Mucosa of the GIT in health and disease

Question 1

what are the 4 main functions of the GIT

Answer 1

• ingestion and digestion of food
• absorption of nutrients
  -elimination of waste products
• Secretion: saliva, mucous,enzymes, hormones

Question 2

Name the types of mucosa in the GIT

Answer 2

• protective mucosa - chracterisezed by stratified squamous epithelium - found in the oral cavity, pharynx,esophagus and anal canal
• secretory mucosa contains cells responsible for secretion of digestive enzymes and acid and is found exclusively in the stomach
• Absorptive mucosa is responsible primarily for absorbing digested nutrients and is found along the entirety of the small intestine
• Absorptive mucosa primarily involved in water absorption and electrolyte balance is found in the large intestine

Question 2

Label and draw parts of the stomach and histology of the stomach

Answer 2

Question 3

Name parts of the small intestine

Answer 3

duodenum
jejunum
Ileum

Question 4

what are burners glands

Answer 4

• only appear in submucosa of the oesophagus and duodenum
• no where else in the gIT
  -Peyers patches, diffuse lymphoid tissue that play an important immunological role in sampling the contents of the tract
• Peyers patches are unique to the ileum

Question 5

what cells are found in the small intestine

Answer 5

• Goblet cells ( store and secret mucous)
  -Paneth cells ( serve immune function and are found at the base of the crypts, secrete gastric inhibitory peptide)
• Enteroendocrine cells produce hormones that govern motility and secretion and pancreatic exocrine, just as they do in the stomach
• Stem cells replenish the other cell types and are found at the base of the crypts

Question 6

describe endocrine cells in the GIT

Answer 6

Stomach - G and D cell
Small intestine - K cell
Large instating - L cells ( secrete GLP-1hormone and PYY peptides)

Question 7

what does the GLP-1 and PYY do

Answer 7

• induce secretion of insulin form pancreatic Beta cells
• decreased gastric emptying
  -Increased satiety
• PYY slows GI motility and reduces food intake

Question 8

what does the liver and bile duct do?

Answer 8

• Liver is the body’s largest compound gland.
• major metabolic organ and is important for degrading alcohol and drugs
• Stores glycogen, secretes glucose, plasma proteins and lipoproteins into the blood, and secretes bilirubin, secretory IgA and bile salts as components of bile
• The liver is also involved in blood clotting by producing some of the blood clotting factors

Question 9

Describe GERD- Barrett’s oesophagus
leading to metaplasia

Answer 9

• lower portion of oesophagus is exposed tot large amounts of stomach acid and undergoes metaplastic change
• this metaplastic response involved the development of a columnar, secretary epithelial typical of the duodenum and small intestine
• while this new mucous producing epithelium is protective, the metaplasia may serve as a precursor to oesophageal cancer
• columnar epithelium with goblet cells

Question 10

describe the histopathology of peptic ulcer

Answer 10

• affects digestion and can lead to anaemia due to lack of intrinsic factor and or due to bleeding from perforaition

Question 10

what is malabsorption syndrome

Answer 10

• failure to absorb nutrients from the diet, due to a problem, or a disease within the small intestine often resulting in a combination of diarrhoea, steatorrhea, mulntutrion, weight loss and anaemia

Question 11

what is the autoimmune enteropathy

Answer 11

• probably a family of diseases and while it occurs primarily in your g children, can also be found in adults
• histological findings of villous blunting and crypt hyperplasia are similar to those seen in GSE
  -reusltant intractable secretory diarrhoea is unresponsive to a gluten- free diet

Question 12

what is intestinal lymphagniectajia

Answer 12

• abnormal dialteiton oft he intestinal lymphatics/ lacteals is associated with malabsorption, resulting in protein losing enteropathy, steatorrhea, p[eriperhal oedema and lymphyochytopenia