Cardiovascular Physiology

Question 1

What are the five components of the vasculature?

Answer 1

Arteries, arterioles, capillaries, venules, veins

Question 2

Describe three characteristics of arteries.

Answer 2

Under high pressure, carry oxygenated blood, thick-walled (elastic tissue and smooth muscle)

Question 3

Describe two characteristics of arterioles.

Answer 3

Site of highest resistance in circulation, innervated by ANS.

Question 4

Where are alpha1-adrenergic receptors found in arterioles?

Answer 4

Skin, splanchnic, renal

Question 5

Where are beta2-adrenergic receptors found in arterioles?

Answer 5

skeletal muscle

Question 6

Describe three characteristics of capillaries.

Answer 6

Largest total cross-sectional and surface area, site of nutrient, water, and gas exchange, consist of a single layer of endothelial cells.

Question 7

Describe four characteristics of veins.

Answer 7

Under low pressure, contain the highest proportion of blood, this blood volume is called the unstressed volume, contain alpha1-adrenergic receptors.

Question 8

Describe the equation for velocity of blood flow.

Answer 8

The velocity is directly proportional to blood flow and inversely proportional to cross-sectional area.

Question 9

How does blood velocity compare between the aorta and the capillaries? Why is this physiologically relevant?

Answer 9

Aorta has a small CS-area –> fast blood velocity

Capillaries have large CS-area –> slow blood velocity

Allows efficient exchange of nutrients, gases, and water.

Question 10

Write down the equation for cardiac output. What other physical law is it analogous to?

Answer 10

cardiac output = (mean arterial press. - right atrial press.)/(total periph. resis.)

Analogous to Ohm’s law I = V/R

Question 11

Describe Poiseiulle’s equation.

Answer 11

Resistance is directly proportional to the length of the vessel and inversely proportional to the fourth power of the radius.

Question 12

How do series and parallel resistances combine? Where are parallel resistances found? Where are series resistances found?

Answer 12

Combine as do electrical resistors. Parallel is found in systemic circulation; series is found within an organ (arteries, arterioles, capillaries).

Question 13

Describe how the Reynold’s number affects the flow of a fluid.

Answer 13

Re4000 turbulent flow; large pipes, high velocity

Question 14

Describe how fluid velocity differs within pipes.

Answer 14

The cylinder of fluid on the pipe axis has the highest velocity, each cylinder built out from that moves slower, the cylinder adjacent to the pipe wall has zero velocity.

Question 15

Describe how capacitance (compliance) relates to fluids.

Answer 15

Capacitance/compliance is the volume stored at a given pressure. It is inversely related to the amount of elastic tissue in a blood vessel.

Question 16

Which part of the circulation has the highest compliance? What is this volume called?

Answer 16

The veins (unstressed volume).

Question 17

How would a change in venous capacitance affect circulation?

Answer 17

Decreases in unstressed volume shifts blood to the arteries thereby increasing stressed volume.

Question 18

What is the mean pressure in the aorta, arterioles, capillaries, and vena cava?

Answer 18

100 mmHg, 50 mmHg, 20 mmHg, and 4 mmHg

Question 19

Describe the difference between systolic and diastolic pressure and pulse pressure.

Answer 19

Systolic is the highest arterial pressure when the heart contracts, diastolic pressure is the lowest arterial pressure when the heart relaxes. Pulse pressure is the difference between the two.

Question 20

What is the effect on capacitance by aging? What increases? What decreases?

Answer 20

Capacitance decreases, cause an increase in pulse pressure.

Question 21

Describe mean arterial pressure.

Answer 21

Average of arterial pressure with respect to time.

Approximately diastolic + (1/3) pulse pressure.

Question 22

Describe the capacitance of the veins.

Answer 22

Very high capacitance, very low venous pressure, therefore can hold large volumes of blood at low pressure.

Question 23

How do we measure left atrial pressure?

Answer 23

Pulmonary wedge pressure. Catheter inserted into smallest branches of pulmonary artery is roughly the left arterial pressure.