Organs of Human Respiratory System

By | September 19, 2015
  • The human respiratory system consists of external nares or nostrils, nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchiole and lungs.
  • The air enters into the nasal cavity through the nostrils.
  • Larynx is a small box and it forms the connection between pharynx and the windpipe or trachea. Larynx is also called voice box.
  • Larynx is covered by pieces of cartilage forming a box. In males, the adam’s apple is the protruding cartilage of the voice box.
  • Larynx is covered by pieces of cartilagte forming a box. In males, the adam’s apple is the protruding cartilage of the voice box.
  • Trachea is a tubular structure of about 12 cm in length and 2.5 cm in diameter.
  • Lungs are paired structure present in the thoracic or pleural cavity.
  • During inhalation, diaphragm contracts and lungs increases while during exhalation, the diaphragm relaxes and the lungs are compressed.
  • The cycle of breathing (ventilation of lungs) consists of three phases: 1) Inspiration 2) Expiration and 3) Pause
  • Inspiration is an active process. It is the result of muscle contraction.
  • Expiration is a passive process. It is the result of muscle relaxation.
  • the main muscles of respiration in the normal breathing are intercostal (external) muscles and diaphragm.
  • Larynx does not contribute to the breathing movements.
  • Breathing occurs involuntarily but its rate is controlled by the respiratory centre of brain. Under normal conditions rate of breathing is 15-18 times per minute.
  • Breathing rate is lowest while we are sleeping.
  • A person with fever may breathe faster than normal.
Respiatory system