Cardiff Q - Physiology

Question 1

Haemoglobin subunits

Answer 1

2 alpha globin chains
2 beta globin chains

Each binds 1x oxygen molecule

Question 2

Hb structure

Answer 2

Quaternary structure

Question 3

Allosteric binding

Answer 3

As first O2 molecule binds to Hb, conformational structure changes making it easier for subsequent O2 to bind to other subunits

Therefore Hb tends to have 4 O2 or no O2 bound

Question 4

Nernst equation use

Answer 4

Used to calculate the equilibrium potential of different ions

Question 4

Hufner’s constant

Answer 4

1.39 ml O2 carried per gram of Hb

Question 5

Cardiac cycle

Answer 5

Relationship between electrical and mechanical events within the heart in each heartbeat

Filling vs emptying

Question 6

Proportions of cardiac cycle in diastole and systole

Answer 6

2/3 of cycle is diastole
1/3 of cycle is systole

Question 7

Percentage of ventricular filling that occurs in systole vs diastole

Answer 7

80% of filling occurs during diastole

Question 8

7 steps of the cardiac cycle

Answer 8

Atrial systole (P wave)
Isovolumetric contraction
Rapid ejection into aorta (QRS)
Reduced ejection (T wave)
Isovolumetric relaxation
Rapid filling
Reduced filling

Question 9

Area within LV pressure-volume graph represents

Answer 9

Stroke volume

End diastolic volume - End systolic volume

Question 10

West zones with VQ mismatch

Answer 10

Zone 1
Zone 2
Zone 3

Question 11

West zone 1

Answer 11

Apex

PA > Pa > Pv

In theory arterial and venous system collapsed but ventilation remains

Only theoretical in healthy people as there remains sufficient pressure to maintain Pa in healthy individuals

Question 12

West zone 2

Answer 12

Middle

Pa > PA > Pv

Question 13

West zone 3

Answer 13

Base

Pa > Pv > PA

Question 14

VQ ratio

Answer 14

Ratio between amount of air getting into alveoli and the amount of blood entering the lungs

Question 15

V/Q = 0 represents

Answer 15

Shunt

Perfused but not ventilated

Question 16

V/Q = infinity represents

Answer 16

Dead space

Ventilated but not perfused

Question 17

Effect of carbon monoxide on oxygen dissociation curve

Answer 17

Shifts curve to the left

Carboxy-Hb still binds O2 but does not release O2

(whereas Right shift has lower affinity for O2 but more likely to release O2 molecules)