digestive Pt 3 Flashcards
3 subdivisions of SI in order from proximal to distal
- duodenum
- jejunum
- ileum
circular folds
permanent folds; bumps to slow/alter flow of chyme
villi
finger like projections of mucosa
brush border
give a fuzzy appearance
- brush border enzymes complete final carbohydrate + protein digestion
5 types of cells found in the villi/crypts
- enterocytes
- goblet cells
- enteroendocrine
- paneth cels
- stem cells
entercytes
make up the bulk of the epithelium
- in the villi, absorb nutrients and electrolytes
- in the crypts, produce Intestinal juice
goblet cells
secrete mucus in the villi and crypts
enteroendocrine
source of enterogastrones - hormones that inhibit secretions
paneth cells
secretory cells found deep in the crypts - secrete antimicrobial agents
stem cells
continuously divide to produce other cell types - epithelium is renewed every 2-4 days
Peyers patches
aggregate lymphoid nodules, located in the lamina propria
duodenal gland
secrete alkaline mucus to neutralize acidic chyme and prevent duodenal ulcers
Intestinal juice
- 1-2L are secreted daily in response to distension or irritation of the mucosa
- production stimulated by acidic chyme
- slightly alkaline, isotonic with blood plasma
- largely water + mucus from the duodenal glands and goblet cells
why is the slow pace of chyme entering SI crucial
- chyme entering duodenum is hypertonic - to avoid water loss from blood, chyme entry must be slow
- acidic chyme must be neutralized
- takes time for chyme to be mixed with bile and pancreatic juice
ileocecal valve
typically closed; relaxes to admit chyme into the LI; closes to prevent regurgitation
gastroileal reflex
long neural reflex triggered by stomach activity - force of segmentation is increased in the ileum and ilececal valve relaxes
Be prepared to label the main pancreatic duct, the hepatopancreatic ampulla, and the major duodenal papilla. .
functions of LI
- reabsorb lost of the remaining water from indigestible food residue
- temporarily stores residue
- absorb metabolites produces by resident bacteria
- eliminate residue from the body as semisolid feces
teniae coli
3 bands of longitudinal smooth muscle in the muscularis
haustra
pocket like sacs caused by the muscular tone of teniae coli
Be prepared to label the subdivisions and major landmarks of the LI.
appendix
contains masses of lymphoid tissue
- part of MALT
- storehouse for bacteria, capable of recolonizing the gut when necessary
- susceptible to blockages because of twisted shape
which of the anal sphincters are under voluntary control
external anal sphincter
what type of vitamins are produced in the LI
B and K
K (needed by liver to produce clotting factors)
gut bacteria can influence what
- body weight
- susceptibility to diseases
- allergies
- moods/mental health
haustral contractions
primary contractions of the colon; slow, segmenting movements primarily in the ascending and transverse colon; haustra sequentially contract in response to distention
gastrocolic reflex
initiated by the presence of food in the stomach; causes mass movements; slow, powerful peristaltic waves that are activated 3-4 times/day
diverticula
herniations of mucosa through the colon’s walls
diarrhea
watery, loose stools; LI does not have time to absorb remaining water
- causes: irritation of the colon by bacteria, jostling of digestive viscera
- prolonged diarrhea may result in dehydration and electrolytes imbalances
constipation
food residue remains in the colon for extended periods of time; too much water is absorbed
- stool becomes hard and difficult to pass
- causes: insufficient fiber and/or fluid in the diet, improper bowel habits, lack of exercise, or laxative abuse
