GIT Lec 7: Large intestine Flashcards
1
Q
large intestine size
A
-6.5 cm in diameter (name giver), 1.5m in length
2
Q
Ileocecal value
A
- sphincter between cecum +ileum
- opens when ileum contracts (post-meal)
- closed when large intestine distended
- retains large intestine contents in
3
Q
functional domains of large intestine
A
- cecum/appendix
- ascending/ transverse/descending/sigmodal colon
- rectum
- anus
4
Q
large intestine epithelial
A
-has only crypts (no villi)- lower SA than small intestine
5
Q
ascending/ transverse/descending/sigmodal colon
A
- reabsorption of water
- reservoir for storage of wastes +indigestible materials
- absorption of products of bacterial metabolism
6
Q
cecum/appendix
A
-no apparent function in humans, other species: cellulose digest by bacteria
7
Q
rectum
A
reservoir for feces
8
Q
anus
A
- two sphincters that control defecation
- external sphincter (skeletal muscle)- control through potty training
- internal sphincter (smooth muscle)
9
Q
stem cells in crypts differentiation
A
- absorptive cell/enterocytes- no brush border enzymes
- goblet cells- abundant
- very few paneth + endocrine cells
10
Q
Ecosystem of bacteria
A
- greater than 100 trillion microbes
- gut microbiome: >1000 species of bacteria –> influenced by diet, medications, bowel function
- produce vitamins
- cab liberate short-chain fatty acids from dietary fibre
- influences health- obesity, allergy, C.difficile infection
11
Q
secretion of water (large intestine)
A
identical to small intestine (cl-)
12
Q
absorption of water (large intestine)
A
-Na+/K+ ATPase set Na+ gradient
13
Q
motility of large intestine purpose
A
mixing of contents
14
Q
mixing of contents segmentation
A
slower basic rhythm- 30 min
18-24 hr retention in colon
15
Q
mixing of contents propulation
A
- 3-4/day
- intense contraction (mass movement)
- pushes contents to anus
- occurs after eating, prior to defecation
