Cardio III

Question 1

What is the formula for flow velocity in a vessel? Define each variable.

Answer 1

flow = A x v
Where A is cross-sectional area
v is mean velocity

Question 2

What vessels are capacitance vessels?

Answer 2

Veins and venules

Question 3

What vessels are exchange vessels?

Answer 3

Capillaries

Question 4

What are resistance vessels?

Answer 4

Small arteries and arterioles

Question 5

What are distribution vessels?

Answer 5

Large artery and aorta

Question 6

Name the sequence of branching that takes place from the heart and back towards the heart.

Answer 6

Aorta, large artery, small artery, arteriole, capillaries, venule, vein, vena cava

Question 7

The blood comes back to the heart via the […]

Answer 7

venae cavae (2 vena cava)

Question 8

Name the two venae cavae and their function.

Answer 8

Inferior vena cava: carries deoxygenated blood from the legs, feet, and organs in the abdomen and pelvis back into the heart.
Superior vena cava: carries deoxygenated blood from the upper body.

Question 9

How do the numbers of aorta, arteries, arterioles, capillaries, venules, veins, and vena cava differ from one another (order of magnitude) in the systemic circulation?

Answer 9

Aorta: 1
Arteries: 160
Arterioles: 50 M
Capillaries: 10 B
Venules: 100 M
Veins: 200
Vena cava: 2

Question 10

How do the aorta, arteries, arterioles, capillaries, venules, veins, and vena cava differ in terms of diameter?

Answer 10

Aorta: 25 mm
Arteries: 4
Arterioles: 0.03
Capillaries: 0.006
Venules: 0.02
Veins: 5
Vena cava: 30

Question 11

How do the aorta, arteries, arterioles, capillaries, venules, veins, and vena cava compare in terms of length?

Answer 11

Aorta: 40 cm
Arteries: 10
Arterioles: 0.2
Capillaries: 0.1
Venules: 0.2
Veins: 10
Vena cava: 40

Question 12

How do the aorta, arteries, arterioles, capillaries, venules, veins, and vena cava compare in terms of wall thickness?

Answer 12

Aorta: 2 mm
Arteries: 1
Arterioles: 0.02
Capillaries: 0.001
Venules: 0.007
Veins: 0.5
Vena cava: 1.5

Question 13

Describe how the cross-sectional area of the vascular bed varies as blood travels throughout.

Answer 13

As you move from aorta to capillaries, the total cross-sectional area increases, As you move from capillaries to vena cava, the total cross-sectional area decreases again.

Question 14

Describe how the velocity flow changes throughout the vascular bed as blood flows throughout

Answer 14

As you move from aorta to capillaries, the velocity of blood flow decreases. As you move from capillaries to vena cava, the velocity increases again. However, note that the speed in the aorta is higher than in the vena cava.

Question 15

Explain why the velocity of blood changes throughout the vascular bed.

Answer 15

The total flow is the same throughout the entire vascular. If the area is going up but the flow is staying the same, the speed of the flow must be changing. This is why in the aorta, it’s very fast, while in the capillaries, it’s very slow.

Question 16

ow does the speed of blood in the aorta compare to that of the vena cava? Why?

Answer 16

The speed in the aorta is higher than in the vena cava. This is because the sum of the cross-sectional areas of the 2 venae cavae is bigger than the aorta, so the blood flows more slowly in each vena cava.

Question 17

Name 4 advantages of a branching vascular bed network.

Answer 17

1. Any cell is close to a capillary.
2. A high total area of the walls of the capillaries, promoting diffusion (Fick’s law)
3. A low blood flow velocity in the capillaries, allowing time for exchange.
4. High total cross-sectional area, lowering the resistance.

Question 18

What are the typical units for blood pressure?

Answer 18

Arterial blood pressure: mm Hg
Venous pressure cm H2O

Question 19

What is the typical arterial blood pressure?

Answer 19

120/80 mm Hg

Question 20

What is the typical central venous pressure?

Answer 20

5-10 cm H2O

Question 21

How does pressure change as you move down the systemic vascular tree?

Answer 21

Decreases as you move from aorta to capillaries to veins. The most dramatic drop occurs in the small arteries and arterioles, which is why they’re resistance vessels.

Question 22

What vessels experience the largest differences in mean pressure across them? What does this indicate about them?

Answer 22

Arterioles and small arteries. This indicates that the resistance to flow is very high in these, hence their designation as resistance vessels, so a bigger pressure is needed to get the same flow.

Question 23

What vessels experience the largest differences in mean pressure across them? What does this indicate about them?

Answer 23

Arterioles and small arteries. This indicates that the resistance to flow is very high in these, hence their designation as resistance vessels, so a bigger pressure is needed to get the same flow.