Active Cellular Physiology Flashcards
Excitable cells use..
chemical and electrical gradients for rapid signalling events
Meaning of diffusion
Movement of molecules from high to low concentration
Osmosis is..
the movement of water across a membrane to equalise solute concentration
The cell membrane divides out body fluid volumes into
intracellular and extracellular spaces
Water concentration is dynamic on both sides of the membrane..
as is the concentration of solutes and ions
Osmosis works to balance..
the tonicity between the intracellular and extracellular spaces
ICF
Intracellular fluid
ECF
Extracellular fluid
Isotonic
The intracellular and extracellular fluids are in balance.
Hypertonic
Water loss from extracellular fluid decreases volume and makes this solution hypertonic with respect to the intracellular fluid.
Isotonic
An osmotic water shift from the intracellular fluid into the extracellular fluid restores osmotic equilibrium but decreases the intracellular volume.
Hypotonic
if the solute concentration outside the cell is lower than inside the cell, and the solutes cannot cross the membrane, then that solution is hypotonic to the cell.
Ion concentration is also
dynamic in both the intracellular and extracellular spaces
Uneven distribution of molecules across the membrane creates a..
chemical gradient
How is a chemical gradient created
Through the uneven distribution of molecules across the membrane
Uneven distribution of charges across the membrane creates an….
electrical gradient
How is an electrical gradient created
Uneven distribution of charges across the membrane
Chemical and electrical gradients allow
rapid signalling in excitable cells
What allows rapid signalling in excitable cells
Chemical and electrical gradients
The cell membrane is semi permeable and won’t allow
ions through
The moment a pathway opens,
the ions will rush in/out along their gradient
The bigger the gradient,
the faster and stronger the signal
Ions can move down the chemical gradients through
passive ion channels
The sodium and potassium gradients are maintained by..
active pumps that use energy to move ions against their concentration gradient
How are sodium and potassium gradients maintained
by active pumps that use energy to move ions against their concentration gradient
At rest, the intracellualr space has..
more negative charge than the extracellular space, creating an electrical gradient which is the resting membrane potential
Resting membrane potential
At rest, the intracellular membrane has more negative charge than the extracellular space, creating an electrical gradient.
Excitable cells
Nerves, muscles
Excitable cells use the movement..
of ions as a signal via depolarization
Difference between osmosis and diffusion
Diffusion is the movement of molecules down a concentration gradient, while osmosis is the movement of water across a membrane to balance the tonicity on both sides.
Ions are distributed unevenly across the cell membrane at rest to..
create chemical and electrical gradients
The electrical gradient when the cell is at rest is known as..
the resting membrane potential
Positive ions enter the cell during a depolarization,
which acts as a signalling event for excitable cells
Positive ions are then removed during repolarization
to return to the resting membrane potential
