Digestive System

SRJC, BIO 2.2, Swinstorm. Lecture exam 3

Describe the digestive tract

Mouth → Pharynx → Esophagus →Stomach → Small intestine/ duodenum → Cecum/appendix→ Large intestine / colon→ Rectum → Anus

What is the purpose of the sphincter muscle?

To keep food moving in one direction and to control amount of food passing into the next stage of digestion.

How many sphincter muscles are there? Where can you find them?

6- by the pharynx to esophagus, Esophagus to stomach, stomach to small intestine, small intestine to cecum, and 2 sphincter muscles from rectum to anus

What are the accessory glands and where can I find them?

Salivary glands, in the mouth. Liver, gallbladder and pancreas near the small intestine. 

How does digestion start in the mouth?

Anticipation of food triggers salivary glands to secrete saliva. Saliva contains a mucus that has water, cells, glycoproteins, and salts. It also contains lysozyme which protects amongst bacteria and amylase which breaks down starch.

How does digestion in the stomach begin?

when the bolus enters the stomach, the stomach expands. As it expands it triggers gastrin to be released. This hormone circulates in the blood stream returning to the stomach triggering more gastrin to be made.

What is found in gastric juices?

HCl and pepsin

How are the gastric juices released into the stomach?

H+ are released via parietal cells into the stomach. parietal cells in a specific membrane chamber release Cl-. In the lumen HCl forms. Chief cells release pepsinogen which converts to pepsin in an acidic environment, the lumen. HCl clips pepsinogen creating pepsin and pepsin also helps with clipping

How does digestion occur in the small intestine?

chyme enters small intestine → duodenum releases CCK and secretin → CCK stimulates trypsin and chymotrypsin from pancreas and bile from gallbladder → secreting stimulates pancreas in releasing HCO3- to neutralize chyme → if chyme is rich in fats secretin increases and CCK inhibits peristalsis→ CCK and Secretin inhibit gastric juices

How are fats transported?

Fat is hydrolyzed by lipase which generates fatty acids and monoglycerides. It is absorbed by epithelial cells and recombined into triglycerides. Chylomicros leave small intestine and enter lacteal → large lymphatic vessels → L veins → return blood to heart

How are nucleic acids transported?

capillary blood absorbs it and via passive or active transport