Subjects
Maths
Chemistry
Biology
English Language
History
Responding to change (a2 only)
Infection and response
Homeostasis and response
Energy transfers (a2 only)
Cell biology
Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
Organisation
Substance exchange
Bioenergetics
Genetic information & variation
Inheritance, variation and evolution
Genetics & ecosystems (a2 only)
Ecology
Cells
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Britain & the wider world: 1745 -1901
1l the quest for political stability: germany, 1871-1991
The cold war
Inter-war germany
Medieval period: 1066 -1509
2d religious conflict and the church in england, c1529-c1570
2o democracy and nazism: germany, 1918-1945
1f industrialisation and the people: britain, c1783-1885
1c the tudors: england, 1485-1603
2m wars and welfare: britain in transition, 1906-1957
World war two & the holocaust
2n revolution and dictatorship: russia, 1917-1953
2s the making of modern britain, 1951-2007
World war one
Britain: 1509 -1745
Show all topics
Biology
30 Nov 2025
240
2 pages
Demetra @demetra_21
Your nervous system is basically your body's electrical wiring - it's how your brain communicates with every part... Show more
Think of your nervous system as having two main parts that work together like a computer network. The peripheral nervous system (PNS) acts like sensors, picking up information from the outside world through touch, sight, and other senses, then sending electrical signals to your brain.
The central nervous system (CNS) is where all the processing happens - it's made up of your brain and spinal cord. Your brain is the control centre that makes sense of all incoming information and decides what to do about it. Meanwhile, your spinal cord works like a major motorway, carrying messages between your brain and the rest of your body.
Neurons are the specialist cells that make this whole system work. These nerve cells are incredible - each one can communicate with about 1000 other neurons at once, creating massive networks of information. About 80% of your neurons are packed into your brain, especially in the cerebral cortex (the wrinkly outer layer you see in pictures).
Quick Fact Neurons come in wildly different sizes - some are tiny at less than 1mm, whilst others stretch up to 1 metre long!
There are three types of neurons you need to know sensory neurons carry messages from your senses to your CNS, motor neurons carry commands from your CNS to your muscles and glands, and relay neurons connect everything together within your CNS.
Each neuron is designed like a tiny electrical circuit with specific parts that have important jobs. The cell body (soma) contains the nucleus and keeps the whole cell alive and functioning - think of it as the neuron's headquarters.
Dendrites are like the neuron's receivers - they're covered in connection points called synapses that pick up electrical signals from other neurons. Once a signal is received, it travels along the axon, which is like the neuron's electrical cable, carrying the impulse away from the cell body towards other neurons.
The myelin sheath is brilliant - it's a fatty, protein-rich coating that wraps around the axon like insulation around electrical wire. This speeds up nerve impulses dramatically. The nodes of Ranvier are strategic gaps in this coating that force electrical impulses to jump from gap to gap, making transmission even faster.
Remember The myelin sheath is produced by Schwann cells, which basically act as the maintenance crew for your neurons.
This whole structure works together to ensure your nervous system can send messages at incredible speeds - that's how you can pull your hand away from something hot before you've even consciously registered the pain!
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
2
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the essential concepts of carbohydrates, including definitions, classifications (monosaccharides, disaccharides, polysaccharides), and key reactions such as glycosidic bond formation. This summary covers important examples like glucose, maltose, and sucrose, along with tests for reducing and non-reducing sugars. Ideal for AQA A-level Biology students.
BiologyExplore the fundamental concepts of human cell biology, including cell division, DNA structure and replication, gene expression, and metabolic pathways. This comprehensive summary covers key topics such as mitosis, meiosis, mutations, and cellular respiration, providing essential insights for Higher Human Biology students. Ideal for exam preparation and understanding cellular processes.
BiologyExplore the structure and function of neurons, synapses, and reflex arcs in the nervous system. This summary covers key concepts such as neural transmission, types of neurons, and the role of the nervous system in homeostasis. Ideal for Edexcel Biology students preparing for exams.
BiologyExplore key concepts in neurobiology and immunology, including immune responses, synaptic transmission, the effects of recreational drugs like cocaine and cannabis, and models of memory. This comprehensive overview covers the human nervous system, biological defenses, and the role of neurotransmitters, providing essential knowledge for higher human biology studies.
BiologyExplore the stages of photosynthesis, including light-dependent reactions and the Calvin cycle. This summary provides a detailed diagram of chloroplasts, the role of chlorophyll, and the conversion of light energy into chemical energy. Understand the factors affecting photosynthesis and the production of glucose and oxygen. Ideal for students studying biology and plant processes.
BiologyExplore the key concepts of neuronal communication, including synaptic transmission, neuron structure, and the mechanisms of action potentials. This summary provides a clear overview of how sensory receptors and neurons interact to transmit signals within the nervous system, ideal for A Level Biology students. Understand the processes of depolarization, repolarization, and the role of myelin in nerve impulse conduction.
BiologyApp 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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Demetra
@demetra_21
Your nervous system is basically your body's electrical wiring - it's how your brain communicates with every part of your body in milliseconds. Understanding how neurons work and how they're organised will help you grasp everything from reflexes to complex... Show more
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Think of your nervous system as having two main parts that work together like a computer network. The peripheral nervous system (PNS) acts like sensors, picking up information from the outside world through touch, sight, and other senses, then sending electrical signals to your brain.
The central nervous system (CNS) is where all the processing happens - it's made up of your brain and spinal cord. Your brain is the control centre that makes sense of all incoming information and decides what to do about it. Meanwhile, your spinal cord works like a major motorway, carrying messages between your brain and the rest of your body.
Neurons are the specialist cells that make this whole system work. These nerve cells are incredible - each one can communicate with about 1000 other neurons at once, creating massive networks of information. About 80% of your neurons are packed into your brain, especially in the cerebral cortex (the wrinkly outer layer you see in pictures).
Quick Fact: Neurons come in wildly different sizes - some are tiny at less than 1mm, whilst others stretch up to 1 metre long!
There are three types of neurons you need to know: sensory neurons carry messages from your senses to your CNS, motor neurons carry commands from your CNS to your muscles and glands, and relay neurons connect everything together within your CNS.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Each neuron is designed like a tiny electrical circuit with specific parts that have important jobs. The cell body (soma) contains the nucleus and keeps the whole cell alive and functioning - think of it as the neuron's headquarters.
Dendrites are like the neuron's receivers - they're covered in connection points called synapses that pick up electrical signals from other neurons. Once a signal is received, it travels along the axon, which is like the neuron's electrical cable, carrying the impulse away from the cell body towards other neurons.
The myelin sheath is brilliant - it's a fatty, protein-rich coating that wraps around the axon like insulation around electrical wire. This speeds up nerve impulses dramatically. The nodes of Ranvier are strategic gaps in this coating that force electrical impulses to jump from gap to gap, making transmission even faster.
Remember: The myelin sheath is produced by Schwann cells, which basically act as the maintenance crew for your neurons.
This whole structure works together to ensure your nervous system can send messages at incredible speeds - that's how you can pull your hand away from something hot before you've even consciously registered the pain!
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
2
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the essential concepts of carbohydrates, including definitions, classifications (monosaccharides, disaccharides, polysaccharides), and key reactions such as glycosidic bond formation. This summary covers important examples like glucose, maltose, and sucrose, along with tests for reducing and non-reducing sugars. Ideal for AQA A-level Biology students.
BiologyExplore the fundamental concepts of human cell biology, including cell division, DNA structure and replication, gene expression, and metabolic pathways. This comprehensive summary covers key topics such as mitosis, meiosis, mutations, and cellular respiration, providing essential insights for Higher Human Biology students. Ideal for exam preparation and understanding cellular processes.
BiologyExplore the structure and function of neurons, synapses, and reflex arcs in the nervous system. This summary covers key concepts such as neural transmission, types of neurons, and the role of the nervous system in homeostasis. Ideal for Edexcel Biology students preparing for exams.
BiologyExplore key concepts in neurobiology and immunology, including immune responses, synaptic transmission, the effects of recreational drugs like cocaine and cannabis, and models of memory. This comprehensive overview covers the human nervous system, biological defenses, and the role of neurotransmitters, providing essential knowledge for higher human biology studies.
BiologyExplore the stages of photosynthesis, including light-dependent reactions and the Calvin cycle. This summary provides a detailed diagram of chloroplasts, the role of chlorophyll, and the conversion of light energy into chemical energy. Understand the factors affecting photosynthesis and the production of glucose and oxygen. Ideal for students studying biology and plant processes.
BiologyExplore the key concepts of neuronal communication, including synaptic transmission, neuron structure, and the mechanisms of action potentials. This summary provides a clear overview of how sensory receptors and neurons interact to transmit signals within the nervous system, ideal for A Level Biology students. Understand the processes of depolarization, repolarization, and the role of myelin in nerve impulse conduction.
BiologyApp 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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Sociology