lab digestive system

digestive tract

the mouth, esophagus, stomach, small intestine, large intestine, rectum, anus

accessory glands

liver, pancreas, gallbladder, salivary glands

oral cavity, teeth, tongue

mechanical processing, mixing , with salivary secretions

pharynx

muscular propulsions of food into the esophagus

esophagus

transport materials into the stomach

stomach

chemical break down of materials by acid and enzymes, mechanical processing through muscular contractions

small intestine

enzymatic digestion and absorbtion of water, organic substrates, ions, and vitamins

salivary glands

secretion of lubricating fluids containing enzymes that break down carbohydrates

liver

secretion of bile (important for lipid digetsion) storage of nutrients and many other vital functions

gallbladder

storage and concentration of bile

pancreas

exocrine cells secrete buffers and digestive enzymes; endocrine cells secrete hormones

essentially the alimentary canal has four basic layers or tunics. Starting with the lumen these are

1. mucosa

2. submucosa

3. muscularis

4. serosa or adventia

mucosa

inner most layer contacts chyme. Functions to produce mucosa to lubricate chyme as it is propelled down the canal. Also secretes acid to digest food. Nutrients are absorbed through this layer

submucosa

this is where capillaries can be found, and nutrients that are diffused across the mucosa can enter the blood stream

muscularis

muscle layer with 2 layers of muscle (circular and longituidal) oriented in different directions to propel food by peristalis

main difference between serosa and adventia

above the diagphram outer most layer of the digestive tract is a connective tissue called adventia. Below the diaphragm it is called serosa

the adventia

secures organs to surrounding tissues like a net

the serosa

completely covers organs and secretes serous fluid which lubricates the external surface preventing friction