Digestive System

Question 1

What are the four layers of the gut?

Answer 1

Mucosa, submucosa, external muscle layers, serosa

Question 2

What are the three layers of the mucosa?

Answer 2

Epithelia, Lamina propria, muscularis mucosae

Question 3

What is the submucosa?

Answer 3

A layer of connective tissue bearing glands, arteries, veins and nerves

Question 4

What are the major functions of the gastrointestinal tract?

Answer 4

mechanically disrupt, temporarily store, chemically digest food
Kill pathogens in food, move food, absorb nutrients and eliminate waste

Question 5

What is digestion?

Answer 5

The conversion of what we wet by physical and chemical disruption into a solution from which we can absorb our nutrients

Question 6

What is saliva used for?

Answer 6

Starts digestion with amylase and lipase

Bacteriostatic, high in calcium, alkaline, assists swallowing, protects mouth

Question 7

What does the mouth do to food?

Answer 7

By using teeth, tongue and saliva’s enzymes forms a bolus

Question 8

How does the oesophagus move food?

Answer 8

Rapid Peristaltic transport

Question 9

What is the Muscularis externa?

Answer 9

smooth muscle layers which move food by peristalsis

Question 10

What is the Adventitia?

Answer 10

Thin outermost layer of connective tissue

Question 11

How does the stomach physically and chemically disrupt food?

Answer 11

Physically- By churning with the three muscle layers

Chemically- By acid and enzymes

Question 12

What does the stomach do?

Answer 12

Store, initial disruption and disinfection

Question 13

How does the stomach protect itself from the acid?

Answer 13

Secretes mucus which contains HCO3- which neutralise the stomach

Question 14

What is Rugae?

Answer 14

Folds of gastric mucosa forming longitudinal ridges in empty stomach

Question 15

What can damage mucus cells in the stomach?

Answer 15

Alcohol and aspirin

Question 16

What is the duodenum?

Answer 16

Connects the liver and pancreas
Dilutes and neutralises chyme
Draws in water to make chyme isotonic otherwise would damage the liver

Question 17

What do enzymes do from the pancreas and intestine?

Answer 17

Cleave peptides to amino acids
cleave polysaccharides to monosaccharides
Break down and re-form lipids
Break down nucleic acids

Question 18

What does absorption require?

Answer 18

Lots of energy, large surface area, good blood supply

Question 19

What are the three parts of the small intestine?

Answer 19

Duodenum- absorbs iron
Jejunum- absorbs most sugars, aa and fatty acids
Ileum- absorbs vitamin B12, bile acids and remain nutrients

Question 20

What does the large intestine do?

Answer 20

continues water recovery so by the end is semi-solid

Question 21

What does the bacteria in the large intestine do?

Answer 21

syntheisie vitamin K, B12, thiamine and riboflavine, breaks down 1 to 2 bile acids, converts bilirubin into non-pigmented metabolites

Question 22

Where contains most bacteria in the GI tract?

Answer 22

Colon

Question 23

How much food is converted not faeces?

Answer 23

1kg into 0.15kg of faeces via 14 litres of fluid

Question 24

What is the problem with fluid balance?

Answer 24

delicate balance and gut is dealing with large quantities

Question 25

How is the fluid balance controlled?

Answer 25

Neural, Paracrine and Endocrine systems

Question 26

How is the fluid balance controlled neurally?

Answer 26

Somatic- ingestion and excretion

Autonomic- gut nervous system, neurotransmitters, post ganglion neurones

Question 27

How is the fluid balance controlled by the paracrine system?

Answer 27

Substances act locally e.g. histamine (production of acid control) and Vasoactive substances(blood flow to gut control)

Question 28

How is the fluid balance controlled by the endocrine system?

Answer 28

Range of hormones control the secretion of acid, alkali and enzymes
These are Secretin, Cholecystokinin and Gastrin

Question 29

What does secretin do?

Answer 29

Promotes HCO3- secretion from duct cells of pancreas
Promotes bile production by the liver
inhibits secretion of acid by parietal cells of stomach

Question 30

What does cholecystokinin do?

Answer 30

Promotes release of digestive enzymes from the pancreas

Promotes relase

Question 31

What does cholecystokinin do?

Answer 31

Enteroendorcrine cells in duodenum synthesises and secrete
Promotes release of digestive enzymes from the pancreas
Promotes release of bile from gall bladder
hunger suppresent

Question 32

What does Gastrin do?

Answer 32

Released by G cells, pancreas and duodenum

Promotes production of HCl by parietal cells of the stomach

Question 33

What are the main roles of the gut?

Answer 33

Secretion, movement and absorption