Question

Discuss the small intestine and include one usual abnormal finding

Answer 1

Small intestine

It is an organ in the gastro intestinal tract.
(Food passes from oral cavity-->pharynx--> Oesophagus-->Stomach-->Small intestine--> Large intestine--> Rectum--> anus)

It is distinguished into duodenum, jejunum, and ileum.

1)Duodenum - continues from stomach. 9-11 inches long. Ducts from gall bladder, liver and pancreas open into small intestine.

2) Jejunum - Second part which is seen in the upper left quadrant of abdomen. Completely intraperitoneal structure.

3) Ileum - Last and longest part. Seen in the right lower quadrant. Terminal ileum extends into pelvis.

Histology

Histollogically, Small intestine has 4 layers.

Internal to external - mucosa, submucosa, muscularis and serosa.

Function

Main functions are absorption and secretion.

Epithelial cells secretes enzymes which helps to digest chime into smaller particles. Carbohydrates and proteins are absorbed in the duodenum and jejunum respectively.

Ileum has function of vitamin B12 absorption.

Water and electrolyte absorption also occurs in the small intestine.

Blood supply

Arteries : Superior mesenteric artery, celiac trunk.

Veins : Superior mesenteric vein, hepatic portal vein.

Innervation

Parasympathetic : Vagus nerve

Sympathetic : Thoracic splanchnic nerve

**Abnormal findings found in small intestine are

Diarrhea, infectious diseases, obstructive disorders, congenital conditions, neoplastic growths, duodenal ulcer, celiac disease, crohn's disease, irritable

Duodenal ulcer

It is a disease affecting mucosa of duodenum.

Cause : Duodenum has a protective barrier of mucosa to protect it from the acid from stomach. Due to many factors like H. Pylori infection, this protective barrier is damaged and it results in an ulcer.
Some drugs like aspirin(anti-inflammatory drugs) will damage this mucosal barrier and predisposes to ulcer.
Smoking, alcohol and stress also cause ulcer in duodenum.

Symptoms : Abdominal pain, indigestion, bloating, vomiting, weight loss.

Diagnosis : Definitive diagnosis can be done by endoscopy (gastro duodenoscopy).
Biopsy can be taken from the lesion during endoscopy.
Blood test, stool sample and breath test are done to find out H. Pylori infection.

Treatment : H.pylori infection is treated with triple therapy. It involves 2 antibiotics to kill bacteria and one drug to decrease gastric acid production.
If ulcer is caused by drugs, stop the drugs.
Quit smoking, avoid alcohol, take antacids.