L2 Cell Membrane and Cell Transport Flashcards
Extracellular fluid
EFC
Fluid outside cells
Contains plasma and interstitial fluid
Intracellular fluid
IFC
Fluid inside all body cells
Total body water is
ICF and ECF
Plasma membrane components
Phospholipid bilayer
Integral proteins
Peripheral proteins
Short, unsaturated hydrocarbon tails of lipid bilayer does what to permeability?
Increases
Long, saturated hydrocarbons tails of lipid bilayer does what to permeability?
Lowers
What are the two properties of particles that influence whether they can permeate a cell membrane without assistance?
Relative solubility of particle in lipid
Size of particle
Passive forces
No energy required
Move down concentration gradient
Active forces
Energy required
Moves against concentration gradient
Passive transport types
Diffusion
Osmosis
Channel mediated
Facilitated
Active transport types
Primary
Secondary
Diffusion
Depends on random movement/brownian motion
Molecules are really moving in both directions
There’s a net movement in the high conc. to low conc. direction
Crucial to survival of every cell
Factors that affect diffusion rate?
Concentration gradient (deltaC) Surface area of membrane (A) Lipid solubility (beta) Molecular weight (MW) Distance/thickness (delta X)
What’s Fick’s Law of Diffusion?
Based on how factors affect rate of diffusion
Q=(deltaC)•(A)•(beta) /
sqrt (MW)•(deltaX)
Channel mediated transport
Main way ions move across membrane
Carrier-mediated transport
Membrane carrier changes shape
Can be passive or active
Example: GLUT 1 glucose transporter in erythrocytes
What are the three types of mechanisms for active transport?
Uniporter (pump)
Symporter (cotransport)
Anti porter (countertransport)
What’s the Na+ K+ ATPase pump an example of? What does it pump?
Primary active transport
Pumps 3 Na+ out and 2 K+ in
Uses ATP
Symporter
What’s glucose transport an example of? What happens?
Secondary active transport
ATP not directly used
Energy provided by Na+ gradient
Glucose travels with Na+
Antiporter
How do you differentiate between carrier mediated transport and simple diffusion?
Concentration and transport rate would increase linearly for simple diffusion
Concentration and transport rate would increase and then taper off once point of saturation is reached for carrier mediated transport
What’s osmosis?
Net movement of water down its concentration gradient
Against solute gradient
Diffusive
Aquaporin channel
Allows more water to flow through membrane
Permeable membrane
Membrane permeable to both water and solute
Water and solute both move down concentration gradient
Semipermeable membrane (assume membrane is not fixed)
Permeable to water but impermeable to solute
Water will move down its concentration gradient but solute cannot
Membrane will shift
Semipermeable membrane (assume membrane is fixed)
Permeable to water but impermeable to solute
Water moves down its concentration gradient but solute cannot
Hydrostatic pressure moves in opposite direction causing solute side to have more water
Hydrostatic pressure
Pressure of a fluid due to pull of gravity on fluid
When osmotic pressure and hydrostatic pressure are equal and opposite what happens
Net movement stops
What’s osmolarity/osmolality?
Total concentration of particles (permeable and nonpermeable) per amount of solution
What’s the osmolarity/osmolality of ICF and ECF?
~290mOsm
Same inside and outside
Isotonic
Osmolarity same on both sides
Hypertonic
Outside has higher osmolarity than inside
Water goes towards outside
Hypotonic
More water outside than inside
Water will move inside
