The Digestive System SNC2D8

The Digestive Tract The digestive system is also known as the digestive tract It is made up of hollow (empty) tubes and organs that connect the mouth to the anus Responsible for breaking down food (digestion) and taking nutrients (absorption)

Those Other Organs Include the liver and the pancreas and gall bladder They make chemicals and enzymes that help with digestion Remember: no food enters these organs for digestion

Those Other Organs Liver makes a chemical called bile that helps digest food in the small intestine Gall Bladder stores bile that is not being used (i.e. between meals) Pancreas makes enzymes (chemicals that speed up digestion reactions) – it also produces insulin which helps control sugar levels in blood

The Mouth Digestion begins in the mouth where an enzyme (a chemical that speeds up other chemical reactions) in the saliva (spit) start to break down those carbohydrates known as starches (sugars).

Peristalsis Once the food is swallowed, it is moved through the digestive tract down your esophagus (throat) Peristalsis is an automatic muscle movement controlled by the nervous system The epiglottis blocks food from entering your windpipe – it closes when you swallow

To The Stomach Food travels down the esophagus to the stomach. there is a muscle called the lower esophageal sphincter, which opens to let food pass through.

To The Stomach the lower esophageal sphincter opens to let food pass through. If it opens when it shouldn’t (from damage), you can get acid reflux (heartburn).

In the Stomach Cells in the stomach produce stomach acid (HCl) and an enzyme to break down proteins in food A thick layer of mucus helps protect the lining of the stomach from its own acid

In the Stomach Bacterial infections can destroy the mucus so that the acid damages at its own lining - this is an ulcer

In the Stomach The stomach muscles mixes the food with acid and other chemicals This mixture is then emptied into the small intestine through the pyloric sphincter.

The Intestines The first part of the small intestine is called the duodenum the bile produced by the liver enters here and breaks down fat

The Intestines The small intestine is covered with fingerlike structures called villi. The villi absorb nutrients from food and send them to your blood stream

The Intestines The large intestine, or colon, does not break down food but absorbs water and some nutrients before what remains of the food is removed from the body as waste.

The Body’s Defences The digestive system’s first defence against contaminants is vomiting, which can forcibly remove contents from the middle of the small intestine and up.

Very Limited Defences There is really nothing else to prevent contaminants from being absorbed into the bloodstream although the liver can help filter the blood.