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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
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Britain: 1509 -1745
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Biology
4 Dec 2025
108
2 pages
Jess Drew @rj2105
Your nervous system is like your body's electrical wiring - it controls everything from blinking to breathing. Understanding... Show more
Think of your nervous system as your body's control centre - it's built from individual neurones, your brain, and your spine working together. There are three main types of neurones, and they're all specially adapted to carry electrical signals super quickly.
These neurones have brilliant adaptations the myelin sheath (like insulation on a wire), branched terminals for better connections, and long, thin shapes for efficient signal travel. Your nervous system splits into two parts the CNS (Central Nervous System) - your brain and spine - and the PNS (Peripheral Nervous System) - all your other nerves.
Here's how information flows Stimulus → Receptor Cell → Sensory Neurone → Relay Neurone + CNS → Motor Neurone → Effector → Response. Motor neurones carry signals away from your CNS to muscles (effectors), with their cell body at the dendrite end. Sensory neurones are different - their cell body sits in the middle of the axon, and they carry information from your senses towards your CNS.
Quick Tip Remember that sensory neurones sense things and send signals TO your brain, while motor neurones send messages FROM your brain to make muscles move!
Relay neurones only exist in your CNS and are absolutely crucial for reflexes - they're more rounded than other neurones and act like middlemen between sensory and motor neurones. But how do neurones actually "talk" to each other? That's where synapses come in.
When an electrical signal reaches the axon terminal, it triggers calcium channels to open. Here's the clever bit neurotransmitter-filled vesicles are already docked at the membrane using proteins. The calcium ions bind to these proteins, pulling the vesicles closer until the membranes merge and release neurotransmitters into the synaptic cleft.
Reflex arcs are your body's emergency response system. A stimulus hits receptor cells, travels via sensory neurones to your spinal cord, gets processed by relay neurones, then shoots back through motor neurones to effector muscles - all without your brain getting involved! This means you can pull your hand away from something hot before you've even consciously felt the pain.
Remember Reflexes bypass your brain completely - they're processed in your spinal cord, which is why they're so incredibly fast!
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.
3
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the mechanisms of reflex arcs and synaptic transmission in the human nervous system. This summary covers how sensory, relay, and motor neurones interact to produce fast, automatic responses to stimuli, highlighting the role of synapses and the importance of reflexes in injury prevention. Ideal for Biology students preparing for exams.
BiologyExplore the intricate workings of the nervous and endocrine systems in this comprehensive summary. Understand neuronal communication, reflex arcs, and hormonal regulation of blood glucose levels. Ideal for SQA National 5 Biology students, this resource covers neuron types, synapses, and the physiological responses to stimuli.
BiologyExplore the structure and function of neurones and synapses, including the role of dendrites, axons, myelin sheath, and neurotransmitters in nerve impulse transmission. Understand why reflex actions are faster than conscious responses due to fewer synapses involved. This summary provides essential insights for biology students studying the nervous system.
Biologybiology
BiologyExplore the structure and function of the central nervous system, including sensory and motor neurons, reflex arcs, and synaptic transmission. This summary covers key concepts such as neuronal communication, types of neurons, and the role of the nervous system in maintaining homeostasis.
BiologyExplore the structure and function of the human nervous system, including neurons, reflex arcs, and the adaptation of the eye. This summary covers key concepts such as neural transmission, synapses, and the anatomy of the eye, providing essential insights for AQA GCSE students.
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
Jess Drew
@rj2105
Your nervous system is like your body's electrical wiring - it controls everything from blinking to breathing. Understanding how neurones (nerve cells) work and communicate through synapses will help you grasp how your body responds to the world around you,... Show more
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Think of your nervous system as your body's control centre - it's built from individual neurones, your brain, and your spine working together. There are three main types of neurones, and they're all specially adapted to carry electrical signals super quickly.
These neurones have brilliant adaptations: the myelin sheath (like insulation on a wire), branched terminals for better connections, and long, thin shapes for efficient signal travel. Your nervous system splits into two parts: the CNS (Central Nervous System) - your brain and spine - and the PNS (Peripheral Nervous System) - all your other nerves.
Here's how information flows: Stimulus → Receptor Cell → Sensory Neurone → Relay Neurone + CNS → Motor Neurone → Effector → Response. Motor neurones carry signals away from your CNS to muscles (effectors), with their cell body at the dendrite end. Sensory neurones are different - their cell body sits in the middle of the axon, and they carry information from your senses towards your CNS.
Quick Tip: Remember that sensory neurones sense things and send signals TO your brain, while motor neurones send messages FROM your brain to make muscles move!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Relay neurones only exist in your CNS and are absolutely crucial for reflexes - they're more rounded than other neurones and act like middlemen between sensory and motor neurones. But how do neurones actually "talk" to each other? That's where synapses come in.
When an electrical signal reaches the axon terminal, it triggers calcium channels to open. Here's the clever bit: neurotransmitter-filled vesicles are already docked at the membrane using proteins. The calcium ions bind to these proteins, pulling the vesicles closer until the membranes merge and release neurotransmitters into the synaptic cleft.
Reflex arcs are your body's emergency response system. A stimulus hits receptor cells, travels via sensory neurones to your spinal cord, gets processed by relay neurones, then shoots back through motor neurones to effector muscles - all without your brain getting involved! This means you can pull your hand away from something hot before you've even consciously felt the pain.
Remember: Reflexes bypass your brain completely - they're processed in your spinal cord, which is why they're so incredibly fast!
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.
3
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the mechanisms of reflex arcs and synaptic transmission in the human nervous system. This summary covers how sensory, relay, and motor neurones interact to produce fast, automatic responses to stimuli, highlighting the role of synapses and the importance of reflexes in injury prevention. Ideal for Biology students preparing for exams.
BiologyExplore the intricate workings of the nervous and endocrine systems in this comprehensive summary. Understand neuronal communication, reflex arcs, and hormonal regulation of blood glucose levels. Ideal for SQA National 5 Biology students, this resource covers neuron types, synapses, and the physiological responses to stimuli.
BiologyExplore the structure and function of neurones and synapses, including the role of dendrites, axons, myelin sheath, and neurotransmitters in nerve impulse transmission. Understand why reflex actions are faster than conscious responses due to fewer synapses involved. This summary provides essential insights for biology students studying the nervous system.
Biologybiology
BiologyExplore the structure and function of the central nervous system, including sensory and motor neurons, reflex arcs, and synaptic transmission. This summary covers key concepts such as neuronal communication, types of neurons, and the role of the nervous system in maintaining homeostasis.
BiologyExplore the structure and function of the human nervous system, including neurons, reflex arcs, and the adaptation of the eye. This summary covers key concepts such as neural transmission, synapses, and the anatomy of the eye, providing essential insights for AQA GCSE students.
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