CHAPTER 03: MEMBRANE POTENTIAL Flashcards

1
Q

active expiration

A

Emptying of the lungs more completely than when at rest by contracting the expiratory muscles; also called forced expiration

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2
Q

active force

A

A force that requires expenditure of cellular energy (ATP) in the transport of a substance across the plasma membrane

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3
Q

active transport

A

Active carrier-mediated transport involving transport of a substance against its concentration gradient across the plasma membrane

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4
Q

adenylyl cyclase

A

The membrane-bound enzyme that is activated by a G protein intermediary in response to binding of an extracellular messenger with a surface membrane receptor and that in turn activates cyclic AMP, an intracellular second messenger

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5
Q

anion

A

Negatively charged ion that has gained one or more electrons in its outer shell

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6
Q

apoptosis

A

Programmed cell death; deliberate selfdestruction of a cell

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7
Q

ATPase

A

An enzyme that possesses ATP-splitting ability

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8
Q

calmodulin

A

An intracellular Ca2 binding protein that, on activation by Ca2, induces a change in structure and function of another intracellular protein; especially important in smoothmuscle excitation-contraction coupling

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9
Q

carrier molecules

A

embrane proteins, which, by undergoing reversible changes in shape so that specific binding sites are alternately exposed at either side of the membrane, are able to bind with and transfer particular substances unable to cross the plasma membrane on their own

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10
Q

carrier-mediated transport

A

Transport of a substance across the plasma membrane facilitated by a carrier molecule

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11
Q

cascade

A

A series of sequential reactions that culminates in a final product, such as a clot

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12
Q

cations

A

Positively charged ions that have lost one or more electrons from their outer shell

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13
Q

caveolae

A

Cavelike indentations in the outer surface of the plasma membrane that contain an abundance of membrane receptors and serve as important sites for signal transduction

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14
Q

cell adhesion molecules

A

proteins that protrude from the surface of the plasma membrane and form loops or other appendages that the cells use to grip each other and the surrounding connectivetissue fibers

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15
Q

channels

A

Small, water-filled passageways through the plasma membrane; formed by membrane proteins that span the membrane and provide highly selective passage for small water-soluble substances such as ions

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16
Q

chemical mediator

A

A chemical that is secreted by a cell and that influences an activity outside of the cell

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17
Q

chemically gated channels

A

Channels in the plasma membrane that open or close in response to the binding of a specific chemical messenger with a membrane receptor site that is in close association with the channel

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18
Q

cholesterol

A

a type of fat molecule that serves as a precursor for steroid hormones and bile salts and is a stabilizing component of the plasma membrane

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19
Q

concentration gradient

A

A difference in concentration of a particular substance between two adjacent areas

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20
Q

cyclic adenosine monophosphate (cyclic AMP or cAMP)

A

An intracellular second messenger derived from adenosine triphosphate (ATP)

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21
Q

desmosome (dez+-muh-soxm)

A

(dez+-muh-soxm) An adhering junction between two adjacent but nontouching cells formed by the extension of filaments between the cellsU plasma membranes; most abundant in tissues that are subject to considerable stretching

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22
Q

diffusion

A

Random collisions and intermingling of molecules as a result of their continuous thermally induced random motion

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23
Q

electrical gradient

A

A difference in charge between two adjacent areas

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24
Q

electrochemical gradient

A

The simultaneous existence of an electrical gradient and concentration (chemical) gradient for a particular ion

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25
Q

endocytosis

A

Internalization of extracellular material within a cell as a result of the plasma membrane forming a pouch that contains the extracellular material, then sealing at the surface of the pouch to form a small, intracellular, membrane-enclosed vesicle with the contents of the pouch trapped inside

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26
Q

equilibrium potential

A

The potential that exists when the concentration gradient and opposing electrical gradient for a given ion exactly counterbalance each other so that there is no net movement of the ion

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27
Q

exocytosis

A

Fusion of a membrane-enclosed intracellular vesicle with the plasma membrane, followed by the opening of the vesicle and the emptying of its contents to the outside

28
Q

extracellular matrix

A

An intricate meshwork of fibrous proteins embedded in a watery, gel-like substance; secreted by local cells

29
Q

facilitated diffusion

A

Passive carrier-mediated transport involving transport of a substance down its concentration gradient across the plasma membrane

30
Q

Fick’s law of diffusion

A

The rate of net diffusion of a substance across a membrane is directly proportional to the substanceUs concentration gradient, the membraneUs permeability to the substance, and the surface area of the membrane and inversely proportional to the substanceUs molecular weight and the diffusion distance

31
Q

first messenger

A

An extracellular messenger, such as a hormone, that binds with a surface membrane receptor and activates an intracellular second messenger to carry out the desired cellular response

32
Q

G protein

A

A membrane-bound intermediary, which, when activated on binding of an extracellular first messenger to a surface receptor, activates the enzyme adenylyl cyclase on the intracellular side of the membrane in the cAMP second-messenger system

33
Q

gap junction

A

A communicating junction formed between adjacent cells by small connecting tunnels that permit passage of charge-carrying ions between the cells so that electrical activity in one cell is spread to the adjacent cell

34
Q

hormone

A

A long-distance chemical mediator that is secreted by an endocrine gland into the blood, which transports it to its target cells

35
Q

hydrogen ion

A

The cationic portion of a dissociated acid

36
Q

hypertonic

A

Having an osmolarity greater than normal body fluids; more concentrated than normal

37
Q

hypotonic

A

Having an osmolarity less than normal body fluids; more dilute than normal

38
Q

impermeable

A

Prohibiting passage of a particular substance through the plasma membrane

39
Q

ion

A

An atom that has gained or lost one or more of its electrons, so that it is not electrically balanced

40
Q

isotonic

A

Having an osmolarity equal to normal body fluids

41
Q

membrane potential

A

A separation of charges across the membrane; a slight excess of negative charges lined up along the inside of the plasma membrane and separated from a slight excess of positive charges on the outside

42
Q

Na-K pump

A

A carrier that actively transports Na out of the cell and K into the cell

43
Q

net diffusion

A

The difference between two opposing movements

44
Q

neurohormones

A

Hormones released into the blood by neurosecretory neurons

45
Q

neurotransmitter

A

The chemical messenger that is released from the axon terminal of a neuron in response to an action potential and influences another neuron or an effector with which the neuron is anatomically linked

46
Q

osmosis

A

Movement of water across a membrane down its own concentration gradient toward the area of higher solute concentration

47
Q

paracrine

A

A local chemical messenger whose effect is exerted only on neighboring cells in the immediate vicinity of its site of secretion

48
Q

passive force

A

A force that does not require expenditure of cellular energy to accomplish transport of a substance across the plasma membrane

49
Q

permeable

A

Permitting passage of a particular substance

50
Q

phosphorylation

A

Addition of a phosphate group to a molecule

51
Q

plasma membrane

A

A protein-studded lipid bilayer that encloses each cell, separating it from the extracellular fluid

52
Q

primary active transport

A

A carrier-mediated transport system in which energy is directly required to operate the carrier and move the transported substance against its concentration gradient

53
Q

protein kinase

A

An enzyme that phosphorylates and thereby induces a change in the shape and function of a particular intracellular protein

54
Q

receptor site

A

Membrane protein that binds with a specific extracellular chemical messenger, thereby bringing about a series of membrane and intracellular events that alter the activity of the particular cell

55
Q

resting membrane potential

A

The membrane potential that exists when an excitable cell is not displaying an electrical signal

56
Q

saturation

A

When all the binding sites on a carrier molecule are occupied

57
Q

second messenger

A

An intracellular chemical that is activated by binding of an extracellular first messenger to a surface receptor site and that triggers a preprogrammed series of biochemical events, which result in altered activity of intracellular proteins to control a particular cellular activity

58
Q

secondary active transport

A

A transport mechanism in which a carrier molecule for glucose or an amino acid is driven by a Na concentration gradient established by the energy-dependent Na pump to transfer the glucose or amino acid uphill without directly expending energy to operate the carrier

59
Q

signal transduction

A

The sequence of events in which incoming signals (instructions from extracellular chemical messengers such as hormones) are conveyed to the cellUs interior for execution

60
Q

specificity

A

Ability of carrier molecules to transport only specific substances across the plasma membrane

61
Q

state of equilibrium

A

No net change in a system is occurring

62
Q

target cell receptors

A

Receptors located on a target cell that are specific for a particular chemical mediator

63
Q

target cells

A

The cells that a particular extracellular chemical messenger, such as a hormone or a neurotransmitter, influences

64
Q

tight junction

A

An impermeable junction between two adjacent epithelial cells formed by the sealing together of the cellsU lateral edges near their luminal borders; prevents passage of substances between the cells

65
Q

transport maximum (Tm)

A

The maximum rate of a substanceUs carrier-mediated transport across the membrane when the carrier is saturated; known as tubular maximum in the kidney tubules

66
Q

vesicular transport

A

Movement of large molecules or multimolecular materials into or out of the cell by means of being enclosed in a vesicle, as in endocytosis or exocytosis

68
Q

active expiration

A

Emptying of the lungs more completely than when at rest by contracting the expiratory muscles; also called forced expiration