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Question 1

What is the overall function of the gastrointestinal system?

Answer 1

• Secretion• Digestion• Motility• Absorption

Question 2

What are the qualities of the products of digestion?

Answer 2

• Sterile• Neutral• Isotonic

Question 3

What solutions does the process of digestion create?

Answer 3

• Small sugars• Amino acid and small peptides• Lipids in very small particles

Question 4

Define absorption

Answer 4

• Specific active or passive uptake of nutrient molecules, water and electrolytes

Question 5

Give three waste products of the GI tract

Answer 5

• Residue from food• Gut debris • Materials secreted from liver

Question 6

What needs to happen to food for digestion to occur?

Answer 6

• Disrupted physically to release large molecules• Broken down chemically to release small molecules

Question 7

Why do ingested foods need to be stored?

Answer 7

• We can eat much faster than we can digest

Question 8

Outline the overall process of digestion

Answer 8

• Initial physical disruption• Ingestion & transport to storage• Initial chemical disruption & creation of suspension – forming chyme• Disinfection• Controlled release of chyme• Dilution and neutralisation of chyme• Completion of chemical breakdown• Absorption of nutrients and electrolytes• Final absorption of water and electrolytes,• Producing faeces for controlled excretion

Question 9

List the two mechanisms involved in physical disruption of food

Answer 9

MasticationSaliva

Question 10

Outline the functions of saliva

Answer 10

• Protects mouth• Lubricates food• Starts digestion

Question 11

Give four ways in which saliva protects the mouth

Answer 11

• Wet - maintains mucosae• Bacteriostatic• Alkaline - protects teeth• High calcium - protects teeth

Question 12

What does saliva initially digest?

Answer 12

• Sugars

Question 13

What is food called after it has been physically disrupted?

Answer 13

• Bolus

Question 14

Where does storage, initial disruption and disinfection take place?

Answer 14

Stomach

Question 15

How is chyme produced in the stomach?

Answer 15

• Action of acid, enzymes and agitation

Question 16

Where does dilution and neutralisation of chyme take place?

Answer 16

• Duodenum and jejunum

Question 17

Why does dilution take place?

Answer 17

• To ensure that the chyme is of the same osmotic potential as the small intestine

Question 18

What do enzymes from pancreas and intestine do?

Answer 18

• Cleave peptides to amino acids• Cleave polysaccharides to monosaccharaides• Breakdown and re-form lipids• Break down nucleic acids

Question 19

How does absorption of nutrients and electrolytes take place?

Answer 19

• Intestine has large SA due to brush border• Epithelial cells absorb small molecules - some actively, some passively• Often coupled to sodium absorption

Question 20

What are absorbed nutrients taken into?

Answer 20

• Hepatic portal circulation

Question 21

Where does final absorption of water and electrolytes occur?

Answer 21

• Large intestine

Question 22

Where does faeces accumulate?

Answer 22

• Descending and sigmoid colon

Question 23

How does defecation occur?

Answer 23

• Faeces propelled into rectum• Controlled relaxation of sphincters and expulsion of faeces occurs

Question 24

What is the function of the stomach?

Answer 24

• Relaxes to accommodate food• Rhythmical contraction• Secretes acid and proteolytic enzymes to break down tissues• Disinfects bolus

Question 25

Outline the process of receptive relaxation

Answer 25

• Stomach strongly contracted between meals• Relaxes as bolus enters• Prevents a rise in pressure of the stomach

Question 26

What takes place in the duodenum and jejunum?

Answer 26

• Water drawn in from ECF• Bile added to chyme• Pancreas, liver and intestinal secretions (enzymes and bile acids)• Liver and pancreas secrete alkali and neutralise acid

Question 27

How is duodenum adapted to the highly concentrated chyme it receives from the stomach?

Answer 27

• Wall permeable to water• Draws water in to dilute contents

Question 28

Outline the four layers of alimentary canal

Answer 28

• Mucous membrane• Submucosa• Muscularis externae• Serosa

Question 29

What makes up the mucous membrane?

Answer 29

• Lining epithelium• Connective tissue• Thin layer of smooth muscle

Question 30

What makes up the submucosa?

Answer 30

• Fibroelastic tissue with• Vessels• Nerves of the submucosal plexus• Leucocytes • Fat cells

Question 31

What makes up the muscularis externa?

Answer 31

An inner circular layerOuter longitudinal layer

Question 32

What lies between the two layers of the muscularis externae?

Answer 32

• Myenteric plexus

Question 33

What is the serosa?

Answer 33

• A thin outer covering of connective tissue

Question 34

What is endoscopy?

Answer 34

• A long, thing tube which allows direct visual examination, biopsy sampling and therapeutic treatment of the gastro-intestinal tract

Question 35

What is nasendoscopy?

Answer 35

• Allows visualisation of the nose, mouth and pharynx

Question 36

What structure marks the beginning of the oesophagus?

Answer 36

• Cricopharyngeal sphincter

Question 37

Where does the diaphragm cuff the oesophagus, and why is this clinically relevant?

Answer 37

• At the oesophagogastric mucosal junction• This relationship may be disrupted by a hiatus hernia, which allows the stomach to herniate into the thorax

Question 38

Outline the venous drainage of the oesophagus

Answer 38

• Drains into the left portal system via the left gastric vein

Question 39

How is the oesophagus adapted to rapid transport?

Answer 39

• Streamlined structure which minimises friction

Question 40

What are the longitudinal ridges of the stomach called?

Answer 40

• Rugae, increase SA

Question 41

Where is gastric ulceration most common?

Answer 41

• Lesser curve at the angulus

Question 42

What is the normal maximal fluid contents of the gut?

Answer 42

• 14L• 1kg food, 1.5L saliva, 2.5L gastric secretions, 9l of water and alkali

Question 43

How are the contents of the gut removed?

Answer 43

• Small intestine absorbs 12.5l• Large intestine absorbs 1.35• 150g faeces expelled

Question 44

What happens if the balance between secretion and absorption altered?

Answer 44

• Considerable loss of water and electrolytes, mostly from body fluids• Rapid dehydration and electrolyte disturbance

Question 45

Name three control systems of the gut

Answer 45

• Neural• Paracrine• Endocrine

Question 46

Why are three overlapping control systems needed in the gut?

Answer 46

• Motility and secretion need precise control

Question 47

What is the somatic motor used for in the gut?

Answer 47

• Ingestion (chewing) and excretion (defecation)

Question 48

What is the most significant neural control system of the gut?

Answer 48

• Autonomic (specifically parasympathetic) control

Question 49

What do post ganglionic neurones form in the gut?

Answer 49

• Plexuses

Question 50

What does the "gut nervous system" control?

Answer 50

• Coordinates secretion and motility

Question 51

What enteric nervous system of the gut made up of?

Answer 51

• Two nerve plexuses which may act independently of CNS and be modified by both branches of the ANS

Question 52

What is paracrine secretion?

Answer 52

• Chemical messengers diffuse locally

Question 53

Name a chemical messenger secreted via the paracrine method

Answer 53

Histamine

Question 54

Give three factors the endocrine system controls in the digestive system

Answer 54

• Stomach acid• Alkali secretion from liver and pancreas• Enzyme secretion

Question 55

What type of structure do gut hormones share?

Answer 55

• All peptide derived

Question 56

What are the two groups of gut hormones?

Answer 56

• Gastrin group• Secretin group