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.
Heterozygote (adj, heterozygous)
An organism with unlike members of any given pair or series of alleles that consequently produces unlike gametes.
hyperpolarization
(hı̄′pĕr-pō′lări- zā-shŭn) Change in the membrane potential to a value more negative than the resting potential.
inhibitory postsynaptic potential (IPSP)
A change in the postsynaptic membrane potential by the action of a synaptically released neurotransmitter, making the postsynaptic neuron less likely to fi re action potentials.
initial segment
Specialized membrane region at the base of a nerve axon (adjacent to the cell body) that is rich in voltagegated Na+ channels plus other classes of ion channels that all contribute to the encoding of membrane depolarization into action potential frequency.
inner membrane
Mitochondrial membrane that encloses the matrix space and forms extensive invaginations called cristae.
inner mitochondrial membrane
Mitochondrial membrane that encloses the matrix space and forms extensive invaginations called cristae.
integument
(in-teg′ū-ment) The membrane that covers the body; includes the epidermis, dermis, and all derivatives of the epidermis; also called skin or the cutaneous membrane.
intramembranous ossification
Bone formation that takes place within a membrane; the formation of flat bones of the skull.
ionic driving force
The difference between the real membrane potential, Vₘ, and the ionic equilibrium potential, Eᵢₒₙ.
isolation chip (iChip)
A chamber composed of a plastic membrane that allows molecules to pass through; used to grow bacteria in their natural environment.
K+ leak channel
K+-transporting ion channel in the plasma membrane of animal cells that remains open even in a “resting” cell.
Kt (Ktransport)
A kinetic parameter for a membrane transporter analogous to the Michaelis constant, Km, for an enzymatic reaction. The rate of substrate uptake is half-maximal when the substrate concentration equals the Kt.
length constant
A parameter used to describe how far changes in membrane potential can passively spread down a cable such as an axon or a dendrite, represented by the symbol λ. The length constant λ is the distance at which the depolarization falls to 37% of its original value; it depends on the ratio of membrane resistance (rₘ) to internal resistance (rᵢ).
localized anaphylaxis
An immediate hypersensitivity reaction that is restricted to a limited area of skin or mucous membrane; for example, hayfever, a skin rash, or asthma. See also systemic anaphylaxis.
Malate-aspartate shuttle
The reversible shuttling of hydrogen, in the form of malate, across the inner mitochondrial membrane.
malleus
An ossicle in the middle ear attached to the tympanic membrane; shaped somewhat like a hammer.
membrane attack
Effector pathway of complement based on formation of the membrane-attack complex (MAC).
membrane resistance
The resistance to electrical current flow across a membrane; represented by the symbol rₘ.
meninges
Three membranes that cover the surface of the central nervous system: the dura mater, arachnoid membrane, and pia mater. Singular: meninx.
meningitis
Inflammation of the meninges, the three membranes covering the brain and spinal cord.
meninx
(mē′ninks; pl., meninges, -jēz) Any one of the membranes covering the brain and spinal cord.
menses
(men′sēz) Periodic physiologic hemorrhage from the uterine mucous membrane; commonly referred to as the menstrual period.
mesentery
(mes′en-ter-ē) Fanshaped fold of peritoneum attaching the small intestine to the posterior abdominal wall; may refer to other membranes associated with organs of the abdominal cavity.
mesosome
An irregular fold in the plasma membrane of a prokaryotic cell that is an artifact of preparation for microscopy.
metalloid
A member of the class of elements found on the boundary between the metals and nonmetals of the periodic table, with properties intermediate between those of both groups; also called semimetals.
middle ear
The tympanic membrane plus the ossicles.
miniature postsynaptic potential
A change in postsynaptic membrane potential caused by the action of neurotransmitter released from a single synaptic vesicle.
motor end-plate
The postsynaptic membrane at the neuromuscular junction.
mucosa
(mū-kō′să) Mucous membrane composed of an epithelium and lamina propria that lines the body tracts (e.g., respiratory) that open to the external environment.
mucous membranes
Membranes that line body openings, including the intestinal tract, open to the exterior; also called mucosa.
multidrug transporters
Plasma membrane transporters in the ABC transporter family that expel several commonly used antitumor drugs, thereby interfering with antitumor therapy.
myelin sheath
Insulating layer of specialized cell membrane wrapped around vertebrate axons. Produced by oligodendrocytes in the central nervous system and by Schwann cells in the peripheral nervous system.
NaK ATPase
The electrogenic ATP-driven active transporter in the plasma membrane of most animal cells that pumps three Na outward for every two K moved inward.
neurilemma
(nūr-i-lem′a) The delicate outer membrane sheath around an axon.
nonmetal
A member of the class of elements that tend to be poor conductors of heat and electricity and usually gain electrons during chemical reactions.
NPC1L1-flotillan-cholesterol membrane microdomain
NPC1L1 binds cholesterol on the gut lumen side and subsequently transfers it to the area of the small intestine enterocyte membrane that becomes cholesterol enriched, which is referred to as a microdomain.
nucleoplasm
The portion of a eukaryotic cell’s contents enclosed by the nuclear membrane.
osmotic lysis
Rupture of the plasma membrane resulting from movement of water into the cell.
outer membrane
Mitochondrial membrane that is in contact with the cytosol.
outer mitochondrial membrane
Membrane that separates the organelle from the cytosol.
outer nuclear membrane
One of two concentric membranes comprising the nuclear envelope; surrounds the inner nuclear membrane and is continuous with the inner nuclear membrane and the membrane of the endoplasmic reticulum.
overshoot
The part of an action potential when the membrane potential is more positive than 0 mV.
parenteral route
A portal of entry for pathogens by deposition directly into tissues beneath the skin and mucous membranes.
Passive diffusion
Nonsaturable diffusion across a membrane.
passive transport (facilitated diffusion)
Transport of a solute across a membrane down its concentration gradient or its electrochemical gradient, using only the energy stored in the gradient.
patch clamp
A method that enables an investigator to hold constant the membrane potential of a patch of membrane while current through membrane channels is measured.
patch-clamp recording
Electrophysiological technique in which a tiny electrode tip is sealed onto a patch of cell membrane, thereby making it possible to record the flow of current through individual ion channels in the patch.
pemphigus vulgaris
An autoimmune disease characterized by severe blistering of the skin and mucosal membranes.
pericardium
(per-i-kar′dē-ŭm) Fibroserous membrane covering the heart.
perimetrium
(per-i-mē′trē-ŭm) Serous membrane of the uterus.
periosteum
(per-ē-os′tē-ŭm) Thick, fibrous membrane covering the entire external surface of a bone, except for the articular cartilage on the epiphyses.
periplasm
The region of a gram-negative cell wall between the outer membrane and the cytoplasmic membrane.
peritoneum
(per′i-tō-nē′ŭm) Serous membranes lining the internal walls of the abdominopelvic cavity and covering most of the organs within the cavity.
permeability
(per′mē-ă-bil′i-tē) Capacity of a membrane to allow passage of a substance.
pia mater
The innermost of the three meninges, the membranes that cover the surface of the central nervous system.
Plant growth-promoting rhizobacteria (PGPR)
Bacteria supporting plant growth such as Pseudomonas spp. (Gammaproteobacteria) and Bacillus spp. (Firmicutes) but also members of Azospirillum(Alphaproteobacteria), Azotobacter, Enterobacter, Pseudomonas, Serratia and Xanthomonas (all Gammaproteobacteria).
pleura
(plūr′ă; pl., pleurae, ploor′ē) Serous membranes enveloping the lungs and lining the internal walls of the thoracic cavity.
Polyp
A benign tumor of mucous membranes.
postsynaptic potential (PSP)
A change in the postsynaptic membrane potential by the presynaptic action of an electrical synapse or a synaptically released neurotransmitter.
preprophase band
Circumferential band of microtubules and actin filaments that forms around a plant cell under the plasma membrane prior to mitosis and cell division.
psyllium
A name applied to several members of the plant genus Plantago, whose seeds are used commercially for the production of mucilage.
rapidly inactivating K+ channel
Neuronal voltage-gated K+ channel, open when the membrane is depolarized, with a specific voltage sensitivity and kinetics of inactivation that induce a reduced rate of action potential firing at levels of stimulation only just above the threshold required, thereby resulting in a firing rate proportional to the strength of the depolarizing stimulus.
receptive field
The region of a sensory surface (retina, skin) that, when stimulated, changes the membrane potential of a neuron.
Reissner’s membrane
The cochlear membrane in the inner ear that separates the scala vestibuli from the scala media.
repolarization
(rē′pō-lăr-izā′ shŭn) Change in membrane potential from a depolarized value back to the resting value.
respiration-linked phosphorylation
ATP formation from ADP and Pi, driven by electron flow through a series of membrane-bound carriers, with a proton gradient as the direct source of energy driving rotational catalysis by ATP synthase.
rising phase
The first part of an action potential, characterized by a rapid depolarization of the membrane.
round window
A membrane-covered hole in the bony cochlea of the inner ear that is continuous with the scala tympani in the cochlea.
segmented filamentous bacteria (SFB)
Referring to commensal Grampositive Firmicute species and members of the Clostridiaceae family that adhere to the intestinal wall of rodents and several other species that induce TH17 and IgA responses.
Sodium-potassium ATPase
The sodium-potassium pump in the plasma membrane of all cells.
Spherocytosis
Inherited defects in the membrane skeleton of erythrocytes, leading to spherical shape of the cells.
spike-initiation zone
A region of the neuronal membrane where action potentials are normally initiated, characterized by a high density of voltage-gated sodium channels.
surface tension
The energy required to increase the surface area of a liquid by a unit amount; responsible for the tendency of liquids to minimize their surface area, giving rise to a membrane-like surface.
suture
(sū′chūr) Synarthrosis in which cranial bones are united by a dense regular connective tissue membrane.
synaptic cleft
The region separating the presynaptic and postsynaptic membranes of neurons.
T tubule
A membrane-enclosed tunnel running within a skeletal muscle fiber that links excitation of the sarcolemma with the release of Ca²⁺ from the sarcoplasmic reticulum.
Trafficking
The movement of materials through the cytoplasm of a cell, usually guided by membranes, vesicles, and components of the cytoskeleton.
translocon
The assembly of a translocator associated with other membrane complexes, such as enzymes that modify the growing polypeptide chain.
tympanic membrane
A membrane at the internal end of the auditory canal that moves in response to variations in air pressure; also called eardrum.
ultrafiltrate
A solution produced by passage through a semipermeable membrane.
undershoot
The part of an action potential when the membrane potential is more negative than at rest; also called after-hyperpolarization.
Vesicle trafficking
The complex regulatory network controlling the directional movement of vesicles between organelles and the plasma membrane.
voltage clamp
A device that enables an investigator to hold the membrane potential constant while transmembrane currents are measured.
voltage-gated cation channel
Type of ion channel found in the membranes of electrically excitable cells (such as nerve, endocrine, egg, and muscle cells). Opens in response to a shift in membrane potential past a threshold value.
Voltage-gated ion channels
Ion channels that open in response to membrane depolarization.
voltage-gated Na+ channel
Ion channel in the membrane of nerve and skeletal muscle cells that opens in response to a stimulus causing sufficient depolarization, allowing Na+ to enter the cell down its electrochemical gradient
Zooplankton
Heterotrophic members of plankton community.
β-Lactam
A four-membered lactam, or cyclic amide. Penicillin and cephalosporin antibiotics contain b-lactam rings.
tectorial membrane
A sheet of tissue that hangs over the organ of Corti in the cochlea in the inner ear.
undulating membrane
A highly modified flagellum on some protozoa.
