Afn-Patho/phys

Front 1

List an explain basic functions of the cell membrane (4)

Back 1

1-Regulate passage of substance in/out-PLB establishes selective permeability-can also transport solutes but must be lipid in nature and most are polar.

2-Detect chemical messengers via receptors

3-Link cells together via membrane junctions

4-Anchor cell to EC matrix

Front 2

Two primary components of cell membrane?

Back 2

1)Proteins (Integral membrane protein/peripheral)

2)phospholipid bilayer

Front 3

Orientation of polar and nonpolar regions?

Back 3

Polar heads (aqueous in nature) face out to ECF/ICF-water to water

Non-polar (lipid tails) tails face each other in membrane.

Front 4

Explain the role of cholesterol in cell membrane

Back 4

Membrane stability-in conjuction with sphingolipids-microdomains.

Front 5

Describe the two types of membrane proteins

Back 5

Integral proteins-transmembrane; strongly anchored in the lipid core. have polar/nonpolar regions.-also flexible like PLB.

Peripheral proteins-weakly attached to surface.

Front 6

List and give examples of the 4 functions of membrane proteins

Back 6

1)Channels/pumps- channels of solutes/water

-i.e. ion channel moving Na+ through;water channels (aquaporins)

2)Receptors-transmit chemical signals-neurotransmitters,cytokines etc. Selective based on chemical nature.

3)Cell shape/motility-differing proteins can affect cell shape.

4) Enzymes- Na+ATPase; K+ ATPase-these are proteins embedded in cell membrane.

Front 7

Structure and function of membrane junctions(connect cells together) with tissue examples-

Back 7

1)Desmosome-dence accumulation of protein filaments at ICF that link to protein plaque and through to adjacent cells-skin/heart

2)Gap junctions-essentially little tubes that connect two cells-connexon/pores-different from ion channels in that ion channels are just on one cell membrane. what you get is fluid/lyte movement between cells. i.e. heart-innervated by more than nerve fibers. e.g. Na+ moving through these and causing depolarization.

3)Tight junctions-physical joining of EC surface to adjacent cells-limits movement of substance between cells(parallel direction). GI and renal epithelial cells-physically block something(nutrients, etc) that would travel from gut lumen to blood. leaves it to the cell to decide which molecule it wants to move via transporters.

Front 8

4 major classes of cell membrane transport

Back 8

Water channels-aquaporins

Ion channels-various gating mechanisms

Solute carriers (SLC family)-uni-sym-anti-port

ATP dependent-

--ATPase ion transporters-involves enzyme that takes phosphate from ATP molecule and phosproylate protein to enable protein function

--ATP Binding cassete(ABC)-requires ATP to bind to it but doesnt require phosphorylation event. Phosphate still removed but doesn't need to be added to protein.

----All ABC's take something out of cell; SLC's go in either direction

Front 9

4 functional modes of cell membrane transport

Back 9

Diffusion-

Carrier-mediated- passive and active

Vesicular-

Epithelial-

Front 10

Diffusion principles

Back 10

Molecules are in constant motion and move in random direction but ultimately will move from high concentrations to low concentrations to form a uniform distibution

Front 11

Diffusion across a membrane

Back 11

Substance can move back and forth across a membrane-nothing to prevent moving back.

Flux-amount of particle moving per unit of time.

Net flux-the general direction the majority of the solute is going. (O2 in alveolus net fluxing to blood)

Diffusion equilibrium-will ultimately level out on both sides-PO2 in blood reaching 105.

Front 12

Ficks law of diffusion

Back 12

J=DA(C2-C1)/T

J-flux;

D-diffusion coefficent-constant

A-surface area

C2-C1-Concentration gradient i.e. PO2 difference in initial alveolar PO2 to blood PO2.

T-Thickness

Front 13

Types of substances that diffuse through PLB

Back 13

Small, non-polar, uncharged molecules.

Front 14

Types of substances that use membrane proteins for diffusion

Back 14

Large, polar, charged molecules-Ions. Still diffusion process.