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Hole's Chapter 3: Cell Movement
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Anatomy
Undergraduate 2
09/17/2009

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Term
physical (or passive) processes
Definition
diffusion, osmosis, facilitated diffusion, and filtration.
Term
physiological (or active) processes
Definition
active transport, endocytosis, and exocytosis.
Term
diffusion
Definition
the tendency of atoms, molecules, and ions in a liquid or air solution to move from areas of higher concentration to areas of lower concentration (become more distributed - more diffuse).
Term
diffusion
Definition
occurs because atoms, molecules, and ions are in constant motion.
Term
concentration gradient
Definition
difference in concentration
Term
diffusional equilibrium
Definition
when concentration of substance becomes uniform throughout solution and there is no net movement.
Term
requirements for diffusion
Definition
1. cell membrane is permeable to that substance, 2. concentration gradient exists such that the substance is at a higher concentration on one side of membrane or the other.
Term
physiological steady state
Definition
concentrations of diffusing substances are unequal but stable, more appropriate in reference to organisms
Term
most important factors in diffusion rate
Definition
distance, the concentration gradient, and temperature.
Term
facilitated diffusion
Definition
movement that follows concentration gradient but uses membrane proteins as "carriers" , very important to ions and other larger water-soluble molecules
Term
facilitated diffusion
Definition
moves molecules from higher to lower concentration BUT number of carrier molecules in cell membrane limits rate
Term
osmosis
Definition
the movement of water across a selectively permeable membrane into a compartment containing solute that cannot cross the same membrane
Term
osmosis rule
Definition
greater concentration of impermeant solute particles, the lower the water concentration of that solution, the greater osmotic pressure
Term
isotonic
Definition
solutions with the same osmotic pressure as body fluids, cells do not change size in this solution
Term
hypertonic
Definition
solutions with a higher osmotic pressure than body fluids, if cells put into this solution there will be net movement of water by osmosis out of cell into surrounding solution - cells shrink
Term
hypotonic
Definition
solutions with lower osmotic pressure than body fluids, gain water by osmosis and swell or possibly even burst
Term
filtration
Definition
molecules are forced through membranes by this process
Term
filtration
Definition
commonly used to separate solids from water
Term
filtration
Definition
a passive process since gravity can be the applied force
Term
filtration
Definition
tissue fluid forms when water and dissolved substances are forced out through the walls of capillaries, but cells and large molecules are left inside
Term
active transport
Definition
movement against a concentration gradient from lower to higher concentration, requires energy derived from cellular metabolism
Term
active transport
Definition
uses carrier molecules within cell membrane that have binding sites that combine with specific particles being transported - triggers release of cellular energy - alters shape of carrier protein - "passenger" molecules can move through membrane
Term
endocytosis
Definition
moves molecules or other particles that are too large to enter a cell by diffusion or active transport; conveyed in a vesicle that forms from a section of the cell membrane
Term
3 forms of endocytosis
Definition
pinocytosis, phagocytosis, receptor-mediated endocytosis
Term
pinocytosis
Definition
intake of liquid droplets
Term
pinocytosis
Definition
cell takes in tiny droplets of liquid, small portion of cell membrane indents, open end of tubelike part seals off and produces vesicle, sac detaches from surface and moves into cytoplasm, cell is able to take in water and particles dissolved in it
Term
phagocytosis
Definition
intake of solids, often with the fusion of lysosomes which digest the material
Term
phagocytes
Definition
certain types of cells that can take in solid particles such as bacteria and cellular debris, ex. some white blood cells
Term
phagocytosis
Definition
important line of defense against infection
Term
phagocytosis
Definition
phagocyte encounters solid particle, particle attaches to cell membrane, portion of membrane projects outward surrounding particle and slowly draws it inside cell, part of membrane surrounding solid detaches forming vesicle, lysosome usually joins vesicle and lysosome enzymes decompose contents
Term
receptor-mediated endocytosis
Definition
moves specific kinds of particles into the cell
Term
receptor-mediated endocytosis
Definition
process involves protein molecules that extend through cell membrane and are exposed on its outer surface
Term
receptor-mediated endocytosis
Definition
protein-receptors present on cell membrane bind to specific ligands
Term
ligands
Definition
molecules that bind specifically to receptors
Term
low-density lipoproteins (LDL)
Definition
spherical particles where cholesterol molecules are synthesized in liver cells and packaged
Term
apolipoprotein-B
Definition
coating on LDL particle containing binding protein
Term
receptor-mediated endocytosis
Definition
molecules that can bind to receptor sites selectively enter cell; other types of molecules left outside
Term
receptor-mediated endocytosis
Definition
provides specificity
Term
exocytosis
Definition
reverse of endocytosis, expels the residue after lysosomal enzymes have digested solids brought in through phagocytosis
Term
exocytosis
Definition
allows cell to secrete material produced by cell, for example nerve cells use this to release neurotransmitters chemicals
Term
transcytosis
Definition
combines exocytosis and endocytosis to selectively and rapidly transport a substance/particle from one end of a cell to the other
Term
transcytosis
Definition
enables substances to cross barriers formed by tightly connected cells; occurs in normal physiology and in disease
Term
transcytosis
Definition
enables healthy immune system to monitor pathogens in small intestine, protecting against some forms of food poisoning
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