L8: physiology and pharmacology of the bowel

Question 1

vast majority of nutrients are taken up by

Answer 1

small intestine

Question 2

what does the large intestine mainly take up

Answer 2

water

Question 3

what prevents back flow in the large bowel

Answer 3

tight junctions

Question 4

on average how many litres enter the small intestine everyday

Answer 4

10 L

Question 5

% absorbed by small intestine

Answer 5

70-80%

Question 6

% of material reaching the large intestine

Answer 6

10%

Question 7

small intestine dysfunction leads to

Answer 7

large increase in fecal material (large intestine not designed to take yo nutrients from a large volume)

Question 8

large intestine dysfunction leads to

Answer 8

moderate increase in fecal material

Question 9

2 types of wave movement

Answer 9

peristalsis

segmentation

Question 10

peristalsis=

Answer 10

movement of material in one direction

Question 11

what movement is mainly involved in defecation

Answer 11

peristalsis

Question 12

segmentation=

Answer 12

breaking up of material

Question 13

use of segmentation

Answer 13

to increase SA and nutrient absorption

Question 14

ileocecal valve role

Answer 14

prevents movement of food back into small intestine

Question 15

parts of large bowel

Answer 15

cecum 
ascending colon 
transverse colon 
descending colon 
sigmoid colon 
rectum

Question 16

most absorption in large bowel happens in

Answer 16

ascending colon

Question 17

most storage in large bowel happens in

Answer 17

descending colon

Question 18

2 histology parts of small intestine

Answer 18

microvilli

crypts

Question 19

type of crypts in small intestine

Answer 19

can be branches

Question 20

crypts in small intestine contain

Answer 20

goblet cells

paneth cells

Question 21

paneth cells produce–>

Answer 21

innate mucosal defences

Question 22

crypts in the large intestine

Answer 22

no longer branched

more associated with goblet cells (less enzy,es for digestion)

Question 23

3 absorptions in colon

Answer 23

• NaCI
• short chain fatty acids/Na symporter
• Na channel

Question 24

aldosterones effect on colon

Answer 24

increases the level of sodium channels present increasing movement of water into cells

Question 25

composition of faeces

Answer 25

75% water | 25% solids

Question 26

colour of poo determined by

Answer 26

stercobilin | urobilin

Question 27

stercobilin=

Answer 27

breakdown of heme in RBCs

Question 28

bristol stool chart constipation=

Answer 28

1-2

Question 29

bristol stool chart ideal stool=

Answer 29

3-4

Question 30

bristol stool chart diarrhoea

Answer 30

5-7

Question 31

what is the wall of the rectum like

Answer 31

- highly compliant wall - anal-rectal angle - anal sphincters

Question 32

what does the anal-rectal angle prevent

Answer 32

unwanted fecal defecation

Question 33

holding position=

Answer 33

- anal-rectal angle - external anal sphincter contracted - fecal material being stored

Question 34

what maintains the anal-rectal angle

Answer 34

contracted puborectalis muscle

Question 35

what does the parasympathetic defecation reflex cause

Answer 35

peristaltic waves | relaxation of the external anal sphincter

Question 36

what causes the intrinsic myenteric defecation reflex

Answer 36

faeces causing distension of the rectal wall send signals to descending and sigmoid colon

Question 37

what happens in the intrinsic myenteric defecation reflex

Answer 37

- increased peristaltic waves in the descending and sigmoid colon so fecal matter moves closer to anus - and internal sphincter relaxes

Question 38

what muscles contract in GI evacuation

Answer 38

diaphragm | rectus muscles

Question 39

what muscles relax in GI evacuation

Answer 39

puborectalis muscle external sphincter internal sphincter

Question 40

preganglionic neurotransmitter in sympathetic NS

Answer 40

Ach

Question 41

post ganglionic neurotransmitter in sympathetic NS

Answer 41

Nor adrenaline

Question 42

5 effects of sympathetic NS

Answer 42

``` increases HR dilates pupils dilates trachea inhibits peristalsis inhibits contraction of bladder and rectum ```

Question 43

course of parasympathetic NS

Answer 43

long preganglionic, post ganglionic near effector organ

Question 44

5 functions of parasympathetic NS

Answer 44

slows HR constricts pupils increase blood flow to skin and viscera increased peristalsis

Question 45

pelvic nerve is controlled by

Answer 45

parasympathetic

Question 46

effect of pelvic nerve

Answer 46

brings about explosive movements of distal colon and sustained contraction

Question 47

pudendal nerve controls

Answer 47

external anal sphincter

Question 48

what is the pudendal nerve controlled by

Answer 48

somatic

Question 49

reflex of pudendal nerve

Answer 49

defection reflex

Question 50

symptoms of IBS

Answer 50

stomach bloating altered bowel habit abdominal pain

Question 51

treatment for IBS

Answer 51

antispasmodics

Question 52

2 antispasmodics

Answer 52

diculoverine | propantheline

Question 53

do you give antidiarrhoea for cholera

Answer 53

no

Question 54

3 treatments for crohns disease

Answer 54

aminosalicylates glucocorticoids cytokine inhibits

Question 55

suphasalazine used for

Answer 55

mild to moderate UC

Question 56

what transforms suphasalazine into its active form

Answer 56

bacteria in colon

Question 57

2 treatment for IBD

Answer 57

sulphasalazine | mesalazine

Question 58

3 anti-motility drugs for diarrhoea

Answer 58

loperamide codeine diphenoxylate

Question 59

what is loperamide

Answer 59

mu-opioid agonist

Question 60

what does loperamide and codeine do in GI

Answer 60

decreased peristalsis increase transit time increasing water absorption

Question 61

codeine=

Answer 61

mu-opioid receptors in neural plexus of intestines

Question 62

co-phenotrope is made up of

Answer 62

diphenoxylate | atropine

Question 63

diphenoxylate=

Answer 63

opiate | does not cross BBB

Question 64

kaolin combined with

Answer 64

calcium carbonate and morphine

Question 65

what does kaolin do

Answer 65

absorbs toxic molecules

Question 66

calcium carbonate=

Answer 66

antacid

Question 67

morphine=

Answer 67

opioid decreases peristalsis and increases transit time

Question 68

3 types of laxatives

Answer 68

bulk forming osmotic stimulant

Question 69

bulk forming laxative=

Answer 69

ispagula husk and methylcellulose

Question 70

what should bulk forming laxatives be taken with

Answer 70

lots of water

Question 71

when do you give bulk forming laxatives

Answer 71

when fibre content in diet cannot be increased

Question 72

time of onset of ispaghula husk and methylcellulose

Answer 72

full effect takes some days

Question 73

what is lactulose

Answer 73

osmotic laxative

Question 74

how does lactulose work

Answer 74

releases osmotically active sugars to increase levels of water in stool

Question 75

stimulant laxatives=

Answer 75

senna, sennosoids (senokot) sodium picosulphate bisacodyl

Question 76

how does senokot work

Answer 76

stimulates nerve endings in small bowel and activate myenteric plexus to increases bowel movements -less time for water absorption so softens faeces

Question 77

how long does senokot take to work

Answer 77

8-12 hours

Question 78

what can senokot be combined with

Answer 78

ispaghula

Question 79

what can sodium picosulphate be described as

Answer 79

irritant

Question 80

how does sodium picosulphate work as an irritant

Answer 80

decreases water absorption and softens faeces

Question 81

oral sodium picosulphate work in

Answer 81

6-12 hours

Question 82

suppository sodium pico-sulphate works in

Answer 82

1 hour

Question 83

what is used prior to radiological investigations of the bowel

Answer 83

sodium picosulphate

Question 84

2 things you can get from excessive use of laxatives

Answer 84

melanosis coli | tolerance

Question 85

what is melanosis coli

Answer 85

areas of lipofuscin pigmentation | colon looks like tiger