Download The Digestive System

The Digestive System is a vital part of the human body’s survival. Without it, we
could not exist. We use it everyday without thinking. So why is it so important?
It all starts with your mouth. As you chew food, salivary glands inside your mouth
release saliva which starts to partly break up food. The saliva also makes the food
slippery and easy to swallow. Then, the food (now called bolus) travels down your
Oesophagus by the muscles squeezing the food down into your stomach. These muscles
contract with wave like movements. Once the food is into the stomach, strong muscles
churn each mass of bolus up. After it has been churned and it is mushy, the stomach acids
kick in and in about 3-6 hours the bolus is now chyme (a soupy kind of liquid) and is off
into the small intestine.
The small intestine is a like a long folded up tube that fits neatly into your body. One part
of it is called the jejunum. This is where the nutrients are absorbed and here’s how it
happens: first of all, the jejunum wall produces enzymes along with the ones made by the
pancreas. Then, the enzymes separate all the carbohydrates, fat and protein from the
waste. Then those nutrients are sent into your blood stream and flow around the body
giving it energy. The undigested food and water is sent out into the large intestine where
it is excreted through the rectum
as faeces.
Parts
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The Liver
The Gallbladder
The Stomach
The Pancreas
The Large Intestine
The Appendix
The Small Intestine
The Rectum
The Anus
The Oesophagus
The Jejunum
The Ileum
The Duodenum
The Salivary Glands
The Mouth
(Above) Taken from: http://www.enchantedlearning.com
The Liver:
The liver is your largest internal organ. It produces bile (a digestive juice).
It looks dark-reddish in colour. Blood flows from the Intestines flows to the liver, where
it stores some of the nutrients from the process of digestion and makes sugars into starch
for storage. If the body detects a possibly dangerous substance such as alcohol the liver
will break it down.
The Gallbladder:
The pear shaped gallbladder can store bile. If it is damaged, the person may feel pain. It
releases bile that it has stored into the small intestine.
The Stomach:
The stomach is a very important organ. Once bolus is inside, it squishes them up and
makes them into a substance called chyme which is much easier to digest. It also uses
juices such as bile and powerful acidic enzymes to dissolve food even more. It is stretchy
and is J shaped and leads into the small intestine.
Fact: The stomach secretes 3 litres of gastric juice each day.
The Pancreas:
The pancreas has roles in and outside of the digestive system. Outside it mainly secretes
hormones and inside the system it is used for secreting digestive juice and enzymes into
the small intestine because of the nearby position of the pancreas.
The Large Intestine:
The large intestine is mainly used for draining waste and undigested food where it later
comes out of the anus as faeces. It consists of the colon, caecum and rectum.
The Appendix:
The Appendix is a small, short tube that branches off the caecum. So far, it has no known
function. If it gets inflamed then it has to be removed.
The Small Intestine:
This amazing 5m long tube has all the action. Inside it, nutrients are absorbed, waste is
separated from the carbohydrates, protein and fat and then all the nutrients are taken into
the bloodstream. It is layered with tiny finger-like fronds called villi that make enzymes
like the ones in the stomach. It consists of the jejunum, the ileum and duodenum. Inside
the duodenum, the bile made and stored by organs such as the liver and the gall bladder
breaks down the fat so it is smaller. When it receives the chyme, it neutralizes the acidic
contents of it very quickly.
The duodenum is C shaped and is about 25 centimetres long
Inside the jejunum, the break down of the nutrients begins. As I have stated before, the
lining of the small intestine is covered with structures called villi.