Cellular respiration requires oxygen to produce energy from glucose and produces carbon dioxide as a byproduct, so gaseous exchange is necessary to supply oxygen and remove carbon dioxide from the body. Breathing involves three steps - ventilation, external respiration, and internal respiration - to take in oxygen through inspiration and expiration and exchange gases between the air, blood, and tissue cells to supply cells with oxygen and remove carbon dioxide. The human respiratory system includes the nose, air passages like the pharynx, trachea, bronchi and bronchioles, and lungs containing alveoli to facilitate this gas exchange through breathing.

1. Respiratory System and
Gaseous Exchange

2. CELLULAR RESPIRATION
•Process whereby organisms uses oxygen & food à produce
energy (ATP) & 2 by products e.g. water & carbon dioxide
•
•Glucose + O
2
ATP + H
2
O + CO
2
Therefore gaseous exchange is necessary to get oxygen for cellular
respiration & remove CO
2
from body

3. Breathing
•Sequence of events that results in gas exchange (O2
& CO2
).
•In terrestrial vertebrates it includes 3 steps:
1. Ventilation: Inspiration (O2
) &
expiration (CO2
).
2. External respiration: Gas exchange
between air (in lungs) & blood.
Blood then transport Oxygen to the
body tissue cells.

4. Continue
3. Internal respiration: Gas exchange
between blood & tissue fluid (cells).
Blood then transports carbon
dioxide to the lungs.

5. HUMAN RESPIRATORY SYSTEM
● Nose
● Air passages:
● Pharynx (throat)
● Trachea
● Bronchus
● Bronchioles
● Lungs – Alveoli