My Reflection

Reflection for the science biojournal

When I am researching on the digestive system, I found a lot of interesting information on the digestive system, like example an adult’s esophagus can be fourteen inches long or like the liver is the largest internal organ. I also learnt that an average human stomach can hold up to one thousand five hundred milliliters of material and our entire digestive tract is up to thirty FEET long!!! There are a lot of interesting and new information that I have found but one of the most fascinating information is that there are almost up to 400 types of bacteria in our body that is definitely something I have never learnt before! I feel that this biojournal has made me learn a few extra things other than what has been learnt in class, also allowing me answer some unanswered questions.

Even after researching, I still have some unanswered questions that I can’t find on the internet, like what does the mucus in the stomach contain so that it will prevent getting digested by the gastric juices? Or like which is the most important part in the digestive system? Another question is “Why is the appendix function (all it does is give people appendicitis)? “ There are a lot of questions and finding all of them is difficult so these are some questions that I wasn’t able to find.

There are some problems for example, some information might be fake and probably causing more time wasted. Apparently I solved this problem by checking multiple web pages to ensure uniformity and not making any mistakes. Another problem is that most of my friends want to use my glog as example but I am afraid they might just copy and paste and tell the teacher that I copied theirs instead of the other way round and I would be their scapegoat, to solve my problem, I only gave my Uniform Resource Locator (URL) to some people that I trust. Another problem is time constraint to do this project because researching and paraphrasing were not easy processes. To overcome this problem, I paced out my time so that I complete one section every time which takes about one hour per day.

I chose this topic because I like to research on the human body because it is very appealing. I like most of the systems inside the body because I find it very interesting and especially that we only learnt a few things about the digestive system in primary school but now the information is more in-depth making me more interested. Researching improves on the information and thus I can learn even newer things.

In this project I also learn how to use the application called glogster and I also learnt that you need to be able to plan your time well so that you can complete it. I also learn that you can’t start at the last minute because as I see it, some of my friends did it at the last minute and their end product might not be as good.

I feel this project is very good because most of us learn new things, it also enhances our information on our topic so that we are even more prepared on that certain topic during the exam. This project also is good because we have to do our own reflection as reflection is important or you might as well copy paste and not learn anything. Also this first part of the project would make our chemistry project a lot easier.

Interesting facts about the digestive system

1) an adult's esophagus is around 10 to 14 inches long and 1 inch in diameter

2)our salivary glands can make around 1 to 3 pints of saliva a day

3)an average male can store up to 1.5L of material inside the stomach

4)a normal person can hold up to 400 species of bacteria in their large

intestine

5)food stays in the stomach for 2-3 hours

6)The entire digestive tract(path of the food) is about 30 feet long!

7)the large intestine is shorter than the small intestine by 5 feet but its

actually the diameter is bigger than the small intestine by about 4-5 inches

8) the largest internal organ is the liver

References

1)my science textbook

2)a Casco Science study guide for lower sec

3)http://www.google.com.sg/imghp?hl=en&tab=wi

4)http://digestive.niddk.nih.gov/ddiseases/pubs/yrdd/

5)http://science.nationalgeographic.com/science/health-and-human-body/human-body/digestive-system-article.html

6)http://kidshealth.org/kid/htbw/digestive_system.html

7)http://www.innerbody.com/image/digeov.html

8)http://www.gesa.org.au/digestive_system.cfm

9)http://en.wikipedia.org/wiki/Digestion

Glossary( 5 stops of the system and enzymes)

Bolus-------------A soft mass of chewed food within the mouth or alimentary canal

Hydrochloric Acid-------an acid containing hydrogen and chlorine

Churn-------------------to mix something, especially a liquid, with great force

Peristalsis--------------The rippling motion of muscles in the digestive tract. In the stomach, this motion mixes food with gastric juices, turning it into a thin liquid.

Molecules-----------------The smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms; a group of like or different atoms held together by chemical forces.

Enzymes-------------Any of numerous proteins or conjugated proteins produced by living organisms and functioning as biochemical catalysts.

Sigmoid--------------Having the shape of the letter S.

Gallbladder----------A small, pear-shaped muscular sac, located under the right lobe of the liver, in which bile secreted by the liver is stored until needed by the body for digestion.

Stomach

After the bolus reaches the stomach, the proteases in the gastric juice, start break down proteins into smaller Animo acids. The hydrochloric acid in the gastric juice provides a good condition for the proteases because proteases need to be in an acidic environment to work well. The hydrochloric acid also kills bacteria that is swallowed down with the food. The stomach will churn by contracting and relaxing, breaking down the food into smaller pieces and also mix the food well with the gastric juice.

By the time the food is ready to leave the stomach, the food is already in semi-liquid form, then it proceeds to the duodenum.

Extra info!

• Heartburn occurs when gastric juices is allowed to seep through into the oesophagus, thus inflaming it.
• The stomach cannot digest itself because there is a layer of mucus.The stomach is made out of Five layers which are the mucosa, submucosa, muscularis, subserosa and serosa .
• parietal cells in the stomach produces the hydrochloric acid

Digestive Enzymes

Salivary glands produce saliva that has Amylase which breaks down starch molecules into smaller molecules called maltose

The gall bladder produces bile that helps to break down the fat molecules into smaller molecules to increase surface area so that the other enzyme, lipase, can act on the fats faster.

The pancrea produces pancreatic juice which contain amylase and also lipase.Lipase breaks down fat molecules into fatty acids and glycerol.

The walls of the intestine produce something called intestinal juice that contain amylase, protease and lipase.protease is an enzyme that break down proteins into smaller Amino acids.

Gullet A.K.A the Oesophagus

*Digestion DOES NOT occur here.

Here, the muscles contract and relax, a process called constalsis, to to produce a wave-like movement that causes the bolus to go down into the stomach.

There is not much to say about the gullet but the bolus is able to go down the gullet at 2 inches per second and an average adult's gullet is about 30cm.

there is nothing much to say about the oesophagus and yes thats about it.

Mouth------> the start of the digestive system

physical and chemical processes take place in the mouth.

Chemical====>salivary glands which produce saliva==>contains amylase which breaks ..........................................................down starch which will turn ..........................................................into maltose that is a type ..........................................................of sugar


Physical----> breakdown food into smaller pieces------> increase surface area of the .......................................................................food exposed to enzymes


The stuff swallowed down into the gullet is called a bolus.
The process(in the mouth) is called ingestion

The mouth is also known as the oral cavity.

The

Large intestine???

Between the ileum and the colon, there is something called the caecum.The digested food goes past here and proceeds to the colon.In the colon,the mixture of fibre, water, and vitamins,mixes with mucus and with bacteria which live in the large intestine,the bacteria in the colon will chemically break down the fibre producing nutrients for themselves and also to promote growth for the cells on the walls of the large intestine.The walls of the intestine absorbs most of the water,vitamins and minerals salts. Faeces is the mixture of the dead bacteria and undigested food piled together ready to be passed out.
Faeces is pushed along the intestine until finally,the faeces move into the rectum.
the undigested food will come out of the system, this process is called egestion or defaecation.

Small intestines....

The small intestine begins at the pyloric sphincter and and ends with its connection to the large intestine at the ileocaecal valve

DUODENUM

• The duodenum receives partly-digested food and acid from the stomach. This acid is quickly neutralised in the alkaline environment of the duodenum.
• The duodenum also receives bile from the gallbladder that breakdown fats, the pancreas makes pancreatic juice that digest carbohydrates, fats and protein. The intestine walls also produces a juice that contain enzymes like amylase, protease, lipase.
• Glands produce mucus to help ease passage of the undigested food.
• The digestion takes place in the duodenum before the material travels further into the small intestine.

JEJUNUM and ILEUM

The walls of the jejunum and ileum contain mini finger-like bumps called 'villi', on the villi there is also more finger like bumps known as micro-villi, this is even smaller than the villi ,this increased surface area improves the small intestine's ability to absorb nutrients,the villi absorb the nutrients and transfer them to the bloodstream and the liver.The final stage of digestion is completed in this part of the small intestine, where food and liquid are broken down into nutrient components.