Blood is the vital fluid that supports life by transporting... Show more
Algebra
Calculus 1
Algebra 1
OverigeSign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
6
0
Drizzle Hinata
12/8/2025
AP Biology
Introduction to Blood
1 / 4
Blood: The Transport Medium
Blood is truly your body's lifeline, carrying oxygen from your lungs to tissues and carbon dioxide back to your lungs for removal. It delivers nutrients from digestion and hormones from glands to cells throughout your body. Blood also transports disease-fighting substances to tissues and carries waste products to your kidneys for elimination.
An average human has about 5 liters of blood with a slightly alkaline pH of 7.4. Blood is denser than water at 1.057 and consists of two main components: plasma (the liquid portion) and formed elements (cells and platelets).
Plasma makes up about 55% of your blood and is mostly water (90-92%). This watery base contains crucial plasma proteins (7-8%) like albumin, globulins, and fibrinogen that maintain blood pressure, transport substances, and aid in clotting. The remaining components include salts, ions, gases, nutrients, and waste products.
Did you know? When a blood sample sits in a test tube, it separates into three visible layers: plasma (top 55%), a thin "buffy coat" of white blood cells and platelets (less than 1%), and red blood cells at the bottom (45%).
Red Blood Cells: Oxygen Carriers
Red blood cells (erythrocytes) are the tiny workhorses of your blood, with about 25 trillion of them circulating through your body at any time. These small biconcave disks lack a nucleus at maturity, allowing them to pack in more hemoglobin - the protein responsible for carrying oxygen.
Each red blood cell contains about 250 million hemoglobin molecules. Hemoglobin consists of four protein chains, each with an iron-containing heme group that can loosely bind to oxygen. This structure makes hemoglobin perfect for picking up oxygen in your lungs and delivering it to your tissues.
Your red blood cells are manufactured in the red bone marrow found in your skull, ribs, vertebrae, and the ends of long bones. Before they're released into circulation, they synthesize hemoglobin and lose their nuclei. These cells have a limited lifespan of about 120 days before being broken down in your liver and spleen.
Important! If you don't have enough red blood cells or if they don't contain enough hemoglobin, you'll develop anemia, which can cause fatigue, weakness, and other symptoms due to reduced oxygen delivery to tissues.
Blood Types: A Matter of Antigens
Blood typing is crucial for safe transfusions because red blood cell membranes carry specific glycoproteins that act as antigens to blood recipients. An antigen is a molecule, usually a protein or carbohydrate, that can trigger an immune response if your body recognizes it as foreign.
The ABO system classifies blood based on the presence or absence of A and B antigens on red blood cells. There are four blood types: A (has A antigen), B (has B antigen), AB (has both), and O (has neither). Your plasma naturally contains antibodies against the antigens you don't have on your cells. For example, if you have type A blood, your plasma contains anti-B antibodies.
When mismatched blood types mix during a transfusion, agglutination (clumping of red blood cells) can occur, leading to a potentially fatal reaction. This is why understanding blood compatibility is essential for safe transfusions.
Fascinating fact: Your blood type antibodies develop naturally in the first few months of life due to exposure to similar antigens found on common microorganisms in your environment!
The Rh Factor and Pregnancy Concerns
The Rh factor is another important antigen (also called antigen D) found on red blood cells. About 85% of people in the United States are Rh positive , meaning they have this antigen, while 15% are Rh negative and lack it.
People with Rh- blood don't naturally have antibodies against the Rh factor. However, if they're exposed to Rh+ blood, their immune system may produce anti-Rh antibodies. This becomes especially important during pregnancy.
If an Rh- mother carries an Rh+ baby , and fetal blood crosses the placenta, the mother's immune system might produce anti-Rh antibodies. In this or subsequent pregnancies with another Rh+ baby, these maternal antibodies can cross the placenta and attack the baby's red blood cells, causing Hemolytic Disease of the Newborn (HDN).
Critical knowledge: HDN can be prevented with an injection of Rh immunoglobulin (RhIG) given to Rh- mothers during pregnancy and after delivery of an Rh+ baby. This prevents the mother's immune system from developing antibodies against the Rh factor.
We thought you’d never ask...
What is the Knowunity AI companion?
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.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content: Blood
Most popular content in AP Biology
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.9/5
App Store
4.8/5
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
Understanding Blood: Its Composition and Types
Blood is the vital fluid that supports life by transporting essential substances throughout your body. This remarkable transport medium carries oxygen, nutrients, hormones, and immune cells to tissues while removing waste products. Understanding blood composition and types helps explain how... Show more
Blood: The Transport Medium
Blood is truly your body's lifeline, carrying oxygen from your lungs to tissues and carbon dioxide back to your lungs for removal. It delivers nutrients from digestion and hormones from glands to cells throughout your body. Blood also transports disease-fighting substances to tissues and carries waste products to your kidneys for elimination.
An average human has about 5 liters of blood with a slightly alkaline pH of 7.4. Blood is denser than water at 1.057 and consists of two main components: plasma (the liquid portion) and formed elements (cells and platelets).
Plasma makes up about 55% of your blood and is mostly water (90-92%). This watery base contains crucial plasma proteins (7-8%) like albumin, globulins, and fibrinogen that maintain blood pressure, transport substances, and aid in clotting. The remaining components include salts, ions, gases, nutrients, and waste products.
Did you know? When a blood sample sits in a test tube, it separates into three visible layers: plasma (top 55%), a thin "buffy coat" of white blood cells and platelets (less than 1%), and red blood cells at the bottom (45%).
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Red Blood Cells: Oxygen Carriers
Red blood cells (erythrocytes) are the tiny workhorses of your blood, with about 25 trillion of them circulating through your body at any time. These small biconcave disks lack a nucleus at maturity, allowing them to pack in more hemoglobin - the protein responsible for carrying oxygen.
Each red blood cell contains about 250 million hemoglobin molecules. Hemoglobin consists of four protein chains, each with an iron-containing heme group that can loosely bind to oxygen. This structure makes hemoglobin perfect for picking up oxygen in your lungs and delivering it to your tissues.
Your red blood cells are manufactured in the red bone marrow found in your skull, ribs, vertebrae, and the ends of long bones. Before they're released into circulation, they synthesize hemoglobin and lose their nuclei. These cells have a limited lifespan of about 120 days before being broken down in your liver and spleen.
Important! If you don't have enough red blood cells or if they don't contain enough hemoglobin, you'll develop anemia, which can cause fatigue, weakness, and other symptoms due to reduced oxygen delivery to tissues.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Blood Types: A Matter of Antigens
Blood typing is crucial for safe transfusions because red blood cell membranes carry specific glycoproteins that act as antigens to blood recipients. An antigen is a molecule, usually a protein or carbohydrate, that can trigger an immune response if your body recognizes it as foreign.
The ABO system classifies blood based on the presence or absence of A and B antigens on red blood cells. There are four blood types: A (has A antigen), B (has B antigen), AB (has both), and O (has neither). Your plasma naturally contains antibodies against the antigens you don't have on your cells. For example, if you have type A blood, your plasma contains anti-B antibodies.
When mismatched blood types mix during a transfusion, agglutination (clumping of red blood cells) can occur, leading to a potentially fatal reaction. This is why understanding blood compatibility is essential for safe transfusions.
Fascinating fact: Your blood type antibodies develop naturally in the first few months of life due to exposure to similar antigens found on common microorganisms in your environment!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The Rh Factor and Pregnancy Concerns
The Rh factor is another important antigen (also called antigen D) found on red blood cells. About 85% of people in the United States are Rh positive , meaning they have this antigen, while 15% are Rh negative and lack it.
People with Rh- blood don't naturally have antibodies against the Rh factor. However, if they're exposed to Rh+ blood, their immune system may produce anti-Rh antibodies. This becomes especially important during pregnancy.
If an Rh- mother carries an Rh+ baby , and fetal blood crosses the placenta, the mother's immune system might produce anti-Rh antibodies. In this or subsequent pregnancies with another Rh+ baby, these maternal antibodies can cross the placenta and attack the baby's red blood cells, causing Hemolytic Disease of the Newborn (HDN).
Critical knowledge: HDN can be prevented with an injection of Rh immunoglobulin (RhIG) given to Rh- mothers during pregnancy and after delivery of an Rh+ baby. This prevents the mother's immune system from developing antibodies against the Rh factor.
We thought you’d never ask...
What is the Knowunity AI companion?
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.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
6
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Mock Exam
Quiz
Flashcards
Essay
Similar Content
Metabolism
Covers metabolism for AP Biology 6.1
AP BiologyCellular Respiration Stages
Overview of the key stages of cellular respiration, from glycolysis to oxidative phosphorylation, and the production of ATP.
AP Biology10th
Cellular Respiration worksheet
AP Bio, Cellular Respiration- An Overview
AP BiologyMetabolism Notes
A little study guide I made for my cellular respiration test in my bio class
AP BiologyThe Citric Acid Cycle
The citric acid cycle —also known as the Krebs cycle or the TCA cycle —is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.
AP BiologyCellular respiration, anaerobic and aerobic
Glycolysis , Krebs cycle, why mitochondria is the powerhouse of the cell, ATP synthase and phosphorylation, college general biology I
AP BiologyCollege
Most popular content: Blood
Most popular content in AP Biology
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.9/5
App Store
4.8/5
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