Physiology Chapter 3
Plasma Membrane BIOL 2305-017 (23314)
Terms in this set (57)
A thin layer of phospholipids that forms the outer boundary of every cell and encloses the intracellular contents.
The phospholipid bilayer appears as a sandwich with two dark layers and light middle layer.
Consists of a hydrophilic polar head and a hydrophobic non-polar tail.
Two layers of phospholipids make up the cytoplasmic membrane with the tails facing each other.
Contributes to the fluidity as well as the stability of the membrane. Prevent fatty acids from packing together and crystallizing.
Attached to or inserted within the lipid bilayer. Allows some large and some small molecules to pass through depending on the protein.
Fluid Mosaic Model
Refers to the belief that CP membrane consists of a phospholipid bilayer with cholesterol and proteins as well.
These are short-chain carbohydrates that protrude from the membrane.
Proteins that span the membrane and allow water-soluble substances to pass through. Highly selective, dependent on structure. Allows small substances to get through.
Transfer specific substances across the membrane that ordinarily cannot pass through.
Use a lock-and-key mechanism to release contents via exocytosis.
Located on the surface of the cell. Cells are specialized in the types of enzymes that are in the plasma membrane. When stimulated, the cell releases the substance to cause the desired effect.
These are sites on a cell that bind to chemical messengers in the blood. Specific to cells that have the appropriate site.
Cell Adhesion Molecules (CAMs)
Protrude from the cell allow cells to hook each other. Allows tissues and organs to stay in formation. Also act as signaling molecules.
Extracellular Matrix (ECM)
An intriciate meshwork of fibrous proteins embedded in a watery, gel-like substance composed of complex carbohydrates. 3 major types of protein fibers are collagen, elastin, and fibronectin.
Forms cablelife fibers that provide tensile strength.
Rubberlike protein fiber that allows tissues to stretch and go back to normal shape.
Promotes cell adhesion and holds cells in position.
Forms most of the extacellular matrix.
Anchor adjacent cells that are not touching. Consist of two plaques located on the inner surface of each of the two adjacent cells, strong glycoprotein filaments containing cadherins.
A gap is between the cells, but junctions exist between the cells which allows the passage of nutrients and allows muscle cells to contract simultaneously.
Made up of six protein subunits arranged in a hollow tubelike structure. Two abut from each cell and join end-to-end to form a tunnel between the two cells.
A membrane is this if substances can cross.
A membrane is this if substances if no substances can cross.
A membrane is this if substances if some substances can cross but not others.
Forces that do not need the cell to spend energy in order to produce movement.
Forces that require the cell to spend energy in order to produce movement.
The movement of molecules from an area of high concentration to an area of low concentration.
"Concentration gradient" A difference in concentration between two adjacent areas.
Total movement between concentration. E.g. 10 molecules move from A to B while 2 molecules move from B to A. Total movement is 8 molecules from A to B.
Movement of molecules from one area to another is equal.
The net effect of chemical and electrical gradients on the ion.
Channels specific for the passage of water.
A difference in charge between two adjacent areas that promotes the movement of ions toward the area of opposing charge.
The movement of water from an area of high concentration to an area of lower concentration.
The pressure extered by a standing fluid on an object.
Measure of the tendency of water to move into the solution because of its relative concentration of nonpenetrating solutes and water. Stops only when hydrostatic force counterbalances this pressure.
Th effect the solution has on cell volume.
When a solution has the same concentration of non-penetrating solutes as normal body cells.
A solution with less non-penetrating solutes than the body cells. Water will move into the cell.
A solution with more non-penetrating solutes than the body cells. Water will move out of the cell.
Meant for the transfer of small water-soluble molecules across the membrane.
Movement of large molecules and multi-molecular structures
The maximum amount of substance that a carrier can carry across a membrane.
Uses a carrier to facilitate the transfer of a particular substance across the membrane from high to low concentration.
ADP is put together with phosphate to form ATP.
Hydrogen ion Pump
Transports H ions across a gradient.
Na+ - K+ ATPase pump
Transports Na+ out of the cell, concetrating it in the ECF, and picks up K+ from the outside, concentrating it in the ICF.
Have two binding sites.
Primary Active Transport
Energy is directly required to move a substance uphill.
Secondary Active Transport
Energy is required in the entire process, but is not directly required to run the pump.
Ion Concentration Gradient
Ions are stored here. The energy found here is used to power the secondary active transport.
When a cell ingests a substance.
When a cell expels a substance.
Resting Membrane Potential
Present in the cells of nonexcitable tissues when they are at rest.
K+ Equilibrium Potential
The point at which no more net movement of K+ can occur.
Na+ Equilibrium Potential
The point at which no more net movement of Na+ can occur.