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Anatomy and Physiology > Transport Accross Membrane > Flashcards

Transport Accross Membrane Flashcards

1
Q

Factors influence the diffusion rate of substances across plasma membranes:

A

Steepness of the concentration gradient
Temperature
Mass of the diffusing substance
Surface area
Diffusion distance

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2
Q

Two sources of cellular energy can be used to drive active transport:

A

primary active transport and secondary active transport

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3
Q

Energy obtained from hydrolysisof adenosine triphosphate (ATP) is the source in

A

primary active transport

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4
Q

energy stored in an ionic concentration gradient is the source in

A

secondary active transport

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5
Q

The greater the difference in concentration between the two sides of the membrane, the higher the rate of

A

diffusion

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6
Q

energy source of primary active transport

A

atp

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7
Q

is a well-known primary active transport mechanism.

A

sodium-potassium pump

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8
Q

into the cell against their respective concentration gradients, using ATP as an energy source.

A

sodium-potassium pump

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9
Q

Secondary Active Transport also known as

A

cotransport or coupled transport

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10
Q

does not directly use ATP. Instead, it relies on the energy generated by primary active transport (usually the sodium gradient) to transport other molecules against their concentration gradients.

A

Secondary active transport

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11
Q

the transported molecule moves in the same direction as the ion

A

Symport (cotransport)

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12
Q

the transported molecule moves in the opposite direction to the ion

A

Antiport (exchanger):

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13
Q

of the PM allows a living cell to maintain different concentrations of certain substances on either side of the plasma membrane

A

selective permeability

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14
Q

is a difference in the concentration of a chemical from one place to another

A

concentration gradient

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15
Q

Many ions and molecules are more concentrated in either the

A

cytosol or the extracellular fluid

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16
Q

A difference in electrical charges between 2 regions constitutes an

A

electrical gradient

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17
Q

Because it occurs across the plasma membrane, this charge difference is termed the

A

membrane potential

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18
Q

Similarly, a positively charged substance will tend to move toward a

A

negatively charged area

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19
Q

A negatively charged substance will tend to move toward a

A

positively charged area

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20
Q

The combined influence of the concentration gradient and the electrical gradient on movement of a particular ion is referred to as its

A

electrochemical gradient

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21
Q

Substances generally move across membranes via transport processes that can be classified as

A

passive or active

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22
Q

a substance moves down its concentration or electrical gradient to cross the membrane using only its own kinetic energy

A

passive processes

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23
Q

Another way that some substances may enter and leave cells is an active process in w/c tiny, spherical membrane sacs called

A

vesicles

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24
Q

endocytosis, in which ___________________________________________ while bringing materials into a cell

A

vesicles detach from the plasma membrane

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25
Q

exocytosis, the_________________________________ to release materials from the cell

A

merging of vesicles with the plasma membrane

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26
Q

A passive process in w/c the random mixing of particles in a solution occurs because of the particles’

A

kinetic energy

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27
Q

Both the solutes, the dissolved substances, and the solvent, the liquid that does the dissolving, undergo

A

diffusion

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28
Q

If a particular solute is present in high concentration in one area of a solution and in low concentration in another area:

A

solute molecules will diffuse toward the area of lower concentration—they move down their concentration gradient

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29
Q

A passive process in which substances move freely through the lipid bilayer of the PM of cells without the help of membrane transport proteins

A

simple diffusion

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30
Q

Nonpolar, hydrophobic molecules move across the lipid bilayer through the process of

A

simple diffusion

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31
Q

also pass through the lipid bilayer by simple diffusion

A

Small, uncharged polar molecules such as water, urea, and small alcohols

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32
Q

Such molecules that can pass through the lipid bilayer through simple diffusion

A

oxygen, carbon dioxide, and nitrogen gases; fatty acids; steroids; and fat-soluble vitamins (A, D, E, and K)

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33
Q

Simple diffusion through the PM is important in the movement of

A

O & CO2bet. blood & body cells, and between blood & air w/in the lungs during breathing

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34
Q

It also is the route for absorption of some nutrients and excretion of some wastes by body cells

A

Simple Diffusion

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35
Q

Solutes that are too polar or highly charged to move through the lipid bilayer by simple diffusion can cross the PM by

A

facilatated diffusion

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36
Q

In this process, an integral membrane protein assists a specific substance across the membrane

A

facilatated diffusion

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37
Q

The integral membrane protein can be either a

A

membrane channel or a carrier

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38
Q

A solute moves down its concentration gradient across the lipid bilayer through a membrane channel

A

Channel-Mediated Facilitated Diffusion

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39
Q

These channels allow passage of small, inorganic ions

A

ion channels

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40
Q

Most membrane channels are

A

ion channels, integral transmembraneproteins

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41
Q

Diffusion of ions through channels is _________________ than free diffusion through the lipid bilayer

A

generally slower

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42
Q

A channel is said to be ____________ when part of the channel protein acts as a “plug” or “gate”

A

gated

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43
Q

Some gated channels randomly alternate between the

A

open and closed positions

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44
Q

is used to move a solute down its concentration gradient across the plasma membrane

A

carrier

45
Q

Carrier also called a

A

transporter

46
Q

The rate of carrier-mediated facilitated diffusion is determined by

A

the steepness of the concentration gradient across the membrane

47
Q

The no. of carriers available in a PM places an upper limit, called the _________________________, on the rate at which facilitated diffusion can occur

A

transport maximum

48
Q

Once all of the carriers are occupied, the ________________________ is reached

A

transport maximum

49
Q

Substances that move across the plasma membrane by carrier-mediated facilitated diffusion include

A

glucose, fructose, galactose, and some vitamins

50
Q

The selective permeability of the plasma membrane is often regulated to achieve

A

homeostasis

51
Q

An inability to produce or utilize insulin is called

A

diabetes mellitus

52
Q

A type of diffusion in which there is net movement of a solvent through a selectively permeable membrane

A

Osmosis

53
Q

Like the other types of diffusion, osmosis is a

A

passive process

54
Q

water moves through a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration

A

Osmosis

55
Q

During osmosis, water molecules pass through a plasma membrane in two ways:

A

(1) by moving through the lipid bilayer via simple diffusion, as previously described, and
(2) by moving through aquaporins, integral membrane proteins that function as water channels

56
Q

occurs only when a membrane is permeable to water but is not permeable to certain solutes

A

Osmosis

57
Q

The solution with the impermeable solute also exerts a force, called the

A

osmotic pressure

58
Q

is proportional to the concentration of the solute particles that cannot cross the membrane

A

osmotic pressure

59
Q

The higher the solute concentration, the higher the solution’s

A

osmotic pressure

60
Q

When body cells are placed in a solution having a different osmotic pressure than cytosol, however, the

A

shape and volume of the cells change

61
Q

is a measure of the solution’s ability to change the volume of cells by altering their water content

A

tonicity

62
Q

the concentrations of solutes that cannot cross the plasma membrane are the same on both sides of the membrane in this solution

A

Isotonic

63
Q

a solution that has a lower concentration of solutes than the cytosol inside the cell

A

Hypotonic

64
Q

The rupture of other types of cells due to placement in a hypotonic solution is referred to simply as

A

lysis

65
Q

Pure water is very _____________ and causes rapid _____________

A

hypotonic; hemolysis

66
Q

has a higher concentration of solutes than does the cytosol inside the cell

A

hypertonic solution

67
Q

In such a solution, water molecules move out of the cells faster than they enter, causing the

A

cells to shrink

68
Q

Such shrinkage of cells is called

A

crenation

69
Q

Some polar or charged solutes that must enter or leave body cells cannot cross the plasma membrane through any form of passive transport

This is because they would need to move “uphill,” against their concentration gradients

Such solutes may be able to cross the membrane by a process called

A

active transport

70
Q

is an active process because energy is required for carrier proteins to move solutes across the membrane against a concentration gradient

A

active transport

71
Q

Two sources of cellular energy can be used to drive active transport:

A

(1) Energy obtained from hydrolysis of adenosine triphosphate (ATP) is the source in primary active transport;

(2) energy stored in an ionic concentration gradient is the source in secondary active transport

72
Q

is the source in primary active transport

A

Energy obtained from hydrolysis of adenosine triphosphate (ATP)

73
Q

is the source in secondary active transport

A

energy stored in an ionic concentration gradient

74
Q

Like carrier-mediated facilitated diffusion, active transport processes exhibit a

A

transport maximum and saturation

75
Q

carrier proteins that mediate primary active transport are often called

A

pumps

76
Q

The most prevalent primary active transport mechanism expels sodium ions from cells and brings potassium ions Because of the specific ions it moves, this carrier is called the

A

sodium-potassium pump

77
Q

If these transporters move two substances in the same direction they are called

A

symporters/symport

78
Q

move two substances in opposite directions across the membrane

A

Antiporters/antiport

79
Q

is a small, spherical sac

A

vesicle

80
Q

materials move into a cell in a vesicle formed from the plasma membrane

A

endocytosis

81
Q

materials move out of a cell by the fusion with the plasma membrane of vesicles formed inside the cell

A

exocytosis

82
Q

Both endocytosis and exocytosis require

A

energy supplied by ATP

83
Q

transport in vesicles is an

A

active process

84
Q

Three types of endocytosis:

A

Receptor-mediated endocytosis, phagocytosis, and bulk-phase endocytosis

85
Q

A highly selective type of endocytosis by which cells take up specific ligands

A

Receptor-mediated endocytosis

86
Q

A vesicle forms after a receptor protein in the plasma membrane recognizes and binds to a particular particle in the extracellular fluid

A

Receptor-mediated endocytosis

87
Q

Receptor-mediated endocytosis of LDLs (and other ligands) occurs as follows:

A
  • Binding
  • Vesicle formation
  • Uncoating
  • Fusion with endosome
  • Recycling of receptors to plasma membrane
  • Degradation in lysosomes
88
Q

On the extracellular side of the PM, an LDL (low-density lipoprotein) cholesterol particle that contains cholesterol binds to a specific receptor in the PM to form a receptor,

A

LDL complex

89
Q

The receptors are integral membrane proteins that are concentrated in regions of the plasma membrane called

A

clathrin-coated pits

90
Q

a protein called ____________ attaches to the membrane on its cytoplasmic side

A

clathrin

91
Q

The invaginatededges of the membrane around the clathrin-coated pit fuse, and a small piece of the membrane pinches off. The resulting vesicle, known as a

A

clathrin-coated vesicle

92
Q

clathrin-coated vesicle, contains the receptor,

A

LDL complexes

93
Q

Almost immediately after it is formed, the clathrin-coated vesicle loses its clathrincoat to become an

A

uncoated vesicle

94
Q

A form of endocytosis in which the cell engulfs large solid particles, such as worn-out cells, whole bacteria, or viruses

A

Phagocytosis

95
Q

Only a few body cells, termed _________________, are able to carry out phagocytosis

A

phagocytes

96
Q

Two main types of phagocytes are

A

macrophages and neutrophils

97
Q

located in many body tissues

A

macrophages

98
Q

a type of white blood cell

A

neutrophils

99
Q

In most cases, any undigested materials in the phagosomeremain indefinitely in a vesicle called a

A

residual body

100
Q

a vital defense mechanism that helps protect the body from disease

A

phagocytosis

101
Q

a form of endocytosis in which tiny droplets of extracellular fluid are taken up

A

bulk-phase endocytosis (pinocytosis)

102
Q

No receptor proteins are involved; all solutes dissolved in the extracellular fluid are brought into the cell

A

bulk-phase endocytosis (pinocytosis)

103
Q

releases materials from a cell

A

exocytosis

104
Q

All cells carry out exocytosis, but it is especially important in two types of cells:

A

(1) secretory cells that liberate digestive enzymes, hormones, mucus, or other secretions

(2) nerve cells that release substances called neurotransmitters

105
Q

liberate digestive enzymes, hormones, mucus, or other secretions

A

secretory cells

106
Q

release substances called neurotransmitters

A

nerve cells

107
Q

During exocytosis, membrane-enclosed vesicles called _________________________ form inside the cell, fuse with the plasma membrane

A

secretory vesicles

108
Q

vesicles undergo endocytosis on one side of a cell, move across the cell

A

Transcytosis

109
Q
A

Anatomy and Physiology (16 decks)

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