Human digestive system

The digestive system is the parts of the body that  digest food. It is the gastrointestinal system. It breaks down food into simple chemicals which can be  absorbed into the blood stream. It also produces waste, which be expelled by passing gas, pooping, or even passing urine (peeing). 

From the blood stream, nutrients go to the liver, which is a kind of chemical factory for the body. The liver adjusts the nutrients so that the mix is what the body needs. 

In the stomach, gastric acid is introduced. This is basically dilute hydrochloric acid. It is very reactive and has a pH level of 1.5 to 3.5.Elaine N. Marieb, Katja Hoehn, Katja N. Hoehn 2018. Human anatomy and physiology, 11th edition. Pearson Education, p1264. ISBN 978-0134580999 The stomach has a layer of mucus to protect itself from the acid. 

The digestive system also gets rid of waste material. The gastrointestinal system starts at the lips and ends at the anus. Animals like worms, insects, mammals, birds, fish, and people all have digestive systems. Passing gas (farting or burping) during digesting is normal.

The digestive system is not just the gut, but also many other organs which help digest food. For example, digestive enzymes are needed to break down carbohydrates and meat into substances which can be absorbed. The absorbed food then goes to the rest of the body to feed it and enable it to repair itself.

The parts of the human digestive system are the same in many animals:
Mouth
Pharynx
Oesophagus
Stomach
Intestines
Small intestine
Duodenum
Jejunum
Ileum
Large intestine
Cecum
Colon
Rectum
Anus

Other organs that are part of the gastrointestinal system but are not part of the gut are:
Liver and gall bladder
Pancreas
Salivary glands, lips, teeth, tongue, epiglottis, thyroid, and parathyroids
Food does not go through these organs. But they help the gut digest the food. They also have other work. For example, the pancreas, thyroid, liver, and parathyroids are also endocrine glands that make hormones like insulin.

There are many diseases that affect the gastrointestinal system. Doctors who study the gastrointestinal tract are called gastroenterologists. They also study why people pass faeces (poo) excessively.

 Related pages 

 Appendix
 Gastroenterology
 nervous system 
 polyps

 References 

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Category:Digestive system