A closer look at the circulatory system of humans for Year 8 Science students.

1. FUNCTIONING ORGANISMS.
03. Circulatory system.
Ian Anderson
Saint Ignatius College Geelong

2. CIRCULATORY SYSTEM.
 Responsible for
 Transporting oxygen and
nutrients to our cells.
 Collecting wastes from our cells.
 Consists of
 Heart.
 Blood vessels.
 Blood.
Source: http://www.cakechooser.com/

3. CIRCULATORY SYSTEM.
 Double circuit.
 Oxygenated and deoxygenated
blood is kept separate from each
other.
 One circuit pumps oxygenated
blood to body.
 Other circuit pumps deoxygenated
blood to lungs.
Source: Russell et al. (2011)

4. THE HEART.
 Muscular pump (actually two pumps in one!).
 The left side of the heart receives oxygenated blood
from the lungs and then pumps it around the body.
 The right side of the heart receives deoxygenated blood
from the body and then pumps it to the lungs.
 Made up of four chambers.
 Left and right atria.
 Collect blood from either the body or lungs.
 Left and right ventricles.
 Pump blood to either the body or lungs.
 Valves between atrium & ventricle prevent backflow of
blood.

5. THE HEART.
Systemic circuit (LHS).
 Pumps oxygenated
blood to body.
Lungs
Left
atrium
Left
ventricleBody
Source: Sharwood (2005)

6. THE HEART.
Source: Sharwood (2005)
Systemic circuit (LHS).
 Oxygenated blood to
body.
 Wall of left ventricle
thicker than right
ventricle.
 Pumps blood to whole
body under high
pressure.

7. THE HEART.
Source: Sharwood (2005)
Pulmonary circuit (RHS).
 Deoxygenated blood to
lungs.
Body
Right
atrium
Right
ventricleLungs

8. THE HEART.
Source: Sharwood (2005)
Pulmonary circuit.
 Deoxygenated blood to
lungs.
 Wall of left ventricle
thinner than left
ventricle.
 Pumps blood to lungs
under lower pressure.

9. BLOOD VESSELS.
Blood is transported around the body in three different
kinds of blood vessels:
 Arteries.
 Veins.
 Capillaries.

10. BLOOD VESSELS.
Arteries.
 Carry blood away from the heart to the body.
 Carry oxygenated blood except for the pulmonary
artery.
 Have thick, muscular walls with
elastic fibres.
 In order to withstand the
increased pressure of the
blood as it is pumped
from the heart.
Source:
http://www.passmyexams.co.uk/GCSE/biology/arteries.html

11. BLOOD VESSELS.
Veins.
 Carry blood towards the heart from the body.
 Have valves in order to prevent backflow of blood.
 Have relatively thin walls.
 Blood is under lower
pressure than in arteries.
Source:
http://www.passmyexams.co.uk/GCSE/biology/veins.html
Source:
http://www.texasveinandvascular.com

12. BLOOD VESSELS.
Capillaries.
As arteries move away from the heart they divide,
eventually forming arterioles, before finally forming
capillaries.
 Carry blood to and from body cells.
 Most cells are very close to
a capillary.
 Blood under very low
pressure.
 Very narrow.
 Thin, permeable walls.
 Site of exchange of O2,
CO2, nutrients & wastes.
Source:
http://www.passmyexams.co.uk/GCSE/biology/capillaries.html

13. BLOOD.
Made up of
 Plasma.
 Red blood cells (erythrocytes).
 White blood cells (leukocytes).
 Platelets.
Total blood volume
is ~4-5L.
Source: Russell et al. (2011)

14. BLOOD.
Plasma.
 The liquid component (clear, straw coloured).
 Makes up ~55-58% of blood.
 Contains ions, dissolved gases, proteins, hormones
and wastes.
 Main role is to transport all the components of blood.

15. BLOOD.
Red blood cells (erythrocytes).
 Makes up ~45% of blood.
 Transport O2 and CO2.
 Lack a nucleus.
 Contain haemoglobin
(iron containing protein that
carries oxygen).
Source: http://embryology.med.unsw.edu.au

16. BLOOD.
White blood cells (leucocytes).
 Makes up <1% of blood.
 Have a nucleus.
 Play an active role in the defence against infection
and in the immune system.
 Able to move out of
bloodstream into
surrounding tissues.
Source:
http://siananigan.blogspot.com.au/2012/05/fever.html

17. BLOOD.
Platelets.
 Specialised fragments of larger cells.
 Play an important role in the clotting of blood.
Source:
http://www.marvistavet.com/html/body_immune_mediated_thrombocytopen.html

18. BIBLIOGRAPHY.
Russell, P.J., Hertz, P.E., & McMillan, B. (2011).
Biology: The Dynamic Science. Canada: Thomson
Brooks/Cole.
Sharwood, J. (Ed.). (2005). Science Edge 2.
Melbourne: Thomson Learning.

19. http://sickscience8.wikispaces.com/