Ch. 22 - The Digestive System

Question 1

Identify the organs of the Digestive System

Answer 1

The digestive system consists of:

The Alimentary Canal

Mouth

Pharynx

Oesophagus

Stomach

Small Intestine

Large Intestine

Rectum

Anus

&

Accessory Organs

Salivary Glands

Liver

Gallbladder

Pancreas

Question 2

Digestive Organ Locations

Answer 2

Question 3

Digestive Pathway/Alimentary Canal

Answer 3

Question 4

Layers of the Alimentary Canal

Answer 4

Question 5

Explain the processes by which materials move through the digestive tract

Answer 5

There a 7 essential steps that move material through the digestive tract:

1. Ingestion
   - materials enter the digestive tract via the mouth.
2. Propulsion
   - the movement of food, including voluntary swallowing and involuntary ‘peristalsis’, which is the primary means of propulsion and involves alternating waves of muscular contraction and relaxation in the walls of the alimentary canal.
3. Mechanical Processing(breakdown)
   - Materials are crushed and broken into smaller fragments, making them easier to move through the digestive tract.
   - Enzymes begin to attack the particles during chewing, as the teeth and tongue are used to tear and mash the food.
   - Additional mechanical processing is provided by the mixing motions of the stomach and intestines.
   - Mechanical processing increases ingested foods’ surface areaa.
   - Segmentation mixes food with digestive juices, improving their absorption by moving various parts of the food mass over the intestinal wall repeatedly.
4. Digestion
   - Chemical breakdown of food into particles that are small enough to be absorped by the digestive epithelium from the lumen or cavity of the canal.
   - Simple molecules such as glucose are absorped intact.
   - Polysaccharides, proteins and triglycerides must first be broken down before they can be absorped.
   - Catabolic process.
5. Secretion
   - Release of water, acids, buffers, enzymes and salts by the epithelium and glandular organs of the digestive tract.
6. Absorption
   - The movement of organic substrates, electrolytes, vitamins, and water across the epithelium of the digestive tract into the interstitial fluid.
   - Organic substrates are molecules acted on by enzymes.
   - Absorption occurs via active or passive transport into blood or lymph.
7. Excretion
   - Removal of waste products from the body via secretions from the digestive tract and glandular organs.
   - After mixing with residue that cannot be digested, these waste products become faeces, which are eliminated during the process of defecation.

Question 6

Peristalsis Diagram

Answer 6

Question 7

Define Digestion

Answer 7

The mechanical and chemical breakdown of foods and the absorption of resulting nutrients by the body’s cells.

Mechanical digestion - process of breaking large pieces of food into smaller ones without altering their chemical makeup.

Chemical digestion - use of chemicals to break food into simpler chemicals.