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Hannah Murdoch
25/07/2025
Biology
higher human biology - key area 2.6 ( structure and function of the heart)
371
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25 Jul 2025
•
Higher Human Biology Key Area 2.6 - Heart Structure & Function (SQA Notes PDF)
The Heart's Conduction System
The heart's conduction system is responsible for initiating and coordinating the heartbeat. This intricate system ensures the heart functions efficiently and rhythmically.
Components of the Conduction System
The conduction system consists of specialized cardiac muscle cells that generate and transmit electrical impulses throughout the heart.
Highlight: The sino-atrial node , located in the right atrium wall, is known as the heart's natural pacemaker, initiating each heartbeat.
The main components of the conduction system include:
- Sino-atrial node
- Atrio-ventricular node
- Bundle of His
- Left and right bundle branches
- Purkinje fibers
Vocabulary: Auto-rhythmic cells are specialized cardiac cells capable of generating their own electrical impulses.
The electrical activity of the heart can be measured and recorded using an electrocardiogram .
Example: On an ECG, the P wave represents atrial depolarization, the QRS complex represents ventricular depolarization, and the T wave represents ventricular repolarization.
Nervous System Control of Heart Rate
The autonomic nervous system plays a crucial role in regulating heart rate through its sympathetic and parasympathetic branches.
Definition: The medulla oblongata is the part of the brain stem that controls involuntary functions, including heart rate.
- Sympathetic stimulation increases heart rate through the release of noradrenaline.
- Parasympathetic stimulation decreases heart rate through the release of acetylcholine.
Highlight: During stress, the sympathetic nervous system activates the adrenal glands to release adrenaline, further increasing heart rate.
Blood Pressure and Its Measurement
Blood pressure is a critical indicator of cardiovascular health and is influenced by the cardiac cycle.
Blood Pressure Fluctuations
Blood pressure varies throughout the cardiac cycle:
- It increases during ventricular systole
- It decreases during diastole
Measuring Blood Pressure
Blood pressure is typically measured using a sphygmomanometer, which consists of an inflatable cuff and a pressure gauge.
Example: A typical healthy blood pressure reading is expressed as 120/80 mmHg, where 120 represents systolic pressure and 80 represents diastolic pressure.
The measurement process involves:
- Inflating the cuff to stop blood flow in the artery
- Gradually deflating the cuff
- Listening for the onset of blood flow
- Noting when blood flows freely
Highlight: High blood pressure is a significant risk factor for various cardiovascular diseases, including coronary heart disease.
Understanding blood pressure and its measurement is crucial for assessing cardiovascular health and identifying potential risks.
The Structure and Function of the Heart
The heart is a vital organ responsible for pumping blood throughout the body. This section covers the cardiac cycle, cardiac output calculation, and the heart's conduction system.
Cardiac Cycle and Output
The cardiac cycle consists of several phases, including atrial and ventricular systole and diastole. Cardiac output is a crucial measure of heart function, calculated by multiplying heart rate and stroke volume.
Definition: Cardiac output is the volume of blood pumped through each ventricle per minute.
Highlight: The cardiac cycle involves the coordinated opening and closing of heart valves, resulting in the characteristic heartbeat sounds heard with a stethoscope.
The cycle can be broken down into three main phases:
- Atrial systole: Atria contract, pushing blood into ventricles.
- Ventricular systole: Ventricles contract, ejecting blood from the heart.
- Ventricular diastole: Ventricles relax and fill with blood.
Example: To calculate cardiac output, if the heart rate is 70 beats per minute and the stroke volume is 70 mL, the cardiac output would be 70 x 70 = 4900 mL/min or 4.9 L/min.
Vocabulary: Stroke volume is the amount of blood ejected from a ventricle during one heartbeat.
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Samantha Klich
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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
Higher Human Biology Key Area 2.6 - Heart Structure & Function (SQA Notes PDF)
The cardiac cycleis a crucial process in the human body, involving the rhythmic contraction and relaxation of the heart chambers to pump blood throughout the body. This summary explores the structure and function of the heart, cardiac output calculation,... Show more
The Heart's Conduction System
The heart's conduction system is responsible for initiating and coordinating the heartbeat. This intricate system ensures the heart functions efficiently and rhythmically.
Components of the Conduction System
The conduction system consists of specialized cardiac muscle cells that generate and transmit electrical impulses throughout the heart.
Highlight: The sino-atrial node , located in the right atrium wall, is known as the heart's natural pacemaker, initiating each heartbeat.
The main components of the conduction system include:
- Sino-atrial node
- Atrio-ventricular node
- Bundle of His
- Left and right bundle branches
- Purkinje fibers
Vocabulary: Auto-rhythmic cells are specialized cardiac cells capable of generating their own electrical impulses.
The electrical activity of the heart can be measured and recorded using an electrocardiogram .
Example: On an ECG, the P wave represents atrial depolarization, the QRS complex represents ventricular depolarization, and the T wave represents ventricular repolarization.
Nervous System Control of Heart Rate
The autonomic nervous system plays a crucial role in regulating heart rate through its sympathetic and parasympathetic branches.
Definition: The medulla oblongata is the part of the brain stem that controls involuntary functions, including heart rate.
- Sympathetic stimulation increases heart rate through the release of noradrenaline.
- Parasympathetic stimulation decreases heart rate through the release of acetylcholine.
Highlight: During stress, the sympathetic nervous system activates the adrenal glands to release adrenaline, further increasing heart rate.
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Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Blood Pressure and Its Measurement
Blood pressure is a critical indicator of cardiovascular health and is influenced by the cardiac cycle.
Blood Pressure Fluctuations
Blood pressure varies throughout the cardiac cycle:
- It increases during ventricular systole
- It decreases during diastole
Measuring Blood Pressure
Blood pressure is typically measured using a sphygmomanometer, which consists of an inflatable cuff and a pressure gauge.
Example: A typical healthy blood pressure reading is expressed as 120/80 mmHg, where 120 represents systolic pressure and 80 represents diastolic pressure.
The measurement process involves:
- Inflating the cuff to stop blood flow in the artery
- Gradually deflating the cuff
- Listening for the onset of blood flow
- Noting when blood flows freely
Highlight: High blood pressure is a significant risk factor for various cardiovascular diseases, including coronary heart disease.
Understanding blood pressure and its measurement is crucial for assessing cardiovascular health and identifying potential risks.
The Structure and Function of the Heart
The heart is a vital organ responsible for pumping blood throughout the body. This section covers the cardiac cycle, cardiac output calculation, and the heart's conduction system.
Cardiac Cycle and Output
The cardiac cycle consists of several phases, including atrial and ventricular systole and diastole. Cardiac output is a crucial measure of heart function, calculated by multiplying heart rate and stroke volume.
Definition: Cardiac output is the volume of blood pumped through each ventricle per minute.
Highlight: The cardiac cycle involves the coordinated opening and closing of heart valves, resulting in the characteristic heartbeat sounds heard with a stethoscope.
The cycle can be broken down into three main phases:
- Atrial systole: Atria contract, pushing blood into ventricles.
- Ventricular systole: Ventricles contract, ejecting blood from the heart.
- Ventricular diastole: Ventricles relax and fill with blood.
Example: To calculate cardiac output, if the heart rate is 70 beats per minute and the stroke volume is 70 mL, the cardiac output would be 70 x 70 = 4900 mL/min or 4.9 L/min.
Vocabulary: Stroke volume is the amount of blood ejected from a ventricle during one heartbeat.
We thought you’d never ask...
What is the Knowunity AI companion?
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.
Where can I download the Knowunity app?
You can download the app from Google Play Store and 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.
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
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