Mrs Gren, Circulation of gases
M = movement
R = respiration
S = sensitivity
G = growth
R = reproduction
E = excretion
N = nutrition
Lung> picks up O2> pulmonary veins> Left atrium> Left ventricle> aorta> body> capillaries where O2 given up and CO2 picked up> superior vena cava> inferior vena cava> Right atrium> Right ventricle> pulmonary artery> lung
Air we breathe
When we breathe in we take in :
0.03% of carbon dioxide
21% of oxygen
and 79% of nitrogen
In the arewe breathe out we let out:
3% carbon dioxide
18% of oxygen
and 79% of nitrogen
Lungs, Lung Structure, Air Passages
The lungs have a spongy, elastic structure and are enclosed in the throax. They can be expanded or compressed by the movementof the throax in such a way that the air is repeatedlyy taken in and expelled.
The trachea divides into two bronchi which enter the lungs and divide into smaller branches. These divide furthur into bronchioles which terminate in a mass of little thin-walled, pouch-like air sacs or aveoli.
Rings of cartilage keep the trachea and bronchi open and prevent their closing up when the pressure inside them falls during inspiration. The lining of the air passaes is covered with numerous cilia. These are minute hairs which constantly flick to and fro. Mucus is secreted by glandular cells, also in the lining. Dust particles, bacteria, etc., which are carried in with the air during inspiration become trapped in the mucus film and,
Air Passages, Alveoli
by the movements of the cilia, are swept away in it up to the larynx. The epiglottis and other structures at the top of the trachea prevent food particles from entering the air passages, particulary during swallwing.
The alveoli have thin, elastic walls consisting internally of a single cell layer, or epithelium, and beneath this, a dense network of capillaries suppiled with de-oxygenated blood pumped from the right ventricle through the pulmonary artery.
The Action of breathing
- Intercostal muscles contract lifting the rib cae up and out.
- The diaphragm contracts and flattens.
- These actions increase the volume of the chest cavity but decrease the pressure and air rushes in to fill the space inflating the lungs.
- Intercostal muscles relax, the rib cage goes down and in.
- The diaphragm relax's and goes up.
- These actions decrease the volume of the chest cavity but increase the pressure and air rushes out, deflating the lungs.
The heart pumps blood around your body. Blood flow through a network of tubes called blood vessels. There are three types of blood vessels:
Arteries carry blood away from the heart.
Veins carry blood towards the heart.
Capillaries carry blood between the arteries and veins.