Cell Membranes Flashcards
Basic unit of the human body
Cell
Approximate number of human cells + bacterial cells inside the human body
68 trillion
Approximate number of human cells
30 trillion
The MOST ABUNDANT type of cell in the body
RBCs
Approximate number of glial (supporting) cells
1 trillion
Approximate number of neurons
100 B (86 B)
Major hallmarks of cancer
LOSS OF CELL TO CELL ADHESION
LOSS OF ANCHORAGE INDEPENDENT GROWTH
Guardian of the cell
semipermeable
made up of lipid bilayer (fluid mosaic model
CELL MEMBRANE
divides the body into ECF and ICF compartments
MANY proteins
LITTLE carbohydrates
NO water
Lipid Bilayer (Fluid Mosaic Model)
PROTEINS (55%)
PHOSPHOLIPIDS (25%)
outer leaflet: phosphatidylcholine, sphingomyelin
inner leaflet: phosphatidylenolamine, phosphatidylserine, phosphatidylinositol
CHOLESTEROL (13%)
OTHER LIPIDS (4%)
CARBOHYDRATES (3%)
Confers membrane FLUIDITY and PERMEABILITY to water soluble substances
CHOLESTEROL
LDL - major lipoprotein source of cholesterol
Confers ANTIGENICITY
GLYCOLIPIDS
MOST IMPORTANT COMPONENT OF THE CELL MEMBRANE
CHOLESTEROL
Factors that determine the permeability of the cell membrane
TEMPERATURE
TYPES OF SOLUTE PRESENT
LEVEL OF CELL HYDRATION
TIGHT attachment
spans the entire cell membrane
INTEGRAL PROTEINS
aquaporins, ion channels, solute carriers (GLUT, symport, antiport), ATP dependent transporters
LOOSE attachement
inner leaflet or outer leaflet
PERIPHERAL PROTEIN
DISK shaped
TIGHT intercellular adhesion
MACULA ADHERENS
epithelium
RING shaped
INCREASED SURFACE AREA for contact
ZONULA ADHERENS FASCIA ADHERENS (myocytes)
epithelium and enthothelial cells
intercalated disks of cardiac muscles
Barrier to movement of proteins across membranes
DIVIDES cell into APICAL and BASOLATERAL side
ZONULA OCCLUDENS (tight junctions)
LEAKY: PCT, jejunum
TIGHT: CD. terminal colon, BBB
Movement across apical and basolateral sides
Transcellular transport
Movement through tight junction
Paracellular transport
Regulated cytoplasmic bridge for sharing of small molecules b/w cells
for RAPID INTERCELLULAR communication
GAP JUNCTIONS
syncytia
conneXON - FUNCTIONAL unit
conneXIN - SUBUNIT
cardiac and unitary smooth muscles
Low resistant pathways b/w myocardial cells that allow for the spread of AP
gap junctions
NON CARRIER MEDIATED TRANSPORT
Simple Diffusion
Endocytosis
Exocytosis
HIGH to LOW
passive; downhill
SIMPLE DIFFUSION
oxygen, nitrogen, CO2, alcohol, lipid hormones, anesthetic drugs
CARRIER MEDIATED TRANSPORT
Osmosis
Facilitated Diffusion
Primary Active Transport
Secondary Active Transport
LOW to HIGH (diluted to concentrated)
OSMOSIS
aquaporins
WATER
HIGH to LOW
passive; downhill
utilized INTEGRAL proteins
FACILITATED DIFFUSION
GLUT transporters
AA transporters
LOW to HIGH
active; uphill
uses ATP for energy
PRIMARY ACTIVE TRANSPORT
Na K ATPase pump
H K ATPase pump of the parietal cells (stomach)
Ca ATPase pump in the cell membrane and SR
multidrug resistance transporters
LOW to HIGH
active; uphill
uses sodium gradient for energy
SECONDARY ACTIVE TRANSPORT
SGLT-1 (SI) SGLT -2 (PCT) Na K 2 CL in TAL of LG Na Ca exhange in almost cells Na H exchange in the PCT (kidneys)
Simple Diffusion
J = PA (C1 - C2)
J (flux (flow mmol/sec) P (permeability cm/sec) A (area cm2) C1 (higher conc) mmol/L C2 (lower conc) mmol/L
Factors that INCREASE permeability
INCREASED oil/water partition coefficient
DECREASED radius (size) of the solute
DECREASED membrane thickness
small hydrophobic solutes (CO2 and O2) - HIGHEST PERMEABILITIES
Characteristic of Carrier Mediated Transport
STEREOSPECIFICITY
SATURATION
COMPETITION
Concentration of osmotically active particles in a solution
OSMOLARITY = # of dissociable particles x concentration (g x c)
300 mOsm/L - normal value
Osmotic Pressure (van Hoff’s Law)
osmotic pressure = g x C x RT
g - number of particles in a solution
C - concentration
R - gas constant (0.082)
T - absolute temperature (K)
Effective Osmotic Pressure
Osmotic Pressure X Reflection Coefficient
Osmotic pressure exerted by proteins
Oncotic Pressure or Colloid Osmotic Pressure
