The heart

Question 1

What are the 4 components of blood?

Answer 1

1. Red blood cells
2. Platelets
3. Plasma
4. White blood cells

Question 2

What are the 2 adaptations of red blood cells?

Answer 2

1. Large SA for faster diffusion
2. No nucleus so more space for haemoglobin

Question 3

What is haemoglobin?

Answer 3

A quaternary protein with a haem group at the centre of each polypeptide chain containing Fe2+

Question 4

What do haem groups contain?

Answer 4

One Fe2+ which one oxygen molecule binds to

Question 5

What is the term used to describe the attraction between haemoglobin and oxygen?

Answer 5

Affinity

Question 6

Where does haemoglobin load/associate with oxygen?

Answer 6

Lungs

Question 7

Where does haemoglobin unload/dissociate with oxygen?

Answer 7

Respiring tissues

Question 8

What is % saturation of haemoglobin?

Answer 8

A measure of how oxygenated blood is

Question 9

What is partial pressure of oxygen?

Answer 9

A measure of concentration of oxygen not attached to the haemoglobin molecule

Question 10

Why does the second oxygen molecule attach easier?

Answer 10

Each time a molecule of oxygen attaches the whole haemoglobin changes shape which exposes more of the next O2 binding site and makes it easier for the next O2 molecule to attach

Question 11

What is the advantage of the sigmoid shape of an oxygen dissociation curve?

Answer 11

Shows that O2 isn’t unloaded until it reaches the respiring tissues

Question 12

What does the Bohr effect curve shifting right mean?

Answer 12

More respiration so higher partial pressure of O2 and Hb has lower affinity for O2 so more O2 unloaded at respiring tissues

Question 13

What does the Bohr effect curve shifting left mean?

Answer 13

Lower partial pressure of O2 and Hb has higher affinity for O2 so more O2 loaded at the lungs

Question 14

What is systole?

Answer 14

Contraction (occurs separately in atria and ventricles)

Question 15

What is diastole?

Answer 15

Relaxing

Question 16

What are the valves called between atria and ventricles?

Answer 16

Atrioventricular valves

Question 17

What are the valves called between ventricles and arteries?

Answer 17

Semi-lunar valves

Question 18

Which direction should blood flow?

Answer 18

From atria –> ventricles –> arteries

Question 19

What happens if there is higher pressure in the ventricles than the atria?

Answer 19

The atrioventricular valves close

Question 20

What happens if there is higher pressure in the arteries than the ventricles?

Answer 20

The semi-lunar valves close

Question 21

Define cardiac output

Answer 21

Mean volume of blood leaving the left ventricle per minute

Question 22

Define stroke volume

Answer 22

Mean volume of blood leaving the left ventricle during each contraction

Question 23

How does blood flow around the body?

Answer 23

Vena Cava –> right atrium –> right ventricle –> lungs –> left atrium –> left ventricle –> Aorta

Question 24

How are arteries/arterioles adapted to their function?

Answer 24

1. More muscular tissue constricts width to control blood flow (thickest in arterioles)
2. More elastic tissue allows elastic recoil due to pressure of systole (thickest in arteries)
3. Narrow lumen maintains high pressure

Question 25

How are veins adapted to their function?

Answer 25

1. Less muscular tissue - blood is returning to heart so less need to control flow to tissues 2. Less elastic tissue - blood under less pressure returning to heart 3. Less overall thickness - pressure too low to burst walls (allows flattening, allowing compression by muscles) 4. Valves prevent backflow of blood due to low pressure

Question 26

How are capillaries adapted to their function?

Answer 26

1. One squamous epithelial cell thick for short diffusion distance 2. Many and highly branched for large SA 3. Narrow lumen so red blood cells are squeezed flat (reduces diffusion distance for O2) 4. Spaces between cells allow white blood cells to leave blood and enter cells

Question 27

What is coronary heart disease?

Answer 27

Coronary arteries become narrower so less blood supplied to heart muscle and less O2 + glucose for respiring cells

Question 28

What is myocardial infarction (heart attack)?

Answer 28

Coronary artery becomes completely blocked so no O2/glucose so no respiration so cell and tissue death