Digestion is an often complicated system or process that allows for the breakdown of different types of chemicals or molecules.
This allows a large molecules to be broken down into consumable and usable nutrients that can be absorbed more readily.
Absorption is done through cells and into the blood stream
Ingestion – introduces food to the digestive process
Categories of Human digestion
1.) Cephalic phase
– Saliva from mouth begins breakdown.
– Mastication or chewing of food helps with breakdown
– Taste and smells stimulate release gastric secretion
– Starches are broken down here
2.) Gastric phase
– Stimulated by expansion of stomach with food particles
– pH may change
– Gastric juices are released
3.) Intestinal phase
– Movement of food particles through intestines
– Will end in Defecation
– Some absorption occurs
– Active transport and enzymes are essential
– Force from teeth and tongue to breakdown food into smaller particles. [Mastication]
– Peristalsis – smooth muscle movement
– The reactive force to breakdown molecules into simple structures
Additional Aspects of Digestion:
– Peptides become Amino Acids – Breakdown begins in the stomach but is further broken down in the Small Intestines.
– Enzymes from the Pancreas can cut protein into smaller peptides
– Lipids (Fats) become Fatty acids and Glycerol.
– Pancreatic lipase with the help of bile, together they cause the breakdown of Triglycerides into the free fatty acids.
– Carbohydrates become sugars such as glucose.
– Pancreatic amylase breaks carbohydrates into complex sugars. Then the enzymes in the small intestines break the complex sugars into simple sugars.
4 main hormones involved in regulation of the Digestive System
– Found in stomach and stimulates gastric glands to secrete “pepsinogen” and “hydrochloric acid“.
– Found in the duodenum and signals release of “sodium bicarbonate” in pancreas which causes the release of “bile” from the liver
3.) Cholecystokinin (CCK)
– Found in duodenum and stimulates release of digestive enzymes in pancreas and causes release of “bile” from gallbladder.
4.) Gastric inhibitory peptide (GIP)
– Found in duodenum and causes decrease activity of stomach.
– Also stimulates the release of insulin from pancreas
– Addition of nutrients to cells and blood stream
– Active Transport
– The removal of waste and undigested material
– Done through Defecation
1.) Oral Cavity
4.) Small Intestines
5.) Large Intestines