Author: science4all

University of Auckland B. Science degree in Biological Science University of Auckland GDip. Teaching (Secondary) course in 2009.
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excretory system

The job of the excretory system is to remove various produced by the body. The removal is known as excreation. It is important for the body to remove these various waste, also known as toxic, because toxic build up can lead to servere death.

About sixty percent of your body contains water. A portion of the water is in the tissues and cells. The word excretion means the removal of waste substances from the body. Several organs are involved with the excretory system, including the kidneys, sweat glands, lungs . and rectum, The primary organs of excretions, however, are the kidney. Excretion is vital to the health of the body because the wastes are poisonous. If the wastes build up and are not eliminated, they can cause serious problems. As you know , carbon dioxide and water vapor are removed by the lungs.

Other wastes , namely urea, uric acid, various salts, and assorted nitrogenous wastes , are removed by the kidneys and sweat glands. Urea is produced when protein is broken down to glucose. The nitrogen part is the urea which is toxic to our body.

The water contains salt. the salt needs to be kept at the right concentrations. If there is little salt the body feeds it more, if there is too much salt the body gets rid of the salt not needed. This is the task of the two Kidneys.

The liver acts as a filter for the blood. It cleans out toxic waste and acid in the blood.

The skin plays a major role in excretion. It helps the body get rid of excess water, salts, and waste such as urea.

Urethra leads urine from bladder to outside, therefore it is also part of the excretory system.

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what happens in the small intestine?

The small intestine is the longest portion of the digestive tract – it is more than 6 meters long and is located within the middle of the abdomen. It has three sections, the duodenum, jejunum and ileum.

Small intestine has an important function in digestion of fats, proteins and carbohydrates contained in the foods you consume. The resulting nutrients produced are absorbed through the lining of the small intestine and transferred to the bloodstream.

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nucleus

Nucleus is at the centre of an atom which contains neutron and proton. Neutron has no charge but proton has positive charge. Electrons are outside the nucleus and they have negative charge. Electrons are like cloud outside the nucleus.

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Memorizing Periodic Table?

Hey, don’t hard out your self for learning the whole periodic table. Because you don’t need to. You are only expected to remember the first 30 elements on your periodic table. Your school will never ask you to remember the whole Periodic table and there is a big theory behind the Periodic table. It will be not even until Year11.

You will always get your periodic table during the test – BUT YOU NEED TO REMEMBER THE SYMBOL AND THE NAME of elements.

So, don’t learn their mass numbers of atomic numbers. It will be just a waste of time. When the time is right, you will get used to the properties of elements and understand why they have such placements.

But here is a tip for first 20 elements.

Harry He Like Beer Cold But Not Over Frothy. Nelly the Nanny Might Although Silly Punk She Climbs Around Kinky Cave.

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How to remember the scientific “terms”?

Learning science is like learning another language. If you are learning to speak another language like Chinese or Japanese – WHAT WOULD YOU DO?

It is the same procedure while  you are learning science. My advise is – use the word more often. How would you use the word more often though?

Well, everybody has different ways and methods. You could build your own table of glossary per each topic in science or make a memory card (front page with the definition and back page with the term), or even write the word many times. Some psychologists say that humans learn words by saying it or by forgetting the word few times. This is why teachers make you to do different activities and ask you to get involved into the discussion in the class.

Probably, the best way to learn science language is by ENJOYING IT! :) So, don’t bore yourself. Move on to something else if you can’t really learn the word -because you can alway come back to it.

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Blood

Blood

 

Oxygen is carried by red blood cells. Glucose is dissolved in the liquid part of the blood, called plasma. Plasma leaks out of the capillaries and forms tissue fluid around cells in the body. Some of the oxygen leaves the red blood cells dissolves in the tissue fluid. The red blood cells stay inside the capillary.

If you press two fingers firmly onto your wrist, you can feel your blood being pumped. This is called your pulse. Your pulse rate is the number of beats you can feel in one minute.

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How blood capillary works

Oxygen and digested food travel around the body in the blood. Blood flows through tubes called blood vessels. The smallest blood vessels are capillaries. They have thin walls with tiny gaps in so that small molecules, like water, can easily get into and out of them.

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Human circulatory system

Human circulatory system

 

Blood from the lungs is pumped by the heart through arteries to all parts of the body. This is known as circulation. Your heart lies in your chest. It is about the size of your fist. It is divided into four chambers. Blood consist of different types of cells floating in liquid plasma. These cells included white blood cells and red blood cells. It contains iron compounds called haemoglobin, which gives red colour to red blood cells and allow red blood cells to pick up oxygen from lungs.

The right atrium receives blood from all over the body. This side of the heart pumps blood to the lungs where oxygen enters it. The left atrium receives blood from the lungs and pumps around the rest of the body. This side of the heart is bigger because it has to pump harder to get the blood all the way around the body.

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About diet and nutrition

Diet

In science, the word diet means ‘what you eat’. Your food is a source of raw materials for your body. These raw materials are needed to make new substances for:

  1. Energy
  2. Growth and repair
  3. Health

Testing nutrients

We can find out which nutrients a food contains by testing it.

Starch is a type of carbohydrate. We can test for starch by adding two drops of iodine solution to a food sample. If starch is there you will see a blue/black colour.

We can test for fat by rubbing a small dry food samples on some white paper. Hold the paper up to the light. Fat will leave a greasy mark.

Balanced diet

Different foods contain different substances. There is no one food that contains all the substances that you need. You need to eat a wide variety of foods. This is called having a balanced diet. It does not matter exactly what you eat as long as you eat a balanced diet. In some parts of the world, people cannot get enough to eat and they starve. In other areas people get diseases caused by a lack of a nutrient. In New Zealand, many people are concerned about eating too much fat and sugar. Scientists and nutritionists think that eating too much fat can cause diabetes and heart diseases.

Some people go on weight control that makes them ill because the diets are not balanced or contain too little energy. People who do not eat enough often feel weak and tired. In some cases this can lead to life threatening disease called anorexia.

To stay healthy you have to keep the balanced right and eat a wide range of foods which contain all the nutrients you need.

Special diets: Diabetes

People with diabetes cannot control the amount of sugar called glucose in their blood. The amount of glucose in the blood increases after meal, but if it gets too high it can damage the kidneys and the brain. People with the disease inject a chemical called insulin which lowers the amound of glucose in the blood. Many diabetics also avoid eating too many sugary things to stop the glucose level getting too high.

People who have coeliac disease (see-li-ack) avoid eating wheat products. This is because they are allergic to a protein in wheat called gluten. The gluten causes parts of the intestine to become damaged and stops nutrients getting from their food into their bodies.

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Corrosion of metals

Corrosion of metals

Metals tend to be eaten away slowly by chemical reactions. They corrode. Corrosion is a big problem in all our lives. Building materials, fasteners, tools, utensils, car bodies and many other metal things are all slowly disappearing. Metals corrode because they combine with oxygen in the air. If people made no attempt to stop corrosion we would not be able to afford to replace the metal which is disappearing back into the earth.

Iron          +      Oxygen                 –>                      Iron Oxide