Membrane Physiology 1

Plasma membrane

intracellular vs extracellular fluid

trilaminar structure ¹

phospholipids

hydrophilic [polar] vs hydrophobic [nonpolar]

cholesterol

membrane proteins

channels

selectivity

defective chloride channels and cystic fibrosis (CF) ²

carrier molecules

receptor sites

membrane-bound enzymes

filamentous elements and the cytoskeleton

recognition markers

fluid mosaic model

membrane carbohydrates

orienting and anchoring proteins

recognition markers

Cell-to-cell adhesions

extracellular matrix as the biological “glue”

glycosaminoglycan gel

proteins

collagen

elastin

fibronectin

cell junctions

desmosomes (macula adherens)

tight junctions

gap junctions

connexons

Membrane transport

permeability

impermeable

semipermeable

solubility

forces

passive forces

active forces and ATP (adenosine triphosphate)

diffusion down a concentration gradient (chemical gradient) ³

net diffusion

equilibrium state

Fick’s law of diffusion ⁴

movement along an electrical gradient

cations

anions

osmosis

solute

solvent

concentration

hydrostatic pressure

osmotic pressure

isotonic, hypotonic, and hypertonic solutions

carrier-mediated transport

characteristics

specificity

saturation and the transport maximum ( T_m )

competition

facilitated diffusion

active transport uses “pumps”

phosphorylation at low-concentration side

ATPase activity

conformational shifts

dephosphorylation at high-concentration side

Na⁺-K⁺ ATPase (sodium-potassium pump)

phosphorylation of carrier on intracellular side

vesicular transport

endocytosis

pinocytosis

phagocytosis

exocytosis

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