Digestive System

Question 1

Digestive System

Answer 1

oral cavity - pharynx - esophagus - stomach - small intestines - large instestines - anus

Question 2

Oral Cavity

Answer 2

• mechanical and chemical digestion of food begins
• mechanical digestion is the breakdown of large food particles into smaller particles through physical actions
• chemical digestion refers to the enzymatic breakdown of macromolecules into smaller molecules and begins in the mouth when the salivary glands secrete saliva
• saliva contains salivary amylase, which hydrolyzes starch to maltose

Question 3

Esophagus

Answer 3

• the muscular tube leading from the mouth to the stomach
• food is moved down the esophagus by contractions called penstalsis
• esophagus is closed off from the stomach by contraction of a muscular structure called the lower esophogeal sphincter

Question 4

Stomach

Answer 4

• stores and partially digests food
• the walls of the stomach are lined by the gastric mucosa to protect the stomach lining from the harshly acidic juices
• chief cells found within the gastric glands synthesize pepsinogen, which is converted to pepsin and break down proteins
• parietal cells present in the gastric glands, synthesize and release HCl, which alters the pH of the stomach and kills bacteria
• the churning of the stomach, combined with the enzymatic activity , produces an acidic, semifluid mixture of partially digested food known as chyme

Question 5

Small Intestine

Answer 5

• chemical digestion is completed here
• divided into three sections: duodenum, jejunum, and the ileum
• highly adapted to absorption
• has numerous finger-like projections called villi
• most digestion occurs in the duodendum
• intestinal mucosa secretes: lipases (fat digestion), aminopeptidases (polypeptide digestion), and disaccharides (for maltose, lactose, and sucrose digestion)

Question 6

Gastrin

Answer 6

produced in the G cells of the duodenum. Stimulates the parietal cells to produce HCl, which denatures proteins and activates digestive enzymes

Question 7

Intrinsic Factor

Answer 7

a secretion of the parietal cells that facilitates the absorption of vitamin B12 across the intestinal lining

Question 8

Cholecystokinin (CCK)

Answer 8

produced and stored in the I cells of the duodenal and jejunal mucosa

Question 9

Secretin

Answer 9

synthesized and stored in the S cells of the upper intestine

Question 10

Liver

Answer 10

produces bile that is stored in the gall bladder before being released into the small intestine

Question 11

Pancreas

Answer 11

produces enzymes such as amylase for carbohydrate digestion, trypsin, for protein digestion, and lipase for fat digestion

Question 12

Large Intestine

Answer 12

• absorbs salts and any water not already absorbed by the small intestine
• the rectum provides for transient storage of feces before elimination through the anus