large intestine function

Question 1

how long is the colon ?

Answer 1

1.5-1.8 metres

Question 2

what are the three main features of the large intestine ?

Answer 2

teniae coli (incomplete longitudinal muscle layer)

hausfrau/seggmentations

ommental appendices (fatty deposits)

Question 3

what are the crypts like in the large intestine ?

Answer 3

large straight crypts with goblet cells for faeces lubrication

Question 4

what is the anal canal ?

Answer 4

2-3cm tube between distal rectum and anus

thicker muscularis that rectum

epithelium transitions from simple columnar to stratified squamous

Question 5

how does the colon make solid faeces ?

Answer 5

actively transports sodium from lumen into blood

this causes osmotic absorption of water

dehydration of chyme which causes solid faecal pellets

Question 6

how much microfloral bacteria is there in the colon ?

Answer 6

10 (14)

Question 7

what does colonic bacterial fermentation of undigested carbohydrates produce in the large intestine ?

Answer 7

vitamin K (for blood clotting)

short chain fatty acids (energy)

gas (nitrogen, CO2, hydrogen, methane, hydrogen sulphide)

Question 8

what is the defection reflex ?

Answer 8

under parasympathetic control (pelvic sphlancnic nerves) the rectum contracts

causes relaxation of internal anal sphincter and contraction of external sphincter

this increases peristaltic activity in the colon which increases pressure on external sphincter

Question 9

what is the defection reflex ?

Answer 9

under parasympathetic control (pelvic sphlancnic nerves) the rectum contracts

causes relaxation of internal anal sphincter and contraction of external sphincter

this increases peristaltic activity in the colon which increases pressure on external sphincter

external sphincter relaxes under voluntary control to get rid of faeces

Question 10

what are the symptoms of constipation ?

Answer 10

headaches
nausea
loss off appetite
abdominal distension

all due to rectal distension

Question 11

what are the causes of diarrhoea ?

Answer 11

pathogenic bacteria (cholera, E.coli)

protozoans
viruses
toxins
food
stress

Question 12

how many cases and deaths of diarrhoea each year ?

Answer 12

1.5 million cases
0.5 million deaths

Question 13

how does enteroteoxigenic bacteria cause diarrhoea ?

Answer 13

produce protein enterotoxins which turn on intestinal chloride secretion from crypt cells

elevate cAMP, cGMP, calcium

Question 14

how many litres a day of diarrhoea does cholera produce ?

Answer 14

25 litres

Question 15

what do we give for diarrhoea treatment ?

Answer 15

sodium/glucose solution
this drives H2O absorption for rehydration

secretion of water on goes to wash away the infection