RESPIRATORY SYSTEMS

CONTENT

1. Respiration in Higher Animals
2. Respiration in Lower Animals
   
3. Gaseous Exchange in Plants

Respiration in Higher Animals

This type of respiration takes place through the lungs. All mammals have a pair of lungs. lungs adaptations that allow animals to invade the terrestrial environment. Some fishes, and amphibians, reptiles, birds, and mammals, all have their lungs located internally. Mammals breathing system comprises the air passages (nostrils, pharynx, larynx, and trachea), lungs and diaphragm. Oxygen enters the nasal passage through the nostrils into the nasal cavity where it is moistened and kept warm. The nasal cavity has lining cells, which secretes mucus that traps most of the dust and microorganisms present in the air before it diffuses into the lungs.

Nasal cavity leads into the pharynx, the to the trachea (wind pipe), which divides into two bronchi before it enters into the lungs; the cartilages supports the wall of the trachea and bronchus to prevent them from collapsing when the air pressure in them is reduced. Within each lung, the bronchus divides repeatedly and becomes progressively narrower forming numerous tiny tubules called bronchioles, which end in pockets of the air sacs called alveoli.