Gastro-Intestinal Tract (GIT) 1

Question 1

Name the 8 components of the GIT

Answer 1

Mouth, Pharynx, Oesophagus, Stomach, Small Intestine, Large Intestine, Rectum, Anus

Question 2

Name the 6 accessory organs

Answer 2

Tongue, Teeth, 3 pairs of salivary glands, Liver, Gallbladder, Pancreas

Question 3

Name the 3 pairs of salivary glands

Answer 3

Parotid, Submandibular, Sublingual

Question 4

The coverings/walls of the GIT are the same from oesophagus to anus, name the 4 layers from inner to outer

Answer 4

Mucosa, Submucosa, Muscularis, Serosa

Question 5

Describe the mucous lining of the GIT and the function of each layer - 5 points

Answer 5

inner lining, has mucous membrane in direct contact with food contents, has epithelial layer which secretes enzymes and absorbs digested food, connective tissue layer which houses blood vessels & lymphatics, muscular mucosae which contains smooth muscle fibres which throws membrane into folds to increase surface area for digestion

Question 6

Describe the submucosa lining of the GIT - 3 points

Answer 6

connective tissue which binds mucosa to muscularis, has a rich blood supply, houses part of the autonomic nervous system which controls secretion from GIT

Question 7

Describe the muscularis lining of the GIT - 5 points

Answer 7

smooth muscle found in 2 sheets - inner, circular fibres / outer, longitudinal fibres - serves to physically break down food and push it through GIT, has nerve supply which controls mobility

Question 8

Describe serosa lining of GIT - 3 points

Answer 8

serous membrane which has connective tissue layer & epithelial layer, forms the inner layer of the peritoneum = Visceral Peritoneum
Outer layer of the peritoneum = Parietal Peritoneum

Question 9

Describe the Peritoneum

Answer 9

weaves between structures of the abdomen, binding them together and housing blood/lymphatic/nerve supply

Question 10

What is the oral cavity formed by

Answer 10

cheeks, lips, gums, teeth

Question 11

What is the upper portion of the oral cavity formed by

Answer 11

hard palate anteriorly, soft palate posteriorly

Question 12

Describe the uvula - 2 points

Answer 12

part of the soft palate, drawn superiorly during swallowing to prevent food from entering the nasal cavity

Question 13

The teeth, tongue and hard palate work together to begin …

Answer 13

initial mechanical breakdown of food = mastication

Question 14

Chemical breakdown in the oral cavity is where digestion begins, by …

Answer 14

saliva which is secreted from the sublingual glands, the submandibular glands and the parotid glands

Question 15

Where are the sublingual glands found

Answer 15

under the tongue

Question 16

Where are the submandibular glands found

Answer 16

posteriorly beneath the base of the tongue

Question 17

How does saliva from the parotid glands reach the oral cavity

Answer 17

secrete via the parotid duct to an area near the upper molars

Question 18

Food is swallowed from the oral cavity and passes through …

Answer 18

the oral pharynx on route to the oesophagus

Question 19

Describe the role of the Epiglottis

Answer 19

prevents food entering trachea during deglutination (the swallowing action)

Question 20

What 5 things does saliva contain and what is their purpose

Answer 20

Salivary Amylase - acts on starch
Mucus - lubricates food
Water - helps dissolve food, allowing taste and early digestive reaction
Bacteriolytic Enzyme (Lysozyme) - kills bacteria and helps protect mucus membrane
Immunoglobin - prevents attachment of microbes which may attack epithelium

Question 21

Describe Starch and what must be done for it to enter the bloodstream

Answer 21

found in most carbohydrates, made up of complex glucose chains - polysaccharides & disaccharides - bloodstream only absorbs monosaccharides therefore salivary amylase begins breakdown of these chains

Question 22

Describe the role of Lingual Lipase - 3 points

Answer 22

secreted by lingual glands in the mouth, stimulated within the acidic environment of the stomach, begins breakdown of triglycerides into diglycerides in the process of fat breakdown

Question 23

Describe the Oesophagus and its role - 3 points

Answer 23

muscular, collapsable tube which is behind the trachea, propels food to the stomach by muscular contractions of circular/longitudinal layers of the muscularis, secretes mucus & transports food to the stomach

Question 24

Describe any chemical digestion occurring and describe the role of the fibres of the muscularis layer when it interacts with a bolus of food - 3 points

Answer 24

there is no chemical digestion/absorption in oesophagus, circular fibres above the bolus of food constrict to the push the food downwards, longitudinal fibres inferior to the bolus of food shorten and allow the muscular walls of the oesophagus to be pushed outwards to accept the bolus

Question 25

Describe Peristalsis

Answer 25

involuntary movement controlled by the medulla oblongata in brain

Question 26

Describe the placement and role of the cardiac sphincter - 6 points

Answer 26

found at the lower end of the oesophagus, opens to allow food to enter the stomach, it prevents hydrochloric acid (HCl) in stomach refluxing into oesophagus - necessary because the acid is harmful to the lining of the lower end of the oesophagus, if theres a malfunction of the sphincter the patient will present with 'oesophageal reflux' - smoking and alcohol relax the sphincter which can worsen the problem

Question 27

Name the 6 parts of the stomach and their positioning

Answer 27

``` Cardia - surrounds the lower oesophageal sphincter Fundus - above and left of Cardia Body - large, central portion Pylorus - narrow, inferior portion Lesser Curvature - concave medially Greater Curvature - convex laterally ```

Question 28

Describe the walls of the submucosa and serosa of the stomach

Answer 28

similar make up to the remainder of the GIT

Question 29

Describe the mucosa inner lining of the stomach

Answer 29

lies in folds = rugae (these can become damaged if the stomach is ulcerated), contains gastric glands which secrete digestive enzymes and intrinsic factor (for B12 absorption)

Question 30

Name the 3 types of fibre that makes up the muscularis layer of the stomach and their collective role

Answer 30

outer longitudinal, middle circular, inner oblique fibres | these help with gastric juices to mix the food into a consistency called Chyme

Question 31

What does the stomach absorb

Answer 31

water, drugs and alcohol only

Question 32

Describe the first part of the Mechanical/Chemical Digestion within the stomach (Pyloric and Fundus regions)

Answer 32

Peristaltic waves move the food round the stomach to enable mixing with the gastric juices and pushing the food eventually towards the pylorus and on into the duodenum, Food remains in the fundus for approx. 1 hour so amylase & lingual lipase can continue the breakdown of starch & fat

Question 33

Describe the role of Hydrochloric Acid (HCl), Pepsin and Gastric Lipase in the mechanical/chemical digestion within the stomach

Answer 33

HCl within the stomach causes partial breakdown of proteins - stimulates the release of hormones to stimulate the bile release at a later stage of digestion Pepsin is released within the stomach, breaks down peptide bonds within amino acids which make up proteins, works well in acidic environment but stomach lining produces mucous secretions which protect it from acid damage Gastric Lipase splits triglyceride chains and so continues the breakdown of fats

Question 34

Describe the basic features of the Small Intestine (SI)

Answer 34

2.5cm in diameter, 6.35m long, consists of duodenum (25cm), Jejunum (2.5m) and Ileum (3.6m)

Question 35

Describe the Small Intestine (SI) - where it begins/ends - 3 points

Answer 35

opens at the pyloric sphincter from the stomach, curves around the head of the Pancreas - in close proximity to the liver and the gall bladder within this region, Finishes at the ileo-caecal valve where its becomes the large intestine

Question 36

Describe the Pancreas and its Pancreatic Juice

Answer 36

lies posterior to the greater curvature of the stomach, pancreatic juice is released through the pancreatic duct, - enters the duodenum through the Sphincter of Oddi at the ampulla of Vater (hepato-pancreatic ampulla) - this is the exocrine function of the pancreas, sodium bicarbonate which neutralises acid and stops the action of amylase - also creates optimum conditions for small intestine enzymes to work

Question 37

What does the pancreatic juice contain and its role

Answer 37

Pancreatic Amylase - to digest carbohydrates Trypsin - protein digesting enzyme, doesn't act on the walls of the pancreas and doesn't become active until it mixes with enterokinase as it enters the small intestine Pancreatic Lipase - principle triglyceride digesting enzyme Nucleic Acid - digested by ribonuclease and deoxyribonuclease