circulatory system y7

4. The heart
• The pumping action moves the blood around
the body.
• Heart is divided into two halves.
• Right side receives deoxygenated blood from
the body and pumps it to the lungs.
• Left side receives oxygenated blood from the
lungs and pumps it to the body.

5. • The heart has two chambers.
• Blood flows from the veins into the upper chamber called the atria.
• It passes from the atria into the lower chamber called the ventricles.

6. • The ventricles relax to fill with blood.
• The muscles wall contract the blood into the arteries.
• Valves between the atria and ventricles stop the blood going backwards into
the atria.

7. There are four valves in the heart which
prevent blood from flowing backwards.
1- between the right atrium and ventricle
2- between the left atrium and ventricle
3- entrance to the pulmonary artery
4- entrance to the aorta

8. The muscular wall of the left ventricle is much thicker than the right
Because it has to pump blood around the whole body
The right ventricle is thinner because it only has to pump blood through the lungs

11. Blood vessels

12. Arteries
•Have thick and elastic walls
•Carry oxygenated (red) blood
away from the heart to the
body
•Blood moves at high pressure
Veins
•Have thin walls
•Carry deoxygenated (blue) blood
to the heart from the body.
•Does not move under high
pressure
•Have valves (stop blood flowing
back)

13. Capillaries
•The smallest vessels
•Have thin walls
•Walls are one cell thick
•Substances are able to pass in
and out of the blood.
RED BLOOD CELLS
THIN CELL WALL
BODY CELLS

14. • When artery reaches an organ,
• It splits into smaller and smaller
vessels
• To spread through out the organ
• When the blood leaves the
organ
• Capillaries join together to form
larger and larger vessels
• Until it forms veins

17. Plasma
• It is a watery liquid
• It contains digested food, hormones, waste like urea and carbon dioxide

18. Red blood cells
• It contains haemoglobin
• Haemoglobin transports oxygen from the
lungs to all body parts
• There are 500 red cells for every white cell

19. • They fight disease
• They attack bacteria and produce chemicals to stop virus infections
• They collect at the wound site to eat bacteria and stop it from entering

20. Platelets
• They collect at the site of the wound to form
a clot.
• They block the flow of blood.

24. Glucose
• It contains energy.
• It passes through the wall of the small intestine into the capillaries.
• It stays in the plasma.
• It moves through the veins which goes to the right side of the heart.
• It passes to the lungs where it picks up oxygen.
• Then it goes to the left side of the heart.
• Then it goes to all the body parts through the arteries.

25. • The heart has blood vessels called
coronary arteries and veins.
• They transport the blood to and from
the heart muscle.
• Fatty substance ,cholesterol stick
to the walls of arteries.
• The blood then has less space to
pass and the pressure rises.

26. • The platelets also settle, which may cause a blood clot.
• This narrows the artery even more and can completely block it.
• The artery is unable to supply oxygen and other nutrients to the organ.
• If it happens in the heart, it causes heart attack.
• If it happens in the brain, it causes a stroke.

27. Keeping heart healthy
• The heart is made of muscle
• Like all muscles, it needs exercise if it is to remain strong
• The heart muscle contract more quickly and more powerfully during exercise
• So more blood can be pumped to your muscles
• Muscles need more blood to provide them with extra oxygen while they
work.
• Fatty substances are needed to keep the membranes of the cells healthy
• Eating too much fat leads to heart disease
• A heart can be kept healthy by cutting down on the amount of fat in the diet.