Digestive System

Question 1

What are the accessory organs of the digestive system?

Answer 1

liver, pancreas, gallbladder, salivary glands

Question 2

Name the 4 layers of the gut wall.

Answer 2

Mucosa
Submucosa
External muscle layers (2)
Serosa

Question 3

Outline the structure of the mucosa in the alimentary tract.

Answer 3

1. Epithelium - simple columnar
2. Lamina propria - mucosal glands and peyer’s patches
3. Muscularis mucosae

Question 4

What is present in the submucosa?

Answer 4

Glands

Veins, arteries and nerves

Question 5

What are the 2 layers of external smooth muscle in the gut wall?

Answer 5

Inner circular

Outer longitudinal

Question 6

What is the serosa of the gut wall called and what is it comprised of?

Answer 6

Connective tissue and simple squamous epithelium = mesothelium.

Question 7

Outline major functions of the GI tract.

Answer 7

1. Chemical and physical disruption of food
2. Food storage
3. Kills pathogens
4. Absorb nutrients
5. Excrete waste material

Question 8

What are the properties of saliva?

Answer 8

1. High in calcium
2. Lipases and amylases - begins digestion
3. Alkali
4. Aids swallowing
5. Protects the mouth
6. Bacteriostatic (IgA)

Question 9

What innervates the GI tract?

Answer 9

Myenteric plexus and submucosal plexus

Question 10

What muscle types control the oesophagus?

Answer 10

Upper 1/4 - skeletal muscle, voluntary

Lower end- smooth muscle, involuntary

Question 11

What epithelium lines the oesophagus and its characteristics?

Answer 11

Stratified squamous non - keratinized epithelium.

Withstands abrasion.

Question 12

What does the submucosa contain?

Answer 12

Mucus secreting glands

Question 13

What is the food entering the oesophagus called?

Answer 13

Bolus

Question 14

What is receptive relaxation?

Answer 14

Distension of the stomach wall in order to prevent pressure rising

Question 15

There are 3 layers of smooth muscle in the stomach wall, what are they?

Answer 15

Oblique, circular and longitudinal

Question 16

The stomach contains longitudinal ridges, what are these called?

Answer 16

Rugae

Question 17

What are some of the functions of the stomach?

Answer 17

Chemically (HCl, stomach acid) and physically (churning) disrupt the food.
Secretes acid and proteolytic enzymes
Food store

Question 18

What does the stomach produce?

Answer 18

Hypertonic, acidic chyme

Question 19

What classification are gastric glands?

Answer 19

Long, straight tubular glands

Question 20

What cells dominate the pit of the gland?

Answer 20

Mucus- secreting cells

Question 21

Parietal cells are in gastric glands, what is their function?

Answer 21

Secrete H+ ions into the lumen and HCO3- into the capillaries which move it to the surface mucous cells.

Question 22

What do chief cells of the gastric gland secrete?

Answer 22

Pepsinogens which are converted into pepsins which hydrolyse proteins.

Question 23

Enteroendocrine cells at the bottom of the gastric gland include G-cells, what do these secrete?

Answer 23

Gastric, which stimulates acid secretion.

Question 24

What section of the small intestine has brunner’s glands, what do they do?

Answer 24

Duodenum.

They secrete bicarbonate- rich mucus to neutralise the acidic chyme from the stomach.

Question 25

How else does the duodenum neutralise the chyme?

Answer 25

Alkali secretions from the pancreas and liver

Question 26

What does the duodenum do to the tonicity of the chyme?

Answer 26

Hypertonic to Isotonic by drawing water from ECF.

Question 27

What structures increase the surface area of the small intestine?

Answer 27

pilcae circulares Villi Microvilli

Question 28

What is absorbed in each of the parts of the small intestine?

Answer 28

Duodenum - Iron jejumum - fatty acids, amino acids and sugars Ileum- Vit B12, bile acids and remaining nutrients

Question 29

What is the main function of the large intestine?

Answer 29

Water and electrolyte absorption

Question 30

What functional role does the large population of bacteria in the colon have?

Answer 30

- synthesises vitamin K, B12, histamine and riboflavin. - breakdown of bile acids - conversion of bilirubin to non-pigmented metabolites

Question 31

What are crypts of lieberkuhn?

Answer 31

Mucus secreting tubular glands between villi.

Question 32

What does bile contain?

Answer 32

Water, alkali and bile salts

Question 33

How do paracrine substances contribute to control of the gut?

Answer 33

Histamine - controls acid production | Vasoactive substances affect blood flow to gut

Question 34

What 3 endocrine molecules control the gut?

Answer 34

Gastrin Secretin Cholecystokinin

Question 35

What does gastrin do?

Answer 35

Promotes HCl production by parietal cells

Question 36

What does secretin do?

Answer 36

Inhibits acid secretion by parietal cells Stimulates bicarbonate secretion from pancreatic ducts Promotes bile production by the liver

Question 37

What does cholecystokinin do?

Answer 37

promotes release of digestive enzymes from pancreas Promotes release of bile from the gallbladder Hunger suppressant

Question 38

Where are plicae circulares and what is their function?

Answer 38

Small intestine, increase SA for absorption

Question 39

Which section of the intestine is lined with villi?

Answer 39

Small intestine only