The Respiratory system

PartsDivided into 2:

• Respiratory Tract– Nasal cavity– Pharynx– Trachea– Bronchi

• The Lungs– Alveoli

Role of System• Gaseous exchange between

surrounding air and blood• Oxygen diffuses from alveoli to blood• Carbon dioxide diffuse out from

blood to alveoli

Function of Nasal Cavity• Filters air with hairs• Warm and moisten air with mucus

Function of Lungs• Where gas exchange occurs between

the body and the outside world

Mechanics of Respiration• 2 important structuresA. Intercostal muscles (muscles

located between the ribs)B. Diaphragm (muscle that seperates

rib cage from abdomen)

Inhalation• Air rich in O₂ and poor in CO₂• Intercostal muscles and diaphragm contract• Ribs rise• Diaphragm descends• Rib cage ↑ in size• Lung volume ↑• Air pressure ↓• O₂ rich air from outside flows into lungs until

pressure inside and outside of lungs is equal

Exhalation• Air rich in CO₂ and poor in O₂• Intercostal muscles and diaphragm relax• Ribs descend• Diaphragm rises• Size of rib cage ↓• Lung volume ↓• Air pressure ↑• CO₂ rich air inside lungs flows outside until

pressure inside and outside lungs is equal

Gas exchange within the lungs

• The O₂ that has been absorbed by the lungs must reach all the cells of our body!

• This is why our blood needs to be circulated

• The same goes for the waste product produced (CO₂) needs to be carried by the blood to be expelled from the body

• This exchange of gases occurs in the ALVEOLI

Gas exchange within the lungs

• Alveoli→ miniature sacs that fill with air and make up the bulk of the lungs

• Each alveoli is surrounded by blood vessels called capillaries

• When the blood reaches the alveoli, it is CO₂ rich

• The air in the alveoli is O₂

Gas exchange