Respiratory and circulatory systems

Inside the lungs, the bronchi divide into smaller tubes. At the end of these tubes, there are tiny sacs called...

• Pharynx

• Trachea

• Lungs

• Alveoli

Part of blood that absorbs oxygen in the lungs and transport it to the organs and muscles.

(a)  

They fight germs and infections in our body. They attacked infected cells.

(a)  

All living things need ​ (a)   to survive. This gas makes up ​ (b)   percent of our atmosphere. The majority of our atmosphere is made of ​ (c)   . The air we breathe out contains more ​ (d)   than the inhaled air.

• oxygen
• 21
• nitrogen
• carbon dioxide
• 78
• helium

Organize these options into the right categories

Groups:

(a) Inhaled air

,

(b) Exhaled air

• contains more carbon dioxide

• contains less carbon dioxide

• contains less water vapour

• is warmer

• contains less oxygen

• contains more oxygen

• is cooler

• contains more water vapour

Oxygen is needed for (a)   process. This process also produces carbon dioxide and water.

Label the parts by dragging the names.

a

b

c

d

diaphragm

lung

windpipe

nose

Reorder the following from the beginning to the end.

• Air rushes in through our nose.

• Ribcage moves upwards and outwards.

• Chest cavity gets bigger and lungs expand.

• Diaphragm contracts and flattens.

• Air in our lungs enters the bloodstream.

In which part of our respiratory system will air end up when we breathe it in?

• air sacs

• trachea/windpipe

• bronchus

• diaphragm

Which gas leaves the blood and enters the air sacs?

• nitrogen

• oxygen

• carbon monoxide

• carbon dioxide