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Mammalian Physiology 318 > Membrane Transport (1) > Flashcards

Membrane Transport (1) Flashcards

Exam 1

1
Q

How do cells communicate?

A

Cells communicate with each other by secreting chemical regulators into the extracellular environment

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2
Q

Cells receive nourishment from and release wastes into the ____ ____

A

extracellular environment

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3
Q

What does the extracellular environment include?

A

everything located outside the cells

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4
Q

What does body fluid refer to?

A

body fluid refers to the watery solution of dissolved substances (oxygen, nutrients, and wastes) present in the body

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5
Q

Intracellular Fluid Definition

A

fluid located inside the cells

~67% of all fluid in the body

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6
Q

Extracellular Fluid Definition

A

Fluid in the blood and in spaces surrounding the cells

remaining ~33%

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7
Q

What makes up extracellular fluid?

A

20-25% is in the fluid portion of blood (plasma)

75-80% lies around and between cells (interstitial fluid)

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8
Q

Interstitium Definition

A

space containing interstitial fluid

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9
Q

In membrane transport, what changes the conformation to move a molecule/ion?

A

carrier proteins

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10
Q

In membrane transport, what provides selective channels for the orient of specific substances (e.g., specific ions, water)?

A

Channel proteins

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11
Q

True or False:

The plasma membrane is selectively permeable

A

True

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12
Q

What are the two categories to enter membrane transport?

A
  1. Non-carrier mediated

2. Carrier mediated

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13
Q

What is non-carrier mediated?

A

simple diffusion, osmosis (filtration capillaries)

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14
Q

What type of transport happens in non-carrier mediated and what is the definition of that transport?

A

Active Transport- no energy, moved down gradient (high to low concentration)
Random molecular motion eventually evens things out

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15
Q

What type of transport occurs in carrier mediated and what is the definition of that transport?

A

Active Transport- against gradient (low to high concentration)
needs transport protein and ATP

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16
Q

Simple Diffusion Definition?

A

net movement of particles from high concentration to lower concentration
(down the gradients, spontaneous motion)

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17
Q

Does simple diffusion require a membrane?

A

No, simple diffusion does not require a membrane

if there is a membrane, substances will diffuse is the membrane in permeable

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18
Q

What are diffusion rates?

A

How quickly a cell can acquire or eliminate wastes

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19
Q

What factors effect simple diffusion rate through a membrane?

A
  • temperature (higher temp, faster particle motion)
  • molecular weight (larger molecular size, slower diffusion)
  • concentration gradient steepness (higher gradient, faster rate)
  • Membrane Surface Area (higher SA, faster rate-places like intestines/lungs/kidneys)
  • membrane permeability (higher permeability, faster rate)
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20
Q

Osmosis Definition

A

the net flow of water through a selectively permeable membrane

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21
Q

Osmosis moved from __ concentration to __ water concentration

A

high

low

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22
Q

What are aquaporins?

A

allows water to move across the membrane

  • -specialized channel proteins
  • -different by cell (install channels based on conditions)
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23
Q

What is osmotic pressure?

A

pressure required to stop osmosis

measure of how strongly a solution draws water

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24
Q

___ solute concentration the __ the pressure

A

greater

greater

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25
Q

What is molarity?

A

number of molecules of solute per liter of a solution

same molecule number

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26
Q

Physiological impact of a chemical depends on how many ___ of it are present in a given ___

A

molecules

volume

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27
Q

How many molecules are in a mole?

A

6.022 x10^23 molecules in a mole

28
Q

What is osmolarity?

A

the number of osmoles per liter of solution

(the total number of solute particles (concentration) in a solution

29
Q

one osmole (osm) = __ ___ of dissolved particle

A

1 mole

30
Q

___ osmolarity = ___ water concentration

A

higher

lower

31
Q

What is tonicity?

A

ability of a surrounding solution (bath) to affect fluid volume and pressure in a cell

32
Q

concentration of ___ vs ___ causes water to move in or out of a cell

A

solutes

water

33
Q

Effect of osmosis on cells in isotonic solution

A
  • no change in cell volume
  • concentrations of non permeating solutes in bath of ICF are the same
  • 0.9% saline isotonic to red blood cells
34
Q

Effect of osmosis on cells in hypotonic solution

A
  • concentration of water outside the cell is greater than inside the cell
  • cell gains water
  • lysis (cells may burst)

(blood hemolysis)

35
Q

Effect of osmosis on cells in hypertonic solution

A
  • causes cell to lose water and shrivel (crenate)

- ECF has a higher concentration of non permeating solutes than ICF

36
Q

Ligand Definition and what determines it

A

Chemical that binds (reversibly) to a receptor site on a protein
–charges/shapes must be complementary

Determined by conformational shape of the protein

37
Q

Chemical Specificity Definition and what does it determine

A

ability of a protein-binding site to bind specific ligands

determines what can actually bind to the binding site

38
Q

What is the shape of proteins determined by?

A

determined by amino acid sequence

different amino acid sequences are going to lead to different shapes which will lead to different binding sites

39
Q

True or False

All protein sites only bind to one ligand

A

False

some protein sites only bind to one ligand; others bind to many

40
Q

Affinity Definition and what does it determine

A

strength of ligand-protein binding

determines how likely that the particular bound ligand will leave

41
Q

Chemical specificity depends on the ___; affinity depends on the ____ of the liquid and protein attraction

A
  • shape

- strength

42
Q

What equals a high affinity?

A

Opposite charges + ligand shape + binding site shape

43
Q

Saturation definition

A

fraction of total binding sites that are occupied at any given time

44
Q

Why is there competition among different ligands for binding sites?

A

influenced by the affinity this then impacts the saturation

45
Q

What is carrier-mediated transport?

A

use a membrane protein to transport substances across membrane

46
Q

What are the three kinds of carriers in carrier- mediated transport?

A
  1. uniport (carries one type of solute)
  2. . symport (two or more solutes, moving in the same direction at the same time)
  3. antiport (two or more solutes, moving in opposite directions)
47
Q

What is an example of uniport?

A

calcium pump

48
Q

What is an example of symport?

A

sodium-glucose transporters

49
Q

What is an example of antiport?

A

sodium-potassium pump

50
Q

What do the three mechanisms of carrier-mediated transport use?

A
  • facilitated diffusion
  • primary active transport
  • secondary active transport
51
Q

Facilitated diffusion is where…..

A

a carrier moves a solute from hight to low concentration (down the gradient)

52
Q

Primary active transport is where…

A

a substance moves through a membrane against the gradient

53
Q

Secondary active transport is where…

A

the carrier moves solute through a membrane (uses ATP indirectly)

(uses a combination of facilitated diffusion [symport] with primary active transport [antiport])

54
Q

What does each cycle of the sodium-potassium pump consume?

A

1 ATP and exchanges 3 sodium for one potassium

55
Q

What is the purpose of the sodium-potassium pump?

A

-keep potassium concentration higher and sodium concentration lower inside the cell

56
Q

___ ___ influences osmosis which influences ____ ___

A

solute concentration

cell volume

57
Q

Carrier-mediated transport is a process where….

A

solute particles move through a membrane by means of a transport protein (uniport, symport, antiport)

58
Q

ATP is not necessary in ___ ___

A

facilitated diffusion

59
Q

ATP is necessary in ____ ___ ____

A

Primary active transport

60
Q

What are the three things included in endocytosis?

A
  1. pinocytosis
  2. phagocytosis
  3. receptor-mediated endocytosis
61
Q

What is pinocytosis?

A

“cell drinking” - droplets of ECF containing molecules

62
Q

What is Phagocytosis?

A

“cell eating” - cell surround, engulfs, and digests particle

63
Q

What is receptor-mediated endocytosis?

A

particles bind to specific receptors on plasma membrane

64
Q

What happens in Exocytosis?

A
  • Discharges material

- Replaces plasma membrane removed by endocytosis

65
Q

What is transcytosis?

A

transport of material across the cell

capture on one side; release on the other

66
Q

What do receptor- mediated endocytosis and exocytosis do in transcytosis?

A

receptor-mediated endocytosis moved it into the cell and exocytosis moves it out the other side

Mammalian Physiology 318 (11 decks)

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