Small Intestine Structure and Function

Question 1

What functions does the pancreas have?

Answer 1

Endocrine and exocrine

Question 2

The exocrine pancreas is responsible for

Answer 2

the digestive function of the pancreas

Question 3

The exocrine pancreas secretes from

Answer 3

Acini -> ducts -> pancreatic sucts

glands via ducts, rather than directly into the blood

Question 4

Pancreatic duct cells secrete bicarbonate which

What does this allow?

Answer 4

neutralises gastric acid and gastric contents

allows pancreatic enzymes to work

Question 5

The acinar cells secrete

Answer 5

digestive enzymes

Question 6

Acing cells contain digestive enzymes stored as

Answer 6

inactive zymogen granules

Question 7

What does the storing of enzymes as their zymogen granules prevent?

Answer 7

Autodigestion of the pancreas

Question 8

Enterokinase is bound to

Answer 8

the brush border of the duodenal enterocytes

Question 9

What is the function of enterokinase?

Answer 9

Converts trypsinogen to trypsin

Question 10

What does trypsin do?

Answer 10

Converts all other zymogens to their active forms

Question 11

What are the different categories of pancreatic enzymes?

Answer 11

Proteases 
Nucleases 
Elastases 
Phospholipases 
Lipases 
Alpha-amylase

Question 12

What is the function of proteases?

Answer 12

Cleave peptide bonds

Question 13

What is the function of phospholipases?

Answer 13

Convert phospholipids to fatty acids

Question 14

What is the function of lipases?

Answer 14

Convert triglycerides to fatty acids and glycerol

Question 15

What group of pancreatic enzymes are responsible for hydrolysing DNA and RNA?

Answer 15

Nucleases

Question 16

What group of pancreatic enzymes are responsible for converting starch to maltose and glucose?

Answer 16

Alpha-amylases

Question 17

What group of pancreatic enzymes is responsible for collagen digestion?

Answer 17

Elastases

Question 18

The endocrine functions of the pancreas involve the

Answer 18

secretion of various substances into the blood

Question 19

Bicarbonate secretion is stimulated by

Answer 19

secretin

Question 20

Zymogen secretion is stimulated by

Answer 20

cholecystokinin

Question 21

Bicarbonate secretion is stimulated in response to

Answer 21

acid in the duodenum

Question 22

Zymogen secretion is stimulated in response to

Answer 22

fat/amino acids in the duodenum

Question 23

The pancreas is under neural control from vagal and local reflexes which are triggered by

Answer 23

arrival of organic nutrients in the duodenum

Question 24

What are the three parts of the small intestine?

Answer 24

Duodenum
Jejunum
Ileum

Question 25

What is the longest part of the small intestine?

Answer 25

Ileum

Question 26

What are the functions of the duodenum?

Answer 26

Gastric acid neutralisation, digestion and iron absorption

Question 27

What is the function of the jejunum?

Answer 27

Nutrient absorption

Question 28

What is the function of the ileum?

Answer 28

NaCl and H2O absorption, chyme dehydration

Question 29

What features of the small intestine act to enhance its absorptive surface area?

Answer 29

Circular folds Villi Microvilli

Question 30

The fourth layer of the small intestine is

Answer 30

serosa

Question 31

The small intestinal epithelia contains

Answer 31

crypts

Question 32

What are the functions of goblet cells in the small intestine?

Answer 32

Create a diffusion barrier | Secrete mucous

Question 33

What are lacteals?

Answer 33

Lymphatic capillaries found beneath the epithelial surface of the villi which absorb dietary fats

Question 34

What area of the small intestine has the most extensive vasculature?

Answer 34

Jejunum

Question 35

The villi are responsible for absorption which the crypts are responsible for

Answer 35

secretion

Question 36

Give 6 things absorbed by the villi

Answer 36

``` NaCl Monosaccharides Amino acids Peptides Fats Vitamins Minerals Water ```

Question 37

What is secreted by the crypt cells?

Answer 37

Cl ions and water

Question 38

Active pancreatic enzymes aid the digestion of

Answer 38

fat, proteins and carbohydrates

Question 39

The small intestine can exhibit both peristalsis and

Answer 39

segmentation

Question 40

Do segmentation and peristalsis happen simultaneously or at different times?

Answer 40

At different times

Question 41

Is peristalsis or segmentation more common during a meal?

Answer 41

Segmentation

Question 42

Segmentation involves the

Answer 42

contraction and relaxation of short intestinal segments

Question 43

Contraction moves the chyme into

Answer 43

adjacent relaxed areas on either side

Question 44

What is the function of segmentation?

Answer 44

Thoroughly mixes intestinal contents with digestive enzymes and continuously brings chyme into contact with absorbing surface so maximises absorption

Question 45

Segmentation contraction is generated by

Answer 45

pacemaker cells in the longitudinal muscle layer

Question 46

The intestinal basic electrical rhythm produces

Answer 46

oscillations in the membrane potential which release an action potential and cause contraction

Question 47

The action potential frequency in the intestinal basic electrical rhythm determines

Answer 47

the strength of contraction

Question 48

The frequency of segmentation is determined by

Answer 48

the basic electrical rhythm

Question 49

Which nervous system can increase the strength of segmentation contraction?

Answer 49

Parasympathetic system

Question 50

What kind of mechanism is the frequency of segmentation?

Answer 50

Intrinsic mechanism

Question 51

Peristalsis starts after

Answer 51

segmentation

Question 52

In peristalsis, the receiving segment relaxes with

Answer 52

the contraction behind the bolus

Question 53

Peristaltic waves are generated by

Answer 53

the migrating motility complex

Question 54

What is the migrating motility complex?

Answer 54

The pattern of peristaltic activity travelling down the small intestine, which starts in the gastric antrum

Question 55

Where does the migrating motility complex end?

Answer 55

At the terminal ileum

Question 56

Does the arrival of food in the stomach cause the cessation of the migrating motility complex or segmentation?

Answer 56

Migrating motility complex

Question 57

The migrating motility complex acts to move undigested food into the large intestine and limit

Answer 57

the bacterial colonisation of the small intestine

Question 58

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

Answer 58

Motilin

Question 59

What nerve is the main innervation from the parasympathetic system to the GI tract?

Answer 59

Vagus nerve

Question 60

What effect does the parasympathetic system have on the GI tract?

Answer 60

Stimulatory

Question 61

What nerve is the main innervation from the sympathetic system to the GI tract?

Answer 61

Splanchnic neve

Question 62

What effect does the sympathetic system have on the GI tract?

Answer 62

Inhibitory