3.4 Physiology Of GI Tract

Question 1

What are the four main roles of the digestive system?

Answer 1

1. Ingestion.
2. Digestion.
3. Absorption
4. Defecation.

Question 2

Digestion

Answer 2

Food breakdown that occurs when food is moved, mixed and exposed to enzymes along the GI tract.

Question 3

Digestion can be broken down into what two parts?

Answer 3

1. Mechanical - occurs when food is physically broken down into smaller pieces, using the teeth to chew the food, stomach to churn/mix and as food is moved into GI tract.
2. Chemical - chemical breakdown of food by enzymes into smaller nutrients. 

Question 4

Absorption

Answer 4

The process of moving digested food into the bloodstream

Question 5

Defecation

Answer 5

The excretion of indigestible food from the anus 

Question 6

Salivary Amylase

Answer 6

The enzyme in saliva that chemically breaks down starches

Question 7

Bolus

Answer 7

Food that is broken down into smaller pieces by the teeth and tongue 

Question 8

Question 9

What is the stomach’s main function

Answer 9

Mechanical and chemical breakdown of food 

Question 10

Saliva

Answer 10

Produced by the salivary glands is over 99% water, but also contains enzymes and proteins that lubricate the oral cavity 

Question 11

Gastric juice

Answer 11

Produced by the gastric glands in the stomach lining and contains hydrochloric acid and enzymes that digest food into chyme 

Question 12

Types of gastric juices produced by hormone gastrin

Answer 12

1. Pepsinogen - chief cells
2. Hydrochloric acid - (1. parietal & 2. pepsinogen/pepsin
3. Mucous - (1. mucus secreting cells & 2. Protects stomach epithelium)

Question 13

Parietal cells

Answer 13

Located in the wall of the stomach and secretes Hydrochloric acid generating a pH of 1.3 - 3.5.

Very acidic PH kills ingested bacteria.

Question 14

Pepsinogen

Answer 14

Secreted by the chief cells in the stomach 

Question 15

Pepsin

Answer 15

Hydrochloric acid convert the inactive Pepsinogen into the active enzyme pepsin which breaks down proteins.

Question 16

Peptides

Answer 16

Result from the first step in protein digestion and are digested by peptidases to amino acids.

Question 17

Maltose

Answer 17

Results from the first step in starch digestion, is digested by Maltase to glucose.

Question 18

Hey pancreatic juice includes what three enzymes?

Answer 18

1. Amylase
2. Trypsin
3. Lipase

• digest starches, proteins &fats

4. Bicarbonate - neutralizes the acidic chyme.