The GI Tract

Question 1

What are the different sections of the GI tract?

Answer 1

Mouth
Oesophagus
Stomach
Small intestine
Lagre intestine
Rectum
Anus

Question 2

What are the different accessory organs to the GI tract? What are their functions?

Answer 2

Salivary glands - Secretion of amylase and lipase, also saliva production
Liver - Whole variety
Gallbladder - Concentration and release of bile
Pancreas - Secretion of intestinal enzymes and hormones

Question 3

What is the mesentery? What is its function?

Answer 3

A membranous tissue that surrounds GI tract organs and holds them in place.

It also provides blood and lymphatic vessels.

Question 4

What mechanical digestion process occurs in the mouth?

Answer 4

Mastication

Question 5

What mechanical digestion occurs in the stomach?

Answer 5

Peristaltic contraction

Question 6

What mechanical digestion occurs in the small and large intestine?

Answer 6

Segmentation and peristalsis

Question 7

What mechanical digestion occurs in the oesophagus?

Answer 7

Peristalsis

Question 8

What is peristalsis?

Answer 8

Propulsion of a food bolus through the GI tract caused by smooth muscle contraction.

Question 9

What is the function of the pharynx and epiglottis in the mouth?

Answer 9

To prevent food from travelling to the lungs.

Question 10

What is the function of the oesophagus?

Answer 10

Transports food bolus from the mouth to the stomach.

Question 11

Summarise the main functions of the stomach:

Answer 11

• Mixing of food
• Protein digestion (acid and pepsin)
• Pathogen defence (acid)
• Starts fat emulsification

Question 12

What are the main functions of the small intestine?

Answer 12

• Main site of absorption for the GIT
• Site of carb, fat and protein breakdown

Question 13

What are the 3 sections of the small intestine in order?

Answer 13

1. Duodenum
2. Jejunum
3. Ileum

Question 14

In what ways is the small intestine specialised for absorption?

Answer 14

• Villi and microvilli to increase surface area
• Rich blood supply to steepen conc gradients for absorption

Question 15

What is the main role of the large intestine?

Answer 15

• Water and ion conservation

Question 16

Define ingestion:

Answer 16

The process of intaking food or drink

Question 17

What is segmentation? What is its purpose?

Answer 17

Smooth muscle contractions that separate food into separate boluses in the GIT.

It mixes the food and the digestive juices, maximising digestion.

Question 18

What cells are responsible for saliva production?

Answer 18

Serous cells

Question 19

What cells produce gastric acid in the stomach?

Answer 19

Parietal cells

Question 20

What is the function of G cells?

Answer 20

To secrete gastrin when stimulated by the ENS (in order to stimulate parietal cells).

Question 21

What is the function of chief cells?

Answer 21

To secrete pepsin for polypeptide digestion.

Question 22

What cells are responsible for mucous secretion in the mouth?

Answer 22

Mucous cells

Question 23

What cells secrete pepsin in the stomach?

Answer 23

Chief cells

Question 24

What cells secrete gastrin in the stomach?

Answer 24

G cells

Question 25

What cells secrete gastric acid in the stomach?

Answer 25

Parietal cells

Question 26

Describe the lipid absorption pathway:

Answer 26

- Fatty acids and monoglycerides move by simple diffusion into epithelial cells - These form triglycerides which are sent to the Golgi to form chylomicrons - Chylomicrons diffuse into the lacteal system for transport

Question 27

Describe the polypeptide absorption pathway:

Answer 27

- Amino acids active transported with Na+ into epithelial cells - Amino acids can then be transported into the circulatory system - Alternatively, synthesised into proteins which are sent into circulatory system

Question 28

What is emulsification? Why is it necessary?

Answer 28

The decomposition of large fat droplets into small fat droplets. When lipids collect to form large droplets they limit the rate of enzyme action due to the limited SA. By breaking them down into smaller droplets the SA increases and speeds up digestion.

Question 29

What is the purpose of chylomicrons?

Answer 29

To make lipids water soluble for transport in the blood and lacteal system.

Question 30

Why do many oral drugs have an enteric coating?

Answer 30

In order to avoid degradation in the stomach and pass into the SI.