Composition of Cells

Question 1

What is the typical volume of plasma?

Answer 1

3L

Question 2

What is the typical volume of extracellular fluid?

Answer 2

13L + 5L for “third space”

Question 3

What is the typical volume of intracellular fluid?

Answer 3

27L

Question 4

What is the ICF [Na+]?

Answer 4

14mM

Question 5

What is the ECF [Na+]?

Answer 5

140mM

Question 6

What is the ICF [K+]?

Answer 6

145mM

Question 7

What is the ECF [K+]?

Answer 7

5mM

Question 8

What is the ICF [Cl-]?

Answer 8

5mM

Question 9

What is the ECF [Cl-]?

Answer 9

145mM

Question 10

What is the ICF [A-n]? (big anions)

Answer 10

126mM

Question 11

What is the ECF [A-n]? (big anions)

Answer 11

~0mM

Question 12

What is the ICF [H2O]?

Answer 12

55,000mM

Question 13

What is the ECF [H2O]?

Answer 13

55,000mM

Question 14

Is the membrane permeable to Na+?

Answer 14

functionally impermeable

Question 15

Is the membrane permeable to K+?

Answer 15

yes

Question 16

Is the membrane permeable to Cl-?

Answer 16

yes

Question 17

Is the membrane permeable to A-n (big anions)?

Answer 17

no

Question 18

Is the membrane permeable to H2O?

Answer 18

yes

Question 19

What 2 important properties of plasma membranes is conveyed by lipids?

Answer 19

1. impermeable to charged substances (including molecules with dipoles)
2. Can maintain separation between opposite charges without collapsing. (allows for creation of membrane potential)

Question 20

What are 2 important properties of channels?

Answer 20

1. Most are selective for specific ions

2. Some contain gates - substances can only pass through when the gate is open

Question 21

What physical forces can determine the gating properties of ion channels?

Answer 21

Electric field (voltage gated)
mechanical (hair cells in cochlea, touch receptors)
chemical (neurotransmitter synapse)
temperature (cutaneous thermal receptors)

Question 22

What are water channels called?

Answer 22

aquaporins (contain no gate)

Question 23

What types of molecules pass through channels?

Answer 23

H2O

Ions: Na+, K+, Cl-, Ca2+

Question 24

How is primary transport different from secondary transport?

Answer 24

Primary depends on energy released directly by metabolism (often ATP)
Secondary depends on other sources (i.e. E releases when Na+ leaks into cells through channels)

Question 25

How are transporters different from channels?

Answer 25

require E Slower (max of several hundred cycles per sec) transport ions and smaller ions

Question 26

What types of molecules are transported by transporters?

Answer 26

glucose (large molecules) | Ions (Na+)