Study notes
Circulatory & Respiratory Systems
The human body relies on the respiratory and circulatory systems working together to take in oxygen and transport it to all parts of the body.
Learn it step by step
The Respiratory System
The respiratory system helps us take in oxygen from the air and remove carbon dioxide from our bodies. The main organs involved are the nose, windpipe, and lungs.
How We Breathe
When we inhale, air rich in oxygen enters our lungs. When we exhale, air rich in carbon dioxide and water vapour leaves our lungs.
| Action | Air Inhaled | Air Exhaled |
|---|---|---|
| Oxygen level | More oxygen | Less oxygen |
| Carbon dioxide level | Less carbon dioxide | More carbon dioxide |
Gas Exchange in the Lungs
Inside the lungs, oxygen from the air passes into the blood vessels. At the same time, carbon dioxide passes from the blood into the lungs to be breathed out.
The Circulatory System
The circulatory system consists of the heart, blood vessels, and blood. It acts as a transport system to move useful substances around the body.
How the Heart Works
The heart is a muscular organ that pumps blood continuously through blood vessels to all parts of the body, delivering oxygen and digested food.
Working Together
The respiratory system gets oxygen into the blood, and the circulatory system transports this oxygen to every cell in the body so it can function.
Worked examples
- Recall the organ systems learnt in Primary 5 science regarding breathing and transport.
- Identify the respiratory system for taking in oxygen and the circulatory system for moving blood and oxygen around the body.
- Think about where gas exchange takes place in the lungs.
- Remember that oxygen enters the blood from the lungs during inhalation.
- Conclude that the amount of oxygen in the blood increases.
- Identify that muscles need more oxygen and energy when exercising.
- Realize the heart must pump faster to transport more oxygenated blood to the working muscles quickly.
Mind map
Mind map for human-systems.
- respiratory system
- nose
- windpipe
- lungs
- breathing process
- inhaling oxygen
- exhaling carbon dioxide
- circulatory system
- heart
- blood vessels
- blood
- transport role
- carrying oxygen
- carrying digested food
- system interaction
- lungs add oxygen to blood
- heart pumps blood to cells