F Flashcards
Facilitated Diffusion
A mode of transport in which a protein allows an otherwise impermeable entity to cross a membrane down its electrochemical gradient.
Fast Axonal Transport
Process by which neurotransmitter-containing vesicles are moved from the cell body to the axon terminal of a neuron; requires molecular motors.
Fast-Glycolytic (FG) Muscle Fibers
Muscle cells with a biochemical and mechanical protein profile suited to short-duration, high-intensity contractions that rely on glycolysis for energy; typically muscle fibers that express type IIb myosin.
Fast-Oxidative Glycolytic (FOG) Muscle Fibers
Muscle cells with a biochemical and mechanical protein profile suited to contraction of intermediate duration and intensity; rely on a combination of glycolysis and oxidative phosphorylation for energy. Typically muscle fibers that express type IIa or II x/d myosin isoforms.
Feces
The undigested matter expelled from the gastrointestinal tract.
Feedback
A regulatory mechanism whereby a step late in a pathway causes a change earlier in the pathway, either decreasing use of the pathway (negative feedback) or increasing its use (positive feedback).
Fenestrated Capillaries
Capillaries with relatively high permeability because of the presence of perforations (fenestrae) through the cells of the capillary wall; found in tissues such as parts of the kidney, the endocrine organs, and the intestine.
Fever
A period of elevated whole body temperature that arises from an immune response, typically as a result of some form of infection. Behavioral fever results when a poikilothermic animal responds to an immunological challenge by moving into an environment that increases body temperature.
Fibroblasts
Cells that have a major role in producing the extracellular matrix of most soft tissues.
Fick Equation
The equation relating diffusive flux to the energetic gradient (concentration, partial pressure, electrical, etc.) driving diffusion.
Field Metabolic Rate (FMR)
The metabolic rate of a free-roaming animal, usually measured using doubly labelled water.
Filopodia
Thin, fingerlike extensions of the cell, supported by the actin cytoskeleton
Filtrate
The solution that passes through a filter, such as the primary urine that passes through the glomerulus.
Filtration Slit
The gap between the podocytes that permits movement of fluid into the tubule, excluding cells, particles, and macromolecules that are too large.
Flagella
singular: flagellum
Microtubulebased extensions from a cell that move in a whiplike pattern; usually present alone or in pairs.
Flame Cells
The flagellated cells within a protonephridium that generate movements that bring fluids into the structure.
Flexion
A movement of a limb that causes the limb to bend at the joint (caused by a flexor muscle).
Flexor
A muscle that causes a limb to bend at the joint (flexion).
Fluid Mosaic Model
The model of a lipid bilayer membrane that includes multiple types of lipids and proteins and allows for their free rotation and lateral movement.
Fluidity
The degree of free movement of membrane entities within the membrane; often assessed using the dye DPH, which exhibits an anisotropy that depends on membrane fluidity.
Fluorescence
Absorbance of a high-energy (low-wavelength) light followed by release of a lower-energy (longer-wavelength) light.
Flux
Flow of material through a pathway.
Follicle
A multicellular unit composed of somatic tissue surrounding an ovum.
Follicle
A multicellular unit composed of somatic tissue surrounding an ovum.
Follicle-Stimulating Hormone (FSH)
One of the two major gonadotropins of vertebrates; causes the ovarian follicle to mature.
Follicular Phase
That portion of the ovulatory cycle where a follicle matures to release the ovum.
Food Vacuole
A phagocytic vesicle that fuses with other vesicles and processing organelles to digest the nutrients.
Foot Processes
Long projections of podocytes in Bowman’s capsule that create the filtration slits.
Foramen of Panizza
A structure that connects the left and right aorta in the crocodile heart.
Forebrain
The anterior portion of the vertebrate brain, consisting of the telencephalon and diencephalon. Also called the prosencephalon.
Founder Effect
A phenomenon in which the genotypic distribution of a population is a result of historical events that caused the population to be established by a small number of individuals; often associated with a reduction in genetic diversity.
Fovea
A small region in the center of the retina of a vertebrate eye that is responsible for high-acuity vision.
Frank-Starling Effect
An increase in the force of cardiac contraction in response to increasing venous return to the heart.
Free Energy
The energy in a system that is available to do work.
Freezing-Point Depression
A reduction in the temperature at which a solution freezes;
e.g., in the presence of antifreeze molecules.
Friction Drag
The resistance that arises as an object moves through a fluid as a result of the interaction between the surface and the fluid.
Futile Cycle
A combination of enyzymatic reactions or processes that lead to net breakdown of ATP and/or release of heat without changes in the carbon substrates.
