Human Phys 4.2

Question 1

What is a normal right atrial pressure?

Answer 1

0 mmHg

Question 2

What is the lower limit of right atrial pressure?

Answer 2

-3 to -5 mmHg (pressure of chest cavity)

Question 3

When can right atrial pressure increase to 20-30 mmHg?

Answer 3

Under abnormal conditions (HF or massive blood transfusion)

Question 4

What is the regulation of right arterial pressure?

Answer 4

Ability of the heart to pump blood out of the right side and into the lungs

Tendency for blood flow from the periphery into the right atrium

Question 5

What are factors that increase right atrial pressure?

Answer 5

Hypervolemia

Factors that decrease CO

Heart failure

Increase in large vessel tone

Dilation of arterioles

Question 6

How does an increase in large vessel tone occur?

Answer 6

Sympathetic activation causes increased peripheral venous pressure and decreases venous compliance

Question 7

What are factors that decrease right atrial pressure?

Answer 7

Hypovolemia

Deep inhalation

Question 8

What is the pressure when veins are distended?

Answer 8

Almost zero

Question 9

What may increase venous pressure?

Answer 9

Compression of veins at certain anatomical locations

Question 10

What does the higher venous pressure relative to right atrial pressure drive?

Answer 10

Venous return into the right atrium

Question 11

Jugular vein distention

Answer 11

When right atrial pressure rises above 0 mmHg and blood begins to back up into the large veins

Question 12

What does a right atrial pressure or 4-6 mmHg cause?

Answer 12

Corresponding increase in peripheral venous pressure (heart failure)

Question 13

What is the normal abdominal cavity pressure?

Answer 13

6 mmHg

Question 14

What are reasons that abdominal cavity pressure can rise to 15-30 mmHg?

Answer 14

Pregnancy

Tumors

Abdominal obesity

Excessive fluid

Question 15

Hydrostatic pressure

Answer 15

Pressure exerted by a fluid at equilibrium at a given point due to gravity

Question 16

What is the role of venous valves?

Answer 16

Valves that prevent blood from moving backwards

Question 17

How does the muscle pump work relative to blood flow?

Answer 17

Muscle contraction helps push blood from one vein compartment to the next

Question 18

When does varicose veins happen?

Answer 18

When the valves of veins become incompetent or destroyed due to being overstretched because of excessive venous pressure

Question 19

What does stretching of veins increase?

Answer 19

CSA but the valves do not increase in size and no longer close completely

This leads to increase venous pressure and eventually the valves will fail resulting in varicose veins

Question 20

How do venous ulcers form?

Answer 20

Increase in venous pressure leads to increase leakage of fluid out of the capillaries and constant edema in the legs

Question 21

What does the edema prevent in venous ulcers?

Answer 21

Adequate diffusion of nutrients to muscle and skin cells