Intro to CVS

Question 1

Why do we need a CVS?

Answer 1

Get oxygen and nutrients close to cells

reduce diffusion pathway

Question 2

Why can’t body cells be supplied by oxygen and nutrients in the surroundings?

Answer 2

Large distance between oxygen/nutrients and cells

take too long to diffuse into the cells from the surroundings

Question 3

What part of the CVS has oxygen and nutrients close to the cells?

Answer 3

Capillaries

Question 4

What are capillaries made up of?

Answer 4

Single layer of endothelial cells

their basement membrane

Question 5

How does the structure of capillaries aid in diffusion of oxygen and nutrients?

Answer 5

They are thin walled

Question 6

How do lipid-soluble molecules diffuse across capillaries? Give an example of two molecules that do this

Answer 6

Across the cell membranes of endothelial cells

oxygen and carbon dioxide

Question 7

How do small water-soluble molecules diffuse across capillaries?

Answer 7

In between endothelial cells

Question 8

What does the rate of diffusion depend on?

Answer 8

Area available for exchange

Diffusion resistance

Concentration gradient

Question 9

How does area available for exchange affect diffusion?

Answer 9

Bigger area means faster rate of diffusion

Question 10

What is diffusion resistance? Give some examples

Answer 10

Factors that oppose diffusion

e.g. nature of molecule e.g. water-soluble
barrier
longer pathway

Question 11

What does area available for exchange depend on?

Answer 11

Capillary density - the amount of capillaries in a certain amount of tissue

Question 12

What sort of tissues have a high capillary density? Why?

Answer 12

Metabolically active

because require more oxygen and nutrients

Question 13

How does the concentration gradient affect the rate of diffusion?

Answer 13

Greater concentration gradient means faster rate of diffusion

Question 14

What does the concentration gradient of oxygen in the blood depend on?

Answer 14

Rate of use by tissue

Rate of blood flow through capillary bed

Question 15

If a tissue uses lots of oxygen, how does this affect the conc. gradient?

Answer 15

More oxygen moves from blood to tissues

reduces conc. gradient

Question 16

If a tissue has an increased rate of blood flow, how does affect the conc. gradient of oxygen?

Answer 16

Replaces oxygen in blood

increases conc. gradient

Question 17

What is the perfusion rate?

Answer 17

The rate of blood flow into a tissue

Question 18

Which two organs require a constant blood flow?

Answer 18

Brain

Kidneys

Question 19

What sort of perfusion rate do metabolically active tissues have? Why?

Answer 19

Higher perfusion rate

because demand more oxygen and nutrients

Question 20

When does blood flow to the heart and skeletal muscle increase?

Answer 20

With exercise

Question 21

When does blood flow to the gut increase?

Answer 21

After eating

Question 22

When does blood flow to the skin increase?

Answer 22

When body temperature is high

Question 23

What is the cardiac output at rest of the average 70kg man?

Answer 23

5L/min

Question 24

What is the maximum cardiac output of the average 70kg man?

Answer 24

25L/min

Question 25

What happens if fluid accumulates in the pericardium?

Answer 25

Fibrous layer is non-extensible
compresses heart
heart cannot fill in diastole

Question 26

What is the term to describe compression of the heart and reduced filling in diastole due to excess fluid in the pericardium?

Answer 26

Cardiac tamponade

Question 27

How is cardiac tamponade treated?

Answer 27

Pericardiocentesis - removing fluid from pericardium using a needle

Question 28

What pathological processes are coronary arteries prone to?

Answer 28

Atherosclerosis

Thrombosis

Question 29

What is the signifiance of coronary arteries being end arteries?

Answer 29

If are blocked
no other significant blood supply to region of myocardium they should supply
get ischaemia, infarction as a result