Plasma Membrane Transport

These flashcards cover essential concepts about the plasma membrane and transport processes crucial for understanding membrane dynamics in physiology.

What is the primary role of the plasma membrane (PM)?

It separates intracellular fluid (ICF) from extracellular fluid (ECF).

What is the main composition of the plasma membrane?

A fluid phospholipid bilayer embedded with proteins.

What are the general functions of cell membrane proteins?

1. Provide structural support 2. Transport molecules 3. Hormone receptors 4. Enzymes 5. Surface markers (antigens)

What defines a permeable membrane?

It allows lipid-soluble substances like O2, CO2, and steroids to pass through.

What is Fick's Law concerning the rate of diffusion?

The rate is affected by concentration gradient, permeability of the membrane, surface area, molecular weight, and thickness of the membrane.

Describe simple diffusion.

Movement of substances from high to low concentration without the need for energy.

What is osmosis?

The net diffusion of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

What are the types of transport through the cell membrane?

1. Passive Transport 2. Active Transport

What is facilitated diffusion?

The passive movement of molecules down a concentration gradient across a cell membrane via a membrane protein.

What is the role of the sodium-potassium pump?

It actively extrudes 3 Na+ out of the cell and transports 2 K+ into the cell against their concentration gradients.

What are the requirements for osmosis to occur?

1. Difference in solute concentration across the membrane 2. The membrane must be impermeable to the solute.

What happens to a cell in a hypertonic solution?

It shrinks due to higher solute concentration outside the cell.

What is the effect of osmotic pressure?

The opposing pressure necessary to completely stop osmosis.

What factors affect the rate of diffusion?

Concentration gradient, permeability of the membrane, surface area, molecular weight of substance, and thickness of the membrane.

What is primary active transport?

Transport where energy is supplied directly from the hydrolysis of ATP for the function of the protein carrier.

Explain secondary active transport.

Transport of one or more molecules against their concentration gradient, coupled to the transport of another molecule down its concentration gradient.