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BMSC 207 > Cell Membranes > Flashcards

Cell Membranes Flashcards

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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
Lipid tail
non polar hydrophobic
26
Phospholipid bilayer
forms a sheet
27
micelles
droplets of phospholipids Important for lipid digestion
28
Liposomes
have an aqueous centre
29
What happens to a lipid when placed in an aqueous solution
When placed in aqueous solution phospholipids orient themselves so hydrophilic head interacts with water molecules and hydrophobic tails hide
30
phospholipid
major lipid
31
Sphingolipid
Lipid Raft
32
Cholesterol
Increased viscosity Decreased permeability
33
Fluid Mosaic Model
Proteins dispersed throughout Extracellular surface contains glycoproteins and glycolipids
34
Integral Proteins
transmembrane proteins Lipid anchored proteins
35
Peripheral Proteins
attach to integral proteins loosely attached to phospholipid head
36
lipid anchored proteins
Directly to fatty acid External GPI anchor: sugar - phosphate chain
37
roles of integral proteins
Membrane receptors Cell adhesion molecules Transmembrane movement (channels, carriers, pores, pumps) Enzymes Mediators of intracellular signalling
38
roles of peripheral proteins
participate in intracellular signalling From submembraneous cytoskeleton
39
Lipid anchored proteins
commonly associated with sphingolipids High cholesterol content 3-5x (more viscous regions)
40
Lipid rafts
Commonly contains an abundance of proteins important in cell signal transduction
41
Glycoprotein
Forms protective coat (glycocalyx) Cell to cell recognition/interactions
42
Glycopipid
Forms protective coat (glycocalyx) cell to cell recognition/interactions
43
phospholipids
bulk of the lipid component of cell membrane
44
Sphingolipid
form lipid rafts
45
cholesterol
positioned between phospholipid heads to add viscosity and help to make membrane impermeable to small water - soluble molecules
46
Integral Proteins
transmembrane and lipid anchored - wide variety of functions
47
Peripheral Proteins
Attached to integral proteins participate in cell signalling and attachment of cytoskeleton
48
water in intracellular fluid (ICF)
intracellular fluid in 2/3 of the total body water volume
49
Extracellular fluid
is 1/3 of the total body water volume
50
Extracellular fluid consists of
Interstitial fluid Plasma
51
adipose tissue
90% lipids small fraction water
52
Skeletal Muscle
75% water 18% protein
53
extracellular and intracellular compartment are in
osmotic equilibrium Fluid concentration are equal, the amount of solar per volume solution
54
osmosis
the movement of water across a membrane in response to a solute gradient is called osmosis
55
Water moves from
low solute concentration to high solute concentration.
56
water travels through
Aquaporin channels Water can move freely between the intracellular and extracellular spaces
57
osmotic equilibrium does not equal
chemical or electrical equilibrium many of the solutes are ions with an electrical charge, electrical disequilibrium
58
high in extracellular fluid (ECF)
Na + Cl - Ca 2+ HCO3 -
59
High in intracellular fluid (ICF)
K + Anions (HPO4 - H2PO4 Proteins
60
Osmotic pressure
is the pressure that would have to be applied to oppose and prevent osmosis
61
osmolarity
describes the number of particles in solution
62
Hyperosmotic
describes the solution with the higher osmolarity
63
hyposmotic
describes the solution with the lower osmolarity
64
tonicity
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
osmolality
osmoses per kg of solvent
66
osmolarity
osmoses per litre of solution
67
cell membranes are
selectively permeable
68
Active Transport
Exocytosis Endocytosis Phagocytosis
69
Protein mediated active transport
Direct or primary active transport (ATPases) Indirect or secondary active trasport (concentration gradient created by ATP
70
Protein mediated passive transport
facilitated diffusion ion channel (electrochemical gradient) aquaporin channel (osmosis)
71
non protein mediated passive transport
simple diffusion
72
Diffusion
The movement of molecules from an area of higher concentration to an area of lower concentration
73
Simple diffusion
For small uncharged lipophilic molecules:O2, CO2, NH3, LIPIDS, STEROIDS
74
Rate of diffusion through a membrane is faster if
the membranes surface area is higher the membrane is thinner the concentration gradient is larger the membrane is more permeable to the molecule
75
membrane permeabillity to a molecule depends on
the molecules lipid solubility the molecules size the lipid composition of the membrane
76
Channel proteins
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
open channels
leak channels
78
Gated channels
chemical gated (ligand) voltage gated mechanically gated fascilitated diffusion
79
Carrier proteins
large complex proteins change conformation to move molecules can move small organic molecules that cannot pass through channels Saturates only one molecule
80
Facilitated Diffusion
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
Active Transport
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
Primary Active Transport
energy to move molecule comes directly from hydrolyzing ATP (refereed to as an ATPase)
83
Secondary Active Transport
Uses potential energy stored in the concentration gradient of one molecule to push another molecule against their concentration gradient
84
Specificity
Refers to the ability of a trasnporter to move one molecule or a closely related group of molecule
85
86

BMSC 207 (4 decks)

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