Active Cell Physiology Flashcards
yes its Hubs, though cells ffs
What is tonicity
Tonicity is the measure of the solute concentration difference between two solutions separated by a selectively permeable membrane, which determines the direction of water movement by osmosis.
What is osmosis?
Osmosis is the diffusion of water across a selectively permeable membrane from a region of low solute concentration to a region of high solute concentration.
How does water move across a membrane to balance tonicity?
Water moves toward the area with a higher solute concentration until the concentrations are equal, achieving an isotonic state.
What are chemical and electrical gradients?
A chemical gradient is a difference in concentration of a substance across a membrane
And an electrical gradient is a difference in charge across a membrane.
What is the resting membrane potential
The resting membrane potential is the voltage difference across a cell’s membrane when it is at rest
(typically around –70 mV in neurons). NOTE THE NEGATIVE!!
How is osmosis different from normal diffusion?
Osmosis involves only water and requires a selectively permeable membrane, while normal diffusion refers to the movement of any molecules from high to low concentration without a membrane.
At rest, where are Na⁺ and K⁺ ions located, and what gradients do they create?
Na⁺: Mostly outside the cell
K⁺: Mostly inside the cell
This creates a concentration gradient (high Na⁺ outside; high K⁺ inside) and an electrical gradient
What is the difference between a passive channel and an active pump?
Passive channels: Allow ions to move down their electrochemical gradient without energy.
Active pumps: Use ATP to move ions against their gradient.
What is depolarization? What is repolarization in Osmosis?
Depolarization: The membrane becomes less negative
(as it rests at -70mV) due to Na⁺ increase.
Repolarization: The membrane returns to its more negative resting state(-70mV), mainly due to K⁺
leaving the cell.
Hyperpolarization is..
The cell going more negative than resting -70mV.
When it comes back up its called the relative refractory period
