Digestive system Flashcards
the alimentary canal or digestive tube consists of
the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus
the accessory organs fo digestion include:
the liver, pancreas, and gallbladder
how is food broken down in the mouth?
it is mechanically broken down by the teeth and tongue in the process of mastication (chewing)
saliva, produced by the three pairs of salivary glands ________ and _______ the chewed food
lubricates and dilutes
saliva contains an enzyme called ______ that starts digestion of complex carbohydrates
amylase
a ball of food called a _____ is formed
bolus
constrictive muscles of the pharynx …..
force the food into the upper portion of the esophagus and the food is swallowed
the esophagus is a narrow tube leading from the _______ to the _______
pharynx; stomach
the digestive tract has 4 main layers, from the innermost to outermost:
the mucous membrane, the submucous layer, the muscular layer, and the serous layer
food enters the stomach where gastric glands secrete
hydrochloric acid that breaks down foods
the stomach muscle churns and mixes the bolus of food turning the mass into
a soupy substance called chyme
the stomach also stores food and
regulates the movement of food into the small intestine
digestion and absorption of food occur in the
small intestine
food is acted on by various enzymes from the
small intestine and pancreas and by bile from the liver
the pancreas also contributes water to
dilute chyme and bicarbonate ions to neutralize the acid from the stomach
the small intestine consists of 3 major regions:
the duodenum, the jejunum, and the ileum
nutrients are absorbed through the
walls of the small intestine
the amino acids and simple sugars derived from proteins and carbohydrates are absorbed directly into the
blood
most of the fats are absorbed into the
lymph by lacteals which eventually are added to the bloodstream
all nutrients then enter the hepatic portal vein to be routed to the
liver for decontamination
small fingerlike projections called ______ greatly increase the surface area of the intestinal wall
villi
the large intestine reabsorbed _______ and stores and eliminates _______
water; undigested food
which bacteria is found in the large intestine?
intestinal flora
the large intestine is arranged into 5 portions:
the ascending colon, the transverse colon, the descending colon, the sigmoid colon, and the rectum
the opening for defecation (expelling of stool) is the
anus
during mastication, the teeth reduce ingested food material to smaller particles to
increase surface area for chemical digestion
