Chapter 37

Question 1

What is an Animal’s Digestive System?

Answer 1

A body cavity or a tube that mechanically and chemically breaks down food to small particles to get absorbed into the internal environment. It also expels unabsorbed residues, and helps maintain homeostasis.

Question 2

What is an Incomplete Digestive System?

Answer 2

Some invertebrates have it, food enters and waste leaves a saclike gut through a single opening at the body surface.

Question 3

What is a Complete Digestive System?

Answer 3

All vertebrates have one, a tubular gut with two openings. A mouth at one end and an anus at the other, along the tube there are specialized regions that process food, absorb nutrients, and concentrate water.

Question 4

Five Tasks of a Complete Digestive System

Answer 4

1. Mechanical processing and motility
2. Secretion
3. Digestion
4. Absorption
5. Elimination

Question 5

Complete Digestive System Task: Mechanical Processing and Moltility

Answer 5

Movements that break up, mix, and directionally propel food material.

Question 6

Complete Digestive System Task: Secretion

Answer 6

Release of substances, especially digestive enzymes, into the lumen (the space inside the tube).

Question 7

Complete Digestive System Task: DIgestion

Answer 7

Breakdown of food into particles, then to nutrient molecules small enough to be absorbed.

Question 8

Complete Digestive System Task: Absorption

Answer 8

Uptake of digested nutrients and water across the gut wall, into extracellular fluid.

Question 9

Complete Digestive System Task: Elimination

Answer 9

Expulsion of undigested or unabsorbed solid residues.

Question 10

True or False: Digestive Systems differ due to diet-related adaptations

Answer 10

True, examples include: type of feeding structures and length of the gut

Question 11

Gastrointestinal Tract in Humans

Answer 11

Gut, starts at the stomach and extends through the intestines to the tube’s terminal opening.

Question 12

Oral Cavity in Humans

Answer 12

The mouth, food is partially processed here.

Question 13

Tongue in Humans

Answer 13

Membrane-covered skeletal muscle that positions food for swallowing.

Question 14

Pharynx in Humans

Answer 14

The throat, the entrance to the digestive and respiratory tracts.

Question 15

Esophagus in Humans

Answer 15

A muscular tube in between the pharynx and stomach.

Question 16

Stomach in Humans

Answer 16

A stretchable sac that stores food, secretes acid and enzymes, and mixes them together.

Question 17

Complete Digestion System in Humans

Answer 17

Swallowing forces food and water from the mouth into the pharynx. Food continues through an esophagus to the stomach. Food processing starts in the mouth, most digestion and absorption occurs in the small intestine. The colon absorbs most of the remaining water and ions, which causes the wastes to compact. The rectum briefly stores the wastes before they are expelled through the anus.

Question 18

Function of Teeth

Answer 18

Mechanically breakdown food into particles, salivary amylase begins the chemical digestion of carbohydrates.

Question 19

Carbohydrate Digestion System

Answer 19

Includes the mouth, stomach, and small intestine.

Question 20

Protein Digestion System

Answer 20

Found in the stomach and small intestine.

Question 21

Lipid Digestion System

Answer 21

Found in the small intestine.

Question 22

Nucleic Acid Digestion

Answer 22

Found in the small intestine.

Question 23

Hormonal Controls of Digestion: Gastrin

Answer 23

Source: Stomach
Effect: Increases acid secretion by stomach

Question 24

Hormonal Controls of Digestion: Cholecystokinin (CCK)

Answer 24

Source: Small Intestine
Effect: Increases enzyme secretion by pancreas and causes contractions of gallbladder.

Question 25

Hormonal Controls of Digestion: Secretin

Answer 25

Source: Small Intestine
Effect: Increases bicarbonate secretion by pancreas and slows contractions in the small intestine.

Question 26

Features of the Small Intestine Lining

Answer 26

1. Lining is folded
2. Millions of multicelled, fingerlike absorptive structures called villi extend from these folds, this villi house a lymph vessel and blood vessels
3. Most cells on the villus surface are brush border cells, which have membrane extensions called microvilli that project into the lumen.

Question 27

Brush Border cell Functions

Answer 27

Both digestion and absorption.

Question 28

Absorption Mechanisms

Answer 28

1. Water and Solute Absorptions

2. Fat Absorption

Question 29

Colon Function

Answer 29

By absorbing water and mineral ions, the colon compacts undigested residues and other wastes as feces, which are stored briefly in the rectum before expulsion.

Question 30

Purpose of Absorbed Sugars

Answer 30

Absorbed sugars are the human body’s most accessible energy source. Between meats, the brain draws on glucose in blood; other cells tap fat and glycogen stores, Adipose cells convert and store excess carbohydrates as fats.

Question 31

Liver Functions

Answer 31

Forms bile (assists fat digestion), rids body of excess cholesterol and blood’s respiratory pigments. Controls amino acid levels in the blood; converts potentially toxic ammonia to urea. Controls glucose level in blood, major reservoir for glycogen. Removes hormones that served their function in blood. Removes ingested toxins, such as alcohol, from blood. Breaks down worn-out and dead red blood cells, and stores iron. Stores some vitamins.

Question 32

Vitamins

Answer 32

Organic substances that are essential in very small amounts

Question 33

Minerals

Answer 33

Inorganic substances that are essential for growth and survival.