Digestive System

What can chronic heartburn cause if untreated?

Esophagitis or Barrett's esophagus (which can lead to tumors and esophageal cancer)

What are the locations of the major salivary glands?

Parotid Salivary Glands: inferior to zygomatic process Sublingual Salivary Glands: covered by mucus membrane on floor of mouth Submandible Salivary Glands: floor of mouth

What is haltosis?

bad breath

What is the digestion?

chemical and mechanical breakdown of food into smaller pieces

What is mastication?

chewing (mechanical breakdown of food)

What substance begins digestion in the mouth?

complex carbohydrates by the enzyme salivary amylase

Whats another name for swallowing?

deglutition

What is the primary peristaltic wave?

forces the bolus down the esophagus - lasts 8-9 sec. and travels to stomach even if bolus moves faster

What is the significance of blood vessels in the alimentary canal being located in the submucosal layer?

in the submucosa there is a network of intrinsic nerve fibers and scattered neurons that need a vascular supply in order to properly function

What is peristalsis

involuntary waves of muscular contractions that move food products down the digestive tract (circular muscle contract behind bolus and relax in front; longitudinal smooth muscle ahead of bolus contracts which shortens adjacent segments))

What is visceral peritoneum?

lines surface of the body wall

What is parietal peritoneum?

lines the organ directly

What is the sphincter at the bottom of the esophagus called?

lower esophageal sphincter (cardiac sphincter)

What is the secondary peristaltic wave?

occurs if bolus gets stuck - stretch receptors in esophageal lining are stimulated - will continue until bolus enters stomach

What is secretion?

release of enzymes, water, acids, buffers, and salts

What is a spincter?

ring of muscle surrounding and serving to guard an opening / tube

What is ingestion?

taking food into the mouth

What is the gastrointestinal tract?

the alimentary canal which is the path food follows from the mouth to the toilet

What is peristalsis?

the involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wavelike movements that push the contents of the canal forward.

What is absorption?

the movement of organic substrates, electrolytes, vitamins, and water across digestive epithelium into the interstitial fluid of digestive tract

What type of muscle tissue is responsible for movement of substances through the GI tract?

visceral smooth muscle

How does heartburn occur?

when the cardiac sphincter fails to close, stomach contents splash the esophagus

What are some typical causes of haltosis?

- breakdown of epithelial cells, blood cells, and bacteria combined with saliva - low salivary flow

What are the functions of saliva?

- lubricates mouth - initiates digestion - dissolves chemicals - moistening and lubricating materials in mouth

What are the four phases of swallowing?

1. Buccal Phase - compression of bolus against hard plate. tongue forces bolus into oropharynx 2. Pharyngeal Phase - elevation of larynx and folding of epiglottis 3. Esophageal Phase - pharyngeal muscles contract bolus pushed towards stomach with peristalsis