LI

Question 1

sections

Answer 1

caecum
ascending
transverse
descending
sigmoid
rectum
anal canal

Question 2

caecum

Answer 2

dilated region with an inf blind end, continuous with the ascending colon superiorly

Question 3

veniform appendix

Answer 3

fine tube closed at one end which leads to the caecum
contains more lymphoid tissue but composed like the LI
appendix has NO digestive function

Question 4

ascending colon

Answer 4

passes up from the caecum to the level of the liver where it curves acutely to the left at the hepatic flexure become the TC

Question 5

transverse colon

Answer 5

extends across the abdominal cavity, infront of the duodenum and stomach to the spleen- splenic flexure which curves acutely down to the descending colon

Question 6

descending colon

Answer 6

passes down the las curving towards midline

Question 7

sigmoid

Answer 7

found at the iliac crest level continues to become the rectum

Question 8

anal canal

Answer 8

leads from the rectum to the exterior
two sphincter muscles, control the anus,
internal: smooth muscle under autonomic control
external sphincter: formed by skeletal muscle under voluntary control

Question 9

taenia coli

Answer 9

three bands of longitudinal tissue run alongside the caecum and the colon, stopping at the junction of the SC and rectum, these give a sacculated appearance

Question 10

how are anal sphincters formed

Answer 10

thickened circular muscles

Question 11

where is there the most amount of lymphoid tissue

Answer 11

submucosal layer
non specific defence against microbes

Question 12

mucosal layer of the colon and upper rectum

Answer 12

goblet cells within the simple tubular glands

Question 13

what is the anal canal lined with

Answer 13

stratified squamous epithelium continuous with the mucous membrane lining above the rectum
merges with the skin beyond the anal sphincter
upper portion of the upper canal forms 6-10 vertical folds anal columns, each column contains a terminal branch of superior rectal artery and vein

Question 14

four functions

Answer 14

defeacation
microbial activity
mass movement
absorption

Question 15

absorption

Answer 15

contents passed through the caecum are fluid, water absorption occurs, this continues until a semi solid consistency is reached
mineral salts, vitamins and some drugs are absorbed into the blood capillaries

Question 16

microbial activity

Answer 16

heavily colonised by bacteria which synthesises vitamin K and folic acid
gas = nitrogen, hydrogen, carbon dioxide, methane

Question 17

mass movement

Answer 17

no peristalsis occurs however at some sections, a strong wave of peristalsis occurs which sweeps contents along the TC into the descending sigmoid colon

Question 18

gastro-colic reflux

Answer 18

combination of stimulus and response

Question 19

defection

Answer 19

mass movement travels into the rectum from the SC
nerve ending are stimulated by stretching
external anal sphincter is under conscious control through the pudenal nerve
involves involuntary contractions of rectum and relaxation of internal anal sphincter
contraction of abdominal muscles and lowering of the diaphragm increases intra-abdominal pressure assisting defection
repeated suppression of this reflux could lead to constipation as more water is reabsorbed.

Question 20

where does is begin

Answer 20

right iliac fossa

Question 21

arterial blood supply

Answer 21

superior and inferior mesenteric arteries
superior mesenteric artery supplies the caecum, ascending and most of the TC
inferior mesenteric artery supplies the remaining colon and proximal art of the rectum
middle and inferior rectal arteries supply the distal part of the rectium and anal, and internal iliac arteries

Question 22

venous drainage

Answer 22

superior and inferior mesenteric veins drain from parts supplied by the arteries.
these veins join the splenic and gastric veins to form the portal vein
veins which drain from the distal part of the rectum and anus goin the internal iliac veins, blood then drains to the IVC bypassing portal circulation

Question 23

why is faeces brown

Answer 23

stereobilirubin

Question 24

faeces consists of

Answer 24

dead and live microbes
water
mucus secrete by the LI lining aiding lubrication of faeces
fibre
epithelial cells shed from the walls

Question 25

why is there fibre in faeces

Answer 25

so it is bulky enough the stimulate defection