Small Intestine Flashcards
Define peristalsis
involuntary movement of muscle to move food within the digestive system
Define segmentation
movement in which stationary ringlike constrictions appear at several places along the intestine and then relax as new constrictions form elsewhere
How long is the small intestine?
3-7 meters
What are the 3 segments of the small intestine?
- duodenum
- jejunum
- ileum
Functions of the duodenum
- receives stomach contents, pancreatic juice, and bile
- neutralizes stomach acid
- fats are broken up by the bile acids
Functions of the jejunum
most of digestion and absorption
Functions of the ileum
- absorbs nutrients
- reabsorbs bile acids
- immune defense
- regulation of waste passage
Describe circular folds and their job in the small intestine
- transverse spiral ridges
- promotes thorough mixing and nutrient absorption by slowing the progress of chyme and make it flow on a spiral path allowing for more mucosa contact
Describe villi and their job in the small intestine
- fuzzy-like projections lining the inner intestine
Describe microvilli and their job in the small intestine
- tiny plasma membrane extensions that form a fuzzy brush border on the surface of each enterocyte
- increase surface area for absorption and has enzymes for contact digestion
Describe lacteal and their job in the small intestine
- lymphatic capillary found in the core of a villus
- absorb most lipids
Describe intestinal glands and their job in the small intestine
- aka intestinal crypts; tubular glands found on the floor of the small intestine, between the bases of the villi
- secretes intestinal juice, houses stem cells, secretes lysozymes and defensive proteins
Describe goblet cells and their job in the small intestine
- epithelial cells that are interspersed among the absorptive cells of the small intestine
- secretes mucus
What structures are unique to the 3 sections of the small intestine?
duodenum: duodenal glands in the submucosa
jejunum: large, tall circular folds
ileum: peyers patches
Functions of the small intestine
breaks down food into smaller molecules and absorbs them into the body
General neural controls for the small intestine
- enteric: gut movement, secretion, blood flow
- PNS: increase muscle movement and enzyme release
- SNS: slow digestion, decrease movement and secretion
Hormones released from the duodenum that regulate the digestive system
- secretin: stimulates the liver and pancreas to secrete bicarbonate; stimulates stomach acid
- cholecystokinin (CKK): stimulates the pancreas to secrete enzymes and the gallbladder to release bile
- glucose-dependent insulinotropic peptide (GIP): stimulates insulin secretion
