Cellular physiology of nerve and muscle

Question 1

Describe the structure of the plasma membrane

Answer 1

Composed of a bilayer of phospholipids, with the hydrophobic, fatty acid tails in contact with each other. There are proteins within the membrane, some of which cross the membrane entirely

Question 2

Describe and differentiate among the various types of transport across the plasma membrane

Answer 2

Diffusion: movement of particles down their gradient, can be simple or facilitated by a protein (passive)

Active transport: moving molecules against their gradient (active), usually using ATP as its power source

Secondary active transport: moves multiple molecules across the membrane, powering the uphill movement of one molecule with the downhill movement of the other

Question 3

Describe osmosis and explain its role in fluid homeostasis

Answer 3

Osmosis: water moves from an area of low solute concentration to an area of high solute concentration through a semipermeable membrane

Osmosis allows cells to maintain homeostasis by maintaining concentrations of solvent and solutes constant inside cells