Lecture 6 Flashcards
What is diffusion?
Movement of molecules from high to low concentration.
What is osmosis?
Movement of water across a membrane to equalize solute concentration.
What happens to a cell in an isotonic solution?
No net flow of water, cell remains stable.
What happens to a cell in a hypertonic solution?
Water leaves the cell, causing it to shrink
What happens to a cell in a hypotonic solution?
Water enters the cell, causing it to expand and possibly burst.
What is a chemical gradient?
Uneven distribution of molecules across a membrane.
What is an electrical gradient?
Uneven distribution of charges across a membrane.
What is the resting membrane potential?
The electrical gradient when the cell is at rest, with the inside of the cell more negatively charged than the outside.
What occurs during depolarization?
Positive ions enter the cell, signaling excitable cells.
What occurs during repolarization?
Positive ions are removed from the cell, returning to resting membrane potential.
Where does ion absorption occur?
Across the epithelial lining of the small intestine and colon.
Where are ion reserves primarily located?
In the bones of the skeleton.
What is the primary site of ion loss?
The kidney.
What is the difference between passive ion channels and active pumps?
Passive channels allow ions to move down their gradient, active pumps use energy to move ions against their gradient.
Where are Na+ and K+ ions located at rest?
Na+ is outside the cell, and K+ is inside the cell.
