mechanical digestion
physical breakdown of large pieces of food into smaller pieces
chemical digestion
process by which enzymes break down food into small molecules that the body can use
amylase
enzyme in saliva that breaks the chemical bonds in starches
esophagus
tube connecting the mouth to the stomach
peristalsis
contractions of smooth muscles that provide the force that moves food through the esophagus towards the stomach
stomach
large muscular sac that continues the mechanical and chemical digestion of food
pepsin
enzyme that breaks down proteins into smaller polypeptide fragments
chyme
mixture of enzymes and partially-digested food
small intestine
digestive organ in which most chemical digestion and absorption of food takes place
villus
fingerlike projection in the small intestine that aid in the absorption of nutrient molecules
large intestine
organ in the digestive system that removes water from the undigested material that passes through it; also called colon
excretion
process by which metabolic wastes are eliminated from the body
ureter
tube that carries urine from a kidney to the urinary bladder
urethra
tube through which urine leaves the body
nephron
blood-filtering structure in the kidneys in which impurities are filtered out, wastes are collected, and purified blood is returned to the circulation
filtration
process of passing a liquid or gas through a filter to remove wastes
glomerulus
small network of capillaries encased in the upper end of the nephron; where filtration of the blood takes place
Bowman’s capsule
cuplike structure that encases the glomerulus; collects filtrate from the blood
reabsorption
process by which water and dissolved substances are taken back into the blood
loop of Henle
section of the nephron tubule that is responsible for conserving water and minimizing the volume of the filtrate