Respiratory System Function

Human Breathing Mechanics

Human Breathing Mechanics

The Primary function of the respiratory system is to obtain oxygen for use by body’s cells & eliminate carbon dioxide that cells produce:

Each red blood cell contains 280,000,000 hemoglobin molecules. Hemoglobin is folded protein with four iron containing Haem groups. Each Haem unit binds with one oxygen unit. As a Hemoglobin unit becomes oxygenated its color changes to a brighter red. Collectively, this molecular color change is evident in the bright red color associated with arterial blood.

Capillary (a)

Capillary (a)

Capillary and Body Tissue

Capillary and Body Tissue

The exchange of gases (O2 & CO2) between the alveoli & the blood occurs by simple diffusion: O2 diffusing from the alveoli into the blood & CO2 from the blood into the alveoli. Diffusion requires a concentration gradient. So, the concentration (or pressure) of O2 in the alveoli must be kept at a higher level than in the blood & the concentration (or pressure) of CO2 in the alveoli must be kept at a lower lever than in the blood. We do this, of course, by breathing – continuously bringing fresh air (with lots of O2 & little CO2) into the lungs & the alveoli.

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