Plasma Membrane Transportation

Diffusion

Movement of particles from high to low concentration

Osmosis

Diffusion of water through a semipermeable membrane

Cells ___ in hypotonic solution

Swell

Cells ___ in hypertonic solution

Shrink

Cells ____ in isotonic solutions

Remain unchanged

In hypertonic solutions the plant cell undergoes

plasmolysis

Steady state

Cells maintain an imbalance of ions across the plasma membrane

Voltage‐gated channels:

Conformational state depends on the difference in ionic charge on the two sides of the membrane

Ligand-gated:

Conformational state depends on the binding of a specific molecule (ligand)

Mechano-gated:

Conformational state depends on mechanical forces that are applied to the membrane

facilitative transporter

the diffusing substance binds selectively to a membrane-spanning protein

Cystic fibrosis (CF)

genetic disease characterized by abnormal fluid secretions from tissues and caused by a defective chloride channel

Neurons

specialized cells for information transmission using changes in membrane potentials

Dendrites

receive incoming information

Cell body contains

the nucleus and metabolic center of the cell

Axon

long extension for conducting outgoing impulses.

When cells are stimulated, Na+ channels open, causing

Membrane depolarization

When cells are stimulated, voltage-gated Na+ channels open, triggering

the action potential