Composition of Cells

Question 1

Fluid Volumes in Human

Answer 1

45L Total, 27 ICF, 13 ECF, 5 “third space”

Also 3L plasma

Question 2

ECF vs ICF composition

Answer 2

ICF: High K and A, Low Na and Cl
ECF: High Na and Cl, Low K and no A
Water equal

Question 3

Two important properties of Membranes

Answer 3

Impermeable to charge or dipole neutral molecules
Electrically Strong: entire -50mV potential is across 5nm membrane (100kV/cm!)

Contain proteins as very selective gates for passive diffusion or active pumping.
Gates: voltage, mechanical, temperature, ligand, etc.

Question 4

Routes to cross a membrane (3)

Answer 4

Diffusion, passive transport, active transport

Question 5

Different types of gates (4)

Answer 5

Voltage: membrane potential sensitive
Mechanical: physical stretching of membrane
Chemical: ligand binding
Pumps: energy from ATP hydrolysis