Chapter 6 - Digestive System

Question 1

Define digestion

Answer 1

Digestion is the process of breaking down food into particles small enough to be absorbed into the bloodstream.

Question 2

List the 6 basic activities of digestion

Answer 2

1. Ingestion of food and water through mouth
2. Mechanical digestion of food
3. Chemical digestion of food
4. Movement of food along the alimentary canal
5. Absorption of digested food and water into the blood and the lymph (small intestine)
6. Elimination of material that is not absorbed.

Question 3

Describe the structure and function of the mouth cavity

Answer 3

Mechanical digestion by teeth; chemical digestion of starch by saliva. The mouth grinds and breaks down food.

Question 4

Describe the structure and function of salivary glands

Answer 4

There are three pairs of glands that produce saliva, which dissolves food so it can be tasted. Saliva contains mucus that lubricates the mouth and food.

Question 5

What is the function of the liver?

Answer 5

Produces bile, which is stored and concentrated in the gall bladder. Bile emulsifies lipids in the small intestine.

Question 6

What is the role of the pharynx?

Answer 6

By moving upwards and backwards, the tongue pushes food into the pharynx for swallowing.

Question 7

What is the function of the oesophagus?

Answer 7

Carries food from the mouth to the stomach. It passes through the diaphragm into the abdominal cavity.

Question 8

Describe the mechanical and chemical digestion that occurs in the stomach

Answer 8

Mechanical digestion occurs by a churning action; chemical digestion by pepsin, which begins protein digestion.

Question 9

What is the function of the gall bladder?

Answer 9

Stores bile and releases it into the small intestine where the bile emulsifies lipids.

Question 10

What is the duodenum?

Answer 10

The first part of the small intestine.

Question 11

What is the role of the pyloric sphincter?

Answer 11

A band of circular muscle that regulates the flow of material from the stomach to the duodenum.

Question 12

What does the pancreas produce?

Answer 12

Produces pancreatic juice containing enzymes for digesting proteins, lipids, and nucleic acids.

Question 13

What is the length of the small intestine?

Answer 13

About 6m long.

Question 14

What is the function of the appendix?

Answer 14

Plays a role in immunity and stores useful bacteria.

Question 15

What is the rectum?

Answer 15

The final part of the large intestine in which faeces are formed.

Question 16

What is the anus?

Answer 16

Opening surrounded by the anal sphincter, a muscle that can be voluntarily controlled.

Question 17

Distinguish between mechanical and chemical digestion

Answer 17

Mechanical digestion involves physical processes that break food into smaller pieces without forming new substances. Chemical digestion involves enzymes that metabolize food molecules into smaller molecules.

Question 18

Describe the alimentary canal

Answer 18

Has a thin layer of epithelium with glands for secreting digestive substances, contains smooth muscle cells for movement, and contains sub-mucosa with a blood supply for absorption.

Question 19

Describe the mechanical and chemical digestion that occurs in the mouth

Answer 19

Mechanical digestion involves breaking down food to increase surface area. Chemical digestion involves breaking down macromolecules into smaller molecules.

Question 20

What is the dental formula for humans?

Answer 20

2,1,2,3, totaling 32 teeth.

Question 21

Describe peristalsis

Answer 21

The movement of the muscles in the oesophagus that propels food towards the stomach via contractions.

Question 22

What is the role of circular and longitudinal muscles during peristalsis?

Answer 22

Circular muscles propel food towards the stomach, while longitudinal muscles reduce oesophageal wall stress and compliance.

Question 23

What occurs during mechanical digestion in the stomach?

Answer 23

It continues the mechanical digestion of food, churning the contents and mixing them with gastric juice.

Question 24

What is the role of gastric juice in the stomach?

Answer 24

Gastric juice, which contains hydrochloric acid and gastric protease, continues the chemical digestion of food and starts protein digestion.

Question 25

What is chyme?

Answer 25

The material that has been processed in the stomach after about 4+ hours.

Question 26

Describe the mechanical and chemical digestion that occurs in the small intestine

Answer 26

Muscular contractions churn food; bile salts emulsify lipids. Pancreatic juice and intestinal juice contain enzymes that break down carbohydrates, proteins, and lipids.

Question 27

What are the groups of digestive enzymes produced by the salivary glands, stomach, pancreas, and small intestine?

Answer 27

Salivary amylase, gastric protease, pancreatic amylase, pancreatic protease, and intestinal enzymes.

Question 28

List the ways in which the surface area of the small intestine is maximized for absorption

Answer 28

The small intestine contains many folds, is long, and has villi that increase surface area.

Question 29

Describe the structure of a villus

Answer 29

One cell thick to shorten the distance for diffusion, contains capillaries for absorption, and has microvilli to increase surface area.

Question 30

Distinguish between elimination and excretion

Answer 30

Excretion is the removal of metabolic waste produced by body cells, while elimination refers to the removal of indigestible wastes through the anus.

Question 31

Outline the function of the large intestine

Answer 31

Responsible for absorbing water from undigested food, producing and absorbing vitamins, and storing faeces prior to defecation.

Question 32

What is the composition of faeces?

Answer 32

75% water, 5% bacteria, and 20% undigested material.