Lungs and Gas Exchange

Ever wondered what happens to the air you breathe in? It takes quite a journey through your respiratory system before it actually does its job.

When you breathe in, air travels through your mouth or nose, down your trachea (windpipe), and splits into two bronchi that lead to each lung. From there, it branches out through smaller tubes called bronchioles, like a tree spreading its branches.

The magic happens at the end of these branches in tiny air sacs called alveoli. These microscopic bubbles are where gas exchange occurs - oxygen moves into your blood whilst carbon dioxide moves out. The alveoli are perfectly designed for this job with their thin cell walls that create a short pathway for gases to cross.

What makes this system so efficient is the large surface area of all the alveoli combined and their moist walls that help gases dissolve quickly. Meanwhile, blood capillaries wrapped around each alveolus carry blood that's just returned from your body tissues - the haemoglobin in your red blood cells has already delivered most of its oxygen and picked up carbon dioxide dissolved in the blood plasma.

Quick Tip: When you exercise, your breathing rate increases because your muscles need more oxygen. You can calculate breathing rate by counting breaths per minute!