Lecture 7

Question 1

What is the role of the circulatory system?

Answer 1

to provide O2 and nutrients to every cell in the body and remove CO2/waster products from every cell in the body

Question 2

What two things does a circulatory system require and what things make up each of these two things?

Answer 2

• driving force ie. pump = heart

- conduit system = vascular bed made up of arteries, capillaries, veins

Question 3

Arteries take blood to the heart or from the heart?

Answer 3

away from the heart

Question 4

Veins take blood to the heart or from the heart?

Answer 4

take blood to the heart

Question 5

What are the names of the two juxtaposed systems?

Answer 5

systemic and pulmonary

Question 6

Describe the order of flow in the systemic circuit

Answer 6

• left ventricle (on the right on the slides)
• aorta
• arteries
• arterioles
• capillaries
• venules
• veins
• vena cava
• right atrium
• right ventricle (to then enter the pulmonary circuit)

Question 7

Describe the order of flow in the pulmonary circuit

Answer 7

• right ventricle (on the left had side on the slides)
• pulmonary artery
• arterioles
• capillaries
• venules
• pulmonary vein
• left atrium
• left ventricle (to then enter the systemic circuit)

Question 8

How does the size of the blood vessels change going from arteries, arterioles, capillaries, venules and veins?

Answer 8

it decreases in size from arteries to capillaries and then increases again from capillaries to veins so capillaries are the smallest

Question 9

Which blood vessel has the thickest wall?

Answer 9

the aorta

Question 10

Which three blood vessels are termed “microvasculature”?

Answer 10

terminal arterioles, capillaries, venules

Question 11

Which blood vessels have an endothelium?

Answer 11

all of them

Question 12

Which blood vessel is only made up of the single layer of endothelium?
Why is this?

Answer 12

Capillaries

this is so that there is as short a distance as possible so that the rate of diffusion is as fast as possible

Question 13

The function of a blood vessel depends on the specific vascular _______

Answer 13

region

Question 14

What is the purpose of microvasculature?

Answer 14

this is where the gas exchange control and regulation occurs

Question 15

What two things does the flow depend on?

Answer 15

the driving force (cardiac output) and the resistance

Question 16

What causes the driving force which leads to the flow of blood?

Answer 16

the pressure difference between the aorta and the veins

Question 17

What is the equation for flow of blood around the body?

Answer 17

Q = (P1 - P2)/R

Question 18

What happens to resistance if we reduce the radius?

Answer 18

it increases a lot

Question 19

What is the Poiseuillie Relationship which relates radius and viscosity to blood flow?

Answer 19

Q = (P1-P2)πr^4/8ηl which means that 
resistance = 8lη/πr^4

Question 20

Which factor in the Poiseuillie Relationship is most likely to change?

Answer 20

radius

Question 21

Although it is resistance that is most likely to change, how can viscosity change?

Answer 21

if you are severely dehydrated, the viscosity could increase

Question 22

The vessels branch as you go into the _________

Answer 22

capillaries

Question 23

The cross sectional area of each vessel gets _________ as you get to the capillaries but the total vascular cross sectional area is ________ in the capillaries for both the systemic and pulmonary circuits

Answer 23

smaller

highest

Question 24

As the cross sectional area gets smaller from arteries to veins, the resistance __________

Answer 24

increases

Question 25

Where is most of the blood located?

Answer 25

in the veins

Question 26

How can we calculate velocity?

Answer 26

flow/total CSA

Question 27

If we increase the total CSA, what happens to the velocity?

Answer 27

it decreases

Question 28

If we decrease the total CSA, what happens to the velocity?

Answer 28

it increases

Question 29

There is the mean velocity the lowest? Why is this good?

Answer 29

in the capillaries

so that there can be exchange of gases and nutrients

Question 30

Where is there the largest pressure drop? Why?

Answer 30

in the arterioles

because this is controlling the blood flow into the capillaries

Question 31

The left ventricle generates pressure in the _____. This pressure is highest at the __________ and it decreases as we go through the systemic circuit. Because the heart is “turned on” during systole and “turned off” during diastole, what does this mean for the pressure?

Answer 31

aorta
aorta

it means that the pressure is pulsatile

Question 32

Pulsatility decreases as we go further away from the heart. True or false?

Answer 32

true

Question 33

The high pressure from the heart and the low pressure in the right atria is the gradient to drive blood around where?

Answer 33

the circulatory system

Question 34

A large capillary network means what in terms of the cross sectional area?

Answer 34

the cross sectional area is increased

Question 35

A low velocity in the capillaries means there is more time for ______

Answer 35

diffusion

Question 36

The pressure progressively _________ across the venous system to ________ in the right atrium

Answer 36

decreases

lowest

Question 37

Like the systemic circuit, the pressure is decreasing in pulsatility towards the capillaries and veins. How do they differ?

Answer 37

The blood pressure is much lower

Question 38

Why does the systemic circuit have a greater pressure than the pulmonary circuit?

Answer 38

because the walls of the right atria are thinner than the left and so the pressure generated is lower

Question 39

The resistance to blood flow through the arterioles is higher than in the aorta BECAUSE resistance is proportional to radius^4

Answer 39

True

False