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the study of the structure of an organism


the study of the functions an organism performs


groups of cells with a common structure and function

outside of the body, lining organs and cavities within the body

where is epithelial tissue found?

epithelial tissue

sheets of tightly packed cells that line organs and body cavities

basement membrane

the floor of an epithelial membrane on which the basal cells rest

simple epithelium

epithelium with a single layer of cells

stratified epithelium

epithelium with multiple tiers of cells


shaped like dice


shaped like bricks on end


flat like floor tiles

glandular epithelia

epithelia that absorb or secrete chemical solutions

mucous membrane

smooth moist epithelium that lines the digestive tract and air tubes leading to the lungs

to bind and support other tissues

what's the function of connective tissue?

connective tissue

sparse cells scattered through an extracellular matrix

collagenous fibers

tough fibers of the extra cellular matrix. they are made of collagen that are nonelastic and don't tear easily when pulled lengthwise

elastic fibers

long threads made of the protein elastin. they provide a rubbery quality to the extracellular matrix that complements the nonelastic strength of collagenous fibers

reticular fibers

very thin and branched fibers made of collagen. they form a tightly woven fabric that is continuous with the collagenous fibers of the extracellular matrix

loose connective tissue

The most widespread connective tissue in the vertebrate body. It binds epithelia to underlying tissues and functions as packing material, holding organs in place.


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


An amoeboid cell that moves through tissue fibers, engulfing bacteria and dead cells by phagocytosis.

adipose tissue

a kind of body tissue containing stored fat that serves as a source of energy

fibrous connective tissue

A dense tissue with large numbers of collagenous fibers organized into parallel bundles. This is the dominant tissue in tendons and ligaments.


a band of fibrous tissue that connects muscle to bone


strong connective tissue that holds bones together in movable joints


a type of flexible connective tissue with an abundance of collagenous fibers embedded in chondrin


cartilage cell


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


A bone-forming cell that deposits a matrix of collagen.


the repeating organizational unit forming the microscopic stucture of hard mammalian bone


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

nervous tissue

tissue composed of neurons and supportive cells


A nerve cell; the fundamental unit of the nervous system, having structure and properties that allow it to conduct signals by taking advantage of the electrical charge across its cell membrane.

muscle tissue

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

skeletal muscle

Striated muscle generally responsible for the voluntary movements of the body.

striated muscle

a muscle that is connected at either or both ends to a bone and so move parts of the skeleton

cardiac muscle

A type of muscle that forms the contractile wall of the heart. Its cells are joined by intercalated disks that relay each heartbeat.

smooth muscle

A type of muscle lacking the striations of skeletal and cardiac muscle because of the uniform distribution of myosin filaments in the cell.


a specialized center of body function composed of of several different types of tissue


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

thoracic 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.

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.

organ system

group of organs that work together in performing vital body functions

digestive system

Food processing (ingestion, digestion, absorption, elimination)

circulatory system

internal distribution of materials

respiratory system

gas exchange (uptake of oxygen; disposal of carbon dioxide)

immune and lymphatic system

body defense (fighting infections and cancer)

excretory system

disposal of metabolic wastes; regulation of osmotic balance in blood

endocrine system

coordination of body activities (e.g., digestion, metabolism)

reproductive system


nervous system

coordination of body activities; detection of stimuli and formulation of responses to them

integumentary system

protection against mechanical injury, infection, drying out

skeletal system

body support, protection of internal organs

muscular system

movement, locomotion

interstitial fluid

the internal environment of vertebrates, consisting of the fluid filling the spaces between cells


the steady-state physiological condition of the body

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.

positive feedback

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


the totality of an organism's chemical reactions


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.


Organisms that do not produce enough metabolic heat to have much effect on body temperature.

basal metabolic rate (BMR)

the minimum number of kilocalories a resting animal requires to fuel itself for a given time

standard metabolic rate (SMR)

The metabolic rate of a resting, fasting, and nonstressed ectotherm at a particular temperature.


a diet that is chronically deficient in calories


a diet that is chronically excessive in calories

essential fatty acid

the certain unsaturated fatty acids that animals can't make

essential amino acid

Amino acids that an animal cannot synthesize itself and must be obtained from food. Eight of these are essential in the human adult.


an organic molecule required in the diet in very small amounts; they serve mainly as coenzymes or parts of coenzymes


in nutrition, a chemical element other than hydrogen, oxygen, or nitrogen that an organism requires for proper body functioning


An aquatic animal, such as a sponge, clam, or baleen whale, that feeds by sifting small food particles from the water.


An organism that lives in or on its food source, eating its way through the food


a heterotroph, such as an earthworm, that eats its way through detritus, salvaging bits and pieces of decaying organic matter


an animal that lives by sucking nutrient-rich fluids from another living organisms


animals that eat relatively large pieces of food


A heterotrophic mode of nutrition in which other organisms or detritus are eaten whole or in pieces. step one of digestion


process of breaking down food into molecules small enough for the body to absorb; step two of digestion


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


the passing of undigested materials out of the digestive compartment; step four of digestion

intracellular digestion

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

extracellular digestion

The breakdown of food outside cells

complete digestive tract

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

alimentary canal

A digestive tract consisting of a tube running between a mouth and an anus


rhythmic waves of contractions of smooth muscle that push food along the digestive tract


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

salivary glands

Exocrine glands associated with the oral cavity; the secretions of salivary glands contain substances to lubricate foods, adhere together chewed pieces into a bolus, and begin the process of chemical digestion


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.


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


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

oral cavity

the mouth

salivary amylase

A salivary gland enzyme that hydrolyzes starch


a lubricated ball of chewed food


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.


a cartiliginous flap that blocks the top of the windpipe, the glottis, during swallowing, which prevents the entry of fluid or food into the respiratory system


a channel that conducts food, by peristalsis, from the pharynx to the stomach


an enlarged and muscular saclike organ of the alimentary canal

gastric juice

the collection of fluids secreted by the epithelium lining the stomach


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


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

acid chyme

a mixture of recently swallowed food and gastric juice

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

small intestine

the longest section of the alimentary canal; it's the principle site of the enzymatic hydrolysis of food macromolecules and the absorption of nutrients


The first section of the small intestine, where chyme from the stomach mixes with digestive juices from the pancreas, liver, and gallbladder as well as from gland cells of the intestinal wall.


A mixture of substances that is produced in the liver but stored in the gallbladder and that enables formation of fat droplets in water as an aid in the digestion and absorption of fats

chymotrypsin, trypsin

an enzyme found in the duodenum; specific for peptide bonds adjacent to certain amino acids


an enzyme found attached to the intestinal lining; it plits into small peptides


an enzyme found within the small intestine that splits off one amino acid at a time beginning at the end of the polypeptide that has a free carboxyl group


An enzyme found within the small intestine that splits off one amino acid at a time, beginning at the opposite end of the polypeptide containing a free carboxyl group.


A team of enzymes that hydrolyze DNA and RNA into their component nucleotides


the process that keeps tiny fat droplets from coalescing


an enzyme that hydrolyzes fat molecules in the intestinal lumen


fine, finger-like projections of the epithelial cells in the lumen of the small intestine that increases its surface area


fingerlike projections of the inner surface of the small intestine


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


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

hepatic portal vessel

A large circulatory channel that conveys nutrient-laden blood from the small intestine to the liver, which regulates the blood's nutrient content


a digestive hormone secreted by the stomach; stimulates the secretion of gastric juice


a category of hormones secreted by the wall of the duodenum

cholecystokinin (CCK)

a hormone released from the walls of the duodenum in response to the presence of amino acids or fatty acids

large intestine

the last section of the digestive system, where water is absorbed from food and the remaining material is eliminated from the body


the tubular portion of the vertebrate alimentary tract between the small intestine and the anus; functions mainly in water absorption and the formation of feces


a blind outpocket of a hollow organ such as an intestine


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

digestive system

mouth, pharynx, esophagus, stomach, intestines, liver, pancreas, anus

circulatory system

heart, blood vessels, blood

respiratory system

lungs, trachea, other breathing tubes

immune and lymphatic system

bone marrow, lymph nodes, thymus, spleen, lymph vessels, white blood cells

excretory system

kidneys, ureters, urinary bladder, urethra

endocrine system

pituitary, thyroid, pancreas, other hormone-secreting glands

reproductive system

ovaries, testes, and associated organs

nervous system

brain, spinal cord, nerves, sensory organs

integumentary system

skin and its derivatives (e.g., hair, claws, skin glands)

skeletal system

skeleton (bones, tendons, ligaments, cartilage)

muscular system

skeletal muscles

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