Natural Science Level 4

Year 2015/16

BODY SYSTEMS

Stomach Small Large Liver Pancreas Intestine Intestine

Kidneys Lungs Brain Heart

Eyes Ears Nose Tongue Skin

ORGANS

THE CIRCULATORY SYSTEM

ARTERIES (carry blood

from the heart to the rest of

the body)

The circulatory system consists of the heart , blood vessels and blood. It moves blood through the heart and around our body. Blood gives cells oxygen and nutrients and also collects waste products. There are three types of blood vessels: arteries, veins and capillaries.

VEINS (carry blood back to the

heart from the rest of our

body )

HEART (It is a muscle

divided into four parts: the left and right atriums and the left and

right ventricles.

It is located in the centre

of our body. It contracts and

relaxes to pump blood through the

blood vessels in our body). It beats about

70 times a minute.

CAPILLARIES (very small vessels that

connect arteries and veins)

How blood travels through the heart

1. Blood enters the heart through the veins and goes into the right atrium.

2. The blood passes from the right atrium to the right ventricle.

3. The right ventricle contratcts and pumps the blood to the lungs. Here the blood picks up oxygen and expels carbon dioxide.

4. The blood, now carrying oxygen comes back to the heart from the lungs through the left atricum.

5. The blood passes from the left atrium to the left ventricle.

6. The left ventricle pumps the blood through the arteries to the rest of the body.

THE RESPIRATORY SYSTEM AND THE LUNGS

MOUTH

TRACHEA

BRONCHI

PHARYNX

LUNGS

NOSE

DIAPHRAGM

The respiratory system is made up of organs that help us breathe. We breathe in oxygen and breathe out carbon dioxide.

nose and MOUTH

Pharynx trachea

We breathe in air through our nose and mouth.

The pharynx opens and the air goes down a tube called the trachea.

bronchi lungs

The air travels down two tubes called bronchi and enter the lungs.

The oxygen from the air passes from the lungs into our blood through the alveoli. v

Inside the lungs, the bronchi divide into smaller tubes. At the end of them, there are tiny sacs called alveoli.

Breath in = Inhalation Breath out = exhalation

CO2

Carbon dioxide (CO2) from our body passes from our blood into the lungs through the alveoli. When we breathe out, the carbon dioxide leaves our lungs.

Breathing in and breathing out

We breathe in oxygen from the air and we breathe out carbon dioxide.

The lungs are the main organs in the respiratory system but we cannot breathe in our out without the diaphragm. The diaphragm is a strong muscle below the lungs. It ontracts when we breathe in to allow our lungs to fill with air. The diaphragm relaxes when we breathe out.

Male reproductive system

SCROTUM (bag of skin

where the testicles are

located)

PENIS (connected to the testicles

by small tubes)

URETHRA (tube in the

penis. Sperm travels

through the urethra to the outside of the

body)

TESTICLES (store and

produce sperm (male sex

cell))

THE REPRODUCTIVE SYSTEM

Our reproductive system makes it possible for us to have babies. The reproductive systems are different in men and women. They need to work together.

Female reproductive system

VULVA (on the

outside of the body. Covers

the opening to the vagina)

VAGINA (muscular tube that

connects the uterus to

the outside of the body)

OVARIES (store and

produce ova (female sex

cells))

UTERUS (connected to the ovaries by

tubes)

HOW WE ARE BORN

FERTILISATION: When a sperm joins an ovum cell. The reproduction process begins.

PREGNANCY: When the fertilised ovum develops into a baby in the uterus.

BIRTH: When the baby leaves the uterus and is born after nine months.

In the first three months the embryo is the size of a small seed. It becomes a foetus and is the size of a bean. Then limbs start to grow and organs to develop. In the second three months the face starts to form. The foetus has all its organs and continues to grow. In the last three months the foetus is developed and preparing to be born.