Lecture 1: Membrane Physiology And Transport

Question 1

Fluid portion of the blood

Answer 1

Plasma

Question 2

Fluid outside cells is__

Answer 2

Extracellular fluid (ECF)

Question 3

The fluid surrounding and bathing cells

Answer 3

Interstitial fluid

Question 4

Fluid within cells is __

Answer 4

Intracellular fluid (ICF)

Question 5

Separates the ICF from the ECF

Answer 5

Physical barrier

Question 6

Controls entry/exit of ions, nutrients and other products to/from the cell

Answer 6

Gateway for exchange

Question 7

Plasma membrane:
The function of Containing proteins that enable cell to recognize and respond to changes in the extracellular environment

Answer 7

Communication

Question 8

Plasma membrane:
Function of Membrane proteins that can create specialized barriers between adjacent cells or between cells and the extracellular matrix. These junctions can stabilize tissue structures

Answer 8

Cell structure

Question 9

Hydrophilic polar end can interact with ___ molecules

Answer 9

Aqueous

Question 10

Hydrophobic polar end can interact with ___ molecules

Answer 10

Lipid soluble

Question 11

Aqueous molecules are excluded from passing through the __. Unless they use ___, ___, or ___

Answer 11

Lipid membrane.
Channels
Carriers
Transporters

Question 12

Ion channels, carrier molecules, membrane-bound enzymes, receptors and cell adhesion molecules are different forms of ____

Answer 12

Membrane proteins

Question 13

Separates intracellular fluid from extracellular fluid

Answer 13

Lipid bilayer

Question 14

The head of a phospholipid is __, __, and ___

Answer 14

Negatively charged, polar, and hydrophilic

Question 15

The tail of a phospholipid is __, __, and ___

Answer 15

Uncharged, no polar, and hydrophobic

Question 16

Anything that passes between a cell and the surrounding extracellular fluid must be able to penetrate the ___

Answer 16

Plasma membrane

Question 17

If a substance can cross the membrane, then the membrane is said to be ___ to it

Answer 17

Permeable

Question 18

If a substance cannot pass, then the membrane is ____ to it

Answer 18

Impermeable

Question 19

Plasma membrane is selectively permeable, which is when the membrane __

Answer 19

allows some particles to pass while excluding others

Question 20

What are the 2 general types of forces that produce the movement of a particle across the membrane ?

Answer 20

Passive, active

Question 21

Forces that don’t require cell to expend energy to produce moment across membrane

Answer 21

Passive forces

Question 22

Forces that do require the cell to expend energy (ATP)

Answer 22

Active

Question 23

_____ OR ___ molecules are highly soluble and readily cross

Answer 23

Uncharged or nonpolar

Question 24

__ or __ molecules have low lipid solubility

Answer 24

Charged particles(ions) and polar

Question 25

Lipid bilayer is impermeable to ____ molecules but protein channels can allow passage of ___

Answer 25

water-soluble. Ions

Question 26

Molecules that can permeate the plasma membrane on their own are passively driven by 2 forces – ___ and ___

Answer 26

Chemical and electrical

Question 27

______ - Positively charged ions tend to move toward the more negatively charged area and vice versa

Answer 27

Electrical gradient

Question 28

______ - when both electrical and concentration gradients act simultaneously

Answer 28

Electrochemical gradient

Question 29

If a substance can permeate the membrane, ___ occurs

Answer 29

Diffusion

Question 30

If the membrane is impermeable to a substance, no ___ occurs

Answer 30

Diffusion

Question 31

Diffusion across a lipid bilayer is called _____

Answer 31

Simple diffusion

Question 32

The rate of simple diffusion depends on the ability of the diffusing molecule to____ in the lipid bilayer

Answer 32

Dissolve

Question 33

only non-polar, lipophilic molecules can cross the _______ by diffusion

Answer 33

Lipid bilayer

Question 34

The rate of simple diffusion is directly proportional to the ______ of the membrane

Answer 34

Surface area

Question 35

The rate of simple diffusion is inversely proportional to the ___ of the membrane

Answer 35

Thickness

Question 36

when concentration gradient of substance increases, rate of net diffusion ___

Answer 36

Increases

Question 37

when permeability of membrane to substance increases, rate of net diffusion ___

Answer 37

Increases

Question 38

when surface area of membrane increases, rate of net diffusion ___

Answer 38

Increases

Question 39

when molecular weight of substance increases, rate of net diffusion ___

Answer 39

Decreases

Question 40

when distance (thickness) increases, rate of net diffusion ___

Answer 40

Decreases

Question 41

The net diffusion of water down its concentration gradient

Answer 41

Osmosis

Question 42

_____ tells you what happens to cell volume when a cell is placed into a solution

Answer 42

Tonicity

Question 43

____ solutions have the same concentration of nonpenetrating solutes as normal body cells and will result in cell volume remaining constant

Answer 43

Isotonic

Question 44

____ solutions have a lower concentration of nonpenetrating solutes and tend to swell the cell (water enters by osmosis)

Answer 44

Hypotonic

Question 45

___ solutions which have a higher concentration of nonpenetrating solutes tend to shrink the cell, as water moves out of the cell

Answer 45

Hypertonic

Question 46

Cell must provide mechanisms for transporting these poorly lipid-soluble molecules in and out of cell ◦ Two different mechanisms:_____ and _____

Answer 46

Carrier-mediated transport, vesicular transport

Question 47

____ transport uses a carrier molecule facilitate the transfer of a substance across the membrane from high to low concentration (downhill)

Answer 47

Passive

Question 48

___ transport requires the carrier to use energy to transfer substance against the concentration gradient (uphill)

Answer 48

Active

Question 49

____ diffusion: uses a carrier molecule facilitate the transfer of a substance across the membrane from high to low concentration (“downhill”)

Answer 49

Facilitated

Question 50

transport of glucose into cells: • [Glucose(ex) > [Glucose(in)] • Cells metabolize glucose as fast as it enters • So there is always a gradient for net diffusion • But – glucose is _____, not ___ soluble and is too large for channels

Answer 50

Polar, lipid

Question 51

Carrier protein takes conformation in which solute binding site is exposed to region of __ concentration

Answer 51

Higher

Question 52

Order Steps of carrier proteins: (A)- Solute molecule binds to carrier protein (B)-Transported solute is released and carrier protein returns to conformation. (C)- Carrier protein changes conformation so that binding site is exposed to region of lower concentration (D)- carrier proteins takes conformation in which solute binding site is exposed to region of higher concentration

Answer 52

D, A, C, B

Question 53

With____ diffusion of a molecule down its concentration gradient, the rate of transport of the molecule into the cell is directly proportional to the extracellular concentration of the molecule.

Answer 53

Simple

Question 54

With ____ transport of a molecule down its concentration gradient, the rate of transport of the molecule into the cell is directly proportional to the extracellular concentration of the molecule until the carrier is saturated, at which time the rate of transport reaches a maximum value

Answer 54

Carrier mediated

Question 55

Na+–K+ pump transports Na ___ of the cell against its concentration gradient and K ___ the cell

Answer 55

Out. In

Question 56

Pump has __ high-affinity sites for Na+ and __ low-affinity sites for k+ when exposed to ICF

Answer 56

3. 2

Question 57

When 3 Na+ from ICF bind to pump. It splits ATP into ____ plus phosphate group binds to pump.

Answer 57

ADP

Question 58

____ causes pump to change conformation so that Na+ binding sites are exposed to opposite side of membrane and 3 Na+ are released to ECF as affinity of Na+ binding sites greatly decreases.

Answer 58

Phosphorylation

Question 59

Change in shape also exposes pump’s binding sites for K+ TO ECF and greatly ___ affinity for K+

Answer 59

Increases

Question 60

When 2 K+ from ECF bind to pump, it releases ____ ___. ___ causes pump to revert to its original conformation.

Answer 60

Phosphate group. Dephosphorylation

Question 61

2__ are released to ICF as affinity of K+ binding sites markedly ___ during change in shape. At same time, affinity of Na+ binding sites greatly increases, returning process to step 1.

Answer 61

K+. Decreases.

Question 62

Na+–K+ pump transports ___ out of the cell against its concentration gradient and __ into the cell • Not a direct exchange – __ __ out for __ __ in

Answer 62

Na. K. 3 Na 2 K

Question 63

When Actin-mediated process by which a cell engulfs a particle into a large membrane bound vesicle called a phagosome

Answer 63

Phagocytosis

Question 64

Vesicular transport of materials into the cell

Answer 64

Endocytosis

Question 65

Vesicular transport of materials out of the cell

Answer 65

Exocytosis

Question 66

Exocytosis: Membrane-enclosed vesicle fuses with _______ then opens up and releases its contents to the ___

Answer 66

Plasma membrane. Exterior

Question 67

Exocytosis: Materials for secretion are produced and packaged by ___ and ____ complex

Answer 67

ER Golgi

Question 68

Exocytosis: Secretion of large ____ molecules (i.e., hormones or enzymes) that cannot cross plasma membrane – regulated by specific ____ events

Answer 68

Polar Signalling

Question 69

Release of secretory vesicles is generally regulated by intracellular ___

Answer 69

Ca++

Question 70

What method of transport ? ◦ Through lipid bilayer ◦ Through channels (ie ions) ◦ Special case of osmosis (water only)

Answer 70

Diffusion

Question 71

What method of transport? ◦ Facilitated diffusion – passive ◦ Primary active transport – requires energy

Answer 71

Carrier-mediated transport

Question 72

What method of transport? Endocytosis-active Exocytosis - active

Answer 72

Vesicular transport