Body fluid compartments

Question 1

What percentage of body fluid is intracellular and extracellular?

Answer 1

intracellular - 70%

extracellular - 30%

Question 2

What is the cell membrane composition?

Answer 2

55% protein 
25% phospholipid 
13% cholesterol 
4% other lipids 
3% carbohydrate

Question 3

What are the three types of membrane lipids?

Answer 3

phospholipids
sphingolipids
cholesterol

Question 4

What is the function of membrane proteins?

Answer 4

• provide structural channels
• transporters
• receptors

Question 5

What is the structure of integral proteins in the membrane?

Answer 5

embedded in the membrane and require membrane disruption to purify

Question 6

What is the structure of peripheral proteins in the membrane?

Answer 6

weakly bound to membrane and easily purified

Question 7

What are the solute concentrations in extracellular fluid?

Answer 7

Na + - 140mM
K+ - 5mM
Cl- - 110mM
pH - 7.4

Question 8

What are the solute concentrations in intracellular fluid?

Answer 8

Na+ - 10mM
K+ - 140mM
Cl- - 5mM
pH - 7.0

Question 9

How can polar and non-polar substances diffuse across the membrane?

Answer 9

• passive diffusion of fat soluble non-polar substances

- facilitated diffusion of hydrophilic substances

Question 10

What factors affect the diffusion rate through cell membranes?

Answer 10

• concentration
• electrical potential
• pressure

Question 11

How is diffusion affected by concentration?

Answer 11

net diffusion is proportional to the concentration difference across a membrane

Question 12

How is diffusion affected by electrical potential?

Answer 12

the electrical potential drives the movement of ions to the opposite pole

Question 13

How is diffusion affected by pressure?

Answer 13

pressure difference across membranes increases the forces of molecular motion and diffusion increases

Question 14

What is the permeability co-efficient?

Answer 14

the rate of movement calculated in cm/sec

Question 15

What is membrane permeability?

Answer 15

incorporates the factors inherent in both the molecule and the membrane that determines the probability of a molecule crossing the membrane

Question 16

What is the membrane permeability equation?

Answer 16

P = omegaRT k/a

Question 17

What do the letters stand for in the membrane permeability equation?

Answer 17

omega = viscosity of solution being diffused through 
R = gas constant 
T = absolute temperature 
k = molecule resistance
a = thickness of membrane

Question 18

What are the three types of diffusion across the lipid bilayer?

Answer 18

1. simple diffusion
2. simple diffusion through integral membrane protein channels
3. carrier-mediated transport

Question 19

What membrane proteins are involved in transport?

Answer 19

channel proteins

carrier proteins