BIO - TERMS - MEMBRANE Flashcards
active zone
A presynaptic membrane differentiation that is the site of neurotransmitter release.
adherence
Attachment of a microbe or phagocyte to another’s plasma membrane or other surface.
adherens junction
Cell junction in which the cytoplasmic face of the plasma membrane is attached to actin filaments. Examples include adhesion belts linking adjacent epithelial cells and focal contacts on the lower surface of cultured fibroblasts.
after-hyperpolarization
The hyperpolarization that follows strong depolarization of the membrane; the last part of an action potential, also called undershoot.
antisepsis
A chemical method for disinfection of the skin or mucous membranes; the chemical is called an antiseptic.
apocrine gland
Gland that releases a substance by pinching off the apical membrane of a cell and a portion of its cytoplasm; e.g., apocrine sweat glands.
arachnoid membrane
The middle of the three meninges, the three membranes that cover the surface of the central nervous system.
auditory canal
A channel leading from the pinna to the tympanic membrane; the entrance to the internal ear.
axolemma
(ak′sō-lem′ă) Plasma membrane of an axon.
basal
Situated near the base. Opposite the apical surface. basal lamina (plural basal laminae) Thin mat of extracellular matrix that separates epithelial sheets, and many other types of cells such as muscle or fat cells, from connective tissue. Sometimes called basement membrane.
Basal lamina
A thin layer of extracellular matrix bound tightly to the basolateral surface of cells; the basal lamina is linked to the basolateral membrane by integrins. (Chapter 2)
basilar membrane
A membrane separating the scala tympani and scala media in the cochlea in the inner ear.
Bioavailability
The amount of a substance available to cross an organism’s cellular membrane at a given time point.
budding
(1) Asexual reproduction beginning as a protuberance from the parent cell that grows to become a daughter cell. (2) Release of an enveloped virus through the plasma membrane of an animal cell.
bursa
(ber′să; pl., bursae, ber′sē) Closed, fluid-filled sac lined with a synovial membrane; usually found in areas subject to friction.
C5b
Fragment of C5 that initiates the formation of the membrane-attack complex (MAC).
Ca2+-activated K+ channel
Opens in response to the raised concentration of Ca2+ in nerve cells that occurs in response to an action potential. Increased K+ permeability makes the membrane harder to depolarize, increasing the delay between action potentials and decreasing the response of the cell to constant, prolonged stimulation (adaptation).
capacitation
(kă-pas′i-tā′shŭn) A period of conditioning whereby the sperm cell membrane is modified while in the female reproductive tract prior to being able to fertilize the secondary oocyte.
cargo
The membrane components and soluble molecules carried by transport vesicles.
cell cortex
Specialized layer of cytoplasm on the inner face of the plasma membrane. In animal cells it is an actin-rich layer responsible for movements of the cell surface.
chlorosome
Plasma membrane folds in green sulfur bacteria containing bacteriochlorophylls.
chorion
(kō′rē-on) Multilayered, outermost extraembryonic membrane; together with the functional layer of the endometrium it forms the placenta, the site through which nourishment and waste are exchanged between mother and developing fetus; attachment to the uterus.
clathrin-coated pits
Specialized regions typically occupying about 2% of the total plasma membrane area at which the endocytic pathway often begins.
clathrin-coated vesicles
Coated vesicles that transport material from the plasma membrane and between endosomal and Golgi compartments.
coat-recruitment GTPases
Members of a family of monomeric GTPases that have important roles in vesicle transport, being responsible for coat assembly at the membrane.
Concordance rate
Among pairs of items identified because one member of the pair has a particular trait, the frequency with which the other member of the pair has the same trait.
conductivity
(kon-dŭk-tiv′i-tē) The ability to propagate an action potential along the plasma membrane.
cotransport
The simultaneous transport, by a single transporter, of two solutes across a membrane. See also antiport; symport.
Crossbreeding
Mating between members of different races or species.
Cyanosis
In hypoxia, blue discoloration of mucous membranes that is caused by deoxyhemoglobin.
cytolysis
The destruction of cells, resulting from damage to their cell membrane, that causes cellular contents to leak out.
delayed K+ channel
Neuronal voltage-gated K+ channel that opens following membrane depolarization but during the falling phase of an action potential due to slower activation kinetics than Na+ channels; opening permits K+ efflux, driving the membrane potential back toward its original negative value, ready to transmit a second impulse.
dendritic spine
A small sac of membrane that protrudes from the dendrites of some cells and receives synaptic input.
Diffusivity
This is a property of the permeant in the membrane and is a measure of how easily it will traverse through the tissue. It is expressed as area per unit time (usually cm2/h or cm2/s).
Discordant
Members of a pair showing different, rather than similar, characteristics.
DR4, DR5
Members of the TNFR superfamily expressed by many cell types that can be activated by the TRAIL to induce apoptosis.
dynamin
Cytosolic GTPase that binds to the neck of a clathrin-coated vesicle in the process of budding from the membrane, and which is involved in completing vesicle formation.
early endosome
Common receiving compartment with which most endocytic vesicles fuse and where internalized cargo is sorted either for return to the plasma membrane or for degradation by inclusion in a late endosome.
electrochemical potential
The energy required to maintain a separation of charge and of concentration across a membrane.
electrogenic
Contributing to an electrical potential across a membrane.
Electrogenic transport
Net transport of electrical charges across a membrane.
enanthem
Rash on mucous membranes. See also exanthem.
endocytic vesicle
Vesicle formed as material ingested by the cell during endocytosis is progressively enclosed by a small portion of the plasma membrane, which first invaginates and then pinches off to form the vesicle.
endometrium
(en′dō-mē′trē-ŭm) Mucous membrane forming the inner layer of the uterine wall.
enveloped virus
Virus with a capsid surrounded by a lipid bilayer membrane (the envelope), which is often derived from the host-cell plasma membrane when the virus buds from the cell.
Epoxide
A three-membered-ring ether functional group.
ER lumen
Space enclosed by the membrane of the endoplasmic reticulum (ER).
eukarya
All eukaryotes (animals, plants, fungi, and protists); members of the Domain Eukarya.
excitatory neurotransmitter
Neurotransmitter that opens cation channels in the postsynaptic membrane, causing an influx of Na+, and in many cases Ca2+, that depolarizes the postsynaptic membrane toward the threshold potential for firing an action potential.
excitatory postsynaptic potential (EPSP)
Depolarization of the postsynaptic membrane potential by the action of a synaptically released neurotransmitter.
falling phase
The part of an action potential characterized by a rapid fall of membrane potential from positive to negative.
fontanelle
(fon′tă-nel′) One of several membranous intervals at the margins of the cranial bones in an infant.
free ribosome
Ribosome that is free in the cytosol, unattached to any membrane.
fusion
The merging of plasma membranes of two different cells, resulting in one cell containing cytoplasm from both original cells.
gating
A property of many ion channels, making them open or closed in response to specific signals, such as membrane voltage or the presence of neurotransmitters.
Goldman equation
A mathematical relationship used to predict membrane potential from the concentrations and membrane permeabilities of ions.
Goodpasture’s syndrome
An autoimmune disease in which autoantibodies against type IV collagen (found in basement membranes) are produced, causing extensive inflammation in kidneys and lungs.
graded potential
Small deflection in the resting membrane potential in excitable cells due to the movement of small amounts of ions across the plasma membrane; it may result in either a depolarization or hyperpolarization.
group translocation
In prokaryotes, active transport in which a substance is chemically altered during transport across the plasma membrane.
Halonium ion
A species containing a positively charged, divalent halogen. Three-membered-ring bromonium ions are intermediates in the electrophilic addition of Br2 to alkenes.