Respiratory system
The human respiratory system is adapted to allow air to pass in and out of the body, and for efficient gas exchange to happen. Exercise and smoking both affect the lungs and circulatory system.
The respiratory system
The following structures can be found in the human thorax:
- trachea
- bronchi (left and right bronchus)
- alveoli
- ribs
- intercostal muscles
- pleural membranes
- diaphragm
The trachea branches into two bronchi (one to each lung). Pleural membranes surround each lung. Cartilage rings in the walls of the trachea help to keep it open.
The bronchi split into smaller and smaller tubes called bronchioles. These end in microscopic air sacs called alveoli. There is a muscular diaphragm below the lungs.