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BRS > gastroenterology- small bowel > Flashcards

gastroenterology- small bowel Flashcards

1
Q

function of small bowel?

A

absorb nutrients, salts and water

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2
Q

What is function of mesentery?

A

anchors small and large bowel from abdonminal wall, allowing movement

and provides conduit for vessles and nerves

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3
Q

What makes up small bowel and is exclusive to it?

A

villi

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4
Q

characteristics of villi?

A
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5
Q

what cells make up villi?

A

enteroctyes - absportive

secretory - scattered goblet and enteroendocrine cells

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6
Q

what cells make up up crypts of lieberkuhn?

A

Paneth and stem cells

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7
Q

What are characteristics and function of enterocytes?

A

tall columnar cells with micro villi and basal nucleus

specialsited for absoprtion and trasnport of substnaces

life span 1-6 days

LARGE SA

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8
Q

what is another word for brush border?

A

microvilli

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9
Q

what is the surface of microvilli covered in?

A

glycoclayx

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10
Q

Which membrance is glycocalyx found?

What is its function?

A

apical

protection from digestional lumen

produces ‘unstirred layer’ - that regulates rate of absoprtion from intestinal lumen

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11
Q

What is the unstirred layer?

A

layer of water and mucous

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12
Q

What do goblet cells contain?

A

mucous containnig granules at apical end of cell

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13
Q

What is the function of mucous of the goblet cell?

A

faclitates passage of material through bowel

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14
Q

distribution of goblet cells?

A

as you go down bowel more goblet cells,

more in colon

not a lot in duodenum

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15
Q

where are enternedocrine found?

A

scattered among enterocytes

in lower parts of crypts

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16
Q

What is function of enteroendorine cells?.

A

hormone secreting - affect gut motility

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17
Q

where are pnaeth cells?

A

bases of crypts

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18
Q

what do paneth contain?

A

large acidophlic granules

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19
Q

what do paneth granules contain?

A

lysozyme, protects stem cell

glyocopritnets and zinc

(zinc can be used as essential trace metal for no of enzs)

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20
Q

what are other functions of paneth cells?

A

engulf bacteria and protoza

regulating intestinal flora

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21
Q

What is purpose of stem cells in GI tract?

A

continaully replenish surface of epithelium

migrate to top of villus replace cells at top of villus

can divide to many cell types - pluripotent

22
Q

why do enterocytes and goblet cells have short life span?

only 36 hours

A

can be affected bt toxic substances in diet and lesions are short lived - important as they are first line of defense against GI pathongens

23
Q

How are entercytes replenished?

A

escalator like transit

if impaired by e.g radiation severe intestinal dysfunction

24
Q

is there a sudden transition between duodenum,jejunum,ileum?

A

NO

25
Q

How is duodenum distingushed?

A

they have brunners glands

submucosal coiled tubular mucous glands secrete alkaline fluid, open into base of crypts

26
Q

what is purpose of alkaline secretions of brunner’s gland?

A

neutralizes acidic chyme from stomach

optimise pH for action of pancreatic enzymes

27
Q

difference between jejunum and ileum?

A

jejunum - thick waller than illem as it has more plicae circualres

differnet attachment to aorta - jejunum above and left, ilem below and right

jeje- few arcades and long terminals, iluem - more arcades and shorter terminals

iluem only has peyers patch

28
Q

functions of small intestine motility?

A
29
Q

what are 3 movement parts of motility?

A

segmentations

peristalis

migrating motor complex

30
Q

What is segmentation?

A

mixing

stationary contraction of circular muscless

more freq in duodenum

pix pancratic enzyme and bine to mix chyme

31
Q

what is peristalisi?

A

sequestial contraction of adjacment rings of smooth muscles

propels chyme towards colon

32
Q

what is migrating motor complex?

A

cycles of smooth muscles contraction sweeping through cut

prevents migration of coloinc bacteria in ileum

33
Q

how do pancreatic enzymes and bile enter duodenum?

A

from common bile duct and main pancreatic duct

34
Q

where else are enzymes produced apart from pancrase?

A

duodenal epitherlium

35
Q

where does digestion of carbs being + by which enzyme?

A

mouth

salivary a amylase - destroyed in stomach by low pH

36
Q

Where does pancreatic a amylase have it effects?

A

secreted into duodenum in response to meal

continues digestion in small bowel

37
Q

what does a amylase need to work optimunally?

A

Cl- and neutral/slightly alkaline pH

38
Q

where exactly in small bowel does it have it effect?

A
  1. mainly lumen and adsorbs brush border then after the products

digestion of amylase products occurs at bursh border

39
Q

How is glucose and galactose absorpted?

A

by secondary active tranposrt

SGLT-1 apical membrane

40
Q

How is fructose absoprted?

A

facilitated diffusion, GLUT-5 apical membrane

41
Q

what does GLUT 2 do?

A

facilitates exit at basolateral membrane into intersistial space

42
Q

where does digestion of protien begins?

A

stomach by pepsin

but it is inactivated in alakine of duodenum

43
Q

how are the proteases activated?

A

enterokinase (enz located on duodenal brush border) activates trypsin from trypsinogen

trypsin acitavtes other protients

44
Q

How does digestion of different AA length work?

A

AAn progessively hydrolysed at brush border to AA

some AAn are direclty absobred via action of H+ and PepT1

digested to AAs by peptidases in enterocytes

45
Q

what is first step of lipid digestion?

A

secretion of bile salts and pancreatic lipases

46
Q

what is 2nd step of digestion of lipids?

A

emulisification, increase surface area for digestion

47
Q

what is 3rd step of lipases

A

enyzmatic hydrolosysis of ester linkages

colipase complexes with lipase - prevent bile salts displacing lipase from fat droplet

48
Q

what is the last step of lipid digestion?

A

solublity of lipoytic products in

bile salt MICELLES

49
Q

What happens to FA after mielles?

A

leave it and enter enterocytes

FA and MG resynthesized intro triglyverides by monogltceride acylation (major) or phosphatidic acid pathway (minor)

Forms chylomicrons- liportien, mainly TGs in golgi appartus

and released by exosytsosi into lacteal, lymph capillary transports away from bowel

50
Q

how is ilewum sperated from colon?

A

by ileocaecal valve

51
Q

What is function of ileocaecal valve?

A

relax and contract control passage of material into colon

prevents backflow of bacteria into ileum

BRS (19 decks)

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