Small Intestine Structure and Function

Question 1

Parts of the small intestine

Answer 1

Duodenum
Jejunum
Ileum

Question 2

Duodenum

Answer 2

Gastric acid neutralisation
Digestion
Iron absorption

Question 3

Jejunum

Answer 3

Nutrient absorption - 95%

Question 4

Ileum

Answer 4

NaCl/H2O absorption leading to chyme dehydration

Question 5

Villi cell absorbs

Answer 5

NaCl
Monosaccharides
Amino acids
Peptides
Fats
Vitamins
Minerals
Water

Question 6

Crypt cells secrete

Answer 6

Cl

Water

Question 7

Water secretion by small intestine

Answer 7

From epithelial cells lining crypts of Lieberkuhn

Secreted passively as a result of active secretion of chloride into intestinal lumen

Question 8

Importance of water secretion

Answer 8

Maintains lumenal contents in liquid state
Promotes mixing of nutrients with digestive enzymes
Aids nutrient presentation to absorbing surface
Dilutes and washes away potentially injurious substances

Question 9

Function of microvilli

Answer 9

Increase surface area (don’t move)

Question 10

Types of intestinal movement

Answer 10

Segmentation

Peristalsis

Question 11

Segmentation

Answer 11

Contraction/relaxation of short intestinal ligaments

Provides mixing of chyme with digestive enzymes and brings into contact with absorbing surface

Question 12

Generation of segmentation contractions

Answer 12

Slide 10

Question 13

Following absorption of nutrients

Answer 13

Segmentation stops and peristalsis

Question 14

Migrating motility complex

Answer 14

Pattern of peristaltic activity travelling down small intestine (starts in gastric antrum)
As one MMC ends (terminal ileum) another begins
Arrival of food in stomach results in cessation of MMC and initiation of segmentation

Question 15

MMC

Answer 15

Migrating motility complex

Question 16

Hormone involved in MMC

Answer 16

Motilin

Question 17

MMC acts to

Answer 17

Move undigested material into large intestine

Limit bacterial colonisation of small intestine

Question 18

Law of the intestine (smooth muscle behind bolus contracted and in front relaxed) mediated by

Answer 18

Neurones in myenteric plexus

Question 19

Gastroileal reflex

Answer 19

Opening of ileocaecal valve (sphincter)
Entry of chyme into large intestine
Distension of colon
Reflex contraction of ileocaecal sphincter (prevents backflux into small intestine)