Circulation

Year 8 Science

Blood

• The average human carries about 5 litres of blood in their body, which travels around what is known as the Circulatory System.

• Blood is an integral component in the function of our bodies. It is made up of the following:

Blood

Blood typesThere are four basic types:Type A Type BType ABType O

This is based on whether you have certain proteins on your blood cellsEach of these has a positive and negative (Rh + and Rh -)

CompatibilityNot all bloods can mix. Some blood mixtures will clot when added together

- type A: can only receive types A and O blood.- type B: can only receive types B and O blood.- type AB: can receive types A, B, AB, and O blood.- type O: can only receive type O blood.

Cells are red & white blood cells

Red blood cells carry oxygen

White blood cells defend against disease

Cell fragments are platelets

Platelets function in clotting

Red Blood Cells carry oxygen

Haemoglobin is the iron-containing protein attached to the red blood cells that transports oxygen from the lungs to the rest of the body.

Haemoglobin bonds with oxygen in the lungs, exchanges it for carbon dioxide

When haemoglobin is carrying oxygen is it called oxyhaemoglobin.

Oxyhaemoglobin

Haemoglobin

The Circulatory SystemThere are 3 types of blood vessels

ArteriesVeinsCapillaries

Arteries• These carry blood AWAY from the heart

(Think Arteries Away = AA)

• They are buried deep in the body

• They carry oxygen rich blood (except for the pulmonary artery!)

Veins• These carry blood IN to the heart • (Think veINs=IN)

• They have thinner walls, and valves that prevent blood flowing backwards.

• They carry oxygen poor blood (except for the pulmonary vein!)

Vessel Thickness Comparison

Notice the arteries are thicker as they need to stand up to the pressure of blood that is coming from the heart

Veins have valves to prevent deoxygenated blood from flowing backwards

Capillaries• These carry blood to the cells. They are

between arteries and veins

• They are narrow vessels running throughout the body (one cell thick in some places)

• They carry oxygen rich blood from the arteries, past the cells. The oxygen poor blood is then carried to the veins.

The Circulatory System

ArteriesVeinsCapillaries

Which of these blood vessels:1. Takes blood away from the heart?2. Carries oxygenated blood?3. Contains blood under high pressure?4. Is only 1 cell thick?5. Contains valves?

Diagram of the HeartStudy this diagram and answer these questions in your notebook

1.What side of the heart contains oxygenated blood? Why?2.What side of the heart contains deoxygenated blood? Why?3.The aorta is the thickest blood vessel in the body. Can you explain why?4.The heart has two upper chambers called the left and right atrium. Which letters show these? What do you notice about the blood flow in these two chambers?5.The heart has two lower chambers called the left and right ventricle. Which letters show these?6.Vessels ‘a’ and ‘b’ are called pulmonary vessels. Which are veins and which are arteries?

aorta

Superior Vena cava

Inferior Vena cava

Rob the Red Blood Cells Journey!

Rob is a new red blood cell and needs direction about where he’s going and what will happen to him on his journey around the body.

Can you help advise him?

?

Review Questions• Where did Rob pick up Oxygen?• Where did Rob take it to?• Why did Rob change colour?• What things would be floating around Rob

in the blood?• What other cells are there in the blood with

P____ A____

V___ C___

R____ A____

R____ V______

A______

P_______ V___

L___ A____

L___ V______

Pulmonary Artery

Vena Cava

Right Atrium

Right Ventricle

Aorta

Pulmonary Vein

Left Atrium

Left Ventricle