Subjects
Biology
Chemistry
AP Chemistry
English
AP English Literature
Biology
Dec 7, 2025
245
1 page
Fariha Nabirah @farihanabirah
Your lungs are incredible machines that keep you alive every second of the day by swapping oxygen for... Show more
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!
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
3
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the mechanisms of gas exchange in mammals, fish, and insects. This study note covers specialized structures such as alveoli, gill filaments, and spiracles, detailing their roles in efficient oxygen and carbon dioxide exchange. Ideal for A-Level Biology students studying the Edexcel B curriculum.
BiologyExplore the intricate process of gas exchange in the lungs, detailing how oxygen is collected by blood and delivered to body cells. This summary covers the anatomy of the respiratory system, including the trachea, bronchi, bronchioles, and alveoli, highlighting their roles in efficient gaseous exchange. Ideal for students studying human biology and respiratory physiology.
BiologyExplore the specialized structures and functions of xylem and phloem cells in plant transport systems. This summary covers the key differences between xylem and phloem, including their roles in transporting water and nutrients, cell structure, and flow direction. Ideal for students studying plant biology and vascular systems.
BiologyExplore the mechanisms of gas exchange in the lungs, focusing on the role of alveoli, blood capillaries, and the respiratory system. This summary covers key adaptations of alveoli for efficient oxygen and carbon dioxide exchange, highlighting the importance of surface area and moisture. Ideal for students studying respiratory physiology.
BiologyExplore the gas exchange systems of insects, bony fish, and mammals in this comprehensive AS and A-Level Biology summary. Understand key concepts such as diffusion, alveoli, gill arches, and the tracheal system. This resource highlights the importance of specialized exchange surfaces and the surface area-to-volume ratio in efficient respiration. Perfect for exam preparation and quick revision.
BiologyExplore the mechanisms of carbohydrate, lipid, and protein digestion, including the role of bile salts and enzymes. Understand how nutrients like glucose and fatty acids are absorbed in the small intestine, highlighting key processes and enzyme locations.
BiologyQuotes from every main character
English LiteratureApp Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Fariha Nabirah
@farihanabirah
Your lungs are incredible machines that keep you alive every second of the day by swapping oxygen for carbon dioxide. Understanding how this gas exchange works will help you grasp one of the most essential processes in your body.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
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!
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
3
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the mechanisms of gas exchange in mammals, fish, and insects. This study note covers specialized structures such as alveoli, gill filaments, and spiracles, detailing their roles in efficient oxygen and carbon dioxide exchange. Ideal for A-Level Biology students studying the Edexcel B curriculum.
BiologyExplore the intricate process of gas exchange in the lungs, detailing how oxygen is collected by blood and delivered to body cells. This summary covers the anatomy of the respiratory system, including the trachea, bronchi, bronchioles, and alveoli, highlighting their roles in efficient gaseous exchange. Ideal for students studying human biology and respiratory physiology.
BiologyExplore the specialized structures and functions of xylem and phloem cells in plant transport systems. This summary covers the key differences between xylem and phloem, including their roles in transporting water and nutrients, cell structure, and flow direction. Ideal for students studying plant biology and vascular systems.
BiologyExplore the mechanisms of gas exchange in the lungs, focusing on the role of alveoli, blood capillaries, and the respiratory system. This summary covers key adaptations of alveoli for efficient oxygen and carbon dioxide exchange, highlighting the importance of surface area and moisture. Ideal for students studying respiratory physiology.
BiologyExplore the gas exchange systems of insects, bony fish, and mammals in this comprehensive AS and A-Level Biology summary. Understand key concepts such as diffusion, alveoli, gill arches, and the tracheal system. This resource highlights the importance of specialized exchange surfaces and the surface area-to-volume ratio in efficient respiration. Perfect for exam preparation and quick revision.
BiologyExplore the mechanisms of carbohydrate, lipid, and protein digestion, including the role of bile salts and enzymes. Understand how nutrients like glucose and fatty acids are absorbed in the small intestine, highlighting key processes and enzyme locations.
BiologyQuotes from every main character
English LiteratureApp Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Sociology