Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BRS > Small Bowel > Flashcards

Small Bowel Flashcards

1
Q

What is the purpose of the small bowel?

A

To absorb nutrients salt and water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How long is the small bowel?

A

6m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the diameter of the small bowel?

A

3.5cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How long is the duodenum?

A

25cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How long is the jejunum?

A

2.5m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How long is the ileum?

A

3.75m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Is there a sudden transition between parts of the small intestine?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Do the parts of the small intestine have similar or different basic histological organisation?

A

Same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the mesentery?

A

a fold of membrane that attaches the intestine to the wall around the stomach area and holds it in place

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the functions of the mesentery?

A

Suspends small & large bowel from posterior abdominal wall:
-anchoring them in place
-whilst still allowing some movement

Provides a conduitfor blood vessels, nerves & lymphatic vessels.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where do villi occur?

A

The small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Are villi motile or static?

A

Motile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Do villi have a rich blood supply and lymphatic drainage?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why do villi have a rich blood supply and lymphatic drainage?

A

for absorption of digested nutrients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where do villi have good innervation from?

A

the submucosal plexus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Do villi have a simple epithelium?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How thick is the villi epithelium?

A

One-cell thick

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What type of cell is the villi epithelium mostly made up of?

A

dominated by enterocytes (columnar absorptive cells)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the 3 cell types in the villi epithelium?

A

primarily enterocytes (absorptive cells)
scattered goblet cells
enteroendocrine cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are crypts of Lieberkühn?

A

Pits between villi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What 2 cell types do crypts of Lieberkühn contain?

A

Paneth cells
Stem cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are enterocytes specialised for?

A

absorption & transport of substances.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the lifespan of an enterocyte?

A

1-6 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

By how much do folds and villi of small intestine increase its surface area?

A

500 fold increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What makes up the brush border?

A

Microvilli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the surface of microvilli covered with?

A

glycocalyx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is glycocalyx?

A

rich carbohydrate layer on apical membrane of microvilli

28
Q

Describe the purpose and function of glycocalyx

A

serves as protection from digestional lumen
yet allows for absorption.

traps a layer of water & mucous known as “unstirred layer”
- regulates rate of absorption from intestinal lumen

29
Q

What causes goblet shape of goblet cells?

A

Mucous containing granules accumulating at apical end of cell

30
Q

What is mucus?

A

large glycoprotein that facilitates passage of material through bowel.

31
Q

Describe how abundance of goblet cells changes along bowel

A

increasing abundance of goblet cells along entire length of bowel
↓ in duodenum
↑ in colon

32
Q

Where are enteroendocrine cells most often found?

A

lower part of crypts.

33
Q

Where are Paneth cells only found?

A

The bases of crypts

34
Q

What do Paneth cells contain and what is the purpose of what they contain?

A

large, acidophilic granules that contain:

antibacterial enzyme lysozyme (protects stem cells)

Glycoproteins & zinc (essential trace metal for a no. of enzymes)

35
Q

What do Paneth cells engulf?

A

Some bacteria and protozoa

36
Q

What may Paneth cells have a role in?

A

Regulating intestinal flora

37
Q

Why are epithelial stem cells essential in the GI tract?

A

to continually replenish the surface epithelium

38
Q

What type of ‘potent’ are epithelial stem cells?

A

Pluripotent

39
Q

How do epithelial stem cells replace dying cells?

A

Migrate up to tip of villus, replacing older cells that die by apoptosis
 digested and reabsorbed

40
Q

What are 3 reasons why lifespan of enterocytes is so short?

A

Enterocytes are first line of defense against GI pathogens & may be directly affected by toxic substances in diet.

Effects of agents which interfere with cell function, metabolic rate etc will be diminished.

Any lesions will be short-lived.

41
Q

How is the duodenum distinguished?

A

presence of Brunner’s glands

42
Q

What are Brunner’s glands?

A

Submucosal coiled tubular mucous glands secreting alkaline fluid

43
Q

What do the alkaline secretions of Brunner’s glands do?

A

Neutralizes acidic chyme from stomach, protecting proximal small bowel

Help optimise pH for action of pancreatic digestive enzymes.

44
Q

What are the 3 functions of small intestine motility?

A

To mix ingested food with digestive secretions & enzymes

To facilitate contact between contents of intestine & the intestinal mucosa

To propel intestinal contents along alimentary tract

45
Q

What are the 3 things that cause the motility of the small intestine?

A
  1. Segmentation (mixing)
  2. Peristalsis (propelling)
  3. Migrating motor complex
46
Q

Describe segmentation of the small intestine?

A

Mixes contents of lumen
Occurs by stationary contraction of circular muscles at intervals.
More frequent contractions in duodenum cf. ileum
allow pancreatic enzymes & bile to mix with chyme
Although chyme moves in both directions, net effect is movement → colon

47
Q

Describe peristalsis in the small intestine?

A

Involves sequential contraction of adjacent rings of smooth muscle
Propels chyme towards colon
Most waves of peristalsis only travel about 10cm
Segmentation & peristalsis result in chyme being segmented, mixed & propelled → colon

48
Q

Describe the Migrating Motor Complex

A

Cycles of smooth muscle contractions sweeping through gut
Begin in stomach → small intestine → colon → next wave starts in duodenum
Prevents migration of colonic bacteria into ileum

49
Q

Does digestion in the small bowel occur in an acidic or alkaline environment?

A

Alkaline

50
Q

Where do pancreatic digestive enzymes & bile enter duodenum from?

A

MPD (main pancreatic duct) & CBD (common bile duct)

51
Q

Does the duodenal epithelium produce its own digestive enzymes?

A

Yes

52
Q

Where does digestion occur in the duodenum?

A

Digestion occurs in lumen & in contact with the membrane

53
Q

Where does most of carbohydrate digestion occur?

A

Small intestine

54
Q

What does pancreatic alpha amylase need for optimum activity?

A

Needs Cl- for optimum activity & neutral/slightly alkaline pH

55
Q

Where does digestion of amylase products & simple carbohydrates occur?

A

Brush border

56
Q

Where does pancreatic alpha amylase mainly act?

A

In the lumen

57
Q

How are glucose and galactose absorbed?

A

by 2^o active transport

58
Q

What carrier protein allows glucose and galactose to be absorbed?

A

Carrier protein = SGLT-1 on apical membrane

59
Q

What carrier protein allows fructose to be absorbed?

A

Carrier protein = GLUT-5 on apical membrane

60
Q

Describe digestion of proteins?

A

Protein digestion begins in lumen of stomach by pepsin
-pepsin then inactivated in alkaline duodenum

5x pancreatic proteases secreted as precursors → lumen of small bowel (e.g. trypsinogen)

Trypsin activated by enterokinase
an enzyme located on duodenal brush border

Trypsin → activates other proteases
hydrolyse proteins → single amino acids (AA) & oligopeptides (AA)n

61
Q

Describe action of luminal, brush-border & cytosolic peptidases in protein digestion.

A

Variety of peptidases at brush borders of enterocytes progressively hydrolyse (AA)n → AAs

Enterocytes directly absorb some of small (AA)n via action of H+/oligopeptide cotransporter PepT1

These small peptides are digested to AAs by peptidases in cytoplasm of enterocytes

62
Q

A level lipid digestion
+
What is the purpose of Colipase complexes?

A

prevents bile salts displacing lipase from fat droplet

63
Q

What separates the ileum from the colon?

A

ileocaecal valve

64
Q

What controls passage of material into colon?

A

Relaxation & contraction of the ileocaecal valve

65
Q

What does the ileocaecal valve prevent?

A

back flow of bacteria into ileum

BRS (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions