Physiology: Membrane Transport

Question 1

what influences a cell’s ability to permeate the membrane

Answer 1

lipid solubility and particle size

Question 2

what are the two types of driving forces for moving an ion across the membrane

Answer 2

passive and active

Question 3

how is passive transport driven

Answer 3

diffusion down a conc. gradient and/or movment along an electrical gradient

Question 4

what is Fick’s Law of Diffusion (5)

Answer 4

• size of conc. gradient
• membrane SA
• substance’s lipid solubility
• substance’s molecular weight
• diffusion distance

Question 5

what creates an electrical gradient and where does the ion move

Answer 5

created by two areas with differing charges, ions move to that of opposite charge

Question 6

what are the two types of ions specific channel proteins

Answer 6

leak or ligand gated

Question 7

what is an electrochemical gradient

Answer 7

the net of an ions chemical and electrical gradient

Question 8

what channels allow osmosis

Answer 8

aquaporins

Question 9

omsolarity

Answer 9

conc. of osmotically active particles in a solution

Question 10

tonicity

Answer 10

effect a solution has on cell vol.

Question 11

3 types of tonicity and their effects

Answer 11

• isotonic = no effect
• hypotonic = water into cell and cell swells
• hypertonic = water out of cell and cell shrinks

Question 12

what are the 3 mechanisms of passive transport

Answer 12

• osmosis
• diffusion
• electrical gradients

Question 13

2 mechanisms for selective active transport

Answer 13

• carrier mediated transport

- vesicular transport

Question 14

describe the process of carrier-mediated transport

Answer 14

substance binds to carrier - conformational change - substance transported

Question 15

what are the 3 characteristics in carrier-mediated transport determining the kind and amount of material transferred

Answer 15

• specificity
• saturation
• competition

Question 16

what are the two types of carrier-mediated transport

Answer 16

active and facilitated

Question 17

describe active carrier-mediated transport

Answer 17

carrier expends energy transferring against concentration gradients

Question 18

describe facilitated carrier-mediated transport

Answer 18

carrier facilitates movement from high to low concentration gradient

Question 19

what are the two forms of active transport

Answer 19

primary and secondary

Question 20

describe primary active transport

Answer 20

energy needed directly to move substance against conc. gradient

Question 21

descrive secondary active transport

Answer 21

energy needed but not in ATP form used energy stored in ion conc gradient, coupled with ion transfer used as driving force

Question 22

what type of transporter is Na/K ATPase and what is the movement of its ions

Answer 22

• primary active carrier-mediated transporter

- 3 Na+ out and 2 K+ in

Question 23

what are the 3 role of Na/K ATPase

Answer 23

• helps establish Na+ and K+ gradients
• helps regulate cells vol by controlling solute concs inside the cell
• energy used to drive pump indirectly used by secondary active transporters

Question 24

what are the 2 mechanisms of secondary active transport and how they work

Answer 24

• symport - both move in same direction

- antiport - each move in different directions

Question 25

why is energy needed in vesicular transport

Answer 25

energy needed for vesical formation and movement within cell

Question 26

what are the 2 types of vesicular transport

Answer 26

• endocytosis

- exocytosis

Question 27

describe endocytosis

Answer 27

membrane ‘pinches off’ to engulf substance

Question 28

describe exocytosis

Answer 28

vesicle fuses with the membrane and releases its contents into ECF

Question 29

what is exocytosis used for

Answer 29

• enzyme, protein, hormone secretion

- add carriers, channels and receptors to membrane