Gastrointestinal System

Question 1

What are the two functions of the gastrointestinal system?

Answer 1

Digestion (processes food) and absorption (transfers nutrients to circulation)

Question 2

What are the 2 groups of organs in the GI system?

Answer 2

Digestive tract
Accessory organs

Question 3

List the accessory organs and give their functions:

Answer 3

Salivary glands - secrete mixed watery mucous which buffers mouth pH, protects surface of mouth, antibacterial, maintain tooth structure
Gall bladder - store and concentrate bile produced by liver and aids in fat digestion
Liver
Pancrease

Question 4

List the components of the GI tract in order:

Answer 4

Oral cavity
Pharynx
Oesophagus
Stomach
Small intestine
Large intestine
Rectum
Anus

Question 5

Describe the structure of the pharynx and its function

Answer 5

12-15cm long muscular tube
Divided into 3 parts: nasopharynx, oropharynx, laryngopharynx
Air and food passes through it to oesophagus, conducts air

Question 6

Describe the structure of the oesophagus and its function

Answer 6

20-25cm long muscular tube
Mucosa membrane made from strattified sqauamous epithelium, the lamina propria and muscularis mucosae
Submucosa contains glands and lymphoid follicles
Muscularis mucosae/ externa coprised of cirular and logitudinal
- Changes from skeletal in top 1/3, then both skeletal and smooth and only smooth in bottom 1/3
Serosa

Passes food from pharynx to stomach
Passes behind the heart and trachea

Question 7

What are the 9 areas of the abdomen called?
123
456
789

Answer 7

1: right hypochondrium
2: epigastric
3: Left hypochondrium
4: Right lumbar
5: Umbilical
6: Left lumbar
7: Right iliac fossa
8: Suprapubic
9: Left iliac fossa

Question 8

What organ is found in the right hypochondrium?

Answer 8

liver

Question 9

What organ is found in the epigastric?

Answer 9

duodenum, liver, gall bladder, pancreas, stomach

Question 10

What organ is found in the left hypochondrium?

Answer 10

Spleen and stomach

Question 11

What organ is found in the right lumbar?

Answer 11

ascending colon, kidney

Question 12

What organ is found in the umbilical?

Answer 12

Stomach, head of pancreas, small intestine (duodenum), transverse colon, lower aspects of right and left kidneys

Question 13

What organ is found in the left lumbar?

Answer 13

descending colon, left kidney

Question 14

What organ is found in the right iliac fossa?

Answer 14

caecum, appendix, part of ascending colon

Question 15

What organ is found in the suprapublic?

Answer 15

bladder, uterus, parts of small intestine

Question 16

What organ is found in the left iliac fossa?

Answer 16

sigmoid colon, descending colon

Question 17

What are the 4 layers of the GI tract?

Answer 17

Mucosa/ mucous membrane
Submucosa
Muscularis propria
Adventitia

Question 18

What makes up the mucosa/ mucous membrane? What is the function of each layer?

Answer 18

Epithelium: lines cavity
Lamina propria: thin layers of loose connective tissue, contain inflammatory cells and provides support
Muscularis mucosae: smooth muscle continous thoughout GI tract

Question 19

What is the submucosa formed from?

Answer 19

Dense, irregular connective tissue
Contains many blood, lymphatic vessels and nerves

Question 20

Structure and function of muscularis propria:

Answer 20

Inner circular layer and outer longitudinal layer of smooth muscle
Responsible for peristalsis (movement of food)

Question 21

What is the adventitia? Where is it found?

Answer 21

Outer layer of fibrous connective tissue surrounding an organ
Oral cavity in gut, upper end of oesophagus, ascending and descending colon, rectum

Question 22

What is the serosa/ serous membrane?

Answer 22

Part of tissue that is fixed
Found in the remainder of the GI tract and allows for reduction of friction

Question 23

How does the histology change throughout the GI tract?

Answer 23

Same layers just speicilised in different areas:
- Stomach: epithelium changes to simple columnar (this remains for rest of GI tract), oblique muscle as part of muscularis propria which lie in different direction
- Duodenum: vili increase SA for adsorption, Brunner’s glands secrete bicarbonate ions to neutralise acid from stomach
- Ileum: payer’s patches, lymphoid follicules part of the immune system, prevent growth of harmful bacteria

Question 24

What are the different parts which comprise the stomach?

Answer 24

• Top section = fundus (lets out air)
  From entrance to exit:
  1. Oesophagus
  2. Cardia
  3. Body
  4. Pylorus
  5. Pyloric sphincter
  6. Duodenum
  Greater and lesser curve

Question 25

What are rugae in the stomach? What is their funtion?

Answer 25

Muscular folds in stomach Allow for distention and reduction depending on volume of food in stomach

Question 26

What cells are present in the mucosa in the stomach? What are their function?

Answer 26

Endocrine cells: produce gastin which stimulates parietal cells Parietal cells: produce HCl which breaks pepsinogen into active pepsin Chief cells: produce pepsinogen Surface mucous cells: secrete mucous to help protect mucosal lining

Question 27

3 parts of small intestine:

Answer 27

Duodenum Jejunum Ileum

Question 28

Structure of small intestine epithelium:

Answer 28

Simple columnar Villi increase SA (x30) to increase digestion and absoption (most prevelant in duodenum, decrease towards ilium)

Question 29

Function and specialisations of the duodenum:

Answer 29

Recieves chyme Contains Brunner glands which secrete bicarbonate secretions to reduce stomach acids Recieves common bule duct (fat digestion) which is controlled by Sphincter of Oddi (via opening callled major duodenal papilla) Pancreatic juices enter

Question 30

What are the folds in the small intestine that are naked to the human eye called?

Answer 30

Plicae

Question 31

What are the 2 functions of the pancrease?

Answer 31

Exocrine gland (99% of pancreate): produces digestive enzymes and bicarbonate ions Endocrine part/ Islets of langerhans: produce hormones which control maintainance and stabilisation of glucose levels - Insulin: promotes glucose adsorption and conversion of glycogen - Glucagon: conversion of glycogen to glucose - Somatostatin: reduce acid secretion, slow digestive process, other function

Question 32

How many lobes does the liver have?

Answer 32

4

Question 33

Major functions of the liver (5)

Answer 33

- produces bile which is stored an concentrated in gall bladder, duct passes out of gall bladder through cystic duct - Detoxification of everything from GI tract - Regulates blood glucose - Synthesises proteins involved in platelet regulation and clotting factors - Drug metabolism: inactivates hormones and drugs, as well as insulin and waste products.

Question 34

Blood supply to liver:

Answer 34

75% is deoxygenated and comes from hepatic portal vein from gut, spleen and related organs 25% is oxygenated and comes from hepatic arteries

Question 35

Parts of the large intestive:

Answer 35

-- Ileocecal junction/ ileocecal valve -- Caecum (resevoir for chyme) Ascending colon (hepatic flexure) Transverse colon (splenic flexure) Descending colon Sigmoid colon

Question 36

Specialisation of large intestine

Answer 36

Taenia coli: incomplete layers of longitudinal muscle, circular contractions, anatomical landmarks Haustra/ haustrations: ring-like circular muscle Apendices epipoicae: pouches of peritoneum filled with fat mainly on transverse and sigmoid colon but not rectum

Question 37

3 main vessels supplying GI tract

Answer 37

1. Coeliac trunk - supplies foregut (oesophagus, stomach, liver, spleen and first half of duodenum) 2. Superior mesenteric artery - supplies midgut (last half of duodenum, jejunum, ileum, caecum, appendix, ascending colon and first half to first 2/3 of transverse colon 3. Inferior mesenteric artery - hind gut (last 1/3 transverse colon, descending colon, sigmoid colon and rectum)

Question 38

Venous drainage of the gut:

Answer 38

1. Inferior mesenteric vein - drains hindgut, passes into splenic vein 2. Superior mesenteric vein - drains midgut , joins splenic vein 3. Splenic vein and superior mesenteric vein combine to form portal vein - Portal vein is for unpaired abdominal organs (e.g. gut and spleen 4. Portal vein passes to liver for detoxification, blood ultimately passes back to heart from hepatic vein