Exam One - 1.5 Membrane Dynamics Flashcards
What contributes to homeostatic dynamic disequilibrum?
- two fluid compartments (ICF and ECF)
- osmotic equilibrium
- chemical disequilibrium
- electrical disequilibrium
Explain water content differences between sex and age
- no difference as kids between sex
- during puberty men have more water
- males have more water at older ages
different because of test levels
osmosis
movement of water across a membrane
osmotic pressure
the pressure that must be applied to oppose osmosis
Molarity
expresses concentration
Osmolarity
expresses number of osmotically active particles
the concentration of a solution expressed as the total number of solute particles per liter
Is molarity or osmolarity more relevant for physiology?
osmolarity
osmolality
the concentration of a solution expressed as the total number of solute particles per kilogram
t or f? isosmotic is not always isotonic
true
t or f? hyperosmotic is not always hypertonic
true
t or f? hyposmotic is always hypotonic
true
isosmotic
equal osmotic pressure, equal solutes
cell size doesnt change
hyperosmotic
more solutes
cells shrink
hyposmotic
less solutes
cells swell
tonicity describes…
volume change of cells
tonicity depends on…
the concentration of the nonpenetrating solutes
osmolarity (osmol/liter) =
molarity (M, moles/liter) x particles/molecule (osmol/M)
4 different transport processes
diffusion
protein-mediated transport
vesicular transport
epithelial transport
Diffusion (7)
1 - passive process
2 - high concentration to low concentration
3 - net movement until concentration is equal
4 - rapid over short distances
5 - directly related to temperature
6 - inversely related to molecular weight and size
7 - open system or across a partition
Simple diffusion of lipophilic molecules have two extra properties…
rate depends on solubility in lipids
proportional to surface area of the membrane
electrochemical gradient
ion movement combination of concentration (chemical) gradient and electrochemical gradient
4 major functions of membrane proteins
1 - structural proteins
2 - membrane enzymes
3 - membrane receptor proteins
4 - transport proteins (channel and carrier proteins)
4 types of open, water-filled channel proteins
1 - water channels
2 - ion channels
3 - open channels (leak and pores)
4 - gated channel (chemically, voltage, and mechanically gated channels)
2 types of protein - mediated transport
facilitated diffusion
carrier transport
3 types of carrier transport
symport - carries 2 things at once same direction
antiport - carries 2 things at once in opposite directions
uniport - only carries one thing
Does active transport move substances with or against concentration gradients?
Against
2 types of energy active transport can use:
Primary (direct) - use ATP
Secondary (indirect) - uses potential energy stored in concentration gradients of one molecule to push another against its gradient
sodium potassium pump
antiporter
active transport
use ATP energy
sodium glucose cotransporter
uses concentration gradient for potential energy
Na goes with gradient
Glucose against gradient
transport rate is proportional to _________ until the carriers are _____________
substrate concentration,
saturated
phagocytosis
eats bad stuff
2 kinds of endocytosis
clathrin - mediated
caveolae - mediated
clathrin - mediated
enters cell and most often ends up in lysosome
caveolae - mediated
enters cell and gets used by ER to make stuff
Exocytosis releases molecules ______________ for transport proteins or for large volumes
too large
transporting epithelia are __________
polarized
explain transepithelial absorption of glucose
1 - Na and glucose symporter. Na is going from high to low, glucose is going from low to high
2 - glute transporter - now going from high in the cell to low in ECF
3 - NaK ATPase NA going from low to high(ECF) and K going into cell
transcytosis
vesicles cross an epithelium
requires energy
keeps transported materials intact
body is electrically _______
neutral
chemical disequilibrium between?
ICF and ECF
ICF has a net ________ charge
negative
ECF has a net ___________ charge
positive
Explain why K wants to leave cell due to concentration gradient but enter cell due to electrical gradient
there is more K inside cell than outside therefore it wants to leave due to concentration gradient
K is positive and the inside of the cell is negative. The positive charge outside the cell repels K because K is also slightly positive
Potential energy of the membrane is stored in the ?
electrochemical gradient
What is the resting membrane potential of cell?
about -70mV
depolarization
shift in electric charge distribution, resulting in less negative charge inside cell
repolarization
change in membrane potential that returns it to a negative value just after the depolarization phase of an action potential has changed the membrane potential to a less negative (mroe positive) value
hyperpolarization
change in a cell’s membrane potential that makes it more negative
Insulin secretion and membrane transport if there are low glucose levels in the blood:
1 - low glucose levels in blood
2 - metabolism slows
3 - ATP decreases
4 - KATP channels open and K leaks out of cell
5 - cell at resting membrane potential (Ca+ channels closed) and no insulin is released
Insulin secretion and membrane transport if there are high levels of glucose in the blood:
1 - high levels of glucose in blood
2 - metabolism increases (glycolysis and CAC)
3 - ATP increases
4 - KATP channels close and K doesn’t leak out
5 - cell depolarizes and Ca+ channels open
6 - Ca+ entry acts as an intracellular signal
7 - Ca+ signal triggers exocytosis and insulin is released
