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BMSC 207 > Cell Membranes > Flashcards

Cell Membranes Flashcards

1
Q

Two types of control systems

A

Local
Reflex

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2
Q

Local System

A

Restricted to a small region of the body

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3
Q

Reflex System

A

Systemic (widespread throughout the body)
Will often contain additional components (sensor, target)
Involves the Nervous and/or endocrine systems

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4
Q

Types of reflex systems

A

Negative feedback
Positive Feedback
Feedforward

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5
Q

Example of Reflex Control Systems. Baroreceptor reflex: monitors blood pressure. Increased
blood pressure example Steps:

A

Stimulus, Sensor, Input Signal, Integrating Center, Output signal, Target, Response

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6
Q

Stimulus

A

Stretch of artery wall due to increased pressure

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7
Q

Sensor

A

Baroreceptor

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8
Q

Input Signal

A

Mechanical stretch is converted to electrical signal (AP) that travels back to the CNS (medulla)

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9
Q

Integrating Signal

A

Medulla

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10
Q

Output Signal

A

Electrical signals are sent out toward target tissues

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11
Q

Target

A

heart and peripheral arteries

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12
Q

Response

A

reduced heart rate, stroke volume, peripheral dilation

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13
Q

Feedforward Control

A

A few reflexes have evolved that allow the body to predict a change is about to occur

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14
Q

Biological Rhythms

A

Variables are regulated within a normal range around a set point but set points vary from person to person or may vary within an individual over time
Can be due to genetics, or constant exposure to a new condition

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15
Q

Biorhythms

A

variables that change predictably and create repeating patterns or cycles of changes

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16
Q

Functions of a cell membrane

A

Physical isolation
Regulation of exchange with the environment
Communication between the cell and its environment
Structural Support

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17
Q

Physical Isolation

A

Physical barrier separating ICF and ECF
Separates cell from environment

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18
Q

Regulation of exchange with the environment

A

Controls entry, elimination and release

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19
Q

Communication between the cell and its environment

A

contain proteins that allow for responding or interacting with external environment

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20
Q

Structural Support

A

Proteins in the membrane are used to make cell to cell connections (tissue) and to anchor the cytoskeleton

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21
Q

What does cell membrane consist of

A

55% proteins
45% lipids
small amount of carbohydrates

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22
Q

more protein

A

more active a membrane is

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23
Q

types of lipids in the cell membrane

A

phospholipid
sphingolipid
cholesterol

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24
Q

Lipid head

A

polar hydrophilic

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25
Q

Lipid tail

A

non polar hydrophobic

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26
Q

Phospholipid bilayer

A

forms a sheet

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27
Q

micelles

A

droplets of phospholipids
Important for lipid digestion

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28
Q

Liposomes

A

have an aqueous centre

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29
Q

What happens to a lipid when placed in an aqueous solution

A

When placed in aqueous solution phospholipids orient themselves so hydrophilic head interacts with water molecules and hydrophobic tails hide

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30
Q

phospholipid

A

major lipid

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31
Q

Sphingolipid

A

Lipid Raft

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32
Q

Cholesterol

A

Increased viscosity
Decreased permeability

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33
Q

Fluid Mosaic Model

A

Proteins dispersed throughout
Extracellular surface contains glycoproteins and glycolipids

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34
Q

Integral Proteins

A

transmembrane proteins
Lipid anchored proteins

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35
Q

Peripheral Proteins

A

attach to integral proteins
loosely attached to phospholipid head

36
Q

lipid anchored proteins

A

Directly to fatty acid
External GPI anchor: sugar - phosphate chain

37
Q

roles of integral proteins

A

Membrane receptors
Cell adhesion molecules
Transmembrane movement (channels, carriers, pores, pumps)
Enzymes
Mediators of intracellular signalling

38
Q

roles of peripheral proteins

A

participate in intracellular signalling
From submembraneous cytoskeleton

39
Q

Lipid anchored proteins

A

commonly associated with sphingolipids
High cholesterol content 3-5x (more viscous regions)

40
Q

Lipid rafts

A

Commonly contains an abundance of proteins important in cell signal transduction

41
Q

Glycoprotein

A

Forms protective coat (glycocalyx)
Cell to cell recognition/interactions

42
Q

Glycopipid

A

Forms protective coat (glycocalyx)
cell to cell recognition/interactions

43
Q

phospholipids

A

bulk of the lipid component of cell membrane

44
Q

Sphingolipid

A

form lipid rafts

45
Q

cholesterol

A

positioned between phospholipid heads to add viscosity and help to make membrane impermeable to small water - soluble molecules

46
Q

Integral Proteins

A

transmembrane and lipid anchored - wide variety of functions

47
Q

Peripheral Proteins

A

Attached to integral proteins participate in cell signalling and attachment of cytoskeleton

48
Q

water in intracellular fluid (ICF)

A

intracellular fluid in 2/3 of the total body water volume

49
Q

Extracellular fluid

A

is 1/3 of the total body water volume

50
Q

Extracellular fluid consists of

A

Interstitial fluid
Plasma

51
Q

adipose tissue

A

90% lipids
small fraction water

52
Q

Skeletal Muscle

A

75% water
18% protein

53
Q

extracellular and intracellular compartment are in

A

osmotic equilibrium
Fluid concentration are equal, the amount of solar per volume solution

54
Q

osmosis

A

the movement of water across a membrane in response to a solute gradient is called osmosis

55
Q

Water moves from

A

low solute concentration to high solute concentration.

56
Q

water travels through

A

Aquaporin channels
Water can move freely between the intracellular and extracellular spaces

57
Q

osmotic equilibrium does not equal

A

chemical or electrical equilibrium

many of the solutes are ions with an electrical charge, electrical disequilibrium

58
Q

high in extracellular fluid (ECF)

A

Na +
Cl -
Ca 2+
HCO3 -

59
Q

High in intracellular fluid (ICF)

A

K +
Anions (HPO4 - H2PO4 Proteins

60
Q

Osmotic pressure

A

is the pressure that would have to be applied to oppose and prevent osmosis

61
Q

osmolarity

A

describes the number of particles in solution

62
Q

Hyperosmotic

A

describes the solution with the higher osmolarity

63
Q

hyposmotic

A

describes the solution with the lower osmolarity

64
Q

tonicity

A

term used to describe a solution and how that solution would affect cell volume if a cell were placed in the solution and allowed to come to equilibrium

65
Q

osmolality

A

osmoses per kg of solvent

66
Q

osmolarity

A

osmoses per litre of solution

67
Q

cell membranes are

A

selectively permeable

68
Q

Active Transport

A

Exocytosis
Endocytosis
Phagocytosis

69
Q

Protein mediated active transport

A

Direct or primary active transport (ATPases)
Indirect or secondary active trasport (concentration gradient created by ATP

70
Q

Protein mediated passive transport

A

facilitated diffusion
ion channel (electrochemical gradient)
aquaporin channel (osmosis)

71
Q

non protein mediated passive transport

A

simple diffusion

72
Q

Diffusion

A

The movement of molecules from an area of higher concentration to an area of lower concentration

73
Q

Simple diffusion

A

For small uncharged lipophilic molecules:O2, CO2, NH3, LIPIDS, STEROIDS

74
Q

Rate of diffusion through a membrane is faster if

A

the membranes surface area is higher
the membrane is thinner
the concentration gradient is larger
the membrane is more permeable to the molecule

75
Q

membrane permeabillity to a molecule depends on

A

the molecules lipid solubility
the molecules size
the lipid composition of the membrane

76
Q

Channel proteins

A

made of membrane scanning protein subunits that create a cluster of cylinders with a pore through the center

names according to substance that passes through, mainly smaller substances ie. ions and water

77
Q

open channels

A

leak channels

78
Q

Gated channels

A

chemical gated (ligand)
voltage gated
mechanically gated
fascilitated diffusion

79
Q

Carrier proteins

A

large complex proteins
change conformation to move molecules
can move small organic molecules that cannot pass through channels
Saturates only one molecule

80
Q

Facilitated Diffusion

A

Some molecules and ions appear to move into and out of the cell by diffusion, but based on their chemical properties cannot be simple diffusion across the lipid layer
Use channels or carrier proteins
move down their concentration gradient
no energy required
stops once equilibrium is reacher (or when the channel closes)

81
Q

Active Transport

A

Moves molecules against their concentration gradients: from an area of low concentration to an area of high concentration
support a state of disequilibrium
Requires energy
uses carrier proteins

82
Q

Primary Active Transport

A

energy to move molecule comes directly from hydrolyzing ATP (refereed to as an ATPase)

83
Q

Secondary Active Transport

A

Uses potential energy stored in the concentration gradient of one molecule to push another molecule against their concentration gradient

84
Q

Specificity

A

Refers to the ability of a trasnporter to move one molecule or a closely related group of molecule

85
Q
A
86
Q
A

BMSC 207 (4 decks)

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