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Living things & the processes of life - The processes of life - Living on Earth (Animals) - P5G14a
This is the Teacher's Guide for this targetThis is the Teacher's Guide for this targetTeacher's Guide



1. The children obviously have some experience of the life processes but may not be well aware of everything which goes on inside them. Talk about each of the processes in turn and note the headings on the board. Worksheet C22 (G) could be used to record the life processes. Some of the important points to note are as follows ;-

a) Feeding and digestion - Food passes from our mouths through a tube called the oesophagus into the stomach. There are valves at the top and bottom of the stomach to stop the food coming back out of the top (except when we are being sick) and to stop it leaving the stomach before it has been fully processed.

The stomach is a very stretchy bag which is fully of acid. The lining of the stomach is coated in mucous otherwise the acid would destroy the stomach. Food is ground down first by our teeth then by the churning action of the stomach and the acid. When it leaves the stomach it is sludgy in nature and winds its way along our small intestine by a series of squeezes called peristalsis.

In the small intestine the food becomes alkali as different liquids are added to help digest and breakdown the sludge. Food components now get absorbed by the lining of the small and large intestines as food passes along.

Water gets absorbed from it also - mostly in the large intestine.

What's left is brown in colour, mostly due to the excreted pigments, is passed out through a valve at the bottom of the gut called the anus.

b) Support and movement - We need our skeleton for both support and movement. Our skeleton also provides protection for our brains, heart and lungs and the flexibility of our spine allows us to bend and flex.

Muscles and ligaments are attached to the bones which allow us to move. Remember muscles only work one way - they contract. They work in pairs to allow us movement in two directions.

The inside of our bones produces marrow which makes blood and cells for our immune system - no waste of space in your body!

c) Breathing and circulating blood - We take in air by contracting muscles between our ribs and our diaphragm muscle - the big sheet of muscle between out chest cavity and our gut. This makes more space in our chest cavity which forces our lung tissue to expand to fill it and air is sucked in through our nose or mouth as a result. The rib muscles and diaphragm relax and the lungs are squashed forcing the air out.

The air that comes in contains a mixture of gases. The very thin membrane lining the lung allows an exchange of gases: oxygen in and carbon dioxide out. The surface needs to be moist, so a large amount of water vapour is also passed into the air.

The oxygen is carried round our bodies in blood in a chemical called haemoglobin which is bright red. The oxygen is used by our muscles to burn fuel (from our food) - just like a fire needs oxygen to burn. The more activity our muscles are doing, the more oxygen they need to operate and so our breathing rate increases.

The heart is responsible for getting the blood to move around our bodies. It has two loop system, each operated by one half of the heart. The left side of the heart pushes the blood from the heart into the lungs and back to other side of the heart. The right side of the heart pushes this newly charged blood all the way around the body.

d) Reproduction - All species seek to reproduce themselves and as humans we produce live young after a nine month gestation.

For this we need our reproductive organs: male and female.

Our offspring are helpless for the first few years of their life and rely on a high level of parental care and support to survive. They don’t reach maturity for many years.

d) Excretion and waste removal - Waste leaves our bodies in several ways.

Our kidneys extract waste products and water from our blood and use it to make urine. Lungs breathe out waste gases and water. Skin secretes sweat - a salt water solution which includes waste chemicals, as this dries we lose heat. The faeces also contains waste, but not waste from food as you might think, the waste is the brown coloured substance which it broken down blood released by the liver.

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