B2 : Breathing and gas exchange Flashcards
Where are your lungs found
In your chest or thorax and protected by your ribcage
What layer of muscle spearates the lungs from the digestive system
Diaphragm
What are alveoli
Tiny air sacs found in the lungs increasing surface area for gas exchange
1 cell thick walls to provide short diffusion distance for gas exchange
Have rich blood supply of capillaries
What are the intercostal muscles
Muscles that control the ventilation of the lungs by contraction or relaxation
What does the diaphragm do
Changes the pressure of the lungs resulting in movement of oxygen in the lungs
How does breathing in work
As ribs move up and out and diaphragm flattens, volume of the chest increases
Increased volume means low pressure in the chest
Atmospheric air at higher pressure than chest so air is drawn into lungs
How does breathing out work
As ribs fall and diaphragm moves up, the volume of chest gets smaller
Decreased volume means increased pressure in chest
Pressure in chest higher than outside so air is forced outside lungs
