bio

2. Levels of Organisation (from Year 9)
CELLS are the smallest structural and
functional unit of every organism.
Groups of cells with similar structures,
performing a shared function form a TISSUE.
An ORGAN is a structure made up of a group
of tissues, working together to perform a
specific function.
Several organs with related functions working
together to perform a body function form an
ORGAN SYSTEM.
Groups of organs systems together make up an
ORGANISM.

3. CELLS are the smallest structural and
functional unit of every organism.
Groups of cells with similar structures,
performing a shared function form a TISSUE.
An ORGAN is a structure made up of a group
of tissues, working together to perform a
specific function.
Several organs with related functions working
together to perform a body function form an
ORGAN SYSTEM.
Groups of organs systems together make up an
ORGANISM.
Why is it called the ‘circulatory system’?
Organs: Heart + Vessels (these are
considered to be tubular-like
organs)
Related functions – a pump that
pushes blood around the body,
delivering oxygen to respiring cells,
vessels provide a transport system
for blood ensuring one-way flow!

4. Functions of the Circulatory System
Transports oxygen and nutrients
Carries disease-fighting materials produced by the
immune system
Contains cell fragments and proteins for blood clotting
Distributes heat throughout the body to help regulate
body temperature

5. Components of the Circulatory
System
The circulatory system is composed of 3 main parts:
- Heart
- Blood
- Blood vessels

7. • They carry blood away from the heart.
• Largest Artery: Aorta
- Aorta branches into smaller arteries which
reach all our body organs
- Aorta & all other arteries carry oxygen-
rich/oxygenated blood
• Pulmonary artery:
- Carries oxygen-poor/deoxygenated blood away
from the heart to the lungs

8. • They carry blood away from the heart.
- Largest Artery: Aorta
- Pulmonary artery: Carries oxygen-
poor/deoxygenated blood away from the heart to the
lungs

9. • They carry blood back to the heart.
- Largest veins: Superior & Inferior vena cava
- It is formed from smaller veins that gather to
come back to the heart
- All veins carry deoxygenated blood except
pulmonary veins
- Pulmonary veins: carry oxygenated blood from
lungs to the heart
•

10. • They carry blood back to the heart.
- Largest veins: Superior & Inferior vena cava
- Pulmonary veins: carry blood from lungs to
the heart

13. PARTS OF THE HEART

18. - Tricuspid valve : separates the right atrium from the right
ventricle
- Bicuspid or Mitral valve: separates the left atrium from the
left ventricle

24. Study the diagram:
Why do you think this is called a
double circulatory system?
Bonus Q2) What are the advantages
of this system?
Bonus Q1) Describe the pathway
that the blood takes during one
circulation.