CHAPTER 03: MEMBRANE POTENTIAL Flashcards
active expiration
Emptying of the lungs more completely than when at rest by contracting the expiratory muscles; also called forced expiration
active force
A force that requires expenditure of cellular energy (ATP) in the transport of a substance across the plasma membrane
active transport
Active carrier-mediated transport involving transport of a substance against its concentration gradient across the plasma membrane
adenylyl cyclase
The membrane-bound enzyme that is activated by a G protein intermediary in response to binding of an extracellular messenger with a surface membrane receptor and that in turn activates cyclic AMP, an intracellular second messenger
anion
Negatively charged ion that has gained one or more electrons in its outer shell
apoptosis
Programmed cell death; deliberate selfdestruction of a cell
ATPase
An enzyme that possesses ATP-splitting ability
calmodulin
An intracellular Ca2 binding protein that, on activation by Ca2, induces a change in structure and function of another intracellular protein; especially important in smoothmuscle excitation-contraction coupling
carrier molecules
embrane proteins, which, by undergoing reversible changes in shape so that specific binding sites are alternately exposed at either side of the membrane, are able to bind with and transfer particular substances unable to cross the plasma membrane on their own
carrier-mediated transport
Transport of a substance across the plasma membrane facilitated by a carrier molecule
cascade
A series of sequential reactions that culminates in a final product, such as a clot
cations
Positively charged ions that have lost one or more electrons from their outer shell
caveolae
Cavelike indentations in the outer surface of the plasma membrane that contain an abundance of membrane receptors and serve as important sites for signal transduction
cell adhesion molecules
proteins that protrude from the surface of the plasma membrane and form loops or other appendages that the cells use to grip each other and the surrounding connectivetissue fibers
channels
Small, water-filled passageways through the plasma membrane; formed by membrane proteins that span the membrane and provide highly selective passage for small water-soluble substances such as ions
chemical mediator
A chemical that is secreted by a cell and that influences an activity outside of the cell
chemically gated channels
Channels in the plasma membrane that open or close in response to the binding of a specific chemical messenger with a membrane receptor site that is in close association with the channel
cholesterol
a type of fat molecule that serves as a precursor for steroid hormones and bile salts and is a stabilizing component of the plasma membrane
concentration gradient
A difference in concentration of a particular substance between two adjacent areas
cyclic adenosine monophosphate (cyclic AMP or cAMP)
An intracellular second messenger derived from adenosine triphosphate (ATP)
desmosome (dez+-muh-soxm)
(dez+-muh-soxm) An adhering junction between two adjacent but nontouching cells formed by the extension of filaments between the cellsU plasma membranes; most abundant in tissues that are subject to considerable stretching
diffusion
Random collisions and intermingling of molecules as a result of their continuous thermally induced random motion
electrical gradient
A difference in charge between two adjacent areas
electrochemical gradient
The simultaneous existence of an electrical gradient and concentration (chemical) gradient for a particular ion
endocytosis
Internalization of extracellular material within a cell as a result of the plasma membrane forming a pouch that contains the extracellular material, then sealing at the surface of the pouch to form a small, intracellular, membrane-enclosed vesicle with the contents of the pouch trapped inside
equilibrium potential
The potential that exists when the concentration gradient and opposing electrical gradient for a given ion exactly counterbalance each other so that there is no net movement of the ion