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Phase 1 - S3 Gastrointestinal System > Intestines > Flashcards

Flashcards in Intestines Deck (44)
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1
Q

what enzymes of found in the brush border of the intestines

A

amylase, maltase, isomaltose

2
Q

describe the structure of starch

A

made up of chains of glucose connected by alpha 1-4 bonds (amylose) which are joined to other amylose chains by alpha 1-6 bonds (amylopectin)

3
Q

describe the uptake of glucose in the intestines

A

Na/K/ATPase on the basolateral membrane gives a low Na conc inside the enterocyte

glucose then diffuses in with glucose through the SGLT 1

glucose then moves into the blood via GLUT 2

4
Q

how do oral rehydration fluids work

A

they contain both Na and glucose which move into the enterocyte, water then follows

5
Q

what does vitamin B12 require for absorption

A

intrinsic factor

6
Q

how does autoimmune disease cause megaloblastic anaemia

A

as it destroys the parietal cells - therefore, no intrinsic factor is produced so vitamin B12 can’t be reabsorbed

7
Q

when calcium levels are low, how is it absorbed in the intestines

A

actively
Ca ATPases on the basolateral membrane create a concentration gradient to allow facilitated diffusion on the apical membrane

8
Q

in high calcium levels, how is it absorbed in the intestines

A

passively

through paracellular transport

9
Q

how is iron absorbed

A

co-transported with H+

10
Q

why do PPIs affect iron absorption

A

as gastric acid is important in iron absorption

11
Q

what is coeliac disease

A

immune response against the gliadin in gluten

12
Q

what affect does coeliac disease have on the intestines

A

damages mucosa, lengthens crypts, less villi and give lymphocytes in epithelium
this causes malabsorption

13
Q

what are the symptoms of coeliac disease

A

diarrhoea, weight loss and sensory loss

14
Q

how is sodium absorbed through the apical membrane in the small intestine

A

SGLT 1

15
Q

how is sodium reabsorbed through the apical membrane in the large intestine

A

Na channels induced by aldosterone

16
Q

what digest proteins in the intestines

A

pepsinogens from the stomach

proteases from the pancreas

17
Q

what cells produce pepsinogen

A

chief cells

18
Q

what convertors pepsinogen into pepsin

A

HCl

19
Q

what converts trypsinogen into trypsin

A

enteropeptidase

20
Q

what do exopeptides do

A

cleave the ends of proteins to produce small molecules

21
Q

what do end-peptides do

A

cleave the middle of proteins to reduce protein lengths

22
Q

how are amino acid absorbed

A

co-transporters with Na

23
Q

how are tripeptides/dipeptides absorbed

A

through peptide transporter 1

24
Q

what happens to tripeptides/dipeptides once they are absorbed

A

converted into amino acids by cytosolic peptidases

25
Q

what is the role of the large intestines

A

absorb water

26
Q

how is water absorbed in the large intestines

A

water follows sodium which moves through ENaC channels

27
Q

what causes an increased amount of ENaC channels to be opened

A

aldosterone

28
Q

what vitamin is produced in the large intestines

A

vitamin k

29
Q

what is the gastro-colic reflex

A

when theres mass movement of contents from the distal colon to the rectum stimulated by eating

30
Q

what are haustrau

A

the sacculations of the large intestine

31
Q

what are teniae coli

A

the bands which make up the outer layer of incomplete muscle of the large intestine
contractions of these give the sacculations

32
Q

how does crohns present

A

right lower quadrant pain
weight loss
mild anaemia
non bloody stools

33
Q

what can be seen in crohns disease

A
fistulae 
strictures 
cobblestone appearance 
mucosal oedema 
skip lesions
34
Q

how much of the GI tract does crohns affect

A

anywhere in the GU tract

35
Q

how deep does the inflammation in crohns extend

A

all the way through the GI wall (transmural)

36
Q

how deep does the inflammation in UC extend

A

only to the mucosa - superficial

37
Q

do you see granulomas in UC or crohns

A

crohns

38
Q

why are there strictures seen in crohns

A

the repeated inflammation and healing causes fibrosis

39
Q

what is the presentation of UC

A

lower abdominal pain
bloody stools
weight loss

40
Q

what is seen in UC

A

pseudopolyps
continuous inflammation
loss of haustra

41
Q

where does UC affect

A

colon - starting in the rectum

42
Q

what non-intestinal problems can also be seen in UC and crohns

A

uveitis, erythema nodosum, arthritis, gall bladder problems

43
Q

are crypt abscesses seen in UC or crohns

A

UC

44
Q

what is the treatment for UC

A

colectomy