Small Intestine Structure and Function

Question 1

what is the total length of the small intestine?

Answer 1

around 6 metres

Question 2

how long is the duodenum?

Answer 2

25 cm

Question 3

what is the functions of the duodenum?

Answer 3

Gastric acid neutralisation; Digestion; Iron absorption

Question 4

how long is the jejunum?

Answer 4

2.5m

Question 5

what is the function of jejunum?

Answer 5

nutrient absorption

Question 6

how long is the ileum?

Answer 6

3.5m

Question 7

what happens in the ileum?

Answer 7

nacl/h2o absorption -> chyme dehydration

Question 8

how is the absorptive surface area enhanced?

Answer 8

by folds, villi and microvilli

Question 9

what has the best absorptive surface area enhancement?

Answer 9

microvilli

Question 10

what do villus cells absorb?

Answer 10

NaCl
Monosaccharides
Amino acids
Peptides
Fats
Vitamins
Minerals
Water

Question 11

what is the function of a crypt cell?

Answer 11

secretes cl and water

Question 12

what can be coupled withsodiem in active transport?

Answer 12

glucose
galactose
amino acids
nucleosides

Question 13

how much water does the small intestine secrete a day?

Answer 13

1500ml

Question 14

why is water secretion important for normal digestive processes?

Answer 14

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 15

what is the two disticnt types of movement?

Answer 15

segmentation

peristalsis

Question 16

when is segmentation most common?

Answer 16

during meals

Question 17

what is the function of contraction and relaxation of short intestinal segments?

Answer 17

moves chyme into adjacent areas of relaxation, then relaxed areas then contract and push chyme back.

this ensures thorough mixing of contents with digestive enzymes

Question 18

what are segmented contractions initiated?

Answer 18

depolarisation generated by pacemaker cells in longitudinal muscle layer

Question 19

what is the fequency of segmentation determined by?

Answer 19

basic electrical rhythm

Question 20

what effects does parasympathetic ns have on contractions?

Answer 20

increases

Question 21

what efects does sympathetic ns have on contractions?

Answer 21

decreases

Question 22

whats the function of migrating motility complex?

Answer 22

Move undigested material into large intestine

Limit bacterial colonisation of small intestine

Question 23

what hormone is involved in initiating migrating motility complex?

Answer 23

motilin

Question 24

what nuerones mediate peristalsis of intestine?

Answer 24

myenteric plexus

Question 25

what effect does gastric emptying have on segmentation activity in ileum?

Answer 25

increases

Question 26

what effects does gastric emptying have on gastroileal reflex?

Answer 26

Opening of ileocaecal valve (sphincter)

Entry of chyme into large intestine

Distension of colon

Reflex contraction of ileocaecal sphincter (prevents backflux into small intestine)