The cardiovascular system

Question 1

What are the purposes of the cardiorespiratory system?

Answer 1

• Transport O2and nutrients to tissues.
• Removal of CO2wastes from tissues.
• Regulation of body temperature.

Question 2

What are the 2 major adjustments of blood flow during exercise?

Answer 2

• Increased cardiac output.
• Redistribution of blood flow from inactive organs to active muscle.

Question 3

Describe the pulmonary circuit

Answer 3

• Right side of the heart.
• Pumps deoxygenated blood to the
  lungs via pulmonary arteries.
• Returns oxygenated blood to the left
  side of the heart via pulmonary veins.

Question 4

Describe the systemic circuit

Answer 4

• Left side of the heart.
• Pumps oxygenated blood to the
  whole body via arteries.
• Returns deoxygenated blood to
  the right side of the heart via
  veins.

Question 5

Physical characteristics of blood - plasma

Answer 5

• Liquid portion of blood.
• Contains ions, proteins, hormones.

Question 6

Physical characteristics of blood - cells

Answer 6

• Red blood cells erythrocytes.
• Contain haemoglobin to carry oxygen.
• White blood cells.
• Important in preventing infection.
• Platelets.
• Important in blood clotting.

Question 7

Physical characteristics of blood - hematocrit.

Answer 7

Percentage of blood composed of erythrocytes (red blood cells).

Question 8

Why does the right hand side of the heart not have a lot of pressure?

Answer 8

In order for slow blood flow for efficient gas exchange

Question 9

Define resistance.

Answer 9

Resistance = measure of hindrance or opposition to blood flow through a vessel, caused by friction between the blood in the vessel wall.

Question 10

What is total peripheral resistance?

Answer 10

Total peripheral resistance =
Sum of resistances to flow in all individual organs.

Question 11

What does Darcy’s Law state?

Answer 11

That blood flow is inversely proportional to resistance:
Blood flow = change in pressure/resistance

Question 12

What does resistance depend on?

Answer 12

*Length of the vessel.
*Viscosity of the blood.
*Radius of the vessel (greatest influence on resistance).

Question 13

What is the resistance equation?

Answer 13

Resistance = (length x viscosity)/ Radius(power of 4)

Question 14

What is local vascular resistance?

Answer 14

The resistance to blood flow in an organ or tissue calculated from pressure and local organ/tissue flow.

Question 15

TPR is calculated when MAP and CO are known, what equation links these together?

Answer 15

MAP = CO x TPR

Question 16

What is the oxygen consumption equation?

Answer 16

Oxygen consumption = cardiac output x A-V oxygen difference

Question 17

What is AVO2 difference?

Answer 17

*Amount of O2that is taken up from 100 ml of blood.
*↑ during exercise due to ↑ O2uptake in tissues.
*Used for oxidative ATPproduction

Question 18

What is Fick equation?

Answer 18

Describes relationship between CO (Q), a-VO2 difference, and VO2:
VO2 = Q x a-VO2 difference

Question 19

Where does the initial ‘drive’ of the CV system come from?

Answer 19

higher brain centres.
* Due to centrally generated motor signals at the onset of exercise (rapid adjustments).

Fine-tuned by afferent feedback from:
*Heart mechanoreceptors.
*Muscle chemoreceptors [sensitive to metabolites (K+, lactic acid)] &
mechanoreceptors
*Pressure sensitive receptors (baroreceptors)

Question 20

Given baroreceptors work to rapidly maintain BP homeostasis why do we see a continued increase in systolic BP with exercise?

Answer 20

Baroreflex is reset during exercise.

• Central command and exercise pressor reflex both play an active role in resetting the arterial baroreflex during exercise.