Physiological constants (michaelmas)

Question 1

What are the concentrations of K⁺?

Answer 1

Intracellular: 140 mM

Extracellular: 4.5 mM

Question 2

What are the concentrations of Na⁺?

Answer 2

Intracellular: 15 mM

Extracellular: 140 mM

Question 3

What are the concentrations of Ca²⁺?

Answer 3

Intracellular: 10^-9 mM

Extracellular: 1.2 mM

Question 4

What is the conduction velocity of Aα fibres?

Answer 4

80-120 ms^-1

Question 5

What is the conduction velocity of Aβ fibres?

Answer 5

35-75 ms^-1

Question 6

What is the conduction velocity of Aγ fibres?

Answer 6

12-30 ms^-1

Question 7

What is the conduction velocity of Aδ fibres?

Answer 7

5-30 ms^-1

Question 8

What is the conduction velocity of B fibres?

Answer 8

3-15 ms^-1

Question 9

What is the conduction velocity of C (unmyelinated) fibres?

Answer 9

<2 ms^-1

Question 10

What are the relative contributions of passive and active ventricular filling?

Answer 10

Passive: 100 ml (~80%)

Active (atrial systole): 20 ml (~20%)

Question 11

What is normal stroke volume?

Answer 11

80 ml

Question 12

What is normal end-diastolic volume?

Answer 12

40 ml