Venous Physiology

Question 1

What is known as the pressure on the walls of a vessel? AKA difference in pressure between the vein and tissue

Answer 1

Transmural pressure

Question 2

What type of pressure is determined by the difference between the pressure within a vein and in the tissue?

Answer 2

Transmural pressure

Question 3

What is known as the pressure within the vascular system because of the weight of a column of blood?

Answer 3

Hydrostatic pressure

Question 4

What describes fluid movement across the capillary?

Answer 4

Starling equilibrium

Question 5

What is capacitance?

Answer 5

Volume of blood that a vessel can hold at a given pressure

Question 6

What are the capacitance vessels of the body?

Answer 6

VEINS

Question 7

The venous side holds about how much of the total blood volume within the body?

Answer 7

2/3rds

Question 8

What happens to the resistance as the cross-sectional area of a vessel increases?

Answer 8

Resistance to flow decreases

Question 9

What ability do veins have to accommodate increases in blood flow without increased the pressure gradient?

Answer 9

Their ability to change shape

Question 10

Where is hydrostatic pressure greatest?

Answer 10

Lower in the body

Question 11

What is the formula for hydrostatic pressure?

Answer 11

density of blood x gravity x height of column of blood

Question 12

What does total pressure within a blood vessel include?

Answer 12

dynamic pressure (supplied by heart contraction) + hydrostatic pressure

Question 13

What plays a greater role in determining overall venous pressure?

Answer 13

Hydrostatic pressure

Question 14

When is the pressure within the vascular system about equal to dynamic pressure?

Answer 14

When lying down

Question 15

When lifting a hand above your head, what will happen to the hydrostatic pressure?

Answer 15

Decreases

Question 16

Will exercising increase or decrease the pressure gradient in the venous system?

Answer 16

The pressure will decrease which causes the pressure gradient to INCREASE by vasodilation

Question 17

With a LOW transmural pressure, where is pressure highest and lowest?

Answer 17

Lower pressure INSIDE the vein compared to outside at the tissue

Question 18

Function of compression stockings to decrease blood pooling?

Answer 18

It increases tissue pressure (outside vein) which then decreases transmural pressure (inside vein)

Question 19

What describes movement of fluid across the capillary?

Answer 19

Starling equilibrium

Question 20

What forces act to move fluid OUT of the capillary in relation to starling equilibrium?

Answer 20

1. High intra-capillary pressure (pressure in capillary > tissue) or low interstitial pressure
2. Interstitial osmotic pressure (solutes in tissue > capillary)

Question 21

What forces act to move fluid INTO the capillary in relation to starling equilibrium?

Answer 21

1. Low intra-capillary pressure (pressure in capillary < tissue) or high interstitial pressure
2. Capillary osmotic pressure (solutes in capillary > tissue)

Question 22

Does standing increase or decrease capillary pressure?

Answer 22

Increases - forcing fluid out of capillaries and into tissues

Question 23

What is the fluid that moves out of the capillary and into the tissues picked up by?

Answer 23

Lymphatics system

Question 24

What is known as the pressure exerted by fluid when there is a difference in the concentrations of solutes across the capillary endothelium?

Answer 24

Osmotic pressure

Question 25

What will a DVT do to venous pressures?

Answer 25

Cause an increase due to blood not being able to return to heart as quickly

Question 26

What will a DVT do to capillary pressures?

Answer 26

With increased venous pressures, there will also be increased capillary pressures leading to edema

Question 27

During inspiration, what happens to the pressure in the chest vs. abdomen?

Answer 27

Chest pressure - decreases

Abdominal pressure - increases which partially collapses the IVC

Question 28

Does inspiration or expiration aid in venous blood flow coming up from the legs towards the heart?

Answer 28

Expiration - less pressure within the abdominal cavity

Question 29

What is the minimum pressure inside a vein needed to prevent collapse?

Answer 29

5 mmHg

Question 30

In a 6-foot-tall individual in a standing position, hydrostatic pressure will add approximately how much to the measured pressure at the ankle?

Answer 30

100 mmHg

Question 31

What is the pressure gradient across the capillary bed in an uplifted arm owing to the change in hydrostatic pressure?

Answer 31

40 mmHg

Question 32

When an individual moves from a supine to a standing position, which of the following pressures specific to the venous system increases?

a. osmotic pressure
b. hydrostatic pressure
c. transmural pressure
d. gravitational force

Answer 32

Transmural pressure

Question 33

How does the action of the calf muscle pump, under normal circumstances, offset fluid loss in interstitial tissue?

Answer 33

It helps to DECREASE venous pressure

Question 34

What is the difference between the pressure gradient across the capillary bed in a supine and standing position?

Answer 34

Nothing, it is the same

Question 35

What is the reference point for dynamic pressure?

Answer 35

LV

Question 36

What is the reference point for hydrostatic pressure?

Answer 36

RA (2-6 mmHg)

Question 37

How does standing influence capillary pressure? (hint: will it increase or decrease)

Answer 37

Increases - forcing fluid OUT of the capillaries and into the tissues