The Digestive System

Question 1

What is the first stage involved in the digestive system?

Answer 1

Preparatory stage

Question 2

What is the alimentary canal

Answer 2

Elongated tub extending from mouth to anus

Question 3

The role of the mouth

Answer 3

Mechanical digestion with salivary amylase produced by salivary glands

Breakdown of starch into disaccharide molecules

Question 4

What are the two phases in the preparatory stage?

Answer 4

Involuntary

Voluntary

Question 5

Involuntary phase

Answer 5

The tongue rises against the palette and closes the nasopharynx

Question 6

Voluntary phase

Answer 6

Swallowing occurs and the tongue moves to the hard palette pushing the food into orophynx

Question 7

Peristalsis

Answer 7

Muscles wave like contraction moves food into different parts of digestive region

Occurs in the alimentary canal

Question 8

Structure of alimentary canal

Answer 8

Contracting inner circular muscle sheet

Relaxing longitudinal muscle that pushes bolts in front of alimentary canal

Question 9

What is the role of the oesophagus?

Answer 9

Transports bolus to the stomach in the abdomen

Question 10

Role of the stomach

Answer 10

Stomach wall churns

Question 11

Structure of the stomach

Answer 11

Two- layer coat & external muscular

Wall of the stomach made of columnar

Epithelial lining contains goblet cells: produces mucus that protects stomach lining from acid erosion

Question 12

Role of gastric glands

Answer 12

1. Produces gastric juice : contains gastric protease
2. Parietal cells release HCl: denatures proteins
   denatures pepsinogen to pepsin
   production of gastric intrinsic factors

Question 13

What is Gastric intrinsic factor

Answer 13

A glycoprotein produced by parietal cells

Question 14

Stages of gastric intrinsic factor

Answer 14

1. Protein acts as a buffer
2. Increase of pH
3. Gastrij cells altered
4. HCl is too strong in the stomach + increased pepsinogen
5. Protein digestion= increase in amino acids
6. pH falls

Question 15

What affects HCl production

Answer 15

Histamine

Question 16

Role of histamine

Answer 16

Secreted by Enterochromaffin

Question 17

Cimetidine & Ranitidine

Answer 17

H2 receptor that inhibits stomach acid production

Question 18

What happens when food enters the stomach

Answer 18

Chyme emptied into the duodenum via pyloric sphincter

Question 19

What happens during peristalsis

Answer 19

Pyloric sphincter opens and allows some chyme to pass into duodenum

chyme mixed with juices and moves towards large intestine

Question 20

Role of duodenum

Answer 20

Protein digestion: Trypsin+ chymotrypsin broken down to small polypeptide and peptides

Synthesis and store fats: lipogenesis

Question 21

Structure of duodenum

Answer 21

Duodenal wall contains success entericus

Question 22

3 phases of gastric secretion

Answer 22

1. Cephalic phase
2. Gastric phase
3. Intestinal phase

Question 23

Intestinal phase

Answer 23

Enterogastric reflex: gastric motility inhibited by release of hormones such as secretin& CCK

Closes pyloric sphincter= blocks additional chyme entering duodenum

Duodenum: reduces rate of stomach emptying to small intestine

Question 24

Function of liver

Answer 24

Produces bile which is manufactured by hepatocytes

Bile is temporarily stored in gallbladder

Question 25

Role of pancreas

Answer 25

Releases digestive juices

Question 26

Function of gallbladder

Answer 26

Stores bile needed for the digestion of fats in food

Question 27

Function of bile

Answer 27

Contains bile salts, cholesterol, water and electrolytes

Question 28

Structure of liver

Answer 28

Connected to portal vain: brings in nutrient rich blood from digestive system Hepatic artery: carries oxygenates blood from heart

Question 29

Digestion of disaccharides

Answer 29

Small intestinal brush border enzymes such as sucrase-isomaltase

Question 30

Digestion of polysaccharides

Answer 30

In the mouth by salivary amylase

Question 31

Digestion of fats

Answer 31

Small intestine by pancreatic lipase

Question 32

Digestion of proteins

Answer 32

Stomach by pepsin and chymotrypsin secreted by the pancreas

Question 33

What is the biliary tree

Answer 33

System of vessels that direct secretions from liver, gallbladder and pancreas into the duodenum