Physiology of the small intestine, vomiting and gastric outlet obstruction

Question 1

What is the function of the small intestine

Answer 1

1. Digestion of food particles
2. Absorption of digested food
3. Transport to colon

Question 2

Explain teh structure of the villi in the small intestine

Answer 2

Consists of a layer of absorptive columnar epithelial cells and core of connective tissue containing blood capillaries, lymphatic vessel/lacteal duct and nerve fibres.

Question 3

Explain intestinal movement in terms of:
- Motility
- Segemntation
- Propulsion

Answer 3

Motility: Mixing contractions and propulsion with movement of villi

Segemntation: Mixing of small 1cm long ring-like local contraction of circular layer

Propulsion: 17-18/min any part of the intestine and move towards anus

Question 4

What is the result of over distention and severe stimulation of the small intestine

Answer 4

Peristaltic rush leading to diarrhoea - normal water and nutrient absorption does not take place

Question 5

What are the contractions of the small intestine controlled by

Answer 5

1. Intrinsic reflexes for basic mixing and propulsion
2. Extrinsic neural influence modulating intrinsic motility
3. Hormones: Gastrin, Cholecystokinin, Motilin, Thyroxin increases motility. Secretin, Adrenaline, Glucagon, Somatostatin, NO inhibit motility

Question 6

What is the secretion of succus entericus controlled by

Answer 6

Mechanical contact chyme
Neural refelxes: Local reflexes from presence of chyme and vagal stimulation
Hormones: Cholecystokinin, VIP and secretin increase secretion