Biology Review and Vocabulary Part 13

abdominal cavity-The body cavity in mammals that primarily houses parts of the digestive, excretory, and reproductive systems. It is separated from the more cranial thoracic cavity by the diaphragm.

acclimatization-Physiological adjustment to a change in an environmental factor.

anatomy-The study of the structure of an organism.

basal metabolic rate-The minimal number of kilocalories a resting animal requires to fuel itself for a given time.

bioenergetics-The flow of energy through an animal, taking into account the energy stored in the food it consumes, the energy used for basic functions, activity, growth, reproduction, and regulation, and the energy lost to the environment as heat or in waste.

brown fat-A special tissue in some mammals, located in the neck and between the shoulders, that is specialized for rapid heat production.

collagenous fibers-A tough fiber of the extracellular matrix. Collagenous fibers are made of collagen and are nonelastic and do not tear easily when pulled lengthwise.

columnar-The column shape of a type of epithelial cell.

conformer-A characterization of an animal in regard to environmental variables. The animal is a conformer if it allows some conditions within its body to vary with certain external changes.

coonective tissue-

countercurrent heat exchange-The opposite flow of adjacent fluids that maximizes transfer rates; for example, blood in the gills flows in the opposite direction in which water passes over the gills, maximizing oxygen uptake and carbon dioxide loss.

cubodial-The cubic shape of a type of epithelial cell.

ectothermic-Referring to organisms that do not produce enough metabolic heat to have much effect on body temperature.

ectotherms-An animal, such as a reptile, fish, or amphibian, that must use environmental energy and behavioral adaptations to regulate its body temperature.

elastic fibers-A long thread made of the protein elastin. Elastic fibers provide a rubbery quality to the extracellular matrix that complements the nonelastic strength of collagenous fibers.

endothermic-Referring to organisms with bodies that are warmed by heat generated by metabolism. This heat is usually used to maintain a relatively stable body temperature higher than that of the external environment.

endotherms-An animal, such as a bird or mammal, that uses metabolic energy to maintain a constant body temperature.

epithelial tissue-Sheets of tightly packed cells that line organs and body cavities.

estivation-Summer torpor; a physiological state that is characterized by slow metabolism and inactivity and that permits survival during long periods of elevated temperature and diminished water supplies.

fibroblasts-A type of cell in loose connective tissue that secretes the protein ingredients of the extracellular fibers.

glandular epithelia-An epithelium that secretes chemical solutions.

heat shock proteins-A protein that helps protect other proteins during heat stress. Heat-shock proteins are found in plants, animals, and microorganisms.

hibernation-A physiological state that allows survival during long periods of cold temperatures and reduced food supplies, in which metabolism decreases, the heart and respiratory system slow down, and body temperature is maintained at a lower level than normal.

homeostasis-The steady-state physiological condition of the body.

integumentary system-The outer covering of a mammal’s body, including skin, hair, and nails.

interstitial fluid-The internal environment of vertebrates, consisting of the fluid filling the spaces between cells.

macrophages-A phagocytic cell present in many tissues that functions in innate immunity by destroying microbes and in acquired immunity as an antigen-presenting cell.

mesenteries-A membrane that suspends many of the organs of vertebrates inside fluid-filled body cavities.

metabolic rate-The total amount of energy an animal uses in a unit of time.

mucous membrane-Smooth moist epithelium that lines the digestive tract and air tubes leading to the lungs.

muscle tissue-Tissue consisting of long muscle cells that are capable of contracting when stimulated by nerve impulses.

negative feedback-A primary mechanism of homeostasis, whereby a change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation.

nervous tissue-Tissue made up of neurons and supportive cells.

nonshivering thermogenesis-The increased production of heat in some mammals by the action of certain hormones that cause mitochondria to increase their metabolic activity and produce heat instead of ATP.

organs-A specialized center of body function composed of several different types of tissues.

physiology-The study of the functions of an organism.

positive feedback-A physiological control mechanism in which a change in some variable triggers mechanisms that amplify the change.

regulator-A characterization of an animal in regard to a particular environmental variable. The animal is a regulator for that variable if it uses mechanisms of homeostasis to moderate internal change in the face of external fluctuation.

reticular fibers-A very thin and branched fiber made of collagen. Reticular fibers form a tightly woven fabric that is continuous with the collagenous fibers of the extracellular matrix.

simple epithelium-An epithelium consisting of a single layer of cells that all touch the basal lamina.

squamous-The flat, tile-like shape of a type of epithelial cell.

standard metabolic rate-The metabolic rate of a resting, fasting, and nonstressed ectotherm.

stratified epithelium-An epithelium consisting of more than one layer of cells in which some but not all cells touch the basal lamina.

stress induced proteins-Special molecules, including heat-shock proteins, that are produced within cells in response to exposure to marked increases in temperature and to other forms of severe stress, such as toxins, rapid pH changes, and viral infections.

thermoregulation-The maintenance of internal temperature within a tolerable range.

thoratic cavity-The body cavity in mammals that houses the lungs and heart. It is surrounded in part by ribs and separated from the lower abdominal cavity by the diaphragm.

torpor-In animals, a physiological state that conserves energy by slowing down the heart and respiratory systems.

vasoconstriction-A decrease in the diameter of superficial blood vessels triggered by nerve signals that contract the muscles of the vessel walls.vasolidation-An increase in the diameter of superficial blood vessels triggered by nerve signals that relax the muscles of the vessel walls.

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

Acid chime – A mixture of recently swallowed food and gastric juice.

Appendix – A small, fingerlike extension of the vertebrate cecum; contains a mass of white blood cells that contribute to immunity.

Bile – A mixture of substances that is produced in the liver, stored in the gallbladder, and acts as a detergent to aid in the digestion and absorption of fats.

Bolus – A lubricated ball of chewed food.

Bulk feeder – An animal that eats relatively large pieces of food.

Carnivore – An animal, such as a shark, hawk, or spider, that eats other animals.

Cecum – A blind outpocket of a hollow organ such as an intestine.

Chylomicron – One of the small intracellular globules composed of fats that are mixed with cholesterol and coated with special proteins.

Complete digestive tract (Alimentary canal) – A digestive tube that runs between a mouth and an anus; also called an alimentary canal. An incomplete digestive tract has only one opening.

Digestion – The process of breaking down food into molecules small enough for the body to absorb.

Duodenum – The first section of the small intestine, where acid chime from the stomach mixes with digestive juices from the pancreas, liver, gallbladder, and gland cells of the intestinal wall.

Elimination – The passing of undigested material out of the digestive compartment.

Enzymatic hydrolysis – The process in digestion that splits macromolecules from food by the enzymatic addition of water.

Epiglottis – A cartilaginous flap that blocks the top of the windpipe, the glottis, during swallowing, which prevents the entry of food or fluid into the respiratory system.

Esophagus – A channel that conducts food, by peristalsis, from the pharynx to the stomach. 

Essential amino acid – An amino acid that an animal cannot synthesize itself and must be obtained from food. Eight amino acids are essential in the human adult.

Essential fatty acids – Certain unsaturated fatty acids that animals cannot make.

Essential nutrient – A substance that an organism must absorb in preassembled form because it cannot bye synthesized from any other material. In humans, there are essential vitamins, minerals, aminoacids, and fatty acids.

Extracellular digestion – The breakdown of food outside cells.

Feces – The wastes of the digestive tract.

Fluid feeder – An animal that lives by sucking nutrient-rich fluids from another living organism. 

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

Gastric juice – A digestive fluid secreted by the stomach.

Gastrovascular cavity – An extensive pouch that serves as the site of extracellular digestion and a passageway to disperse materials throughout most of an animal’s body.

Hepatic portal vein – A large circulatory channel that conveys nutrient-laden blood from the small intestine to the liver; which regulates the blood’s nutrient content.

Herbivore – A heterotrophic animal that eats plants.

Ingestion – A heterotrophic mode of nutrition in which other organisms or detritus are eaten whole or in pieces.

Intracellular digestion – The joining of food vacuoles and lysosomes to allow chemical digestion to occur within the cytoplasm of a cell.

Lacteal – A tiny lymph vessel extending into the core of an intestinal villus and serving as the destination for absorbed chylomicrons.

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.

Malnourished – Referring to an animal hose diet is missing one or more essential nutrients.

Microvillus – One of many fine, fingerlike projections of the epithelial cells in the lumen of the small intestine that increases its surface area.

Mineral – In nutrition, a chemical element other than hydrogen, oxygen, or nitrogen that an organism requires for proper body functioning.

Omnivore – A heterotrophic animal that consumes both meat and plant material.

Oral cavity – The mouth of an animal.

Overnourishment – A diet that is chronically excessive in calories.

Pancreas – A gland with dual functions: The nonendocrine portion secretes digestive enzymes and an alkaline solution into the small intestine via a duct; the endocrine portion secretes the hormones insulin and glucagon into the blood. 

Pepsin – An enzyme present in gastric juice that begins the hydrolysis of proteins.

Pepsinogen – The inactive form of pepsin that is first secreted by specialized (chief) cells located in gastric pits of the stomach.

Peristalsis – Rhythmic waves of contraction of smooth muscle that push food along the digestive tract.

Pharynx – An area in the vertebrate throat where air and food passages cross; in flatworms, the muscular tube that protrudes from the ventral side of the worm and ends in the mouth.

Pyloric sphincter – In the vertebrate digestive tract, a muscular ring that regulates the passage of food out of the stomach and into the small intestine.

Rectum – The terminal portion of the large intestine where the feces are stored until they are eliminated.

Ruminant – An animal, such as a cow or a sheep, with an elaborate, multicompartmentalized specialized for an herbivorous diet. 

Salivary amylase – A salivary gland enzyme that hydrolyzes starch and glycogen.

Salivary glands – Exocrine glands associated with the oral cavity. The secretions of salivary glands contain substances to lubricate food adhere together chewed pieces into a bolus, and begin the process of chemical digestion.

Small intestine – The longest section of the alimentary canal; the principal site of the enzymatic hydrolysis of food macromolecules and the absorption of nutrients.

Sphincters – A ringlike valve consisting of modified muscles in a muscular tube, such as a digestive tract; closes off the tube like a drawstring.

Stomach – An organ of the digestive system that stores food and performs preliminary steps of digestion.

Substrate feeder – An organism that lives in or on its food source, eating its way through the food.

Suspension feeder – An aquatic animal, such as a clam or a baleen whale, that shifts small food particles from the water.

Undernourishment – A diet that is chronically deficient in calories.

Villi – A fingerlike projection of the inner surface of the small intestine.

Vitamin – An organic molecule required in the diet in very small amounts. Vitamins serve primarily as coenzymes or parts of coenzymes.

Arteries: A vessel that carries blood away from the heart to organs throughout the body

Arterioles: A vessel that conveys blood between an artery and a capillary bed

Atria: A chamber that receives blood returning to the vertebrate heart

Atrioventricular node: A region of specialized muscle tissue between the right atrium and right ventricle. It generates electrical impulses that primarily cause the ventricles to contract

Atrioventricular valve: A valve in the heart between each atrium and ventricle that prevents a backflow of blood when the ventricles contract

Blood pressure: The hydrostatic force that blood exerts against the wall of a vessel

Blood vessels: A set of tubes through which the blood moves through the body

Blood: type of connective tissue with a fluid matrix called plasma in which blood cells are suspended

Bohr shift: A lowering of the affinity of hemoglobin for oxygen, caused by a drop in pH; facilitates the release of oxygen from hemoglobin in the vicinity of active tissues

Breathing control centers: A brain center that directs the activity of organs involved in breathing

Bronchi: One of a pair of breathing tubes that branch from the trachea into the lungs

Bronchioles: One of the fine branches of the bronchus that transport air to alveoli
Alveoli: One of the dead-end, multilobed air sacs that constitute the gas exchange surface of the lungs

Capillaries: microscopic blood vessel that penetrates the tissues and consists of a single layer of endothelial cells that allows exchange between the blood and interstitial fluid

Capillary beds: A network of capillaries that infiltrate every organ and tissue in the body

Cardiac ouput: The volume of blood pumped per minute by the left ventricle of the heart

Cardic cycle: The alternating contractions and relaxations of the heart

Cardiovascular diseases: Diseases of the heart and blood vessels

Cardiovascular system: Diseases of the heart and blood vessels

Closed circulatory system: A circulatory system in which blood is confined to vessels and is kept separate from the interstitial fluid

Countercurrent exchange: A circulatory system in which blood is confined to vessels and is kept separate from the interstitial fluid

Diaphragm: (1) A sheet of muscle that forms the bottom wall of the thoracic cavity in mammals; active in ventilating the lungs. (2) A dome-shaped rubber cup fitted into the upper portion of the vagina before sexual intercourse. It serves as a physical barrier to block the passage of sperm

Diastole: The stage of the heart cycle in which the heart muscle is relaxed, allowing the chambers to fill with blood

Diastolic pressure: Blood pressure that remains between heart contractions

Double circulation: A circulation scheme with separate pulmonary and systemic circuits, which ensures vigorous blood flow to all organs

Electrocardiogram: A record of the electrical impulses that travel through cardiac muscle during the heart cycle

Endothelium: The innermost, simple squamous layer of cells lining the blood vessels; the only constituent structure of capillaries

Erythrocytes: A red blood cell; contains hemoglobin, which functions in transporting oxygen in the circulatory system

Erythropoietin: A hormone produced in the kidney when tissues of the body do not receive enough oxygen. This hormone stimulates the production of erythrocytes
Fibrinogen: The inactive form of the plasma protein that is converted to the active form fibrin, which aggregates into threads that form the framework of a blood clot

Fibrin: The activated form of the blood-clotting protein fibrinogen, which aggregates into threads that form the fabric of the clot
Hemophilia: A human genetic disease caused by a sex-linked recessive allele; characterized by excessive bleeding following injury

Gas exchange: The uptake of molecular oxygen from the environment and the discharge of carbon dioxide to the environment

Gill circulation: The flow of blood through gills

Gills: A localized extension of the body surface of many aquatic animals, specialized for gas exchange

Heart murmur: A hissing sound that occurs when blood squirts backward through a leaky valve in the heart

Heart rate: The rate of heart contraction

Heart: A muscular pump that uses metabolic energy to elevate hydrostatic pressure of the blood. Blood then flows down a pressure gradient through blood vessels that eventually return blood to the heart

Hemocyanin: A type of respiratory pigment that uses copper as its oxygen-binding component. Hemocyanin is found in the hemolymph of arthropods and many molluscs

Hemoglobin: An iron-containing protein in red blood cells that reversibly binds oxygen

Hemolymph: In invertebrates with an open circulatory system, the body fluid that bathes tissues

Hypertension: Chronically high blood pressure within the arteries
Heart attack: The death of cardiac muscle tissue resulting from prolonged blockage of one or more coronary arteries

Larynx: The voice box, containing the vocal cords

Leukocytes: A white blood cell; typically functions in immunity, such as phagocytosis or antibody production

Low-density lipoproteins: A cholesterol-carrying particle in the blood, made up of cholesterol and other lipids surrounded by a single layer of phospholipids in which proteins are embedded. An LDL particle carries more cholesterol than a related lipoprotein, HDL, and high LDL levels in the blood correlate with a tendency to develop blocked blood vessels and heart disease
High-density lipoproteins: A cholesterol-carrying particle in the blood, made up of cholesterol and other lipids surrounded by a single layer of phospholipids in which proteins are embedded. An HDL particle carries less cholesterol than a related lipoprotein, LDL, and may be correlated with a decreased risk of blood vessel blockage
Atherosclerosis: A cardiovascular disease in which growths called plaques develop on the inner walls of the arteries, narrowing their inner diameters

Lymph nodes: Organ located along a lymph vessel. Lymph nodes filter lymph and help attack viruses and bacteria

Lymph: The colorless fluid, derived from interstitial fluid, in the lymphatic system of vertebrate animals

Lymphatic system: A system of vessels and lymph nodes, separate from the circulatory system, that returns fluid, proteins, and cells to the blood

Myogenic heart: A type of heart, such as in vertebrate animals, in which the pacemaker is made up of specialized muscle tissues and located within the heart itself

Myoglobin: An oxygen-storing, pigmented protein in muscle cells

Neurogenic heart: A type of heart, such as in insects, in which the pacemakers originate in motor nerves arising from outside the heart

Open circulatory system: A circulatory system in which fluid called hemolymph bathes the tissues and organs directly and there is no distinction between the circulating fluid and the interstitial fluid

Pacemaker: A specialized region of the right atrium of the mammalian heart that sets the rate of contraction; also called the sinoatrial (SA) node

Parabronchi: A site of gas exchange in bird lungs. Parabronchi allow air to flow past the respiratory surface in just one direction.Partial pressure:

Peripheral resistance: The impedance of blood flow by the arterioles

Plasma: The liquid matrix of blood in which the cells are suspended

Platelets: A small enucleated blood cell important in blood clotting; derived from large cells in the bone marrow

Pressure breathing: The technique of breathing which is required when oxygen is supplied direct to an individual at a pressure higher than the ambient barometric pressure

Pulmocutaneous circuit: The route of circulation that directs blood to the skin and lungs

Pulmonary circuit: The branch of the circulatory system that supplies the lungs

Pulse: The rhythmic stretching of the arteries caused by the pressure of blood forced through the arteries by contractions of the ventricles during systole

Red blood cells: A blood cell containing hemoglobin, which transports O₂; also called an erythrocyte

Respiratory medium: The source of oxygen. It is typically air for terrestrial animals and water for aquatic organisms

Respiratory pigments: A special protein that transports most of the oxygen in blood

Respiratory surface: The part of an animal where gases are exchanged with the environment

Semilunar valves: A valve located at the two exits of the heart, where the aorta leaves the left ventricle and the pulmonary artery leaves the right ventricle

Sinoatrial node: A region of the heart composed of specialized muscle tissue that sets the rate and timing at which all cardiac muscle cells contract

Sinuses: Any of the spaces surrounding the organs of the body in animals with open circulatory systems

Stem cells: Any relatively unspecialized cell that can divide during a single division into one identical daughter cell and one more specialized daughter cell, which can undergo further differentiation

Stroke volume: The amount of blood pumped by the left ventricle in each contraction

Stroke: The death of nervous tissue in the brain, usually resulting from rupture or blockage of arteries in the head

Systemic circuit: The branch of the circulatory system that supplies all body organs and then returns oxygen-poor blood to the right atrium via the veins

Systemic circulation: Movement of blood through the systemic circuit

Systole: The stage of the heart cycle in which the heart muscle contracts and the chambers pump blood

Systolic pressure: Blood pressure in the arteries during contraction of the ventricles

Thrombus: A clump of platelets and fibrin that blocks the flow of blood through a blood vessel

Tidal volume: The volume of air an animal inhales and exhales with each breath
vital capacity: The maximum volume of air that a respiratory system can inhale and exhale
residual volume: The amount of air that remains in the lungs after forcefully exhaling

Trachea: The windpipe; that portion of the respiratory tube that has C-shaped cartilagenous rings and passes from the larynx to two bronchi

Tracheal system: A gas exchange system of branched, chitin-lined tubes that infiltrate the body and carry oxygen directly to cells in insects
Lungs: An invaginated respiratory surface of terrestrial vertebrates, land snails, and spiders that connects to the atmosphere by narrow tubes

Veins: (1) In animals, a vessel that returns blood to the heart. (2) In plants, a vascular bundle in a leaf

Ventilation: Any method of increasing contact between the respiratory medium and the respiratory surface

Ventricles: (1) A heart chamber that pumps blood out of a heart. (2) A space in the vertebrate brain, filled with cerebrospinal fluid

Venules: A vessel that conveys blood between a capillary bed and a vein

Vocal cords: One of a pair of string-like tissues in the larynx. Air rushing past the tensed vocal cords makes them vibrate, producing sounds

White blood cells: A blood cell that functions in defending the body against infections and cancer cells; also called a leukocyte