Why is digestion important?
Food before digestion is not in a suitable for efficient nourishment. Before food and drink can be absorbed and taken up by the body into the blood, they must be converted into smaller particles of nutrients, thus making it is easier for nutrients to be taken up by cells throughout the body. Digestion allows food and drink to be broken down to their simplest particles so that the body can use them to nourish cells and build them to provide energy.
How are Digestive Processes regulated?
2 ways: by nerve regulators and by hormone regulators:
1. Nerve regulation:
Extrinsic nerves originate from the brain or spinal cord and travel to the digestive organ in question. Extrinsic nerves secrete acetylcholine and adrenaline. Acetylcholine activity increase muscle activity in the “fight and flight” reaction, thus causing food to be moved along the GI tract faster. The stomach releases more digestive juices in reaction to acetylcholine presence also. Adrenaline, however, reduces the blood flow to stomach and intestines thus slowing digestive processes down
Intrinsic nerves, found in walls of the esophagus, stomach, small intestine, and colon, are activated when the wall of these organs are stretched. A subsequent release of substances from the nerves cause the increase or decrese in: the digestive juice production and the movement of food thus regulating digestive processes
2. Hormone regulation:
Gastrin, Secretin and Cholecystokinin are produced in the mucosal layer of the stomach and the 3 parts of the small intestine. Gastrin stimulates the stomach to produce acid for the killing of bacteria. Secretin, relased mainly in the duodenum stimulates: the pancreas to release pancreatic juices, the liver to release bile and the stomach to produce pepsin. Finally, cholecystokinin causes the gall bladder to empty its contents and the pancreas to produce more pancreatic juice rich in bicarbonate for the neutralisation of the acidic nature of chyme.