BIOLOGY DEFINITION OVERVIEW Flashcards
a muscle that moves a limb away from the center of the body
abductor
the process by which substances are taken up into or across tissues
absorption
a neurotransmitter found throughout the nervous system; metabolized by acetylcholinesterase
acetylcholine
the large vesicle at the head of a sperm cell containing enzymes that degrade the ovum cell membrane to allow fertilization
acrosome
a protein found in the cytoskeleton and muscle cells; it is the principal constituent of the thin filaments and microfilaments
actin
an abrupt change in the membrane potential of a nerve or muscle cased by changes in the membrane ionic permiability
action potential
an immune response acquired in response to exposure to an antigen
active immunity
substrate-binding region of an enzyme
active site
the development of characteristics that enable an organism to survive and reproduce in its habitat
adaption
highly-specific form of immunity that retains chemical memory of each invader encountered and is able to tailor the immune response to the specific pathogen
adaptive immunity
the evolutionary process by which one species gives rise to several species, each specialized for difference niches
adaptive radiation
the muscle that moves a limb towards the center of the body
adductor
a purine base present in DNA and RNA; forms H bonds with thymine and uracil
adenine
a nucleotide molecule consisting of adenine, ribose, and three phosphate moieties
adenosine triphosphate
refers to fatty tissue
adipose
refers to a biological process that occurs in the presence of molecular oxygen or to organisms that cannot live without molecular oxygen
aerobic
a neuron that picks up impulses from sensory receptors and transmits them toward the central nervous system
afferent (sensory) neuron
a type of leukocyte that does not contain cytopalsmic granules, including lymphocytes and monocytes
agranulocytes
protein synthesized in the liver that maintains the oncotic pressure of the blood and serves as a carrier for many drugs and hormones
albumin
one of four embryonic membranes; it contains the growing embryo’s waste products
allantois
alternative forms of the same gene coding for a particular trait
allele
a type of autoimmunity in which a person’s immune system becomes overactivated by common substances in the environment
allergy
basic functional unit of the lung; a tiny sac specialized for passive gas exchange between the lungs and the blood
alveolus
the building blocks of proteins, each containing an amino group, a carboxylic acid group, and a side chain attached to the alpha carbon
amino acids
the innermost fluid-filled embryonic membrane; it forms a protective sac surrounding the embryos of birds, reptiles, and mammals
amnion
characteristic of a signaling cascade, in which the binding of a single peptide hormone to a membrane-bound receptor results in a signal that increases in strength through the signaling cascade
amplification
refers to a biological process that can occur without oxygen or to organisms that can live without molecular oxygen
anerobic
the stage of mitosis or meiosis characterized by the migration of chromatids or homologous chromosomes to opposite poles of the dividing cells
anaphase
any male sex hormone, such as testosterone
androgen
substance that kills or inhibits the growth of bacteria or fungi
antibiotic
immune or protective protein whose synthesis is induced by the presence of foreign substances in the body
antibody
a substance that binds to an antibody; may be foreign or a self-antigen
antigen
portion of an antibody that is specific for a particular antigen
antigen-binding region
one of the semilunar valves, separating the left ventricle and the aorta
aortic valve
process by which a cell undergoes programmed cell death in a highly organized manner in response to either external or internal signals
apoptosis
peripheral portion of the skeleton consisting of arms, legs, and pelvic and pectoral girdles
apendicular skeleton
the central cavity in the gastrula stage of embryological development; it is lined by endoderm and ultimately gives rise to the adult digestive tract
archenteron
small arterial structures that link the arteries to the capillaries
arterioles
thick-walled, muscular blood vessel that generally carries blood away from the heart
artery
cartilaginous coating at the ends of bones that provides a smooth surface for articulation of bones within a joint
articular cartilage
any reproductive process that does not involve the fusion of gametes
asexual reproduction
star-shaped structures that form around the centrosome during mitosis
asters
one of two paired structures on either side of the heart, into which blood returning from either the body or the lungs flows
atrium
form of cell-cell communication in which a cell released a substance that then binds to the membrane of the releasing cell to either inhibit or activate a cellular activity
autocrine
inappropriate immune response that targets self-antigens
autoimmunity
subdivision of the peripheral nervous system responsible for involuntary activities, which is further subdivided into the parasympathetic and sympathetic nervous systems
autonomic nervous system
any chromosome other than a sex chromosome
autosome
midline structures of the skeleton including the skull, vertebral column, and ribcage; provides the central framework for the body
axial skeleton
the long fiber of a neuron; it conducts impulses away from the cell body toward the synapse
axon
transition point between the cell body and the axon of a neuron; the site of action potential initiation
axon hillock
rod-shaped bacterium
bacillus
a virus that invades bacteria and sometimes uses bacterial RNA and ribosomes to self-replicate
bacteriophage
type of granulocytic leukocyte that largely participates in allergic reactions and local inflammation
basophil
a solution of salts, pigments, and cholesterol produced by the liver and stored in the gallbladder that emulsifies fats
bile
product of the breakdown of hemoglobin that is modified to a more soluble form in the liver
bilirubin
a type of asexual reproduction characteristics of prokaryotes in which there is equal nuclear and cytoplasmic division
binary fission
the fluid-filled central cavity of the blastula
blastocoel
a mammalian blastula, consisting of the trophoblastic cells and an inner cell mass
blastocyst
opening of the archenteron on the external environment in the gastrula stage of embryonic development
blastopore
the early embryonic stage during which the embryo is a hollow, fluid filled sphere of undifferentiated cells
blastula
process by which a solid mass of early embryonic cells, known as the morula, becomes the blastula, a hollow fluid filled sphere of undifferentiated cells
blastulation
change in the affinity of hemoglobin for oxygen caused by changes in the environment; when pH s low, the oxyhemoglobin dissociation curve shifts right, indicating a decreased affinity of hemoglobin for oxygen and more efficient off-loading of oxygen from hemoglobin
Bohr Effect
an initial dose of medication; in the digestive system, chewed food leaving the mouth, traveling through the esophagus, and entering the stomach
bolus
central portion of bones, especially long bones, that contains fat and developing blood cells, including erythrocytes, leukocytes, megakaryocytes
bone marrow
organic and inorganic minerals that provide strength to compact bone; organic components include collagen, glycoproteins, and other peptides; inorganic components include calcium, phosphate, and hydroxide ions
bone matrix
the cuplike structure of the nephron; it collects the glomerular filtrate and channels it into the proximal convoluted tubule
Bowman’s capsule
tubelike passages for air that connect the trachea to the bronchioles
bronchi
passageways for air that start at the bronchi, dividing into continuously smaller passageways that eventually lead to the alveoli, where gas exchange occurs
bronchioles
group of enzymes present on the luminal surface of cells lining the duodenum that break down larger biomolecules into monomers that are able to be absorbed
brush boarder enzymes
part of the conduction system of the heart; it carries impulses from the AV node to the ventricles
Bundle of His
area of excessive deposition of keratin in response to repeated strain due to friction
callus
small canals connecting lacunae within the bone matrix with Haversian canals, allowing for the flow of nutrients and wastes
canaliculi
small, thin-walled vessel where gas, nutrient, and waste exchange occurs between blood and tissue
capillary
protein coat surrounding a virus
capsid
total blood volume pumped by the left ventricle in one minute, found by multiplying the heart rate by the stroke volume
cardiac output
a firm, elastic, translucent connective tissue produced by cells called chondrocytes
cartilage
the chemical breakdown of complex substances to yield simpler substances and energy
catabolism
the first part of the large intestine; accepts material flowing through the ileocecal valve and is the point of attachment of the appendix
cecum
portion of a neuron where the nucleus, endoplasmic reticulum, and ribosomes are located; also known as the soma
cell body
a foundational belief in modern biology that all living things are composed of cells, that the cell is the basic functional unit of life, that all cells arise from preexisting cells, and that DNA is the genetic material
cell theory
type of immunity that uses cytotoxic chemicals released from cells to cause death of cells that have been infected by viruses
cell-mediated immunity
the brain and spinal cord
central nervous system
a small organelle in the cytoplasm of animal cells; it organizes the spindle apparatus during mitosis or meiosis
centrioles
the area of a chromosome where sister chromatids are joined; it is also the point of attachment to the spindle fiber during mitosis and meiosis
centrosomes
the section of the mammalian hindbrain that controls muscle coordination and equilibrium
cerebellum
the outer layer of the forebrain, consisting of grey matter; it is the site of higher cognitive functions in humans
cerebral cortex
lower end of the uterus that marks the transition between the vagina and the uterus
cervix
enzymatic cleavage of chemical bonds within foodstuffs, resulting in smaller molecules
chemical digestion
movement of cells toward or away from a chemical within the environment
chemotaxis
sites where crossing over occurs between homologous chromosomes during meiosis
chiasmata
cells within the stomach that secrete pepsinogen, a zymogen that is converted to its active form, pepsin, by the acidic environment of the stomach
chief cells
elastic cartilage matrix substance secreted by chondrocytes
chrondin
a differentiated cartilage cell that synthesizes the cartilaginous matrix
chondrocyte
each of the two chromosomal strands formed by DNA replication in the S phase of the cell cycle; held together by the centromere
chromatid
a filamentous body found within the nucleus of a eukaryotic cell or nucleoid region of a prokaryotic cell, composed of DNA
chromosome
soluble lipid molecule that consists of triglycerides and esterified cholesterol molecules; absorbed into lacteals from the digestive tract
chylomicron
aqueous mixture of food and secretions that leaves the stomach to enter the duodenum
chyme
projection from a cell involved in movement of materials on the outside of the cell
cilia
a behavioral pattern based on a 24-hour cycle, related to cycling of hormones such as cortisol and melatonin
circadian rhythm
a series of mitotic divisions of the zygote immediately following fertilization, resulting in progressively smaller cells with increased nucleus-to-cytoplasm ratios
cleavage
phenomenon in which only B- or T-cells specific to a particular pathogen are activated
clonal selection
spherically shaped bacterium
coccus
a genetic effect in which the phenotype of a heterozygote is a distinct reflection of both alleles at a particular locus
codominance
describes the cell capable of responding to induction signals
competent
the temporary joining of two organisms via a tube called a pilus, through which genetic material is exchanged; a form of sexual reproduction used by bacteria
conjugation
animal tissue composed of cells lying in an extracellular proteinaceous network that supports, connects, and surrounds the organs and structures of the body
connective tissue
portion of an antibody molecule that is not variable and participates in the binding of other immune modulators
constant region
the process by which unrelated organisms living in a similar environment develop analogous structures
convergent evolution
layer of cells surrounding an oocyte that aid in the development of the ovum
corona radiata
the remnant of the ovarian follicle, which after ovulation continues to secrete progesterone. its degeneration leads to menstruation; it also maintains the uterine lining during pregnancy
corpus luteum
the external layer found in many organs of the body, including the brain, adrenal glands, and kidney
cortex
release of calcium ions by an ovum after fertilization, resulting in the creation of a fertilization membrane, a structure that prevents fertilization of an ovum by multiple sperm cells
cortical reaction
steroid hormones produced in the adrenal cortex, including glucocorticoids (cortisol), mineralocorticoids (aldosterone), and cortical sex hormones
corticosteroids
the exchange of genetic material between homologous chromosomes during meiosis
crossing over
an intracellular second messenger in the signaling cascade initiated by a peptide hormone; synthesized from ATP by adenylate cyclase
cyclic adenosine monophosphate (cAMP)
chemical substance that stimulates inflammation and recruits additional immune cells to a specific area
cytokine
the division and distribution of parent cell cytoplasm to the two daughter cells during mitotic and meiotic cell division
cytokinesis
the fluid and solutes within a cell membrane, external to the nucleus and cellular organells
cytoplasm
T-cell that seeks out infected cells and induces apoptosis in these cells to prevent spread of the pathogen
cytotoxic T-cell
a type of gene mutation in which some variable amount of DNA is removed
deletion
the portion of a neuron that receives stimuli and conveys them toward the cell body
dendrite
the layer of the skin cells under the epidermis; contains sweat glands, hair follicles, fat, and blood vessels
dermis
rapid mitotic divisions occurring in an embryo that result in cells with predetermined fates; these cells are only capable of differentiating into certain kinds of tissues within an organism
determinate cleavage
designation of a cell within an embryo as having a particular future function
determination
thin, muscular structure that divides the thorax from the abdomen and provides the driving force for inhalation
diaphragm
cylindrical shaft of a long bone
diaphysis
the period of relaxation of cardiac muscle during which the atrioventricular valves open and the ventricles fill with blood
diastole
the process by which unspecialized cells become specialized
differentiation
the breakdown of macromolecular nutrient material via mechanical and chemical means to simple molecular building blocks
digestion
having two chromosomes of each type per cell; symbolized by 2n
diploid
substance secreted into the bloodstream that causes a change in the physiological activity of cells without requiring an intermediary
direct hormone
selective pressures favor the development of an extreme phenotype that provides a selective advantage; this phenotype emerges as the primary phenotype over time
directional selection
type of selection in which selective pressures favor extreme phenotypes over the norm
disruptive selection
a process of change whereby organisms with a common ancestor evolve dissimilar structures
divergent evolution
refers to an allele that requires only one copy for expression
dominant
fetal structure that shunts blood from the pulmonary artery to the aorta to bypass the developing lungs
ductus arteriosus
shunt from the umbilical vein to the inferior vena cava, allowing oxygenated blood returning from the placenta to bypass the liver and the systemic circulation
ductus venosus
first segment of the small intestine; the contents of the stomach and the pancreatic and bile ducts empty into it
duodenum
