Transport,Movement+Passage Flashcards
saturation
characteristic feature of protein mediated transport processes – by increasing the concentration of the molecules to be transported, increase of the transport speed increases less and less as most of the transporter molecules tend to be occupied after a certain concentration
endocytosis
entrance of substances into the cell by membrane invagination to form an internal vesicle
exocytosis
transport of substances stored in internal vesicles from the cell to the surroundings by fusion of the vesicle with the cell membrane
vesicle
small, spherical compartment in the cell surrounded by a membrane (e.g. synaptic vesicle)
filtration
movement of water and small molecules through a membrane (capillary wall) because of the pressure difference
ion channel (leakage, voltage-dependent, ligand-dependent)
pore enabling passage of ions through the membrane; it is formed by intrinsic membrane proteins and is either continuously open (leakage) or opened by a change of membrane potential or by the binding of a ligand (signal) molecule
permeability
ability of a compound to cross the membrane; it depends on the characteristics of the compound and of the membrane
fluid mosaic model
according to this model, biological membranes are built up of a lipid bilayer in which protein molecules can easily move (float) in the horizontal direction
electrical synapse
alternate name for gap junctions between excitable cells through which small molecules, thus ions carrying excitation can pass
convection
bulk flow, movement of substances caused by pressure differences
Poiseuille’s law
equation describing the laminar flow of fluids in rigid tubes as the function of pressure difference, tube diameter and length, and viscosity
laminar flow
movement of a fluid or air, during which layers are sliding smoothly on each other
turbulent flow
a flow pattern in which particles of the fluid move irregularly in all directions of the space
viscosity
physical property of fluids that determines the ease with which the layers of a fluid move past ach other
active transport
energy-requiring translocation of a substance across a membrane against its electrochemical gradient
ion pump
active transport process moving ions through the membrane using energy stored in ATP molecules
ATP
adenosine-triphosphate, energy-rich nucleotide used as a common energy source by all cells
GTP
guanosine triphosphate, energy-rich nucleotide, like ATP
nucleotide
building block of nucleic acids formed by purine or pyrimidine base, a ribose or deoxyribose sugar, and phosphate group
nucleoside
similar to nucleotide, but contains no phosphate group
facilitated diffusion
passive transport of a molecule across a membrane along the concentration gradient thus not using energy, but requiring a transporter to help the passage of the molecule
concentration gradient
change in the concentration of a substance depending on distance (dc/dx)
blood-brain-barrier
mechanism controlling the transport of materials from the blood to the extracellular space of the brain
phagocytosis, pinocytosis
forms of endocytosis to take up solid particles or fluid into the cell
tight junction
area of membrane fusion between adjoining cells that prevents the passage of extracellular material between the cells
osmosis
diffusion of water; water is moving through the membrane from the more diluted solution toward the more concentrated solution following its concentration gradient
axonal transport (anterograde, retrograde)
transport mechanism in neurons providing relatively fast movement of substances toward the axon terminals (forward) and toward the cell body (retrograde)
diffusion
random thermal movement of atoms, molecules and ions from sites with higher concentration toward sites with lower concentration
