Small Intestine Structure and Function Flashcards Preview

Alimentary System > Small Intestine Structure and Function > Flashcards

Flashcards in Small Intestine Structure and Function Deck (62):
1

What functions does the pancreas have?

Endocrine and exocrine

2

The exocrine pancreas is responsible for

the digestive function of the pancreas

3

The exocrine pancreas secretes from

Acini -> ducts -> pancreatic sucts
(glands via ducts, rather than directly into the blood)

4

Pancreatic duct cells secrete bicarbonate which

What does this allow?

neutralises gastric acid and gastric contents

allows pancreatic enzymes to work

5

The acinar cells secrete

digestive enzymes

6

Acing cells contain digestive enzymes stored as

inactive zymogen granules

7

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

Autodigestion of the pancreas

8

Enterokinase is bound to

the brush border of the duodenal enterocytes

9

What is the function of enterokinase?

Converts trypsinogen to trypsin

10

What does trypsin do?

Converts all other zymogens to their active forms

11

What are the different categories of pancreatic enzymes?

Proteases
Nucleases
Elastases
Phospholipases
Lipases
Alpha-amylase

12

What is the function of proteases?

Cleave peptide bonds

13

What is the function of phospholipases?

Convert phospholipids to fatty acids

14

What is the function of lipases?

Convert triglycerides to fatty acids and glycerol

15

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

Nucleases

16

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

Alpha-amylases

17

What group of pancreatic enzymes is responsible for collagen digestion?

Elastases

18

The endocrine functions of the pancreas involve the

secretion of various substances into the blood

19

Bicarbonate secretion is stimulated by

secretin

20

Zymogen secretion is stimulated by

cholecystokinin

21

Bicarbonate secretion is stimulated in response to

acid in the duodenum

22

Zymogen secretion is stimulated in response to

fat/amino acids in the duodenum

23

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

arrival of organic nutrients in the duodenum

24

What are the three parts of the small intestine?

Duodenum
Jejunum
Ileum

25

What is the longest part of the small intestine?

Ileum

26

What are the functions of the duodenum?

Gastric acid neutralisation, digestion and iron absorption

27

What is the function of the jejunum?

Nutrient absorption

28

What is the function of the ileum?

NaCl and H2O absorption, chyme dehydration

29

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

Circular folds
Villi
Microvilli

30

The fourth layer of the small intestine is

serosa

31

The small intestinal epithelia contains

crypts

32

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

Create a diffusion barrier
Secrete mucous

33

What are lacteals?

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

34

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

Jejunum

35

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

secretion

36

Give 6 things absorbed by the villi

NaCl
Monosaccharides
Amino acids
Peptides
Fats
Vitamins
Minerals
Water

37

What is secreted by the crypt cells?

Cl ions and water

38

Active pancreatic enzymes aid the digestion of

fat, proteins and carbohydrates

39

The small intestine can exhibit both peristalsis and

segmentation

40

Do segmentation and peristalsis happen simultaneously or at different times?

At different times

41

Is peristalsis or segmentation more common during a meal?

Segmentation

42

Segmentation involves the

contraction and relaxation of short intestinal segments

43

Contraction moves the chyme into

adjacent relaxed areas on either side

44

What is the function of segmentation?

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

45

Segmentation contraction is generated by

pacemaker cells in the longitudinal muscle layer

46

The intestinal basic electrical rhythm produces

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

47

The action potential frequency in the intestinal basic electrical rhythm determines

the strength of contraction

48

The frequency of segmentation is determined by

the basic electrical rhythm

49

Which nervous system can increase the strength of segmentation contraction?

Parasympathetic system

50

What kind of mechanism is the frequency of segmentation?

Intrinsic mechanism

51

Peristalsis starts after

segmentation

52

In peristalsis, the receiving segment relaxes with

the contraction behind the bolus

53

Peristaltic waves are generated by

the migrating motility complex

54

What is the migrating motility complex?

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

55

Where does the migrating motility complex end?

At the terminal ileum

56

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

Migrating motility complex

57

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

the bacterial colonisation of the small intestine

58

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

Motilin

59

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

Vagus nerve

60

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

Stimulatory

61

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

Splanchnic neve

62

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

Inhibitory