A&P - ch 3
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64 terms
Terms | Definitions |
|---|---|
 G protein | A protein of the plasma membrane that is activated by a membrane receptor and, in turn, opens an ion channel or activiates and intracellular physiological response; important in linking ligand-receptor binding to second messenger systems. |
| Integral protein | A protein that extends through a plasma membrane and contacts both the extracellular and intracellular fluid |
| carrier-mediated transport | A process of transporting materials through a cellular membrane that involves reversible binding to a membrane protein |
| apical surface | The uppermost surface of an epithelial cell, usually exposed to the lumen of an organ |
| cisterna | A fluid-filled space or sac, such as the cisterna chyli of the lymphatic system and a cisterna of the endoplasmic reticulum or golgi complex |
| cytosol | A clear, featureless, gelatinous colloid in which the organelles and other internal structures of a cell are embedded |
| bulk transport | The movement of particles or fluid droplets through the plasma membrane by the process of endocytosis or exocytosis |
| fluid-mosaic model | The current theory of the structure of a plasma membrane, depicting it as a bilayer of phospholipids with embedded proteins, many of which are able to move about in the lipid film |
| cytoskeleton | A system of protein microfilaments, intermediate filaments, and microtubules in a cell, serving in physical support, cellular movement, and the routing of molecules and organelles to their destinations within the cell |
| dextrose | The D-isomer of glucose; the only form of glucose with a normal role in physiology |
| fusiform | Spindle-shaped; elongated, thick in the middle, and tapered at both ends, such as the shape of a smooth muscle cell or a muscle spindle |
| hydrostatic pressure | The physical force generated by a liquid such as blood or tissue fluid, as opposed to osmotic and atmospheric pressures |
| hypotonic | Having a lower osmotic pressure than human cells or some other reference solution and tending to cause osmotic swelling and lysis of cells |
| Intracellular fluid | The fluid contained in the cells; one of the major fluid compartments |
| light microscope | A microscope that produces images with visible light |
| microvillus | An outgrowth of the plasma membrane that increases the surface area of a cell and functions in absorption and some sensory processes; distinguished from cilia and flagella by its smaller size and lack of an axoneme |
| anitport | An active transport carrier that moves two or more solutes in opposite directions through a cellular membrane; for example, the NA+-K+ pump |
| mitochondrion | An organelle specialized to synthesize ATP, enclosed in a double unit membrane with infoldings of the inner membrane called cristae |
| concentration gradient | A gradual change in chemical concentration from one point to another |
| filtrate | A fluid formed by filtration |
| axoneme | The core of microtubules, usually in a "9+2" array, at the center of a cilium or flagellum |
| cilium | A hairlike process, with an axoneme, projecting from the apical surface of an epithelial cell; usually motile and serving to propel matter across the surface of an epithelium but sometimes serving sensory roles |
| inclusion | Any visible object in the cytoplasm of a cell other than an organelle or cytoskeletal element; usually a foreign body or a stored cell product, such as a virus, dust particle, lipid droplet, glycogen granule, or pigment |
| organelle | Any structure within a cell that carries out one of its metabolic roles, such a mitochondria, centrioles, endoplasmic reticulum, and the nucleus; an intracellular structure other than the cytoskeleton and inclusions |
| actin | A filamentous intracellular protein that provides cytoskeleton support and interacts with other proteins, especially myosin, to cause cellular movement; important in muscle contraction, ciliary and flagellar beating, and membrane actions such as phagocytosis, ameboid movement, and cytokinesis |
| ameboid movement | movement of a cell by means of pseudopods, in a manner similar to that of an amega; seen in leukocytes and some macrophages |
| base | A chemical that binds protons from solution; a proton acceptor |
| centriole | An organelle composed of two short perpendicular cylinders of microtubules; origin of the mitotic spindle |
| dynein | A motor protein involved in the beating of cilia and flagella and in the movement of molecules and organelles within cells, as in retrograde transport in a nerve fiber |
| osmosis | The net diffusion of water through a selectively permeable membrane |
| osmotic pressure | The amount of pressure that would have to be applied to one side of a selectively permeable membrane to stop osmosis; proportional to the concentration of nonpermeating solutes on that side and therefore serving as an indicator of solute concentration |
| carrier | A protein in a cellular membrane that performs carrier-mediated transport |
| phagocytosis | A form of endocytosis in which a cell surrounds a foreign particle with pseudopods and engulfs it enclosing it in a cytoplasmic vesicle called a phagosome |
| pinocytosis | A form of endocytosis in which the plasma membrane sinks inward and imbibes droplets of extracellular fluid of specific molecules concentrated from that fluid |
| receptor-mediated pinocytosis | A form of endocytosis in which certain molecules in the extracellular fluid bind to receptors in the plasma membrane, these receptors become gathered together, the membrane sinks inwards at that point, and the molecules become incorporated into vesicles in the cytoplasm |
| reticular fiber | A fine, branching collagen fiber coated with glycoprotein, found in the stroma of lymphatic organs and some other tissues and organs |
| endoplasmic reticulum | An extensive system of interconnected cytoplasmic tubules of channels; classified as rough ER or smooth ER depending on the presence or absence of ribosomes on its membrane |
| gradient | A difference or change in any variable, such as pressure or chemical concentration, from one point in space to another; provides a basis for molecular movements such as gas exchange, osmosis, and facilitated diffusion |
| symport | A carrier protein that moves two solutes simultaneously through a plasma membrane in the same direction, such as the sodium-dependent glucose transporter of the small intestine |
| transmission electron microscope | A microscope that uses and electron bean in place of light to form high-resolution, two-dimensional images of ultrathin slices of cells or tissues; capable of extremely high magnification |
| unit membrane | Any membrane composed of a bilayer of phospholipids and embedded proteins. A single unit membrane comprises the plasma membrane and encloses many organelles of a cell, whereas double unit membranes enclose the nucleus and mitochondria |
| channel protein | A protein in the plasma membrane that has a pore through it for the passage of materials between the cytoplasm and extracellular fluid |
| facilitated diffusion | The process of transporting a chemical through a cellular membrane, down its concentration gradient, with the aid of a membrane carrier that does not consume ATP; enables substances to diffuse through the membrane that would do so poorly or not at all without a carrier. |
| filtration | A process in which hydrostatic pressure forces a fluid through a selectively permeable membrane |
| fluid-phase pinocytosis | A form of endocytosis in which the cell imbibes droplets of extracellular fluid without modifying its composition or concentration |
| microtubule | An intracellular cylinder composed of the protein tubulin, forming the axonemes of cilia and flagella and part of the cytoskeleton |
| second messenger | A chemical that is produced within a cell or that enters a cell in response to the binding of a messenger to a membrane receptor and that triggers a metabolic reaction in the cell |
| cuboidal | A cellular shape that is roughly like a cube or in which the height and width are about equal |
| hypertonic | Having a higher osmotic pressure than human cells or some other reference solution and tending to cause osmotic shrinkage of cells |
| endothelium | A simple squamous epithelium that lines the lumens of the blood vessels, heart, and lymphatic vessels |
| active transport | The movement of a solute through a cellular membrane, against its concentration gradient, involving a carrier protein that expends ATP |
| golgi vesicle | A membrane-bounded vesicle pinched from the golgi complex, containing its chemical product; may be retained in the cell as a lysosome or become a secretory vesicle that releases the product by exocytosis |
| ligand-gated channel | A channel protein in a plasma membrane that opens or closes when a ligand binds to it, enabling the ligand to determine when substances can enter or leave the cell |
| secondary active transport | A mechanism in which solutes are moved through a plasma membrane by a carrier that does not itself use ATP but depends on a concentration gradient established by an active transport pump elsewhere in the cell. Also called cotransport |
| gate | A protein channel in a unit membrane that can open or close in response to chemical or electrical stimuli, thus controlling when substances are allowed to pass through the membrane |
| nucleus | A cellular organelle containing DNA and surrounded by a double unit membrane |
| selectively permeable membrane | A membrane that allows some substances to pass through while excluding others; for example, the plasma membrane and dialysis membranes |
| flagellum | A long,motile, usually single hairlike extension of a cell; the tail of a sperm cell is the only functional flagellum in humans |
| golgi complex | An organelle composed of several parallel cisternae, somewhat like a stack of saucers, that modifies and packages newly synthesized proteins and synthesizes carbohydrates |
| pseudopod | A temporary cytoplasmic extension of a cell used for locomotion and phagocytosis |
| cellular membrane | Any unit membrane enclosing a cell or organelle |
| cytoplasm | The contents of a cell between its plasma membrane and its nuclear envelope, consisting of cytosol, organelles, inclusions, and the cytoskeleton |
| endocytosis | Any process in which a cell forms vesicles from its plasma membrane and takes in large particles, molecules, or droplets of extracellular fluid; for example, phagocytosis and pinocytosis |
| Intracellular | within a cell |
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