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Biology
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AP Chemistry
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AP English Literature
283
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Dec 13, 2025
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Mai
@maimeimi
The cardiovascular system is your body's transport network, delivering oxygen... Show more
Blood is made of two main components: solid blood cells (45%) and fluid plasma (55%). The solid part includes red blood cells (erythrocytes) that carry oxygen, white blood cells (leukocytes) that fight infection, and platelets (thrombocytes) that seal wounds.
Your blood type matters because different types have different proteins (antigens). You might be type A, B, AB, or O, plus either RH+ (85% of people) or RH- (15%). Type O is the universal donor while type AB is the universal receiver - mixing incompatible types can be dangerous!
The heart is a fist-sized, hollow muscle weighing about one pound, located in the chest's mediastinum. It has four chambers (two atria for receiving blood and two ventricles for pumping) and is protected by three tissue layers: the outer pericardium, the muscular myocardium, and the inner endocardium.
Fun Fact: Red blood cells have no nucleus and only live for about 6 weeks before being replaced. Your body constantly manufactures new blood cells in your bone marrow!
Blood flow through the heart follows a specific path. First, oxygen-poor blood enters the right atrium from the body through the superior and inferior vena cava. When the right atrium contracts, blood passes through the tricuspid valve into the right ventricle.
The right ventricle then pumps blood through the pulmonary valve into the pulmonary arteries, which carry blood to the lungs for oxygenation. Freshly oxygenated blood returns to the left atrium through four pulmonary veins, then passes through the mitral valve into the left ventricle.
The left ventricle (the strongest chamber) contracts powerfully to push blood through the aortic valve into the aorta, which distributes oxygen-rich blood throughout the body. The entire process - called the cardiac cycle - consists of diastole (filling) and systole (pumping).
Remember This: The heart's pumping action is controlled by electrical signals that begin in the sinoatrial node (the heart's natural pacemaker). A heart attack occurs when blood flow to part of the heart muscle is blocked, causing tissue death.
Atherosclerosis happens when fatty deposits (plaques) build up inside coronary arteries that supply the heart with oxygen and nutrients. These plaques can catch blood clots or directly block arteries, leading to a heart attack (myocardial infarction) where heart tissue dies from oxygen deprivation.
Another condition, arteriosclerosis, refers to hardening of the arteries. When arteries become stiff and don't stretch properly as blood passes through, blood pressure increases. Both conditions can develop due to genetics, high-fat diets, cholesterol levels, and lack of exercise.
Prevention and treatment options include lifestyle changes like improved diet and regular exercise. Medical interventions might include statin drugs to lower cholesterol, angioplasty to open blocked arteries, or coronary artery bypass grafting (CABG) where blood flow is rerouted around blocked vessels.
Health Tip: Regular exercise strengthens your heart muscle and helps keep your arteries flexible and clear - just 30 minutes of moderate activity most days can significantly reduce your risk of heart disease!
Your circulatory system has two main parts: systemic circulation that supplies the whole body and pulmonary circulation that carries blood between the heart and lungs. This network uses different types of vessels: arteries carry blood away from the heart, capillaries allow exchange with tissues, and veins return blood to the heart.
Arteries have smooth muscle walls controlled by your autonomic nervous system. They branch into smaller arterioles before reaching capillaries, where the real work happens. Capillaries have thin, semipermeable walls that allow chemical exchange between blood and surrounding tissues through filtration and diffusion.
Veins collect blood from capillaries via venules and contain one-way valves to prevent backflow as blood returns to the heart. Blood pressure - the force exerted on vessel walls - is measured as systolic (during heart contraction) and diastolic (between contractions). Your pulse is the rhythmic expansion and contraction of artery walls with each heartbeat.
Cool Connection: Your heart even has its own blood supply system! The coronary circulation provides oxygen and nutrients to the heart muscle itself through specialized coronary arteries - if these get blocked, that's when heart attacks happen.
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.
App 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
Mai
@maimeimi
The cardiovascular system is your body's transport network, delivering oxygen and nutrients while removing waste. It consists of the heart, blood vessels, and blood working together to keep every cell in your body alive and functioning. Understanding how this system... Show more
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Blood is made of two main components: solid blood cells (45%) and fluid plasma (55%). The solid part includes red blood cells (erythrocytes) that carry oxygen, white blood cells (leukocytes) that fight infection, and platelets (thrombocytes) that seal wounds.
Your blood type matters because different types have different proteins (antigens). You might be type A, B, AB, or O, plus either RH+ (85% of people) or RH- (15%). Type O is the universal donor while type AB is the universal receiver - mixing incompatible types can be dangerous!
The heart is a fist-sized, hollow muscle weighing about one pound, located in the chest's mediastinum. It has four chambers (two atria for receiving blood and two ventricles for pumping) and is protected by three tissue layers: the outer pericardium, the muscular myocardium, and the inner endocardium.
Fun Fact: Red blood cells have no nucleus and only live for about 6 weeks before being replaced. Your body constantly manufactures new blood cells in your bone marrow!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Blood flow through the heart follows a specific path. First, oxygen-poor blood enters the right atrium from the body through the superior and inferior vena cava. When the right atrium contracts, blood passes through the tricuspid valve into the right ventricle.
The right ventricle then pumps blood through the pulmonary valve into the pulmonary arteries, which carry blood to the lungs for oxygenation. Freshly oxygenated blood returns to the left atrium through four pulmonary veins, then passes through the mitral valve into the left ventricle.
The left ventricle (the strongest chamber) contracts powerfully to push blood through the aortic valve into the aorta, which distributes oxygen-rich blood throughout the body. The entire process - called the cardiac cycle - consists of diastole (filling) and systole (pumping).
Remember This: The heart's pumping action is controlled by electrical signals that begin in the sinoatrial node (the heart's natural pacemaker). A heart attack occurs when blood flow to part of the heart muscle is blocked, causing tissue death.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Atherosclerosis happens when fatty deposits (plaques) build up inside coronary arteries that supply the heart with oxygen and nutrients. These plaques can catch blood clots or directly block arteries, leading to a heart attack (myocardial infarction) where heart tissue dies from oxygen deprivation.
Another condition, arteriosclerosis, refers to hardening of the arteries. When arteries become stiff and don't stretch properly as blood passes through, blood pressure increases. Both conditions can develop due to genetics, high-fat diets, cholesterol levels, and lack of exercise.
Prevention and treatment options include lifestyle changes like improved diet and regular exercise. Medical interventions might include statin drugs to lower cholesterol, angioplasty to open blocked arteries, or coronary artery bypass grafting (CABG) where blood flow is rerouted around blocked vessels.
Health Tip: Regular exercise strengthens your heart muscle and helps keep your arteries flexible and clear - just 30 minutes of moderate activity most days can significantly reduce your risk of heart disease!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Your circulatory system has two main parts: systemic circulation that supplies the whole body and pulmonary circulation that carries blood between the heart and lungs. This network uses different types of vessels: arteries carry blood away from the heart, capillaries allow exchange with tissues, and veins return blood to the heart.
Arteries have smooth muscle walls controlled by your autonomic nervous system. They branch into smaller arterioles before reaching capillaries, where the real work happens. Capillaries have thin, semipermeable walls that allow chemical exchange between blood and surrounding tissues through filtration and diffusion.
Veins collect blood from capillaries via venules and contain one-way valves to prevent backflow as blood returns to the heart. Blood pressure - the force exerted on vessel walls - is measured as systolic (during heart contraction) and diastolic (between contractions). Your pulse is the rhythmic expansion and contraction of artery walls with each heartbeat.
Cool Connection: Your heart even has its own blood supply system! The coronary circulation provides oxygen and nutrients to the heart muscle itself through specialized coronary arteries - if these get blocked, that's when heart attacks happen.
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.
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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
Health
Algebra
Calculus 1
Algebra 1
Overige