| A | B |
|---|
| digestive system | the organs that break down food so that it can be used by the body |
| stomach | the saclike, digestive organ that is between the esophagus and the small intestine and that breaks down food by the action of muscles, enzymes, and acids |
| liver | the largest organ in the body: it makes bile, stores and filters blood, and stores excess sugars as glycogen |
| urine | a liquid excreted by the kidneys, stored in the bladder, and passed through the urethra to the outside of the body |
| enzyme | a type of protein that speeds up metabolic reactions in plants and animals without being permanently changed or destroyed |
| small intestine | the organ between the stomach and the large intestine where most of the breakdown of food happens and most of the nutrients from food are absorbed |
| large intestine | the broader and shorter portion of the intestine, where water is removed from the mostly digested food to turn the waste into semisolid feces, or stool |
| kidney | one of the organs that water and wastes from the blood, excrete products as urine, and regulate the concentration of certain substances in the blood |
| esophagus | a long, straight tube that connects the pharynx to the stomach |
| pancreas | the organ that lies behind the stomach and that makes digestive enzymes and hormones that regulate sugar levels |
| excretory system | the system that collects and excretes nitrogenous wastes and excess water from the body in the form of urine |
| nephron | the unit in the kidney that filters blood |
| nervous system | the structures that control the actions and reactions of the body in response to stimuli from the environment: it is formed by billions of specialized nerve cells, called neurons |
| neuron | a nerve cell that is specialized to receive and conduct electrical impulses |
| axon | an elongated extension of a neuron that carries impulses away from the cell body |
| dendrite | branch like extension of a neuron that receives impulses from neighboring neurons |
| brain | an organ that is the main control center of the nervous system |
| spinal cord | a column of nerve tissue running from the base of the brain through the vertebral column |
| endocrine system | a collection of glands and groups of cells that secrete hormones that regulate growth, development, and homeostasis: includes the pituitary, thyroid, and adrenal glands, the hypothalamus, the pineal body, and the gonads |
| gland | a group of cells that make chemicals for use elsewhere in the body |
| hormone | a substance that is made in one cell or tissue and that causes a change in another cell or tissue in a different part of the body |
