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Flashcards in Membrane Systems Deck (67):
1

Intracellular fluid is

cytosol

2

Extracellular fluid is

Interstitial fluid

3

The ions of higher concentration inside the cell are

K+ and anionic proteins

4

The ions of higher concentration outside the cell are

Na+
Cl-
Ca2+

5

Define permeability

The ease with which substances can cross the cell membrane

6

A cell membrane is selectively permeable and that selectivity is due to

different transport mechanisms

7

A passive transport mechanism

does not expend energy

8

An active transport mechanism

expends energy

9

Diffusion is

passive
random motion of ions and molecules down their concentration gradient

10

Carrier mediated transport

Can be passive or active
requires transport protein in membrane

11

When an ion moves from high to low concentration, it is said to be

passive

12

When an ion moves from low to high concentration, it is said to be

active

13

Diffusion is define as

the movement of a substance from an area of high concentration to low

14

Molecules with no electrical charges diffuse

down the chemical concentration gradient

15

Charged ions and molecules diffuse

based on electro-chemical gradient

16

What are the four examples of diffusion in body fluids?

O2 moves from lungs to blood
CO2 moves from cells to lungs
Water moves across digestive tract
Anesthetics diffuse into cells

17

For diffusion to occur, the membrane must be

permeable

18

The lipid bilayer portion of cell membranes is permeable to

O2
CO2
Hydrophobic molecules

19

The lipid bilayer portion of the cell membrane is not permeable to

large molecules
hydrophilic molecules

20

Membrane proteins provide channels for what type of diffusion?

Passive

21

Define osmosis

Diffusion of water across a semi-permeable membrane in response to solute differences

22

Water moves

via diffusion down its concentration gradient

23

In osmosis, water wants to move

from low to high solute concentration

24

Define osmotic pressure

force of water movement into a solution

25

Define tonicity

The effects of extracellular solutions on cells

26

Define isotonic

No net osmosis, no net gain or loss of water

27

Define hypotonic

Net gain of water into cells

28

Hypotonic states of cells can result in

Cytolysis (hemolysis in RBCs)

29

Define hypertonic

Net water flow out of the cell

30

Hypertonic states of cells can result in

crenation

31

What is a hypotonic extracellular solution and how will water behave?

Less solutes, more water than intracellular solution

Water will flow into the cell

32

What is hypertonic extracellular solution and how will water behave?

More solutes, less water than intracellular solution

Water will flow out of the cell

33

What factors influence diffusion?

Distance
Size
Temperature
Concentration gradient

34

Diffusion is an effective means of transport from 0- _____ micrometers

123

35

Diffusion will occur faster if

molecule is smaller
temp is higher
concentration gradient is higher

36

For charged ions, the 2 driving forces influencing their rate of diffusion are

electrical gradient
concentration gradient

37

What would happen if a cell suddenly became very permeable to Na+ ions?

Na+ ions would move into the cell

38

Describe diffusion

Passive
Random motion of substances down their gradient
Channel proteins allow hydrophilic substances through

39

Describe carrier mediated transport

Passive or active
Requires a transport protein in membrane

40

Carrier mediated transport relies on what three factors?

specificity
saturation limits
regulation

41

Define specificity in terms of carrier mediated transport

carrier proteins are generally specific for a particular substance

42

Define Saturation limits

Rate of transport is subject to number of transport proteins available

43

Define Regulation

Various control factors exist that effect the activity of carrier proteins

44

To increase your saturation limit, you can use a

enzyme

45

Define co-transport

both substances being transported go same directions across the membrane

46

Define counter-transport

both substances being transported go opposite directions across the memrane

47

Is facilitated diffusion passive or active?

Passive

48

Describe facilitated diffusion

Substance moves down conc. gradient
Requires transport protein
Differs from simple diffusion (can reach saturation)

49

Describe facilitated diffusion with co transport against concentration gradient

One substance moves down gradient
Another moves against gradient
Requires transport protein

50

Describe active transport

Consumes ATP
Independent of conc gradients

51

What are the two examples of active transport??

Ion pumps
Secondary active transport

52

What is trans-membrane potential?

Difference in electrical potential between inside and outside of a cell?

53

At rest, cells have more negative charge ____ than _____

inside than outside

54

What is higher in concentration inside a cell at rest?

K+
Proteins (negatively charged anions)

55

What is higher in concentration outside a cell at rest?

Na+
Cl-
Ca2+

56

What is the electro-chemical gradient?

Sum of all forces of all chemical and electrical gradients acting across the cell membrane

57

The resting trans-membrane potential in nerve cells is

-70mV

58

The resting trans-membrane potential in muscle cells is

-85mV

59

What is the driving force of ion flow across a membrane?

Diffusion along a electro-chemical gradient

60

Chemically regulated channels

Open or close when they bind specific chemicals

61

Voltage-regulated channels

Open or close in response to level of trans-membrane potential

62

____ is released by motor neurons and tell muscles to contract

ACh

63

Define neuromuscular junction

synapse between nerve cell and muscle cell

64

Nerve cell process releases acetylcholine by

exocytosis

65

Define depolarization

trans-membrane potential becomes less negative

66

Define hyperpolarization

trans-membrane potential becomes more negative

67

Define repolarization

trans-membrane potential returns toward resting potential after being depolarized