1. The Respiratory System

2. Worksheet
Your cells obtain energy by aerobic respiration (they need O2) and your body does this by taking it from the air.

4. Using diagram
(1) You breathe in through the nose and the air is filtered by tiny little hairs and warmed by mucus.
(2) The voice box or larynx makes sounds for speaking.
(3) The trachea is a flexible tube held open by rings of cartilage.
(4) In the lungs the trachea divides into two bronchi (single=bronchus)

6. (5) Bronchi then branch out to become smaller tubes called bronchioles.
(6) At the end of the bronchioles there are tiny little air sacks called alveoli. This is where gas exchange takes place (O2 in CO2 out)
(7) The diaphragm is a muscle below the lungs that helps you breathe.
(8) Your intercostal muscles help you breathe in and out and are in between your ribs.

8. (9) Ribs protect your lungs.
(10) The plural membrane is a slippery skin lining the cavity and protect the lungs from rubbing against the ribs.
(11) Lungs are in a space in the body called the thoracic cavity.
(12) Lungs are soft and spongy.
(13) The small flap of skin that stops you swallowing food down the windpipe is called the epiglottis.

9. Alveoli
(1) They are at the end of the bronchiole and are smaller than a grain of salt.
(2) Lungs take in O2 and give out CO2. Gas exchange takes place here as their cell walls are thin.
(3) They are covered with tiny blood vessels called capillaries. Gases can pass through these.

10. Gas Exchange
(1) Blood carries waste CO2 from the body cells to the alveoli.
(2) CO2 passes through the capillary walls into the alveoli.
(3) From here it travels out of the lungs and up the windpipe and you breathe it out.
(4) you breathe in O2. It passes through the alveoli walls and into the capillaries.
(5) The blood carries the O2 away to the body cells.

11. How air changes in your lungs
O2 is taken from air and CO2 added to it.
This means the air you breathe out is different to that you breathe in.