digestive system- intestines to accessory glands Flashcards
small intestine 3 segments
- duodenum
- jejunum
- lleum
circular folds in small intestine
- shapes of folds causes chyme to spiral rather than move in straight line through s intestine
- slows them down and allows more time to allow for nutrients to be absorbed
villi
within circular folds
- lots of thes villi along length of s intestine, serve to increase surface area of mucosa epithelia
- in addition to muscle and connective tissue to support its structure, each villus contains a capillary bed composed of one arteriole and venue and lymphatic capillary called lacteal
microvilli
- small projections of plasma membrane of epithelial CELLS
- look like bristles under microscope - brush border
- greatly increased surface area of the cells to facilitate digestion and absorption
intestinal glands
- production of intestinal juice (alkaline and water mixture)
- mucosa of duodenum= duodenum glands which produce bicarbonate rich alkaline mucus that neutralized acidity contents of stomach
mechanical digestion of small intestine
- segmentation
- migrating motility complexes
segmentation
contents are shoved back and forth.
- combines chyme with digestive juices and pushed food particles against mucosa to be absorbed
- when most of chyme absorbed, small intestinal wall becomes less distended, triggers “motion” which triggers migrating motility complexes
migrating motility complexes
causes small amount of contraction which moves chyme down through intestinal tract until reaches end into large intestinal tract
cecum
- first part of large intestine
- appendix is a winding tube that attaches to cecum
colon
- following cecum is the ascending colon, transverse colon, descending colon
rectum
- from sigmoid colon
anal canal
last part of digestive system
- 2 sphincters- internal and external
- internal: made up of smooth muscles, involuntary
- external: made up of skeletal muscle: voluntary control
differences between walls of large and small intestines
- large: very few enzyme secreting cells in walls, no circular folds of villi, walls have more glands and more mucus because chyme is less fluid
mechanical digestion of large intestine
- haustral contractions: when distended with chyme, contract and mix around material and absorb water
- peristalsis but slower
- mass movement: strong muscle contractions: waves from transverse colon towards rectum
chemical digestion in large intestine:
- sacralitic fermentation : bacteria breaking down certain carbs
defecation
- small intestine absorbs most of what you ingest
- large intestine absorbs remaining water
- converts liquid chyme into semi solid feces
- rectal muscles
accessory organs that aid digestion
- liver
- pancreas
-galbladder
liver
- largest gland in body
- plays role in metabolism and regulation
- detoxification of liver
- produces bile
bile helps with digestion of
lipids.
emulsification
gallbladder
muscular sac stores, concentrates and propels bile into duodenum via common bile duct
pancreas
- both exocrine and endocrine functions
- secrete pancreatic juice through bile duct
