressure… this is regulated by autonomic nervous system

Total peripheral resistance: primarily affects diastolic pressure, regulated by autonomic NS

Question 6

What physiological factor primarily affects systolic pressure?

What physiological factor primarily affects diastolic pressure?

Answer 6

Cardiac output primarily affects systolic pressure

Total Peripheral Resistance primarily affects diastolic pressure

Question 7

What happens during exercise:

Systolic pressure _____

Diastolic Pressure _______

Pulse Pressure _____

MAP ______

Answer 7

During exercise:
Systolic pressure increases

Diastolic pressure remains constant or slightly decreases

Pulse Pressure widens/increases

MAP increases (systolic goes way up, even though diastolic does not change much)

Question 8

An increase in stroke volume _____ pulse pressure and MAP

An increase in HR ____ MAP

Answer 8

Increase in stroke volume increases PP and MAP

Increase in HR increases MAP

Question 9

A decrease in compliance:

____ systolic pressure

____ diastolic pressure

____ pulse pressure

Answer 9

Decrease in compliance (think hard aortic valve)

Increases systolic pressure

Decreases diastolic pressure

Thus pulse pressure increases/widens

Question 10

An increase in TPR does what to diastolic, systolic, MAP and Pulse Pressure

Answer 10

TRP increase

increases diastolic

increases systolic (not as much)

increases MAP

does nothing to PP

Question 11

Explain the factors that affect TPR

Answer 11

Factors that affect TPR:

• blood viscosity
• radius of arterioles (this is controlled globally and locally)
• global response: baroreceptors, hormones, sympathetic NS
• local response: myogenic, endothelial-mediated,

Question 12

Explain how the SNS and PSNS affect MAP

Answer 12

Sympathetic NS: affects heart, arterioles and veins

• heart: increases HR (increases CO) and increases contraction strength (increases stroke volume and increases CO)
• veins: increases venoconstriction, increases venous return, increases CO
• arterioles: increases vasoconstriction, increases TPR, increases MAP

PSNS: only innervates the heart

PSNS: decrease HR, decrease CO