William Beaumont and St. Martin
The digestive, or gastrointestinal (GI), system is comprised of a long, epithelium-lined tube that is open to the outside world. It serves four primary functions:
Absorption
Digestion
Motility
Secretion
Oral Cavity: first stages of digestion:
-chewing
-saliva by salivary glands (sublingual, submandibular, parotid)
esophagus: food=chyme
stomach to anus: gut
stomach: fundus, body, antrum,(rugae), pyloric valve (regulates rate of movement of food into the SI)
small intestine: duodenum (.25 m), jejunum and ileum (2.6 m)
-enzymes, exocrine secretions by accesory glandular organs (pancreas and liver) that enter in the duodenum, sphincter of oddi
-nearly all nutriends and secreted fluids are absorbed
large intesting
1.5 l of chyme per day
colon: watery chime covnereted to semisolid feces
rectum, defecation reflex
anus
external anal sphincter
Wall has four layers
Mucosa: inner lining facing the lumen. Made of