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Physiology > Cell Membrane Transport > Flashcards

Cell Membrane Transport Flashcards

1
Q

What is diffusion

A

Process of moving solute molecules away from an area of high concentration towards area of low concentration

Down the concentration gradient

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2
Q

No external energy just kinetic energy of molecules is what type of diffusion

A

Passive

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3
Q

How long does diffusion occur for

A

Until equilibrium is reached

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4
Q

Explain the rate of diffusion

A

Fast over short distances
Slow over long distances
Distance squared relationship

Rate of diffusion is faster at high temp
Rate of diffusion is faster for small molecules
Rate of diffusion is slower across a membrane

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5
Q

Simple diffusion

A

Across no membrane means diffusion is fast

Across a semipermeable membrane allows selected solutes to pass but more slowly
And some solutes can’t pass

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6
Q

What affects the diffusion of Solutes across a cell membrane

A

The type of molecule

Concentration gradient

Temperature

Surface area

Composition of membrane

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7
Q

How does the type of molecule affect its diffusion rate

A

Size (two big)
Polar or non polar

Hydrophobic non polar = pass through

Small uncharged polar molecules = pass

Large uncharted polar molecules = no pass

Charged molecules = no pass

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8
Q

What are hydrophobic non polar molecules

A 
O2
CO2
Lipids
Steroids
Fat soluble molecules
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9
Q

What are small uncharged polar molecules

A

Urea

H2O

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10
Q

Large uncharged polar molecules

A

Glucose
Proteins
Amino acids

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11
Q

What are charged molecules

A

Ions

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12
Q

How does the composition of membrane affect diffusion

A

Simple bilayer vs many proteins and extracellular matrix

Types of phospholipids and sphingolipids

Presence of cholesterol

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13
Q

What is ficks law of diffusion

A

Rate of diffusion

Surface area x concentration gradient x membrane permeability

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14
Q

What is liposomal drug delivery

A

Some drugs may have low bioavailability due to poor solubility

Some drugs may be toxic at useful doses and must be targeted to a specific cell type

Liposomal drug delivery is an emerging technology that may help address these issues

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15
Q

Body fluids are in two compartments ____

A

Extracellular fluid

Intracellular fluid

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16
Q

Intracellular fluid

A

Is 2/3 of the total body water volume. Material moving into and out of the ICF must cross the cell membrane

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17
Q

Extracellular fluid

A

Includes all fluid outside the cells. The ECF is 1/3 of the body fluid volume

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18
Q

The extracellular fluid consists of

A

Interstitial fluid
- which lies between the circulatory system and the cells is 75% of the ECF volume

Plasma
- the liquid matrix of blood is 25% of the ECF volume

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19
Q

Define osmosis

A

The diffusion of water

Water can have a concentration gradient and will diffuse down the gradient

Pure water has the highest concentration of water
Solutes lower the concentration of water

Movement of water can cause pressure

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20
Q

How to compare osmolarities

A

1 glucose = 1 OsM

2 glucose = 2 OsM

1 NaCl = OsM

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21
Q

Higher OsM means ____

Lower OsM means _____

A

hyperosmotic

Hyposomotic

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22
Q

Why is osmolarity important

A

Changing osmolarity of the extracellular solution causes redistribution of water and some solutes in cells

This causes cells to shrink or swell

23
Q

The ability of a solution to shrink or swell cells is its

A

Tonicity

24
Q

What is the difference between osmolarity and tonicity

A

Osmolarity describes only the number of solute molecules in a cell
Osmolarity can compare any two solutions
Does not tell if a cell swells or shrinks

Tonicity is a comparative term describes whether a cell changes volume
Tonicity compares a solution to a cells intracellular solution
Specifically tells if a cell swells or shrinks

25
Q

Tonicity depends on _____

A

Concentration of penetrating and non penetrating solutes

26
Q

Penetrating solutes

A

Small polar and non polar molecules

For example urea glycerol ethanol

27
Q

Non penetrating solutes

A

Ions and larger polar molecules

For example Na+ glucose amino acids

28
Q

Hyposmotic solutions are always ____

A

Hypotonic

29
Q

Intracellular solutes are _____

A

Non penetrating

30
Q

Water will flow into the compartment that contains the ___ concentration of ____ solutes

A

Higher

Nonpenetrating

31
Q

A _____ is a water filled pore. Can open to both sides

A

Channel protein

32
Q

What are two examples of channel proteins

A

Water channels

Ion channels

33
Q

What are two types of channel proteins

A

Gated

Open

34
Q

____ NEVER form an open channel between the two sides of the membrane

A

Carrier proteins

35
Q

What are three types of carrier proteins

A

Uniport (one molecule through)

Symport (two molecules through same direction)

Antiport (two molecules through different directions)

36
Q

Describe carrier protein process

A

Passage open to one side

Conformational changes occur

Transition stage with both gates closed

Conformational changes

Passage open to other side

37
Q

What are the three categories of energy carrier proteins

A

Facilitated diffusion
Primary active transport
Secondary active transport

38
Q

Moving a molecule across the membrane via a carrier protein

A

Facilitated diffusion

39
Q

True or false

Facilitated diffusion requires ATP

A

False does not require ATP

40
Q

What’s another name for facilitated diffusion

A

Passive transport

41
Q

True or false

Facilitated diffusion cannot accumulate solute against a concentration gradient

A

True

42
Q

What is an example of facilitated diffusion

A

Glucose transporter

43
Q

explain the facilitated diffusion of glucose

A

High concentration of glucose outside of the cell

Glucose moves through FD Into the cell from high to low

44
Q

Explain primary active transport

A

Uses ATP
Establishes gradients
Sometimes called pumps

45
Q

What are the most common molecules to pass through the primary active transport

A

Na
K
ATPase

(Ca H as well)

46
Q

Describe primary active transport steps

A

3 Na from the ICF moves into the protein and fits in the walls

ATP is used to close the gates turns to ADP

Protein changes and 3 Na released into ECF

2 K from the ECF moves into the protein and fits in the walls

ATP and protein changes

2 K is released into ICF

47
Q

What is the Na K ATPase pump

A

Pumps 2 K ions INTO THE CELL

Removes 3 Na ions OUT OF THE CELL

Hydrolyses ATP

This pump accounts for 20 watts of the 100 watts the body produces

48
Q

Secondary active transport

A

Active transport
Does not directly utilize ATP as a source of energy

Uses the concentration gradient of one molecule/ions to move another AGAINST its gradient

49
Q

What’s an example of a secondary active transporter

A

Na glucose

50
Q

Explain secondary active transport

A

Na binds to the carrier from the ECF

Na binding creates a site for glucose

The glucose binding changes the carrier conformation and opens the protein to the inside

Na is released into the cytosol of the cell and glucose follows

51
Q

Epithelial transport utilizes what types of transport

A

Facilitated diffusion
Primary active transport
Secondary active transport

52
Q

Transport of material from the lumen of an organ to the ECF is called ____

A

Absorption

53
Q

Describe the trans-epithelial absorption of glucose

A

Na glucose symporter brings glucose into the cell AGAINST its gradient using energy stored in the NA concentration gradient
(Primary active transport)

GLUT transporter transfers glucose to ECF by facilitated diffusion
(Secondary active transport)

Na K ATPase pumps Na out of the cell keeping ICF Na concentration low
(Facilitated diffusion)

Physiology (15 decks)

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