Homeostasis and Transport Flashcards
Na+ extracellular fluid
142 mEq/L
Na+ intracellular fluid
10 mEq/lL
K+ extracellular fluid
4 mEq/L
K+ intracellular fluid
140 mEq/L
Cl- extracellular fluid
103 mEq/L
Cl- intracellular fluid
4 mEq/L
does not require energy and may require a channel protein or a carrier protein
Diffusion (passive transport)
factors that alter diffusion rate
membrane permeability
concentration difference (chemical force)
electrical potential (chemical force)
pressure
simple diffusion has which 2 types of channels
voltage gated and ligand gated
Voltage channel Na+ channels has which gates
TWO GATES
Resting -70 mV
activation: channel depolarized to -55-+35 mV to allow Na+ to enter the cell
inactivation: inside channel closes from +35 to -70 mV to stop Na+ from entering the cell
Voltage gated K+ channels has which gates
ONE gate
Resting: -70 mV
Slow activation: membrane depolarizes to +35 to -70 mV to allow K+ to leave the cell
(Na+ channels remain closed)
receptor operated ion channel that induces a conformational change
Ligand-gated receptor channel
- acetylcholine bind a receptor on the cell membrane and induces a conformational change and ions can then go through the channel
- sodium and potassium can go through the same channels
- ligan gated G-protein coupled ion channels
facilitated diffusion
- moves from area of high concentration to low concentration
- requires a transport protein to induce a conformational change to enter through the channel
how is facilitated diffusion determined?
Vmax-maximum rate of diffusion
-concentration and rate of movement of carrier molecules across the channel
movement of molecules against the concentration gradient. Requires energy & carrier protein
active transport
what is the source of energy in primary active transport
ATP
EX. Na+/K+ pump
Ca++ pump
H+ pump
uses energy of one solute moving with the concentration gradient (created previously with primary active transport) to move another substance against the concentration gradient
secondary active transport
both ions move in the same direction
cotransporters (symport)
Ex. Glucose and Na+ entering cell in secondary active transport
both ions move in different directions
exchangers (antiport)
Ex. K+ and Na+ in primary active transport- uses ATP
uses a gradient of one molecule to move another against the concentration gradient but in opposite directions
exchangers or antiport (counter-transport)
solvent moving from an area of high solvent concentration to an area of low solvent concentration across a semi-permeable membrane
osmosis
pressure required to maintain an equilibrium with no net movement of solvent
osmotic pressure
- water can move; ions cannot
- movement determined by molar concentration of solute
semi-permeable membrane
moles of solute per liter of solution
molarity
osmoles of solute per liter of solution
osmolarity
the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane
osmotic pressure
how is osmotic pressure determined?
by the NUMBER of particles; not the size
what happens when a cell is placed in a hypertonic solution?
water will rush out of the cell
- the solution has a greater solute concentration (hyper osmotic) compared to the inside of the cell
- cell is shriveled
- move from low solute inside the cell to high solute outside the cell
what happens when a cell is placed in a hypotonic solution?
water will rush into the cell
- the solution has a lesser solute concentration (hypo osmotic) compared to the inside of the cell
- cell is lysed
- high solute outside the cell and low solute inside the cell
a solution that has the same solute concentration as the inside of the cell
isotonic solution
-normal cell
1 M of glucose has how many osmoles or particles?
one
1 M of NaCl has how many osmoles or particles?
two
1 M of CaCl2 has how many osmoles or particles?
three
what is the normal osmolality inside and outside the cell for an isotonic solution?
280-310 mOsm/L
in a normal cell of the body, intracellular concentrations of sodium, calcium, and chloride are ___ than extracellular concentrations
less
potassium has a __ intracellular concentration compared to its extracellular concentration
higher
what is not rate limited by Vmax?
simple diffusion- linear
Ouabain-sensitive transport of Na+ ions from the cyto- sol to the extracellular fluid is what kind of transport?
Primary active transport
- Ouabain inhibits Na+, K+, ATPase.
- ATP dependent enzyme that transports 3 Na+ out of the cell for every 2 K+ enzymes into the cell
glucose uptake into skeletal muscle is what kind of transport?
Facilitated diffusion
-insulin dependent
Na+-dependent transport of Ca++ from the cytosol to the extracellular fluid is what kind of transport?
Counter-transport
-aka secondary active transport
Movement of Na+ ions into a nerve cell during the up- stroke of an action potential is what kind of transport?
Simple diffusion
-During the rapid depolarization phase of a nerve action potential, voltage-sensitive Na+ channels open and allow the influx of Na+ ions into the cytosol. Trans- port through membrane channels is an example of simple diffusion.
moves fluid and gases
circulation
fluid to interstitial space and into and out of cells; gas from extracellular fluid and into and out of cells; ions and molecules from high to low concentration gradient
diffusion
movement of ions/ molecules through channels or transporters into and out of cell; pumping of molecules against a concentration gradient;
transport
- includes both passive and active
a physiological change leads to an even greater change in the same direction
positive feedback
the body senses a change and activates mechanisms to reverse that change
negative feedback
what is the charge outside the cell?
inside the cell?
outside the cell has more positive charges
inside the cell has more negative charges
