Human Physiology

Lesson 33 : Respiratory System & Functions


Respiration is defined as process of intake of oxygen and elimination of carbon dioxide (respiratory gases) by body cells or organisms for energy production.

Ventilation is defined as process of entry and exit of air between atmosphere and lungs through respiratory tract.

Internal Respiration is defined as exchange of respiratory gases between blood and tissue cells. External Respiration is defined as exchange of respiratory gases between lungs and blood. Diffusion is defined as the passage of substances from a region of higher concentration to the region of lower concentration without expense of energy and transport medium.

Tidal Volume is the average volume of air exchanged between lungs and atmosphere with each respiration cycle (inspiration & expiration).

Vital Capacity is the volume of air that can be expired forcefully after a forceful inspiration. Residual Volume is the volume of air remaining in the lungs after forceful expiration.

Respiration Rate is defined as the number of respiratory cycles performed in one minute time (number of breaths per minute).

Artificial /Forced Respiration/Ventilation is the process of pushing air or oxygen into lungs in forceful manner. This is done when normal breathing by animal is arrested. Homeostasis is defined as maintenance of the normal uniform conditions (internal environment) prevalent around the cells in which the cells are functioning.

Inspiration is act of taking in of atmospheric air into lungs.

Expiration is act of expelling out of lung gases into atmosphere.

  • After studying this unit you should be able to:

    • Understand the structural make up of different systems included in the chapters.
    • Undiscover the functional significance of organs and how these are involved in maintaining the life of animal.
    Last modified: Tuesday, 10 April 2012, 12:19 PM