T Flashcards
Tachycardia
Rapid heartbeat.
Tactile Receptors
Receptors on the skin that are sensitive to touch.
Tagmata
In segemented animals, a group of segments that are joined together and share a function, such as head, thorax, or abdomen of insects.
Tank Reactor
In gut reactor theory, a type of gut in which nutrients flow into the gut where they are mixed with gut contents, and simultaneously the gut expels fluids that consist of partially degraded nutrients.
Tapetum
A layer of tissue found in the eye of many vertebrates; involved in reflecting light.
Tastants
Chemicals that are detected by the sense of taste.
Taste Bud
Structure involved in gustation in the vertebrates.
T Cells
A class of lymphocytes that is produced in the thymus.
Tectum
Dorsal region of the vertebrate midbrain involved in coordinating visual and
auditory responses.
Tegmentum
An area within the brainstem of the vertebrate brain.
Teleost Fish
The most common subclass of the bony fishes.
Temporal Heterothermy
A thermal strategy whereby a homeothermic animal exhibits periods of poikilothermy, typically to allow a reduction in metabolic rate; also known as relaxed endothermy.
Temporal Summation
The process by which graded potentials occurring at slightly different times combine to influence the net graded potential of the cell.
Tendon
The connection between a muscle and a bone.
Tension, Muscular
The force produced by a contracting muscle.
Terminal Cisternae
An enlargement of the sarcoplasmic reticulum near the muscle plasma membrane, specifically T-tubules.
Tertiary Structure
The three-dimensional structure of a macromolecule, stabilized by numerous weak bonds.
Testosterone
A steroid hormone that stimulates the development of male characteristics.
Tetanus
The sustained contraction of a muscle arising from multiple stimulations in close succession.
Tetrapods
Vertebrates with four limbs, including amphibians, reptiles, birds, and mammals.
Thalamus
One of the basal ganglia of the vertebrate brain that relays sensory information to the cerebral cortex.
Theca
The outer layer of somatic cells surrounding a follicle, separated from the inner granulosa cells by a basal lamina.
Thermal Conductance
The transfer of thermal energy either within an object or from one object to another.
Thermal Energy
Energy associated with heat production.
Thermodynamics
A branch of physics that deals with the relationship between heat and other forms of energy.
Thermogenesis
Heat production.
Thermogenin
The mitochondrial uncoupling protein found in mammalian brown adipose tissue.
Thermoneutral Zone
The range of ambient temperatures over which an animal does not need to alter metabolic processes to maintain internal constancy.
Thermoreceptor
A sensory receptor that responds to temperature.
Thermoregulation
The physiological strategy an animal uses to control temperature within the desired range.
Thick Filament
A polymer of about 300 myosin dimers that produces the contractile force in muscle.
Thin Filament
A muscle-specific α-actin polymer similar in structure to a microfilament; serves as a framework that translates actinomyosin activity into force generation.
Threshold of Detection
The minimum level of a stimulus that can be detected by a sensory receptor.
Threshold Potential
The critical value of the membrane potential in an excitable cell to which the membrane must be depolarized in order for an action potential to be initiated.
Threshold Stimulus
The smallest stimulus that can provoke a response in a cell.
Thyroid Hormone
An iodine-containing hormone produced by the thyroid gland that is involved in the regulation of metabolism.
Tidal Ventilation
A form of ventilation where inhaled and exhaled medium moves along the same pathway.
Tidal Volume
The volume of a respiratory medium moved into or out of a respiratory structure during a single breath.
Tight Epithelia
An epithelial layer with cell–cell connections that limit or prevent paracellular transport.
Tight Junction
A type of intercellular connection that is capable of preventing the free movement of molecules between the cells.
Time Constant (t)
A parameter that characterizes the rate of decay of a change in the membrane potential.
Tip Link
Part of the hair cell in the inner ear and neuromast of vertebrates.
Tissue
An aggregation of related cells linked together by various types of intercellular connections.
Titin
A very large protein that runs along the thin filament in striated muscle, determining its length and orienting into the sarcomere.
Toll-Like Receptors, or TLRs
An ancient group of receptors found on cells of the innate immune system, responsible for detection of pathogens.
Tonic Muscle
see also phasic muscle
A muscle type with a slow contraction that persists for long periods.
Tonic Receptor
A receptor that produces action potentials throughout the duration of a stimulus.
Tonicity
The property of an extracellular solution that determines whether a cell will swell or shrink.
Torpor
A type of dormancy characterized by a relatively short period of hypometabolism.
Total Lung Capacity
The volume of air in the lungs at the end of a maximal inspiration; the maximum amount of air that can be held in the lungs.
Total Peripheral Resistance
The net resistance of the vasculature.
Totipotent Stem Cell
An embryonic cell that has the capacity to differentiate into any type of cell when given the appropriate cell signaling information.
Trabeculae
Any partition that divides or partially divides a cavity
Trachea (plural: tracheae)
The single large airway leading to the paired bronchi of vertebrate lungs; also, the nonhomologous respiratory structures that are the main conducting airways in arthropod tracheal systems.
Tracheal System
The respiratory structures of insects and some other groups of air-breathing arthropods.
Tracheoles
The terminal structures of arthropod tracheal systems across which gas exchange takes place.
Tracts
Groupings of axons within the central nervous system of vertebrates.
Transcellular Transport
Movement of solutes or water across a cell layer through the cell itself, typically crossing both apical and basolateral cell membranes.
Transcription
RNA synthesis using the DNA template of a gene.
Transcytosis
Vesicular transport of materials across a cell.
Transducin
An inhibitory G protein involved in visual signal transduction in the vertebrates.
Transgenic Animal
An animal that has been genetically modified to possess a heritable mutation.
Transition State
A temporary, intermediate state in the conversion of substrate to product when a molecule obtains enough energy to reach the activation energy barrier.
Translation
Protein synthesis using ribosomes and mRNA template.
Transmembrane Receptor
A receptor protein that spans the cell membrane; consists of an extracellular domain, a transmembrane domain, and an intracellular domain.
Transmembrane Receptor
A receptor protein that spans the cell membrane; consists of an extracellular domain, a transmembrane domain, and an intracellular domain.
Transmural Pressure
The pressure difference across the wall of a chamber (e.g., a blood vessel, heart, or airway).
Transpirational Water Loss
Water loss arising from gas exchange across the respiratory surface.
Transpulmonary Pressure
The difference between the intra-alveolar pressure and the intrapleural pressure in mammalian lungs.
Triacylglycerol
or triglyceride
Three fatty acids esterified to a glycerol molecule.
Tricarboxylic Acid (TCA) Cycle
The cyclical mitochondrial pathway that oxidizes acetyl CoA to form 3 NADH, 1 FADH2, and 1 GTP; the pathway that produces most of the CO2 arising from metabolism.
Trichromatic Color Vision
The system of three different photoreceptors by which humans and some other animals obtain color vision.
Tricuspid Valve
The valve between the right atrium and right ventricle of the mammalian heart.
Trimer
A molecule composed of three subunits.
tRNA
or transfer RNA
A cloverleaf-shaped RNA molecule that binds a particular amino acid and participates in translation, binding to a three-nucleotide sequence of mRNA (codon) to transfer the amino acid to a growing polypeptide.
Triploblastic
Having three primary germ layers.
Trophoblast
An outer layer of cells derived from the mammalian blastocyst that forms the interface between the fertilized ovum and the uterine wall.
Trophosome
Found in the body of vent worms, this sac contains endosymbiotic bacteria.
Tropic Hormones
or trophic hormones
Hormones that cause the release of other hormones.
Tropomyosin
A regulatory protein that stretches across seven actin monomers in a thin filament, controlling myosin’s access to its binding site on the thin filament.
Troponin
A trimeric regulatory protein bound to tropomyosin. It responds to high [Ca2+] by inducing tropomyosin to move into a position that allows myosin to bind actin.
T-tubule
An extension of the plasma membrane (sarcolemma) of some muscles that serves to improve the conduction of the action potential into the fiber.
Tubulin
The monomeric protein subunit of microtubules, itself a dimer of alpha-tubulin and beta-tubulin.
Tunica Externa
Outer layer of the wall of a vertebrate blood vessel.
Tunica Intima
Inner layer of the wall of a vertebrate blood vessel.
Tunica Media
Middle layer of the wall of a vertebrate blood vessel.
Turbulent Flow
A disordered pattern of fluid flow over the surface of an object that reduces the efficiency of movement of the object through the fluid.
Turnover Number
The number of times a single enzyme molecule completes a reaction cycle each second; also known as the catalytic constant (k_cat).
Turnover Rate
The number of catalytic events in a given period of time. For an individual enzyme, it is synonymous with the catalytic constant (k_cat). It can also be used to describe the rate of synthesis and degradation of a metabolite, such as ATP.
T Wave
The portion of an electrocardiogram (EKG) that represents the repolarization of the ventricle.
Twitch Fibers
Muscle fibers that undergo a rapid contraction/relaxation cycle (a twitch), in contrast to tonic fibers.
Twitch Muscle
A muscle that contracts and relaxes once after each neuronal stimulus; a phasic muscle.
Tympanal Organ
Sensory receptor involved in hearing in insects; insect ears.
Tympanic Membrane
Thin membrane that separates the outer ear from the middle ear. Helps to transfer sound vibrations to the inner ear.
