C Flashcards
C Region
The part of an antibody that is constant
in sequence and structure.
Cable Properties
The electrical properties of axons.
Calcitonin
A thyroid hormone that helps regulate Ca2+ levels, typically opposing the effects of parathyroid hormone, lowering plasma Ca2+ levels.
Calcium-Induced Calcium Release
A mode of muscle activation where calcium crossing the
sarcolemma through a Ca2+ channel causes a Ca2+ channel in the sarcoplasmic reticulum to open.
Caldesmon
A calcium-binding protein important in the regulation of smooth muscle
contractility.
Calmodulin
A calcium-sensing protein involved in many signal transduction pathways.
Caloric Deficit
The condition in which energy derived from the diet is less than energetic expenditure, resulting in net loss of energy by the animal.
Calorie
A unit of heat equal to 4.2 joules; nutritional literature may refer to the unit Calorie, which is equivalent to 1,000 calories. The unit of heat required to raise 1 g of water at 1 atm by 1°C.
Calorimetry
The measurement of heat production as an index of metabolic rate.
Calsequestrin
A calcium-binding protein that allows a muscle to concentrate Ca2+ within the sarcoplasmic reticulum.
cAMP (cyclic AMP)
A second messenger produced by adenylate cyclase; most important
action is the stimulation of protein kinase A.
Capacitation
A maturation step experienced by sperm after they encounter fluids from the female reproductive tract.
Capillary
The smallest of the blood vessels in a closed circulatory system; the site of exchange of materials with the tissues.
Capillary Beds
A collection of capillaries.
Carbaminohemoglobin
Hemoglobin bound to carbon dioxide.
Carbohydrate
see also disaccharide, monosaccharide, polysaccharide
A group of organic molecules that share a preponderance of hydroxyl groups.
Carbonic Anhydrase (CA)
An enzyme that catalyzes the conversion of carbon dioxide and water to bicarbonate and protons.
Carboxyhemoglobin
Hemoglobin bound to carbon monoxide.
Cardiac Cycle
see also systole and diastole
The complete sequence of events from one heartbeat to the next.
Cardiac Muscle
A form of striated muscle that occurs in the heart.
Cardiac Output
The volume of blood pumped by the heart per unit time; the product of
heart rate and stroke volume.
Cardiomyocyte
A muscle cell found in the heart.
Cardiovascular Control Center
A region of the brain within the medulla oblongata that is involved in regulating heart rate and blood pressure.
Cardiovascular System
An alternate term for the circulatory system of animals such as
vertebrates. Consists of the heart, blood, and blood vessels.
Carotid Body
A structure located in the carotid artery leading to the head of vertebrates; contains baroreceptors and chemoreceptors.
Carotid Rete
A network of blood vessels that cools the brain.
Carrier Protein (or binding protein; binding globulin)
Blood proteins that help to transport hydrophobic molecules (such as steroid hormones) in the blood.
Carrier-Mediated Transport
All forms of transport across membranes that require a protein.
Cartilage
In vertebrates, a semisolid structure composed of the extracellular matrix of chondrocytes: the major component of the skeleton of chondrichthians but important in other vertebrates as a cushion between joints.
Catabolic Pathway (or catabolism)
A metabolic pathway that degrades macromolecules into smaller molecules.
Catadromous
see also anadromous
A life history strategy of fish (e.g., eels) in which the adult migrates from
freshwater to seawater to breed.
Catalysis
The progression of a chemical reaction that proceeds with the help of a catalyst.
Catalyst
A molecule that accelerates chemical reactions but is not changed in the process.
Catalytic Constant (k_cat)
The number of reactions catalyzed by a single molecule of enzyme per second.
Catecholamines
The biogenic amines epinephrine and norepinephrine.
Cation
An ion with a positive charge.
Caudal
A location near the posterior of an animal.
Cecum
A blind-ended sac that carries out digestive reactions in the gastrointestinal tract..
Cellular Immunity
Also known as cell-mediated immunity
A subdivision of the immune system that relies upon cells, rather than noncellular elements, such as antibodies.
Cellular Membranes
A general term that refers to the collection of membranes within a cell, including plasma membrane and organelle membranes.
Cellulose
A glucose polymer that serves a structural role in plants; indigestible by most animals without the assistance of symbionts.
Central Chemoreceptors
A group of chemoreceptors located in the medulla of vertebrate brains.
Central Lacteal
A small, saclike vessel in an intestinal villus; collects lipids that cross the intestinal epithelium.
Central Nervous System
The portion of the nervous system containing the primary integrating
centers. In vertebrates it consists of the brain and spinal cord. In invertebrates, it consists of the brain, the major ganglia, and the connecting commissures.
Cephalic
Toward the anterior end of an animal.
Cephalization
An evolutionary trend toward the centralization of nervous and sensory functions at the anterior end of the body (in the head).
Cerebellum
A part of the vertebrate hindbrain that is involved in maintaining balance and coordinating voluntary muscle movement.
Cerebral Cortex
Outer surface of the vertebrate brain.
Cerebral Hemispheres
Paired structures of the cerebrum (part of the vertebrate forebrain). The cerebral hemispheres are the most obvious structures of a mammalian brain.
Cerebrospinal Fluid (CSF)
A fluid contained within the meninges that surrounds the brain and spinal cord of vertebrates.
Cerebrum
The largest part of the mammalian forebrain.
cGMP Phosphodiesterase
An enzyme that cleaves cGMP, producing GMP.
Channel
A transport protein that facilitates the movement of specific ions or molecules across a cellular membrane down an electrochemical
gradient.
Chemical Energy
The energy associated with the reorganization of the chemical structure of a molecule.
Chemical Gradient
An area across which the concentration of a chemical differs, often across a membrane.
Chemical Synapse
A junction between a neuron and another cell in which the signal is
transmitted across the synapse in the form of a neurotransmitter.
Chemoautotroph
An organism that uses inorganic chemical energy to convert organic
sources of carbon and nitrogen into biosynthetic building blocks.
Chemokine
A cytokine that induces a cell to move.
Chemokinetic
An increase in nondirectional movement in response to the detection of a chemical.
Chemoreceptor
Used to describe either a cell containing chemoreceptive proteins, or
the proteins themselves. Chemicals such as hormones, odorants, and tastants bind specifically to chemoreceptor proteins, altering
their conformation and causing a signal within the chemoreceptor cell.
Chemotaxic
Movement toward higher concentrations of a chemical.
Chief Cell
The secretory cells of the gastric epithelium that release pepsin.
Chitin
A polymer of N-acetyl glucosamine used by arthropods to construct the exoskeleton.
Chloride Cell
also called a mitochondria-rich cell
An ion-pumping cell of fish gill epithelium.
Chloride Shift
The exchange of chloride and bicarbonate across the erythrocyte membrane.
Chlorocruorin
A type of hemoglobin found in some annelids; known as the green
hemoglobins.
Choanocytes
Flagellated cells of sponges that resemble the protist choanoflagellates.
Choanoflagellates
Flagellated protists that resemble the sponge cells known as choanocytes.
Cholesterol
A steroid compound produced from isoprene units; present in cellular membranes and acts as a precursor for steroid hormones.
Cholinergic Receptor
A receptor that binds the signaling molecule acetylcholine. Cholinergic receptors can be divided into nicotinic and muscarinic receptors.
Chondrocytes
The cells that produce cartilage.
Chordae Tendineae
Chordlike tendons that connect the atrioventricular valves of the mammalian heart to the papillary muscles and prevent the valve from opening backwards.
Chorion
The outer protein layer of an insect egg; the outer membrane of a vertebrate ovum.
Chorionic Gonadotropin (CG)
A third gonadotropin of vertebrates, produced by the placenta but only in primates.
Choroid
A highly pigmented layer of tissue located under the retinal pigment epithelium of the vertebrate eye.
Chromaffin Cells
Cells that secrete the hormone epinephrine (adrenaline). In mammals they are located in the compact adrenal medulla,
but in other vertebrates they are more dispersed.
Chromophore
A molecule that is able to absorb light. In photoreception, the chromophore absorbs the energy from incoming photons and undergoes a conformational change, which sends a signal to an associated G protein, in the first step of visual phototransduction.
Chromosome
A single, contiguous polymer of DNA found within the genome.
Chylomicron
A large lipoprotein complex that carries lipid from the digestive tract through the circulation to processing and target tissues.
Cilia (singular: cilium)
Microtubule-based extensions from a cell that move in a wavelike
pattern.
Ciliary Body
A part of the vertebrate eye that secretes the aqueous humor.
Ciliary Muscle
The muscle that controls the shape of the lens of the vertebrate eye; involved in producing a focused image.
Ciliary Photoreceptors (see also rhabdomeric photoreceptors)
One of two types of animal photoreceptor cells. Vertebrate photoreceptors belong to this class.
Circadian Rhythm
Regular changes in gene expression, biochemistry, physiology, and
behavior that cycle with a period of approximately 24 hours. Endogenous circadian rhythms persist even in constant darkness.
Circulatory System
A group of organs and tissues involved in moving fluids through the
body; consists of one or more pumping structures and a series of tubes or other spaces through which fluid can move.
Clathrin
A triskelion-shaped (three-armed) protein that coats some types of vesicles; vesicle formation begins with a clathrin-coated pit, which enlarges to form a clathrin-coated vesicle.
Cloaca
The distal portion of the hindgut in some fishes, amphibians, birds, and reptiles; in these species both excretory and reproductive products are emitted into the cloaca, and leave the body via a single opening.
Clonal Reproduction
A form of asexual reproduction whereby an animal produces a genotypically identical offspring (a clone).
Closed Circulatory System
A circulatory system in which the blood remains within a series
of enclosed blood vessels throughout the circulation.
Cnida
Within a cnidocyte, the subcellular capsule that houses the harpoon that is launched when the cnidocyte is stimulated.
Cnidocyte
The cells found in cnidarians that possess the cnida and the other structures needed to detect a physical disturbance and trigger the cnida to fire. One type of cnidocyte is a nematocyst.
Cochlea
Spiral structure in the inner ear of mammals; contains the organs of hearing. Less elaborate, but present in birds as the cochlear duct.
Derived from the lagena of other vertebrates.
Cochlear Duct
The part of the inner ear of birds that is involved in hearing; equivalent to the mammalian cochlea, but is present as a straight tube, rather than a spiral coil.
Coelom
The internal compartment of coelomate animals that forms between two layers of mesoderm.
Coenzymes
Organic cofactors.
Coenzyme A
A coenzyme derived from the vitamin pantothenic acid.
Cofactors
Nonprotein components of enzymes, including metals, coenzymes, and prosthetic groups.
Coitus
Sexual intercourse.
Collagen
A trimeric protein found in extracellular matrix. It interacts with other collagen molecules to form rigid fibers or durable sheets.
Collecting Duct
The tube that receives the fluid from the distal tubules of the nephron and empties into the minor calyx of the kidney.
Colligative Properties
Four properties of a solute that are due solely to the concentration of
solutes, and not their chemical nature.
Colon
A region of the large intestine primarily responsible for water resorption.
Compact Myocardium
(see also spongy myocardium)
One of the two types of heart muscle), consisting of tightly packed cells arranged in a regular pattern; the predominant form of muscle in the mammalian heart.
Compatible Solute
A solute that, at high concentration, does not disrupt protein structure
or enzyme kinetics.
Competitive Inhibitors
A mode of enzyme inhibition in which a molecule competes with
the substrate for the active site on the enzyme; competitive inhibitors have the effect of reducing the apparent substrate affinity
without affecting V_max.
Complement
Part of the immune system, this collection of proteins found in the blood augments the innate immune system response, and in some cases also helps promote the adaptive immune system.
Compliance
A measure of the ability of a hollow structure (e.g., blood vessel, lung) to stretch in response to an applied pressure.
Compound Eye
A type of eye seen in arthropods; consists of many individual photoreceptive structures.
Concurrent
An anatomical arrangement of the flow across a gas-exchange surface where the flow of the respiratory medium is in the same direction as the flow of blood through the gas-exchange surface.
Conduction
Transfer of heat from one object to another object or a fluid.
Cone
see also rod
A type of vertebrate photoreceptor cell. Cones are typically responsible for color vision in bright light.
Conformer
A strategy whereby the physicochemical properties of an animal (e.g., temperature and osmolarity) parallel those of the environment
Conservation of K_m
A pattern in which enzymes from different animals share a similar K_m when assayed under conditions that approximate those that occur in the animal.
Constitutive
Usually describes a gene for a protein that is expressed at near-constant levels regardless of conditions; can be applied to the protein itself, as in “a constitutive enzyme.”
Continuous Capillaries
The most common type of capillary, found in organs such as skin
and muscle; these capillaries have low permeability because they are surrounded by a complete basement membrane and most of the intercellular contacts are sealed by tight junctions, although this seal is not complete, allowing fluids and small molecules to pass from the blood to the interstitial fluid.
Contractile Summation
When different motor nits are recruited to increase the force of
contraction of a muscle.
Contractility
A measure of cardiac performance related to the ability of the heart muscle to contract.
Conus Arteriosus
see also bulbus arteriosus
The outflow tract of the heart ventricle in elasmobranchs, lungfish, and
amphibians; muscular and valved.
Convection
Fluid circulation driven by temperature gradients; a special case of bulk flow.
Convergence
A pattern in a neural pathway in which multiple presynaptic neurons form synapses with a single postsynaptic neuron.
Convergent Evolution
The independent evolution of similar traits in distantly related or
unrelated taxa.
Cooperativity
A phenomenon demonstrated by multimeric proteins in which binding of a ligand to one protein subunit increases the
likelihood of binding to other subunits. Seen in vertebrate blood hemoglobins.
Cornea
The clear outer surface of an eye. The cornea of an insect ommatidium and a vertebrate eye are analogous structures, but they are not homologous.
Corneocyte
A cell type derived from keratinocytes that forms the stratum corneum of the skin.
Coronary Artery
Artery that supplies blood to the heart in vertebrates.
Coronary Circulation
The blood vessels that supply oxygenated blood to the heart of vertebrates.
Corpus Allatum (plural: corpora allata)
A paired neurohemal organ in arthropods that secretes juvenile hormone.
Corpus Callosum
A thick band of axons that connects the right and left hemispheres of
the vertebrate brain.
Corpus Cardiacum (plural: corpora cardiaca)
A paired neurohemal organ in arthropods that secretes adipokinetic hormone.
Corpus Luteum
The remnants of a mammalian ovarian follicle that grows in size and becomes an endocrine organ that secretes hormones in support of embryonic development
Cortex
The surface or outer layer of an organ (e.g., the cortex of the kidney; the cerebral cortex; cortical bone).
Cortisol
A steroid hormone that is produced in response to stress in mammals and fish.
Cost of Transport (COT)
The energetic cost for an animal to cross a given distance.
Counteracting Solutes
Pairs of solutes that act in conjunction to offset the detrimental effects that would arise if either solute were present alone.
Countercurrent
A situation in which two fluids flow in opposite directions on either side of an exchange surface.
Countercurrent Exchanger
A structure in which two fluids flow in opposite directions on either
side of an exchange surface, allowing high-efficiency exchange of materials purely by passive means; e.g., heat exchange in a rete.
Countercurrent Multiplier
A structure in which two fluids flow in opposite directions
on either side of an exchange surface, allowing. high-efficiency exchange of materials by active means; e.g., ion concentration in the
loop of Henle.
Covalent Bonds
Strong chemical bonds involving the sharing of electrons between two atoms.
Covalent Modification
Alteration of a macromolecule by the addition (or removal) of another molecule by forming (or breaking) a covalent bond; e.g., glycosylation, methylation, acetylation, and phosphorylation.
Cranial Nerves
A group of vertebrate nerves that originate in the brain. Vertebrates have 12 or 13 pairs of cranial nerves depending on the species.
Creatine Phosphate
A high-energy phosphate compound used to store energy and to facilitate its transfer from the sites of energy production (mitochondria) to the sites of utilization, such as myofibrils.
Cristae
The highly convoluted inner membrane of mitochondria.
Critical Thermal Maximum
The highest environmental temperature tolerated by an animal.
Crop Milk
Produced by some birds, a regurgitated slurry of nutrients arising from ingested material augmented by secretions.
Cross-bridge
The linkage of a myosin head to an actin subunit; an essential step in actinomyosin mechanoenzyme activity.
Crosscurrent
A situation in which the flow of the respiratory medium is at an angle to the flow of blood through the exchange surface; seen in bird lungs.
Crypt of Lieberkühn
A pit at the base of intestinal villi.
Cryptobiosis
A dormant state in which an animal experiences a severe (but reversible) metabolic depression during adverse conditions.
Cryptochrome
A blue light–sensitive flavoprotein; involved in circadian rhythms and
magnetoreception.
Cutaneous Respiration
Gas exchange across the skin.
Cuticle
The outer layer of the arthropod exoskeleton; composed of chitin and proteins.
cyclic AMP (cAMP)
Cyclic adenosine monophosphate formed by the action of adenylate
cyclase; a second messenger that activates protein kinase A.
cyclic GMP (cGMP)
Cyclic guanosine monophosphate formed by the action of guanylate cyclase; a second messenger that activates protein kinase G.
Cytochromes
Metalloproteins produced from porphyrins that are central to many enzymatic reactions, including the mitochondrial electron transport chain (cytochromes a, a3, b, c) and cytochrome P450 enzymes.
Cytochrome P450 Aromatase
An enzyme in steroid metabolism that converts androgens to estrogens.
Cytokines
Hormones that trigger cell division.
Cytoplasm
Soluble and particulate interior of a cell, excluding the nucleus.
Cytosine
A nucleoside composed of cytidine and a ribose sugar.
Cytoskeleton
Intracellular protein network of microtubules, microfilaments, and intermediate filaments.
Cytosol (also known as intracellular fluid)
Fluid portion of the cytoplasm.
