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 local vascular resistance?

Answer 13

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

Question 14

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

Answer 14

MAP = CO x TPR

Question 15

What is the oxygen consumption equation?

Answer 15

Oxygen consumption = cardiac output x A-V oxygen difference

Question 16

What is AVO2 difference?

Answer 16

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

Question 17

What is Fick equation?

Answer 17

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

Question 18

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

Answer 18

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 19

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

Answer 19

Baroreflex is reset during exercise.

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