Small intestine structure and function

Question 1

What is the total length of the small intestine?

Answer 1

6m

Question 2

What is the length of the duodenum?

Answer 2

25cm

Question 3

What is the function of the duodenum?

Answer 3

Gastric acid neutralisation
Digestion
Iron absorption

Question 4

What is the length of the jejunum?

Answer 4

2.5m

Question 5

What is the function of the jejunum?

Answer 5

95% of nutrient absorption

Question 6

What is the length of the ileum?

Answer 6

3.5m

Question 7

What is the function of the ileum?

Answer 7

NaCl/H2O absorption fo dehydration of chyme

Question 8

What do the villi absorb?

Answer 8

NaCl
Monosaccharides
Amino acids
Peptides
Fats
Vitamins
Minerals
Water

Question 9

What are crypt cells?

Answer 9

Intestinal gland cell

Question 10

hat do crypt cells secrete?

Answer 10

Cl

Water

Question 11

What is the small intestine’s primary secretion?

Answer 11

H2O- 1.3litres

Question 12

What is H2O secreted from in the small intestine?

Answer 12

Crypt cells

Question 13

By what mechanism is water secreted into the small intestine?

Answer 13

Passive diffusion due to the active secretion of chloride

Question 14

What is the purpose of secreting water into the small intestine?

Answer 14

Maintains lumen 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 are the 2 types of intestinal movement?

Answer 15

segmentation

Peristalsis

Question 16

What is segmentation?

Answer 16

Contration and relaxation of short intestinal segments

Contraction moves chyme to adjacent areas of relaxation

Question 17

When is segmentation most common?

Answer 17

During a meal

Question 18

What is the function of segmentation?

Answer 18

Provides thorough mixing of contents with digestive enzymes

Brings chyme into contact with absorbing surface

Question 19

How is a segmentation contraction initiated?

Answer 19

Initiated by depolarisation generated by pacemaker cells in the longitudinal muscle
Basic electrical rhythm produces oscillations in the membrane potential, which fire action potentials at threshold and cause a contraction

Question 20

What determines the strength and frequency of segmentation contractions?

Answer 20

Strength- frequency of action potentials

Frequency- basic electrical rhythm

Question 21

What nervous systems control contractions?

Answer 21

Parasympathetic increases contractions

Sympathetic decreases contractions

Question 22

When does peristalsis begin?

Answer 22

Following the absorption of nutrients

Question 23

What is the migrating motility complex?

Answer 23

Pattern of peristaltic activity travelling down the small intestine

Question 24

What is the pattern of peristaltic contraction?

Answer 24

As one contraction ends in the terminal ileum, another begins
Arrival of food in the stomach causes cessation of peristalsis

Question 25

What is the function of peristalsis?

Answer 25

Move undigested food into the large intestine

Limit bacterial colonisation of the small intestine

Question 26

What hormone is involved in initiation of the migrating motility complex?

Answer 26

Motillin

Question 27

What is the law if the intestine?

Answer 27

If intestinal smooth muscle is distended by a bolus, muscle on oral side contracts an muscle on anal side relaxes

Question 28

What mediates peristalsis?

Answer 28

Myenteric plexus

Question 29

What is the gastroileal reflex?

Answer 29

Gastric emptying causes an increase in segmentation activity in the ileum

Question 30

What does the gastroileal reflex initiate?

Answer 30

Opening of ileocaecal valve
Entry of chyme into large intestine
Distension of colon
Contraction of iliocaecal sphincter to prevent back flux