Membranes Flashcards
Water makes up roughly 60% of the body. What proportion of cellular fluid is intracellular and extracellular?
ICF 1/3
ECF 2/3
Which ions are higher in presence in ICF than ECF?
K+
Which ions are higher in ECF than ICF?
Ca 2+, Cl-, Na+
What is osmolarity?
The concentration of particles in solution in osm/volume
What is osmolality?
The concentration of particles in solution in osm/kg
What is osmotic pressure?
The pressure that must be applied for the stopping of osmosis
Aquaporins are always open. How is the rate of osmosis controlled?
Changing the number of aqua porins in the membrane
What is tonicity? What are it’s units?
The comparison of osmolarity of two solutions
No units - comparative term
Why can respiratory gases be transported by simple diffusion?
They are lipophillic so can pass through the phospholipid bilayer
What is the difference between channel proteins and carrier proteins?
Channel proteins are passive
Most carrier proteins are active
What do carrier proteins set up?
An ion concentration gradient
What is the average resting potential inside a cell?
-60 mV to -70mV
Facilitated diffusion involves what?
Channel/carrier proteins
What is primary active transport?
Active transport with energy directly from ATP
In primary active transport, what is an antiport?
A carrier which transports molecules in opposite directions
In primary active transport, what is a uniport?
A protein carrier which transports a molecule in one direction
In secondary active transport, what is a symport? Why is this secondary?
A protein carrier which transports two molecules in the same direction
The transport is driven by one molecule moving down its concentration gradient
Why is active transport sometimes slower than simple diffusion?
Carrier proteins can be saturated
Channel proteins cannot
What is excitability?
The ability to fire actiopotentials
During an action potential, what happens to sodium and potassium ions?
Sodium moves into cell, potassium moves out of cell
Cells have a negative resting potential An action potential is a wave of positivity. What type of polarisation is an action potential?
Depolarisation
What is hyperpolarisation?
A negative shift in the resting potential of a cell
What are voltage gated sodium channels responsible for?
For the upstroke of action potentials in nerve and muscle cells
What is endocytosis?
Molecules move into cell via vesicles (not directly contacting bilayer)
What is exocytosis?
Molecules move out of cells via vesicles, not directly contacting bilayer
Are endocytosis and exocytosis active or passive?
Active
Requires ATP
