Bio chapter 20-30

anatomy

The study of the structures of an organism.

tissue

An integrated group of cells with a common function, structure, or both.

organ

A specialized structure composed of several different types of tissues that together perform specific functions.

organ system

A group of organs that work together in performing vital body functions.

connective tissue

Animal tissue that functions mainly to bind and support other tissues, having a sparse population of cells scattered through an extracellular matrix, which they produce. See adipose tissue; cartilage; bone; blood.

neuron

(nyūr´-on) A nerve cell; the fundamental structural and functional unit of the nervous system, specialized for carrying signals from one location in the body to another.

muscle tissue

Tissue consisting of long muscle cells that can contract, either on their own or when stimulated by nerve impulses; the most abundant tissue in a typical animal. See skeletal muscle; cardiac muscle; smooth muscle.

homeostasis

(hō´-mē-ō-stā´-sis) The steady state of body functioning; a state of equilibrium characterized by a dynamic interplay between outside forces that tend to change an organism's internal environment and the internal control mechanisms that oppose such changes.

positive feedback

A form of regulation in which the accumulation of an end product of a process speeds up that process; in physiology, a control mechanism in which a change in a variable triggers a response that reinforces or amplifies the change.

negative feedback

A form of regulation in which the accumulation of an end product of a process slows that process; in physiology, a primary mechanism of homeostasis, whereby a change in a variable triggers a response that counteracts the initial change.

herbivore

An animal that mainly eats plants or algae. See also carnivore; omnivore.

carnivore

An animal that mainly eats other animals. See also herbivore; omnivore.

omnivore

An animal that frequently eats animals as well as plants or algae. See also carnivore; herbivore.

suspension feeder

An organism that captures food particles from the surrounding medium.

ingestion

The act of eating; the first stage of food processing in animals.

digestion

The mechanical and chemical breakdown of food into molecules small enough for the body to absorb; the second stage of food processing in animals.

elimination

The passing of undigested material out of the digestive compartment; the fourth and final stage of food processing in animals.

absorption

The uptake of small nutrient molecules by an organism's body; the third main stage of food processing, following digestion.

esophagus

(eh-sof´-uh-gus) A muscular tube that conducts food by peristalsis, usually from the pharynx to the stomach.

stomach

An organ in a digestive tract that stores food and performs preliminary steps of digestion.

intestine

The region of a digestive tract located between the gizzard or stomach and the anus and where chemical digestion and nutrient absorption usually occur.

anus

The opening through which undigested materials are expelled.

peristalsis

(per´-uh-stal´-sis) Rhythmic waves of contraction of smooth muscles. Peristalsis propels food through a digestive tract and also enables many animals, such as earthworms, to crawl.

sphincter

(sfink´-ter) A ringlike band of muscle fibers that controls the size of an opening in the body, such as the passage between the esophagus and the stomach.

gallbladder

An organ that stores bile and releases it as needed into the small intestine.

liver

The largest organ in the vertebrate body. The liver performs diverse functions, such as producing bile, preparing nitrogenous wastes for disposal, and detoxifying poisonous chemicals in the blood.

gill

An extension of the body surface of an aquatic animal, specialized for gas exchange and/or suspension feeding.

tracheal system

A system of branched, air-filled tubes in insects that extends throughout the body and carries oxygen directly to cells.

lung

An infolded respiratory surface that connects to the atmosphere by narrow tubes.

trachea

(trā´-kē-uh) (plural, tracheae) In the mammalian respiratory system, the windpipe; the portion of the respiratory tube that passes from the larynx to the two bronchi. In the tracheal system of insects, the largest tubes, which connect to external openings.

diaphragm

(dī´-uh-fram) The sheet of muscle separating the chest cavity from the abdominal cavity in mammals. Its contraction expands the chest cavity, and its relaxation reduces it.

bronchiole

(bron´-kē-ōl) A fine branch of the bronchi that transports air to alveoli.

alveolus

(al-vē´-oh-lus) (plural, alveoli) One of the dead-end air sacs within the mammalian lung where gas exchange occurs.

artery

A vessel that carries blood away from the heart to other parts of the body.

vein

(1) In animals, a vessel that returns blood to the heart. (2) In plants, a vascular bundle in a leaf, composed of xylem and phloem.

capillary

(kap´-il-er-ē) A microscopic blood vessel that conveys blood between an arteriole and a venule; enables the exchange of nutrients and dissolved gases between the blood and interstitial fluid.

atrium

(ā´-trē-um) (plural, atria) A heart chamber that receives blood from the veins.

ventricle

(ven´-truh-kul) (1) A heart chamber that pumps blood out of the heart. (2) A space in the vertebrate brain filled with cerebrospinal fluid.

pulmonary circuit

The branch of the circulatory system that supplies the lungs. See also systemic circuit.

systemic circuit

The branch of the circulatory system that supplies oxygen-rich blood to, and carries oxygen-poor blood away from, organs and tissues in the body. See also pulmonary circuit.

aorta

(ā-or´-tuh) A large artery that conveys blood directly from the left ventricle of the heart to other arteries.

superior vena cava

A large vein that returns oxygen-poor blood to the heart from the upper body and head. See also inferior vena cava.

inferior vena cava

A large vein that returns oxygen-poor blood to the heart from the lower, or posterior, part of the body. See also superior vena cava.

pathogen

An agent, such as a virus, bacteria, or fungus, that causes disease.

innate immunity

The kind of immunity that is present in an animal before exposure to pathogens and is effective from birth. Innate immune defenses include barriers, phagocytic cells, antimicrobial proteins, the inflammatory response, and natural killer cells.

phagocytosis

(fag´-ō-sī-tō´-sis) Cellular "eating"; a type of endocytosis in which a cell engulfs macromolecules, other cells, or particles into its cytoplasm.

phagocyte

(fag´-ō-sīt´) A white blood cell (for example, a neutrophil or macrophage) that engulfs bacteria, foreign proteins, and the remains of dead body cells.

natural killer cell

A cell type that provides an innate immune response by attacking cancer cells and infected body cells, especially those harboring viruses.

white blood cell

A blood cell that functions in fighting infections; also called a leukocyte.

red blood cell

A blood cell containing hemoglobin, which transports oxygen; also called an erythrocyte.

platelet

A pinched-off cytoplasmic fragment of a bone marrow cell. Platelets circulate in the blood and are important in blood clotting.

inflammatory response

An innate body defense in vertebrates caused by a release of histamine and other chemical alarm signals that trigger increased blood flow, a local increase in white blood cells, and fluid leakage from the blood. The resulting inflammatory response includes redness, heat, and swelling in the affected tissues.

adaptive immunity

A vertebrate-specific defense that is activated only after exposure to an antigen and is mediated by lymphocytes. It exhibits specificity, memory, and self-nonself recognition. Also called acquired immunity.

antigen

(an´-tuh-jen) A foreign (nonself) molecule that elicits an adaptive immune response.

antibody

(an´-tih-bod´-ē) A protein dissolved in blood plasma that attaches to a specific kind of antigen and helps counter its effects; secreted by plasma cells.

active immunity

Immunity conferred by recovering from an infectious disease or by receiving a vaccine.

passive immunity

Temporary immunity obtained by acquiring ready-made antibodies, as occurs in the transfer of maternal antibodies to a fetus or nursing infant. Passive immunity lasts only a few weeks or months.

B cell

A type of lymphocyte that completes its development in the bone marrow and is responsible for the humoral immune response.

T cell

A type of lymphocyte that matures in the thymus; T cells include both effector cells for the cell-mediated immune response and helper cells required for both the humoral and cell-mediated adaptive responses.

antigen receptor

(an´-tuh-jen) The general term for a surface protein, located on B cells and T cells, that binds to antigens and initiates the adaptive immune response.

humoral immune response

The branch of adaptive immunity that involves the activation of B cells and that leads to the production of antibodies, which defend against bacteria and viruses in body fluids.

cell-mediated immune response

specialized T cells destroy infected host cells

primary immune response

The initial adaptive immune response to an antigen, which appears after a lag of about 10 days.

secondary immune response

The adaptive immune response elicited when an animal encounters the same antigen at some later time. The secondary immune response is more rapid, of greater magnitude, and of longer duration than the primary immune response.

antigen-presenting cell

(an´-tuh-jen) One of a family of white blood cells that ingests a foreign substance or a microbe and attaches antigenic portions of the ingested material to its own surface, thereby displaying the antigens to a helper T cell.

HIV (human immunodeficiency virus)

The retrovirus that attacks the human immune system and causes AIDS.

AIDS

The late stages of HIV infection, characterized by a reduced number of T cells and the appearance of characteristic opportunistic infections.

immunodeficiency disorder

An immunological disorder in which the immune system lacks one or more components, making the body susceptible to infectious agents that would ordinarily not be pathogenic.

allergy

A disorder of the immune system caused by an abnormally high sensitivity to an antigen. Symptoms are triggered by histamines released from mast cells.

allergen

(al´-er-jen) An antigen that causes an allergy.

antihistamine

(an´-tē-his´-tuh-mēn) A drug that interferes with the action of histamine, providing relief from an allergic reaction.

autoimmune disorder

An immunological disorder in which the immune system attacks the body's own molecules.

osmoregulation

The homeostatic maintenance of solute concentrations and water balance by a cell or organism.

excretion

(ek-skrē´-shun) The disposal of nitrogen-containing metabolic wastes.

urea

(yū-rē´-ah) A soluble form of nitrogenous waste excreted by mammals and most adult amphibians.

uric acid

(yū´-rik) An insoluble precipitate of nitrogenous waste excreted by land snails, insects, birds, and some reptiles.

ammonia

NH3; a small and very toxic nitrogenous waste produced by metabolism.

urethra

(yū-rē´-thruh) A duct that conveys urine from the urinary bladder to the outside.

ureter

(yū´-reh-ter or yū-rē´-ter) A duct that conveys urine from the kidney to the urinary bladder.

endocrine system

(en´-dō-krin) The organ system consisting of ductless glands that secrete hormones and the molecular receptors on or in target cells that respond to the hormones. The endocrine system cooperates with the nervous system in regulating body functions and maintaining homeostasis.

hormone

(1) In animals, a regulatory chemical that travels in the blood from its production site, usually an endocrine gland, to other sites, where target cells respond to the regulatory signal. (2) In plants, a chemical that is produced in one part of the plant and travels to another part, where it acts on target cells to change their functioning.

target cell

A cell that responds to a regulatory signal, such as a hormone.

endocrine disruptor

A chemical, usually synthetic, that interferes with the endocrine system's normal functions.

pineal gland

(pin´-ē-ul) An outgrowth of the vertebrate brain that secretes the hormone melatonin, which coordinates daily and seasonal body activities such as the sleep/wake circadian rhythm with environmental light conditions.

pancreas

(pan´-krē-us) A gland with dual functions

ovary

(1) In animals, the female gonad, which produces egg cells and reproductive hormones. (2) In flowering plants, the basal portion of a carpel in which the egg-containing ovules develop.

testis

(plural, testes) The male gonad in an animal. The testis produces sperm and, in many species, reproductive hormones.

nervous system

The organ system that forms a communication and coordination network between all parts of an animal's body.

central nervous system (CNS)

The integration and command center of the nervous system; the brain and, in vertebrates, the spinal cord.

peripheral nervous system (PNS)

The network of nerves and ganglia carrying signals into and out of the central nervous system.

stimulus

(plural, stimuli) (1) In the context of a nervous system, any factor that causes a nerve signal to be generated. (2) In behavioral ecology, an environmental cue that triggers a specific response.

neurotransmitter

A chemical messenger that carries information from a transmitting neuron to a receiving cell, either another neuron or an effector cell.

endoskeleton

A hard skeleton located within the soft tissues of an animal; includes spicules of sponges, the hard plates of echinoderms, and the cartilage and bony skeletons of vertebrates.

exoskeleton

A hard external skeleton that protects an animal and provides points of attachment for muscles.

bone

A type of connective tissue consisting of living cells held in a rigid matrix of collagen fibers embedded in calcium salts.

ligament

A type of fibrous connective tissue that joins bones together at movable joints.

tendon

Fibrous connective tissue connecting a muscle to a bone.

ball-and-socket joint

A joint that allows rotation and movement in several planes. Examples in humans include the hip and shoulder joints.