Lecture 10

Question 1

Describe systemic pressures

Answer 1

Systemic Arterial pressure from 120 mm Hg
(systolic) to 80 mm Hg (diastolic)
• Drops to 0 mm Hg by the time it
reaches the termination of the vena cava.
• Systemic capillary pressure varies from 35 mm Hg to 10 mm Hg

Question 2

Describe pulmonary pressures

Answer 2

Pulmonary artery systolic pressure = 25 mm Hg.

Pulmonary diastolic pressure = 8 mm Hg.

Question 3

Describe functional parts of circulation

Answer 3

Functional Parts of Circulation
Arteries
• Transport under high pressure
Arterioles
• Control conduits
Capillaries
• Exchange between blood and extracellular fluid
Venules
Veins

Question 4

What % of blood is in system circulation

Answer 4

84%

Question 5

What % of blood is in the veins

Answer 5

64%

Question 6

What % of blood is in the arteries

Answer 6

13%

Question 7

What % of blood is in the systemic arterioles and and capillaries

Answer 7

07%

Question 8

What % of blood is in the heart and lungs

Answer 8

16%

Question 9

Describe velocity of blood flow

Answer 9

Velocity of blood flow (V) is inversely proportional to vascular cross-sectional area (A).
(F = volume of blood flow)
V = F/A

Question 10

List and describe the three basic principles that underlie all circulatory system functions

Answer 10

• Rate of blood flow to each tissue of the body is almost always precisely controlled in relation to the tissue need.
• The cardiac output is controlled mainly by the sum of all the local tissue flows.
• Arterial pressure regulation is generally independent of either local blood flow control or cardiac output control.

Question 11

Describe rate of blood flow

Answer 11

• In each tissue, microvessels monitor
tissue needs.
• O2, other nutrients, CO2
accumulation, tissue waste product accumulation:
- Act directly on local blood vessels and dilate or constrict accordingly.

Question 12

Describe cardiac output

Answer 12

• Heart responds to demands of tissues.

* Nerve signals may be needed to help the heart pump required amount of blood.

Question 13

Describe arterial pressure regulation

Answer 13

• If arterial pressure falls below 100 mm Hg,
nervous reflexes:
• Increase force of heart pumping.
• Constrict large venous reservoirs.
• Generally constrict most of the arterioles throughout the body (increases arterial pressure).
• Kidneys may later play important role in pressure control