Describe how oxygen in the air reaches the capillaries surrounding the alveoli.

As you breathe in, air passes down your trachea and then into the bronchi and bronchioles. The bronchioles divide further into even narrower branches which end in small air filled sacks called alveoli. The alveoli is where gas exchange occurs.
70% of the outside surface of alveoli are covered in capillaries, which provides a large surface area for gas exchange. The walls of both the capillaries and alveoli are very thin, again making it very easy for oxygen to pass from the alveoli into the capillaries.
Inside the alveoli there is a large concentration of oxygen compared to the pulmonary capillaries. This creates a large concentration gradient, increasing the rate of diffusion of oxygen into the capillaries.

NA
Answered by Naomi A. Biology tutor

2991 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

Explain the structure of DNA.


Explain 3 ways in which a leaf is adapted for photosynthesis. [6 marks]


Human breast milk is produced and secreted by gland cells. These gland cells have adaptations that include many mitochondria and many Golgi vesicles. Explain the role of these cell adaptations in the production and secretion of breast milk.


State three differences between daughter cells produced by the process of mitosis and those produced by meiosis.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences