The Digestive System

Question 1

Steps in the Digestive Process 5

Answer 1

• Ingestion
• Digestion
• Movement of GI tract contents
• Absorption
• Elimination

Question 2

Ingestion

Answer 2

• Occurs when the mouth takes in food • AKA - eating

Question 3

Digestion

Answer 3

• The breakdown of larger pieces of food into smaller pieces
• Mechanical
– Chewing
– Stomach muscles
• Chemical
– Digestive enzymes
– Different pH ranges for different enzymes
– Mouth, stomach, small intestine

Question 4

Movement of GI Tract Contents

Answer 4

• Material is moved from one part of the GI tract to the next
• Mainly by contractions of smooth muscle tissue (peristalsis)

Question 5

Absorption

Answer 5

• Nutrients cross the wall of the GI tract and enter the cells lining the tract
• From here, the nutrients enter the blood to be transported throughout the body

Question 6

Elimination

Answer 6

• Removes molecules that cannot be digested and need to be discharged from the body

Question 7

Pharynx

Answer 7

• A hollow space at the back of the throat
• The mouth and nasal passages both lead here
• Opens into the esophagus and trachea
• The esophagus is located to the back of the trachea

Question 8

The Esophagus

Answer 8

• Peristalsis pushes food through the esophagus and continues through the stomach and intestines
• Between the esophagus and stomach there is a sphincter (muscles that encircle a tube and act as a valve)
• Problems with this this sphincter result in heartburn
• Vomiting occurs when strong contractions of the abdominal muscles and diaphragm force the stomach contents backward through the esophagus

Question 9

The Stomach

Answer 9

• Gastric juice includes pepsin and hydrochloric acid
• The HCl gives the stomach a pH of about 2 and kills most bacteria in food
• Between the stomach and small intestine there is another sphincter
• The stomach empties in about 2-6 hours
• Food leaving the stomach is a liquid called chyme
• Only small amounts of chyme enter the small intestine at once

Question 10

The Pancreas

Answer 10

The Pancreas
Produces pancreatic juice
Sodium bicarbonate Neutralizes the acidic chyme
Digestive enzymes Amylase digests starch Trypsin digests protean Pancreatic lipase digests fat
Also an endocrine gland that produces the hormone insulin

Question 11

The Liver

Answer 11

• Largest gland in the body
• Removes poisonous substances from the blood and detoxifies them
• Stores iron and vitamins A, D, E, K, and B12
• Stores glucose as glycogen and releases when needed
• Converts glycerol and amino acids to glucose; produces urea as a byproduct
• Makes plasma proteins for blood
• Breaks down old red blood cells and turns hemoglobin into bilirubin
• Helps regulate cholesterol levels by turning cholesterol into bile salts