Circulation & Hemodynamics

Question 1

What is the relationship b/w the amt of blood in the arteries and their combined cross-sectional area?

Answer 1

small cross-sectional area

lots of blood

Question 2

What is the relationship b/w the amt of blood in the veins and their combined cross-sectional area?

Answer 2

large cross-sectional area

lots of blood

Question 3

What is the relationship b/w the amt of blood in the capillaries and their combined cross-sectional area?

Answer 3

large cross-sectional area

small amt. of blood

Question 4

When an artery is constricted, which changes: resistance or volume?

Answer 4

resistance; volume doesn’t change much

Question 5

When a vein is constricted, which changes: resistance or volume?

Answer 5

volume; blood is pushed back into the arterial side

-resistance isn’t changed much

Question 6

What is the physiological benefit of having a huge cross-sectional area in the capillary beds relative to the amount of blood in the capillary system?

Answer 6

• sluggish velocity

- diffusion over a longer period of time

Question 7

Define laminar flow.

Answer 7

-blood flowing in an even pattern

Question 8

Define turbulent flow.

Answer 8

-chaotic, churning flow

Question 9

What is the equation for Reynold’s number?

Answer 9

(density x diameter x velocity) divided by viscosity

Question 10

What will an increase in blood density do to Reynold’s number and bloodflow?

Answer 10

• increase Reynold’s number

- shift toward turbulent flow

Question 11

What will an increase in diameter of blood vessel do to Reynold’s number and bloodflow?

Answer 11

• increase Reynold’s number

- shift toward turbulent flow

Question 12

What will an increase in velocity do to Reynold’s number and bloodflow?

Answer 12

• increase Reynold’s number

- shift toward turbulent flow

Question 13

What will an increase in viscosity do to Reynold’s number and bloodflow?

Answer 13

• decrease Reynold’s number

- shift toward laminar flow

Question 14

What is the approx. cutoff of Reynold’s number to be considered laminar flow vs. turbulent flow?

Answer 14

> 2000 = turbulent

Question 15

How does velocity relate to bruits?

Answer 15

-increased velocity = increase in bruits

Question 16

How does viscosity related to bruits?

Answer 16

-decrease in viscosity = increase in bruits

Question 17

What happens to blood flow as resistance increases?

Answer 17

blood flow decreases

Question 18

What happens to blood flow as the difference in pressure increases?

Answer 18

blood flow increases

Question 19

What is Poiseuille’s equation to determine resistance?

Answer 19

(8 x viscosity x length) divided by (pi x radius to the 4th)

Question 20

What causes the biggest change in the resistance of a blood vessel?

Answer 20

diameter … because length won’t change … and viscosity likely won’t change either

Question 21

What happens to the total resistance of resistances in a series?

Answer 21

increase

Question 22

What happens to the total resistance of resistances in parallel?

Answer 22

decrease

Question 23

Define arterial systolic pressure.

Answer 23

• the clinically reported “systolic pressure”

- the greatest pressure reached in a large artery

Question 24

Define diastolic pressure.

Answer 24

-the lowest pressure reached in a large artery

Question 25

What’s the equation for blood pressure.

Answer 25

BP = SV x HR x TPR

Question 26

How does stroke volume affect blood pressure?

Answer 26

as stroke volume gets larger, BP increases

Question 27

How does heart rate affect blood pressure?

Answer 27

as heart rate increases, BP increases

Question 28

How does total peripheral resistance affect blood pressure?

Answer 28

as TPR increases, BP increases

Question 29

How does compliance affect blood pressure?

Answer 29

as compliance increases, BP decreases

Question 30

What is pulse pressure?

Answer 30

systolic pressure minus diastolic pressure

Question 31

How does compliance affect pulse pressure?

Answer 31

as compliance decreases, pulse pressure increases

Question 32

What is the equation for MAP?

Answer 32

diastolic pressure x 1/3 pulse pressure

Question 33

Is the MAP closer to systolic pressure or diastolic pressure, and why?

Answer 33

diastolic pressure, bc the body spends more time in diastole

Question 34

What happens to blood vessels during a sympathetic response?

Answer 34

arterioles constrict, causing total peripheral resistance to increase

veins constrict, causing capacitance to decrease

Question 35

What happens to blood vessels during a parasympathetic response?

Answer 35

arterioles dilate, causing total peripheral resistance to decrease

veins dilate, causing capacitance to increase

Question 36

Define compliance.

Answer 36

relationship bw the amount of blood a vessel can hold at a given pressure

ex: vessels w/ high compliance can hold more blood at a certain pressure than a vessel w/ low compliance

Question 37

Do veins have a high compliance or a low compliance?

Answer 37

high

Question 38

Do arteries have a high compliance or a low compliance?

Answer 38

low

Question 39

Pathology: how does arteriosclerosis affect compliance?

Answer 39

-plaque deposits make arteries less compliant

Question 40

Pathology: how does aging affect compliance?

Answer 40

artery walls become stiffer with age

Question 41

Pathology: how does hypertension affect compliance?

Answer 41

once HTN has become “established”, the artery walls have decreased compliance and don’t recoil