facts about the respiratory system

Published on 5th December 2016



•             Uptake of oxygen by all cells for energy production

•             Formation of carbon dioxide and water as waste products

•             Exchange of these gases occurs between:

o             the alveoli of lungs and blood capillaries – external respiration

o             blood capillaries and all cell walls – internal respiration



•             Nasal passages

•             Pharynx

•             Larynx

•             Trachea

•             Bronchi

•             Bronchioles

•             Alveoli

•             Pleura

•             Diaphragm

•             Thoracic cavity



•             Occurs due to diffusion = Transfer of gases from area of high to low pressure/concentration

•             O2 moves out of alveoli in to blood capillaries

•             CO2 moves in opposite direction




•             Intercostal muscles contract. Ribs move up and out

•             Diaphragm contracts and flattens. Lungs pulled downwards

•             Chest Cavity enlarges – so pressure inside chest is lowered and air is sucked in


•             Intercostal muscles and diaphragm relax

•             Chest cavity decreases in size – so pressure inside chest is increased and air is forced out


•             Normal rate about 16 x minute

•             Controlled by chemo receptors in aorta and carotid arteries which monitor levels of gases in blood and send information back to brain

•             Amount of lung expansion and muscle activity are also monitored by the brain


nose / nasal cavity           Warms , moistens and filters air as it is inhaled

pharynx               Passageway for air, leads to the trachea

larynx    The vocal cords are located here

trachea Tube from pharynx to bronchi. Rings of cartilage provide structure

bronchi Two branches at the end of trachea

bronchioles        A network of small branches leading from bronchi into lung tissue

alveoli   Functional units in lungs where gases are exchanged

pleura   Serous membrane covering lungs and

attached to ribcage and diaphragm

diaphragm          Muscle which helps in breathing


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