Bodily Defenses Image Map

What initiates vomiting?
Vomiting can be caused by throat or stomach irritation, head trauma, dizziness, intense pain, toxic chemical agents, or emotional factors.  The act of vomiting is not directly caused by the stomach but by the contraction of your diaphragm and abdominal muscles.  This increases the pressure in the abdominal cavity and pushes the digestive contents out of the  stomach and even the duodenum if you vomit strongly. Ever see a green tint in your vomit. What do you suppose that is? You would only see this green when vomiting is especially uncontrollable (hint: what green substance empties into the small intestine?).

Ever have food poisoning? Why didn't the stomach acid destroy the germs that cause food poisoning? The reason is that these particular germs make spores or have acid-resistant shells around them. See Hazard unit on food poisoning.

What happens to food after the stomach?
As stomach contents enter the small intestine, the pH is raised back to normal by the pancreatic secretion of sodium bicarbonate (NaHCO3). Due to the acidity of gastric juice, it can be harmful to tissues outside the stomach, since they do not have mucus layers to protect them.

Bile, delivered from the liver, makes the fats in the in the liquid become separated so that enzymes can break them down. 

Other food materials are broken down by digestive enzymes secreted from the pancreas. The enzymes secreted by the pancreas work to reduce the pepperoni, the cheese, and the crust to their simplest forms- amino acids, fatty acids, and sugars, respectively. 

What role does the liver play in digestion?
Besides making bile, the liver has many other important functions. First, the liver processes the carbohydrates, fats, and proteins absorbed by the small intestine.  The liver acts as the detoxification center of the body by breaking down hormones, drugs, and other foreign toxins and also makes the proteins in blood that are responsible for blood clotting.  See the Unit on Detoxication for more about the liver.

The liver even serves as a storage compartment for the broken down products of fats, carbohydrates, and many vitamins and minerals.  Lastly, the liver removes worn out red blood cells and bacteria from the blood stream.  The worn out red blood cells are the major component of the bile that is secreted into the digestive tract. As you can tell, the liver is a vital organ - not only for digestion, but for many other systems of the body!

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