Diffusion and Membrane Transport Flashcards Preview

Physiology 2002 > Diffusion and Membrane Transport > Flashcards

Flashcards in Diffusion and Membrane Transport Deck (32):
1

What is Diffusion?

Movement of substances from an are of high to low concentration

2

What is flow?

The amount of substance moving per time (mol/sec)

3

What is flux (j) ?

The rate of flow per unit of area (mol/sec/cm^2)
Flow/Area

4

Flux depends on the _______________.

Concentration gradient

5

What factors affect the rate of diffusion of a substance?

Directly Proportional:
- Concentration
- Surface Area of the membrane
- Lipid Solubility

Inversely Proportional:
- Molecular Weight
- Distance/Thickness

6

Why do particles take longer to diffuse across large distances?

Because individual particles are always randomly changing directions

7

Flow = _____ x ______

Flux x Area, j x A

8

The displacement of particles is about.................

s= (2Dt)^1/2
Where
s=displacement
D=diffusion constant
t= time

9

Permeability, P, consists of ___________, __________________ and ____________

Thickness
Diffusion Coefficient
Solubility

10

Flux = __ x ________

P x ( [x1] - [x2] )
P = Permeability
[x1] and [x2] = concentrations

11

Flux = __ x _____/____

Flux = D x ( [x1] - [x2] ) / s
D = diffusion constant
s = displacement

12

The body is made of about __% water

55%

13

1/3 of the body's water is ______________

Extracellular

14

2/3 of the body's water is ______________

Intracellular

15

Na and Cl are generally __________ the cell

Outside

16

K is generally _________ the cell

Inside

17

Endo/Exocytosis are examples of _______ transport and and can move substances ________________________.

Active
Against their concentration gradient

18

Briefly describe vesicle formation:

1. Substance binds to a receptor
2. Binding triggers invagination into a Clathrin coated pit
3. Actin and Myosin pinch off the vesicle

19

What is the difference between a pore and a channel?

Pores are generally always open whereas a channel is something that can be opened or closed

20

What are the 3 classes of gated channels?

Voltage - open in response to voltage change
Ligand - opens in response to a chemical bonding
Mechanical/Stretch - respond to movement

21

What are gap junctions?

Pores between cells that allow small polar molecules to diffuse directly between the cells

22

How are gap junctions formed?

Transmembrane protein called Connexon binds with a Connexon in an adjacent cell forming a tube

23

How can we change permeability?

Opening and Closing gated channels

24

What is osmotic pressure?

The pressure needed to stop osmosis from happening. It's abbreviated as π

25

What's the formula for osmotic pressure?

π = RT * ΔC
ΔC = change in concentration of water (Osmolarity)
R = Universal Gas Equation
T = Temperature in Kelvin (+270.15)

26

1mOsmol is equivalent to _____ mmHg

19.3mmHg

27

If you put a cell in a Hypotonic Solution it will _______

Crenate

28

If you put a cell in a Hypertonic Solution it will _______

Expand/Burst

29

What is a Hypotonic Solution?

A solution that has a low osmotic pressure than a reference solution

30

What is a Hypertonic Solution?

A solution that has a high osmotic pressure than a reference solution

31

Hyposmotic cells _______

Swell

32

Hyperosmotic cells _______

Crenate