Cell Physiology Flashcards
What makes up the plasma membrane
lipid bilayer + proteins
Basic framework of the plasma membrane
phospholipid bilayer
Components of the bilayer
hydrophilic heads and hydrophobic tails
hydrophobic tails are
nonpolar
form pores so that specific ions can flow across membrane; direction is determined by gradient
Ion channel
selectively move substances across membrane by undergoing a change in shape; good for larger molecules
Carrier/transporter protein
recognizes specific ligand and alters cell function; cellular recognition sites
receptors
catalyze chemical reactions in and outside of cell
enzymes
anchor proteins in the plasma membrane of neighboring cells to one another or to protein filaments.
linkers
Most permeant ion
K+
Lipid bilayer is selectively permeable to
nonpolar, small, and uncharged molecules
Nonpolar, small, and uncharged molecules can pass through membrane via
simple diffusion
small, uncharged polar molecules enter membrane via
channel
small, uncharged polar molecules enter membrane going
along gradient, no ATP
Not permeable to ions or large, uncharged polar molecules need a
transporter or channel and ATP
More hydrophobic (nonpolar)=
greater permeability
Degree of water permeability is influenced by
cholesterol content of bilayer
NaOH diffuses __ in higher concentrations
faster
Bigger the gradient= __ diffusion rate
faster
What makes up the Extracellular fluid
Interstitial fluid + plasma
3 most prevalent ions in the ECF=
Na, Cl, HCO-3 (bicarbonate)
3 most prevalent ions in the ICF=
K, HPO2-, and Mg2+
what is 10 times more prevalent in the plasma than in the interstitial fluid
protein anions
To find the amount of an ion in a concentration gradient….
ECF/ICF
What ions move from inside to outside
K+, Anions
What ions move from outside to inside
Na+, Ca2+, Cl-
Ions flow from a __ concentration to area of __ concentration
higher, lower
What makes up the electrochemical gradient
concentration gradient + electrical gradient
changes in membrane potential, charge separations across the membrane
Electrical gradient
At rest, the inside of the plasma membrane is
slightly negative
K+ ions are attracted to the
inside of the cell
the K+ electrical gradient is
inward, ECF to ICF
the difference in ion concentrations across the membrane
Chemical gradient
determine the direction and rate of ion movement through ion channels because ions are charged
Both electrical and chemical gradients
transmembrane proteins, water filled pores, can be open or closed
ion channels
Electrical signals in neurons are the result of
movement of ions across the membrane through channels
What molecules aren’t affected by the electrical gradient
Uncharged molecules like O2 and H2O
Simple diffusion and channel-mediated diffusion of water have movement…
down concentration gradient
Channel mediated movement of ions have movement…
down electrochemical gradient
Facilitated diffusion (ion channels) require
ATP and membrane proteins
Cell maintains the concentration gradients through the transport protein
Na+/K+ ATPase
Na+/K+ ATPase is a
primary active transporter (pump)
Na+/K+ ATPase is active because…. and primary because….
moves ions against a concentration gradient using ATP, does the transporting and hydrolyzes ATP
The Na+/K+ ATPase uses the energy from…
hydrolyzing ATP
Na+/K+ ATPase pumps what in and out of the cell
pumps K+ ions into cell and Na+ out of cell
In the Na+/K+ ATPase pump, __ Na+ ions move
3, out of the cell (ICF to ECF)
In the Na+/K+ ATPase pump, __ K+ ions move
2 inside the cell (ECF to ICF)
More __ will move inwards to the cell down its electrical gradient
K+
Lipid molecules enter cell via
Simple diffusion
