Gas exchange in humans

Question 1

Describe the jorney of air as we breathe in.

Answer 1

trachea
bronchi
bronchus
bronchioles
alveoli

Question 2

Describe inspiration.

Answer 2

the external intercostal muscles contract
the ribcage moves upwards and outwards increaciing the volume in the thorax
as the volume of the throax increases the lung pressure decreases
air flows into the lungs from an area of high pressure to a area of low pressure into the lungs
inspiration is a active process it requires energy

Question 3

Describe expiration.

Answer 3

The external intercostal muscles relax
ricage moves downward and inwards
the volume of the thorax decreases causeing the pressure to increase
air is forced out of the lungs down a pressure gradient

Question 4

Describe the adaptations of the alveoli.

Answer 4

there is a huge number of alveoli which means there is a big surface area for gas exchange
the alveoli are surronded by a netword of cappilaries
alveolar epithelium is one cell thick this means a short diffusion pathway
oxygn diffuses out of the alveoli across thee alveolur epithelium and the capillary endothelium into the blood