Respiratory System, Breathing and Respiration

The respiratory system

The respiratory system; nasal cavity, trachea, pleural cavity (filled with fluid), intercostal muscles, ribs, diaphragm, lung, bronchiole, alveoli

StructureFunction
Nasal cavityAir is warmed and filtered as it enters the body.
TracheaBrings air into the lungs. Supported by rings of cartilage that prevent it collapsing.
BronchusBranches off the trachea to bring air into the lungs. Also supported by rings of cartilage.
BronchioleBranch off the bronchi.
AlveoliSmall air sacs that are the site of gas exchange.
LungOrgan where gas exchange occurs.
RibsProtect internal organs of the thorax.
ThoraxPart of the body between the neck and abdomen.
Intercostal muscles Muscles between the ribs that aid breathing.
Diaphragm Sheet of muscle below the ribs that aids breathing.
Pleural membranesThin layers that reduce friction between the lungs and the inside of the chest wall during breathing.
Pleural fluidFluid found in the pleural cavity (between the pleural membrane layers). It further reduces friction during breathing.