The air that you breathe in reaches the lungs through the trachea
(windpipe) which has rings of cartilage to prevent it from collapsing.
- The bronchi divide to form bronchioles.
- The trachea divides into two tubes (the bronchi).
- The bronchioles divide until they end in air
sacs called alveoli (there are millions of these)
The alveoli are very close to the blood capillaries. They are efficient at
exchanging oxygen and carbon dioxide because they have...
- A large, moist surface area.
- An excellent blood supply.
Ventilation
When you breathe in, your ribcage moves up and out and your diaphragm flattens
(contracts). When you breathe out (exhale), your ribcage moves in and down and your
diaphragm moves up (relaxes).
Exchange Systems in plants
- Carbon dioxide enters leaves by diffusion
- Water and mineral ions are absorbed by the roots.
In plants..
Roots and leaves are adapted to carry out the exchange of materials:
- Root hairs provide a large surface area in roots.
- Leaves are broad, thin and flat with lots of internal air spaces to
provide the largest surface area possible.
Plants have tiny holes called stomata on the underside of
their leaves. During photosynthesis, the stomata...
- Let carbon dioxide in (needed for photosynthesis)
- Let oxygen out (a product of photosynthesis)
The Circulatory System
The circulatory system transports substances around your body. It consists of your heart,
your blood vessels and your blood. Blood is pumped to your lungs, so carbon dioxide can be
exchanged for oxygen:
- Oxygenated blood provides glucose and oxygen to cells.
The heart is the organ responsible for continuously pumping blood around your
body, so much of its wall is muscle tissue. There are four chambers in your
heart:
- Left and right ATRIA
- Left and right VENTRICLES.
Blood enters your heart through atria. The atria contract and force
blood into the ventricles. The ventricles then contract and force blood out of the heart.
Valves make sure the blood flows in the correct direction.