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166 Cards in this Set
- Front
- Back
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acrosome |
the large vesicle at the head of a sperm cell containing enzymes that degrade the ovum cell membrane to allow fertilization |
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action potential |
a sharp change in the membrane potential of neurons or muscle cells caused by a change in the selective permeability to Na⁺ and K⁺ using voltage-gated ion channels. action potentials are all-or-nothing events |
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adaptive immunity |
a highly specific form of immunity that develops in response to exposure to pathogens; consists of both humoral immunity and cytotoxic immunity |
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adrenal cortex |
synthesizes and releases corticosteroids. glucocorticoids are stimulated by adrenocorticotrophic hormone (ACTH), whereas mineralocorticoids are stimulated by angiotensin 2. cortical sex hormones include androgens like testosterone |
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adrenal medulla |
synthesizes and releases epinephrine and norepinephrine, which stimulate an increase in the metabolic rate and blood glucose levels |
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adrenocorticotrphic hormone (ACTH) |
synthesized and released by another anterior pituitary, ACTH stimulates the adrenal cortex to synthesize and secrete glucocoticoids. ACTH is regulated by corticotropin releasing factor (CRF), which is released by the hypothalamus |
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afferent neurons |
neurons that carry information to the central nervous system from the periphery. also called sensory neurons |
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aldosterone |
a steroid hormone produced in the adrenal cortex that is responsible for reabsorption of sodium and water and excretion of potassium and hydrogen ions |
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allantois |
the embryonic membrane that containsthe growing embryo's waste products |
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alleles |
genes coding for laernative forms of a given trait |
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amino acid-derivative hormones |
hormones that are synthesized by modifying amino acids. most amino acid-derivative hormones act via secondary messengers, while some act in a fashion similar to steroid hormones |
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nion
aam |
the innermost extraembryonic membrane; produces the amniotic fluid in which the growing fetus is suspended |
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anterior pituitary |
synthesizes and releases many vital hormones, including follicle-stimulating hormone, luteinizing hormone, adrenocorticotrpic hormone, thyroid-stimulating hormone, prolactiin, endorphins, and growth hormone ("FLAT PEG"). the anterior pituitary is under the hormonal control of the hypothalamus |
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antidiuretic hormone (ADH) |
a peptide hormone, also known as vasopressin, which acts on the collecting duct to increase water reabsorption. ADH is produced by the hypothalamus and stored in the posterior pituitary |
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antigen |
a substance that is bound by an antibody causing an immune reaction |
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appendicular skeleton |
the bones of the pelvis, the pectoral girdles, and the limbs |
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archenteron |
the central cavity in the gastrula stage of embryological development; it is lined by endoderm and ultimately gives rise to the adult digestive tract |
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arteries |
vessels that carry blood away from the heart. these vessels are muscular and do not have valves |
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ascending limp of the loop of henle |
portion of the nephron not permeable to water. as the filtrate flows up the ascending limn through a decreasing concentration in the interstitium, NaCl is first passively, then actively removed from the filtrate, decreasing filtrate concentration |
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atria |
the two thin-walled upper chambers of the heart, the right atrium receives deoxygenated blood from the venae cavae, while the left atrium receives oxygenated blood from the pulmonary veins |
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atrioventricular valves |
valves located between the atria and the ventricles (tricuspid valve and mitral valve) |
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axial skeleton |
the skull, vertebral column, ribcage, and hyoid bone |
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axon hillock |
the portion of the neuron that connects the cell body (soma) to the axon. the impulses the neuron receives from all the dendrites are summed up at the axon hillock to determine whether or not an action potential will be initiated |
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bacteriophages |
viruses that can only infect bacteria |
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bile |
an alkaline fluid synthesized in the liver, stored in the gall bladder, and released into the duodenum. bile aids in emulsification, digestion, and absorption of fats
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binary fission |
method of asexual reproduction by which prokaryotes divide. the circular DNA molecule replicates and then moves to the edge of the cell. the cell then divides into two daughter cells of equal size |
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blastulation |
the process by which a morula develops into a blastula with a fluid filled cavity called a blastocoel |
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blood antigens |
proteins found on the erythrocyte cell surface. three antigens used to differentiate blood group are A,B, and Rh. If a host organism is transfused with erthrocytes containing antigens that the host does not have, an immune response will be triggered, leading to hemolysis |
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blood buffer system |
relies primarily on the carbonic acid buffer system demonstrated by the equation CO₂+H₂) ↔ H₂CO³↔H⁺ +HCO₃⁻ release of carbon dioxide causes increased formation of water and an increase in pH. increased retention of HCO₃⁻ causes the pH to rise as well |
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calcitonin |
hormone synthesized and released by the thyroid gland that decreases plasma Ca²⁺ concentration |
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capillaries |
blood vessels composed of a single layer of endothelial cells, facilitating exchange of gases, nutrients, and waste products between the blood and interstitial fluid |
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carbonic anhydrase |
enzyme that catalyzes the conversion of carbonic acid to carbon dioxide and water as well as the formation of carbonic acid from carbon dioxide and water. important in the bicarbonate buffer system |
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cardiac muscle |
type of muscle found within the heart; may contain one or two nuclei. involuntary, like smooth muscle, but appears striated, like skeletal muscle. able to depolarize independent of the nervous system. |
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cartilage |
a firm, elastic, translucent connective tissue consisting of collagenous fibers embedded in chondrocytes. cartilage is the principle component of embryonic skeletons and can harden and calcify into bone (ossify) |
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catecholamines |
norepinephrine, epinephrine, and dopamine-neurotransmitters; also, hormones produced by adrenal cortex that play a significant role in the sympathetic nervous system |
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cell-mediated (cytotoxic) immunity |
branch of the immune system in which intracellular pathogens are eliminated by killing their host cells. t-cells are the primary mediators of cytotoxic immunity |
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cell theory |
a foundational belief in modern biology that all living things are composed of cells, the cell is the basic functional unit of life, that all cells arise from preexisting cells, and that DNA is the genetic material |
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central nervous system |
the central nervous system consists of the brain and the spinal cord |
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centrosome |
the portion of the cell containing the centrioles |
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chemical digestion |
enzymatic breakdown of large molecules into smaller molecules |
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cholecystokinin (CCK) |
a hormone that is secreted by the duodenum in response to the presence of chyme. CCK stimulates the release of bile and pancreatic enzmes into the small intestine, and promotes satiety |
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chorion |
the outermost extraembryonic membrane; contributes to the formation of the placenta |
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chromatin |
chromosome in their uncoiled state. chromatin itself is not visible as organized chromosomes under a light microscope |
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chyme |
combination of partially digested food and acid that forms in the stomach |
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codominance |
describes a situation in which an organism heterozygous for a trait will have a phenotype that expresses both alleles in full. both alleles, therefore, are dominant |
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collecting duct |
portion of the nephron permeable to water and ions. as the filtrate flows down the collecting duct through the increasing concentration of the interstitium, the filtrate is concentrated. the degree of water reabsorption in the collecting duct is controlled by the action of the hormone ADH |
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compact bone |
much more dense than spongy bone, compact bone consists of haversian systems (osteons) |
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conjugation |
the temporary joining of the organisms via a tube called a pilus, through which genetic material is exchanged; a form of sexual reproduction used by bacteria |
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corona radiata |
outer layer of cells surrounding the oocyte. these cells are derived from follicular cells |
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corpus luteum |
tissue that forms from the collapsed ovarian follicle. produces and secretes progesterone and estrogen |
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crossing over |
the exchange of genetic material between homologous chromosomes that occurs during prophase I of meiosis. crossing over aids in evolution and genetic diversity by unlinking linked genes |
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dendrite |
an extension of the neuron that transmits impulses toward the cell body |
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depolarization |
a process that occurs when the voltage-gated Na⁺ to rush into the cell and depolarize it |
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dermis |
the layer of skin beneath the epidermis that is subdivided into the papillary layer and the reticular layer. it contains the sweat glands, sense organs, blood vessels, and the bulbs of hair follicles; it is derived from the mesoderm |
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descending limb of the loop of henle |
portion of the nephron permeable only to water. the filtrate becomes more concentrated (loses water) as it travels through the descending limb due to the increasing concentration of the interstitium |
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determinate cleavage |
division of cells during embryogenesis in which each cell specializes early in development. by extension, each cell is not necessarily able to differentiate into an entire organism on its own |
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diaphysis |
cylindrical shaft of a long bone. filled with bone marrow for the production of blood cells |
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diastole |
the stage of the cardiac cycle in which heart muscle relaxes and collects blood into its chambers |
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diploid |
cells with two copies of each chromosome, usually one from the mother and one from the father. eukaryotic somatic cells are diploid |
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direct hormones |
hormones that travel to a target tissue to cause an action without another hormone acting as an intermediary |
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directional stabilization |
type of natural selection where one extreme phenotype is favored over the average phenotype and other extreme phenotypes |
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disjuntion |
the separation of homologous chromosome during anaphase I of meiosis |
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disruptive selection |
type of natural selection where both phenotypic extremes are favored over the average phenotype |
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dizygotic twins |
results when two ova are fertilized by two different sperm. because the two resulting embryos develop from distinct zygotes, they do not have identical alleles |
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dominant |
describes an allele that requires only one copy to be expressed |
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ductus arteriosus |
a shunt that connects the pulmonary artery to the aorta in order to bypass the fetal lung |
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ductus venosus |
a shunt that connets the umbilical vein to the inferior vena cava in order to bypass the fetal liver |
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ectoderm |
the outermost of the three primary germ layers; gives rise to the skin, nervous system, lens of the eye, and inner ear |
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efferent neurons |
neurons that carry information from the central nervous system to other parts of the body. also called motor neurons |
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endocrine glands |
glands that synthesize and secrete hormones into the circulatory system. examples include the hypothalamus, pituitary gland, pineal gland, pancreas, testes, ovaries, adrenal glands, thyroid gland, and parathyroid glands |
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endoderm |
the innermost of the three primary germ layers; gives rise to the linings of the digestive and respiratory tracts and to parts of the liver, pancreas, thyroid, and bladder |
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endometrium |
the mucosal lining of the uterus where the embryo implants. progesterone is necessary for the maintenance of the endometrium during pregnancy |
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endorphins |
synthesized and released by the anterior pituitary, endorphins inhibit the perception of pain |
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endothelial cells |
cells that line blood vessels. these cells are able to produce and release chemicals that aid in vasodilation and vasoconstriction. in addition, damage to these cells results in the release of mediators that aid clotting |
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enteric nervous system |
a collection of millions of neurons within the gastrointestinal system that governs the function of the GI tract. this system is able to function independently of the brain and spinal cord |
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enteropeptidase |
digestive enzyme secreted by cells in the duodenum. this enzyme converts trypsinogen to trypsin. trypsin is then able to activate other pancreatic enzymes to allow digestion to continue within the duodenum |
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epidermis |
the outermost layer of skin, which is composed of the following sublayers: stratum basalis, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum. serves as a protective barrier against microbial attack. derived from the ectoderm |
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epiglottis |
a flap of cartilage that covers the glottis when swallowing food in order to prevent food particles from entering the larynx |
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epiphyseal plate |
portion of the bone where growth occurs; located in the epiphysis |
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epiphysis |
dilated ends of long bones in the appendicular skeleton |
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episomes |
plasmids that have the ability to integrate into the host genome |
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erythrocytes |
the oxygen-carrying component of blood. these anaerobic cells, which lack organelles, are packed with hemoglobin and have a characteristic biconcave, disk-like shape that facilitates gas exchange and mobility within blood vessels. also called red blood cells |
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estrogen |
hormones synthesized and released by the ovaries, ovarian follicles, corpus luteum, and placenta. estrogen stimulates the development of the female reproductive tract and secondary sexual characteristics and is partly responsible for the :H spike that causes ovulation |
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exocrine glands |
glands that synthesize and secrete substances through ducts. the mammary glands and sweat glands are examples of endocrine glands |
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expressivity |
refers to the variability in phenotypes (especially severity of a disease) that can occur with a given genotype |
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facultative anaerobe |
an organism that makes ATP by aerobic respiration if oxygen is present, but that can switch to fermentation for sufficient ATP when oxygen is not available |
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filtrate |
the material that passes from the blood vessels into Bowman's space |
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follicle |
a multilayered sac of cells that protects and nourishes the developing ovum |
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follucle-stimulating hormane (FSH) |
synthesized and released by the anterior pituitary, FSH stimulates maturation of ovarian follicles in females and maturation of the seminiferous tubules and sperm production in males. FSH is regulated by estrogen and gonadotropin releasing hormone (GnRH) |
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foramen ovale |
a shunt that connects the right atrium to the left atrium in order to bypass the fetal lung |
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frameshift mutation |
mutation in which a number of nucleotides (except multiples of three) are either deleted or inserted. such mutations lead to a shift in the DNA reading frame and often result in the translation of nonfuctional proteins |
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ganglia |
a group of neuronal cell bodiesin the peripheral nervous system. may be sensory or autonomic |
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gastric glands |
located in the stomach; secrete HCl and various enzymes (such as pepsin) when stimulated by gastrin |
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gastrulation |
the process by which a single-layered blastula becomes a three-layered gastrula |
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gene |
a unit of DNa that encodes a specific protein or RNA molecule |
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genetic drift |
changes in the composition of the gene pool by chance; often more pronounced in small populations |
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genetic map |
created by analyzing recombination frequencies of linked genes; a schematic that shows the distance between two genes or the order of several genes on a chromosome |
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genotype |
the genetic makeup of an individual |
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glomerulus |
network of capillaries within Bowman's capsule that serves as the site of filtration. blood cells and proteins are too large to be filtered, but ions, glucose, and amino acids readily pass into the filtrate |
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glucagon |
produced and secreted by the α-cells of the pancreas, glucagon increases blood glucose concentration by promoting gluconeogenesis and the conversion of glycogen to glucose in the liver |
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glucocorticoids |
synthesized and released by the adrenal cortex, glucocorticoticoids raise blood glucose levels while decreasing protein synthesis |
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golgi apparatus |
an organelle that plays a role in the packaging and secretion of proteins and other molecules produced intracellularly |
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growth hormone (GH) |
synthesized and released by the anterior pituitary, GH stimulates bone and muscle growth as well as glucose conservation. GH is inhibited by somatostatin and stimulated by growth hormone releasing hormone (secreted by the hypothalamus) |
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haploid |
cells with only one copy of each chromosome. germ cells in humans are haploid |
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hemoglobin |
a protein found in erythrocytes made up of four polypeptide chains, each containing a heme group. hemoglobin is responsible for transporting oxygen from the alveoli to the tissues |
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hepatic portal vein |
carries nutrients (monosaccharides, amino acids, and small fatty acids) absorbed in the small intestine to the liver, where they are modified to enter circulation |
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heterozygous |
organisms that contain two different alleles for the same gene on homologous chromosomes |
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homologous chromosomes |
chromosomes in a diploid cell that contain alleles for the same traits at corresponding loci |
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homozygous |
organisms that contain two identical alleles of the same gene on homologous chromosomes |
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humoral immunity |
the synthesis of specific antibodies by activated B-cells in response to an antigen. these antibodies bind to the antigen and either clump together to become insoluble, neutralize the antigen, or attract other cells that engulf and digest the pathogen |
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hyperventilation |
an increase in the rate of respiration or tidal volume. lack of oxygen or a decrease in blood pH promotes hyperventilation |
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hypodermis |
layer of loose connective tissue below the dermis that binds the dermis to the body |
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immunoglobulin |
synonymous with antibody; produced in response to a specific foreign substance that recognizes and binds to that antigen and triggers an immune response |
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incomplete dominance |
describes a situation in which an organism heterozygous for a trait will have a phenotype that is intermediate between both homozygous phenotypes. neither allele, therefore, is either dominant or recessive |
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indeterminate cleavage |
cell division in embryogenesis that results in each cell maintaining its totipotency, or ability to develop into a complete organism by itself |
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induction |
the influence of a group of cells on the development of other cells. induction is achieved by chemical substances known as inducers. the cells secreting these inducers are sometimes called organizers |
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inferior vena cava |
a large vein that return deoxygenated blood from the lower body and the lower extremities to the right atrium of the heart |
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innate immunity |
nonspecific immunity provided by structures and cells. structures, such as the skin, and cells, such as macrophages, are able to recognize invaders and kill them. some cells of the innate immune system, such as the macrophages and dendritic cells, are able to signal the presence of an invader to the adaptive immune system |
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inner cell mass |
the group of cells in a blastocyst (mammalian blastula) that develop into the embryo |
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insulin |
produced and secreted by the β-cells of the pancreas, insulin decreases blood glucose concetrations by faciliating the uptake of glucose by muscle and adipose cells and the conversion of glucose to glycogen in muscle and liver cells |
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interphase |
phase of the cell cycle in which cell division does not take place. includes the G₁ phase, S phase, and G₂ phase. cells in this phases may or may not be growing |
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interstitial cells |
also called Leydig cells, interstitial cells are located in the testes and secrete testosterone and other androgens |
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interstinal glands
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contains brush-border enzymes such as maltase, sucrase, and lactase to digest disaccharides. other enzymes of these glands include aminopeptidase, dipeptidase, and enteropeptidase |
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intrapleural space |
the space between the two membranes (visceral pleura and parietal pleura) that cover the lungs |
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intrinsic factor |
a protein secreted by parietal cells of the stomach that is necessary for vitamin B₁₂ absorption |
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inversion |
a form of chromosomal rearrangement in which a portion of a chromosome breaks off and rejoins the same chromosome in the reverse position |
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large intestine |
section of the GI tract that consists of the cecum, the colon, and the rectum. the main function of the large intestine is to absorb salts, water, and some vitamins |
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leukocytes |
white blood cells; the component of blood involved in cell defense and immunity. neutrophils, basophils, eosinophils, lymphocytes, and monocytes are types of leukocytes |
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liver |
essential organ of the human body responsibility for the production of bile, detoxification of ingested substances, production of urea, and the processing and modification of nutrients for storage. the liver also produces albumin (a protein that maintains blood oncotic pressure) and clotting factors |
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luteinizing hormone (LH) |
synthesized and released by the anterior pituitary, LH stimulates ovulation and the formation of the corpus luteum. LH is regulated by estrogen, progesterone, and gonadotropin releasing hormone (GnRH) |
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lymph nodes |
swellings along the lymph vessels where lymph is filtered by leukocytes to remove antigens |
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lymphatic system |
a system of vessels and lymph nodes that collect interstitial fluids and return them to the circulatory system, thereby maintaining fluid balance. the lymphatic system is also involved in lipid absorption and lymphocyte activation |
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lysogenic cycle |
phase of viral replication in which the DNA of the bacteriophage becomes integrated in the host's genome and replicates as the bacteria replicates |
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lysosome |
a membrane-bound vesicle that contains hydrolytic enzymes used for intracellular digestion |
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lytic cycle |
phase in viral replication in which the host cell is lysef and releases new virions |
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mean |
the average, calculated as the sum of observed values divided by the number of observed values |
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mechanical digestion |
breakdown of food particles into smaller particles through such activities as biting, chewing, and churning |
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median |
the simplest division of a set of values; the middle value that divides the values into the upper half and lower half |
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meiosis |
a two-phase cell division in germ cells that results in the formation of up to four haploid cells from one diploid cell |
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mendel's law of independent assortment |
the alleles of different genes sort independently from one another during meiosis. we now know that this is true only for unlinked genes |
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Mendel's law of segregation |
Mendel's postulation that there are alternate versions of genes that account for genetic variation. each individual has two alleles for each gene, with one maternal and one paternal in origin. during meiosis, these two alleles separate into two gametes each |
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mesoderm |
primary germ layer that lies between the ectoderm and the endoderm. gives rise to the musculoskeletal system, circulatory system, excretory system, gonads, connective tissue throughout the body, and portions of the digestive and respiratory systems |
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mitochondria |
the site of aerobic respiration that provides the cell with a majority of its energy in the form of ATP. the mitochondrion is a semiautonomous organelle enclosed by two membranes with an intermembrane space between the two membranes and a mitochondrial matrix enclosed by the inner membrane |
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mitosis |
cell division or nuclear division in somatic cells that results in the daughter nucleus receiving a full complement of the organism's genome |
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mitral valve |
a valve located between the left atrium and the left ventricle. the valve consists of two cusps and prevents backflow of blood from the left ventricle to the left atrium |
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mode |
the most frequently occurring value in a set of observations |
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monohybrid cross |
a cross between two organisms where only one trait is being studied |
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monosynaptic reflex |
reflex pathway that has only one synapse between the sensory neuron and the motor neuron (such as a knee-jerk reflex) |
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monozygotic twins |
result when a zygote splits into two embryos. because both embryos contain identical alleles, they are often called identical twins |
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morula |
a solid ball of cells that develops from the zygote through cleavage. when the inferior of the morula becomes hollow, it becomes known as a blastula |
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multipotent |
stem cells that can differentiate into multiple cell types within a particular group. for example, hematopoietic stem cells are able to differentiate into many different types of blood cells, but not into any other cell type |
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myelin sheath |
insulating structure that surrounds axons. action potentials cannot take place in areas of the axon that are myelinated |
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negative pressure breathing |
the contraction of the diaphragm and the intercostal muscles increases the volume of the thoracic cavity, reducing the pressure in the intrapleural space. this decrease in pressure creates a vacuum that causes the lungs to suck in air |
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nephron |
the functional unit of the kidney. can be subdivided into Bowman's capsule, proximal convoluted tubule, descending limb of the loop of Henle, ascending limb of the loop of Henle, distal convoluted tubule, and collecting duct |
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neural crest cells |
cells at the tip of the neural fold, this group of cells gives rise to many components of the peripheral nervous system and a number of other cell types throughout the body |
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neurotransmitters |
chemical messengers released from synaptic terminals of a neuron that can bind to and stimulate a postsynaptic cell |
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nodes of Ranvier |
gaps between segments of myelin sheath where action potentials can take place, allowing saltattory conduction |
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nondisjuntion |
the failure of homologous chromosomes or sister chromatids to separate properly during meiosis I and II, respectively. This usually results in gametes that lack certain genes or have multiple copies of those genes |
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obligate intracellular organisms |
organisms that require a host cell to express their genes and reproduce |
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osmoregulation
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maintenance of water and solute concentrations |
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osteoblasts |
cells in the bone tissue that secrete the organic constituents of the bone matrix |
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osteoclasts |
cells in the bone matrix that are involved in bone degradation |
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osteons |
the structural unit of compact bone that consists of a central canal (either a Haversian or Volkmann's canal) surrounded by a number of concentric rings of bony matrix called lamellae |
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pancreas |
its exocrine functions including secreting pancreatic amylase, trypsinogen, chymotrypsinogen, procarboxypeptidases A and B, and pancreatic lipase into the small intestine. its endocrine functions include secretion insulin and glucagon |
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parathyroid hormone (PTH) |
synthesized and released by the parathyroid gland, PTH increases blood Ca²⁺ concentration by increasing Ca²⁺ reabsorption in the kidneys and by stimulating calcium release from the bone |
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pathway of the electrical impulse in the heart |
the electrical implulse originates in the sinoatrial (SA)node, located in the right atrium. it then travels through the atrioventricular valve (AV) node, then through the bundle of His, and finally through the Punkinje fibers |
