Small Intestine Disorders Flashcards
Name four basic function of the small intestines
- Absorption
- Digestion
- Endocrine and neuronal control
- Barrier functions
Describe the digestive role of the small intestine
Breaks food into its components via secretion of digestive enzymes to digest peptides, carbohydrates and fats into smaller molecules
Describe the endocrine and neural control role of the small intestine
Controlling the flow of materials from the stomach to the colon
Describe the barrier role of the small intestine
Regulates what stays in and out, i.e. maintaining a barrier against pathogens
How is the small intestine involved in maintaining a barrier against pathogens?
- Immune sampling
- Monitoring the presence of pathogens
- Translocation of bacteria
- Gut Associated Lymphoid Tissue (GALT)
What is Gut Associated Lymphoid Tissue (GALT)?
Occurs throughout the intestine, but in the small intestine it contains Peyer’s Patches
GALT is made up of several types of lymphoid tissue that store immune cells, such as T and B lymphocytes, that carry out attacks and defend against pathogens
Why is there a low bacterial population in the small intestine?
Due to toxic environment due to digestive enzymes, bile salts and presence of IgA
Where does digestion commence?
In the mouth via salivary amylase and chewing. Then, HCl and pepsin (digests protein) is released from the stomach via controlled breakdown to avoid osmotic shifts in the gut lumen
How are proteins digested?
Broken down to oligopeptide and amino acids by trypsin or chymotrypsin. Then they are undergo a final hydrolysis by brush border enzymes for absorption
How is fat digested?
Broken down by pancreatic lipase –> glycerol and free fatty acids for absorption via the lacteal and lymphatic system
How are carbohydrates digested?
Broken down by pancreatic amylase –> breakdown to disaccharides and final digestion occurs by brush border disaccharidase
What causes steatorrhoea?
Fat malabsorption causing high fat content in the stool making them less dense and float
Name 5 symptoms of small intestine disorders?
- Weight loss
- Increased appetite
- Diarrhoea (usually watery, or steatorrhoea)
- Bloating
- Fatigue
Name two signs of small intestine disorders?
- Weight loss
* Low to falling BMI
What are markers in the blood of specific deficiencies?
- Iron
- B12, folate
- Ca, Mg
- Vit A, B, C, D, K
What are conditions of deficiency in Ca, Mg and Vit D?
Tetany and osteomalacia
What can deficiency in Vit A cause?
Blindness
What can deficiency in Vit K cause?
Raised PTR (increased time to form blood clot)
Give examples of Vit B complexes and what deficiencies in them can cause?
- Thiamine -> dementia
* Niacin -> dermatitis, unexplained heart failure
What can deficiency in Vit D cause?
Scurvy
What are non-specific signs of specific illnesses?
- Clubbing: coeliac and crohns
- Scleroderma: systemic sclerosis
- Aphtheous ulceration: coeliac, crohns
What is dermatitis herpetiformis?
A cutaneous manifestation of coeliac disease
What are four symptoms of dermatitis herpetiformis?
- Blistering
- Intense itch
- Affects scalp, shoulders, elbows, knees
- IgA deposit in the skin
Name six different investigations to test the structure of the small intestine
- Endoscopy
- Barium swallow
- CT scan
- MRI enterography
- Capsule enterography
- White cell count
Name two investigations to test for bacterial overgrowth
- H2 Breath Test
* Culture a duodenal or jejunal aspirate
What is coeliac disease?
An autoimmune disorder characterised by immune response to gluten and a protein in wheat. It leads to inflammation of small intestine and damages and destroys villi of intestinal wall -> malnutrition and malabsorption
What are seven causes of malabsorption?
- Inflammation
- Infection
- Whipples disease
- Infiltration (amyloid)
- Impaired motility
- Iatrogenic (medical treatment related)
- Pancreatic
What are three infective agents that cause malabsorption?
- Tropical sprue: folate deficiency and responds to antibiotics
- HIV
- Gardia Lambia
What is gardia lambia?
- Unicellular parasite
- Spreads through contaminated water
- Risk factor: hypogammaglobulinaemia (reduction is antibodies that fight infection)
What antibiotic does gardia lambia respond to?
Metronidazole
What does gardia lambia infection cause?
Giardiasis - attached to lining of small intestines and cause villous atrophy
What is Whipple’s disease?
Inhibits digestion by impairing the breakdown of foods, causing:
• Malabsorption
• Weight loss
• Abdominal pain
Histologically: PAS stain in villi
What organism causing Whipple’s Disease?
Tropheryma whippelii
What three conditions cause impaired motility (-> malabsorption)?
- Systemic sclerosis
- Diabetes
- Pseudo obstruction
What are iatrogenic causes of malabsorption?
- Gastric surgery
- Short bowel syndrome
- Radiation
What are pancreatic causes of malabsorption?
- Chronic pancreatitis
* Cystic fibrosis
