Respiratory System
Respiratory System
The respiratory system is the process where oxygen is drawn into the lungs, where it can be exchanged with waste carbon dioxide in the blood.
Oxygen accounts for 21% of the air in the atmosphere. The body uses a small proportion of that so that the air that we breathe out is 16% oxygen and 4% carbon dioxide.
Typical breathing rates for an adult are 12-20 breaths per minute. For a child it is 20-40 and a baby will breathe at 30-60 breaths per minute.
Breathing process
Air is drawn into the lungs when the diaphragm – a thin muscle that stretches across the base of the chest – flattens. This makes the chest walls move out and air is drawn into the enlarged capacity of the thoracic cavity.
The air enters the body via the mouth and nose, which help to warm, filter and moisten the air. The air then travels down the throat, past the epiglottis (which protects the airway from foreign objects when we swallow) and down the trachea, which then divide into two bronchi which connect to each lung.
The bronchi then further divide into smaller bronchioles and then still further into tiny air pockets called alveoli.
It is through these alveoli that the oxygen passes into the blood capillaries (see Circulatory system section). Waste carbon dioxide transfers the opposite way.
A double-walled membrane called the pleura surrounds each lung. The pleura contains a fluid called serous fluid which helps the chest walls to move.
Hypoxia
Hypoxia is low levels of oxygen in your body tissues. It causes symptoms like confusion, restlessness, difficulty breathing, rapid heart rate, and bluish skin.
Cyanosis occurs when there is a lack of oxygen in the blood. The skin and lips turn to a bluish-purple colour as a result of having decreased amounts of oxygen.
