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Flashcards in Forces across membranes Deck (31):
1

if a molecule is hydrophilic it is also.....

lipophobic (and vice versa)

2

describe the general structure of membranes?

- embedded with glycoproteins
- embedded with glycolipids
- phospholipds contain hydrophilic phosphate heads and hydrophobic lipid tails
- cholesterol molecules stabilise membrane

3

what are the function of glycoplipids in membranes?

used in self recognition (antigens) and the immune response

4

what is the function of receptor proteins?

are intergral with allows communication between the ECF and ICF

5

what is the function of peripheral membrane proteins?

- anchor membrane to cytoskeleton
- performs siganlling functions
- attch cell to exctracellular matrix

6

which membranes have the lowest protein content?

myelin (18% protein)

7

which membranes have the highest protein content?

membarens involved in energy transduction e.g inner membranes of mitochondria (~75%)

8

what is the protein content of plasma membranes?

about 50%

9

what are electrochemical gradients?

gradients resulting from the difference between electrical charge and concentration

10

what are the concentrations of ions in the fluid compartments?

ECF: high Na+, low K+
ICF: Low Na+, high K+

11

describe the process of endocytosis

invagination of cell membrane creates a vesicle which transports macromolecules inside cells

12

what is the function of the cell membrane? (4)

- act as a selectively permeable barrier
- maintain concentration gradients
- provide site for receptors
- allows the transport of molecules

13

what properties do molecules need to pass through the bilayer easily?

- small
- uncharged (non polar)
- lipophilic

14

what type of channels allow passage of water

aquaporins

15

describe the structure of open channels

form water filled pores thta allow the passage of water soluble molecules

16

what two general types of channel proteins are there?

closed ion or open ion

17

what two types of gated chennels are there?

voltage gated and ligand gated

18

what is diffusion?

a process by which substances move between two compartments allowing the substance to spread across the whole volume giving equal concentrations

19

how do carrier proteins function?

have binding sites for solutes, the binding of the solute causes a conformtaional change
- can only be open to ECF or ICF but not both at the same time

20

what is movement through a carrier protein with the concentration gradient called?

facilitated diffusion

21

what is movement through a carrier protein against a concentration gradient called?

active transport (requires ATP)

22

how does the Na+/K+ ATP pump work?

is an electrogenic pump
- 3 Na+ out for every 2 K+ in

23

how much of the bodeis resting energy used to power Na+/K+ pump?

40%

24

what is osmosis?

the net movement of water from an area of high water concentration to an area of low water concentration

25

what is the osmotic pressure?

the force required to oppose the increase in volume resulting form osmosis

26

what is osmolarity?

the number of solute PARTICLES in solution

27

what is osmolarity measured in?

osmoles (milliosmoles)

28

what is the osmolarity of plasma

285 millisomoles (300)

29

what is tonicity?

the number of NON-PENETRATING particles in soltution

30

what terms can be used to describe solutions?

-hypotonic
- hypertonic
- isotonic
- hypoosmotic
- hyperosmotic
- isoosmotic

31

what is the difference between osmolarity and osmolality?

OSMOLALITY: the number of solute particles per kg of solvent
OSMOLARITY: the number of solute particles per litre of solvent