Respiratory System

The human lungs

The Lungs

The lungs are protected by a bony cage made from the ribs. The lungs are a major organ in the breathing process. The lungs fill up most of the area inside the chest. The tip of each lung is called the apex. The left and right lung are connected by an area called the hilus

Lung Capacity

  • The average lung of a male can hold 6 liters of air
  • When resting an adult breathes in about .5 liters of air every breath
  • There is always about 1.2 liters of air in the lungs left
  • The maximum air that can be breathed out is 3.5-4.5 liters

The Respiratory System


Cigarette smoking can cause serious damage to lungs, this can lead to diseases which are fatal. The smoke from cigarettes can block tiny alveoli. Pregnant women who smoke put their babies at risk. Babies that are born from mothers who smoke are at a greater risk to heart or breathing problems.