The biological approach examines how our physical makeup shapes behaviour,... Show more
Psychology98 views·Updated May 24, 2026·3 pagesComprehensive Biological Approach Study Notes
annabelle @annabelle_styles
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Understanding Biological Behaviour
Your behaviour isn't just random - it all starts with biology. The biological approach assumes that everything we do has a physical cause, meaning our biological structure directly influences how we behave.
Scientists use twin studies to figure out what's inherited versus what's learned. Monozygotic twins (identical) share 100% of their genes, whilst dizygotic twins share about 50%. When researchers compare concordance rates between these twins, they can work out how much genetics influences specific traits.
Adoption studies offer another piece of the puzzle. By comparing adopted children to both their biological and adoptive parents, researchers can separate nature from nurture influences.
Your genotype is your complete set of genes, but your phenotype (what you actually look like and how you behave) equals your genotype plus your environment. Remember that dominant genes always show up, even with just one copy, whilst recessive genes need two copies to appear.
Key Point: Charles Darwin's theory of natural selection explains how behaviours that help survival and reproduction get passed down through generations, even if some traits become maladaptive in our modern environment due to genome lag.
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The Nervous System in Action
Your nervous system is basically your body's electrical wiring, split into two main parts. The CNS (brain and spinal cord) is mission control, whilst the peripheral nervous system carries messages back and forth.
The peripheral system has two branches you need to know. The somatic nervous system handles voluntary movements like raising your hand. The autonomic nervous system runs the automatic stuff you don't think about, like your heartbeat.
Within the autonomic system, sympathetic arousal kicks in during stress - speeding up your heart, dilating your pupils, and prepping you for action. Parasympathetic arousal does the opposite, slowing things down and helping you relax.
Neurons are the messenger cells that make it all work. Sensory neurons carry information from your senses to your brain, motor neurons control muscle movement, and relay neurons pass messages within the CNS. Synaptic transmission happens when neurotransmitters jump across the tiny gaps between neurons, either causing excitation (firing the next neuron) or inhibition (stopping the signal).
Key Point: Think of synaptic transmission like passing notes in class - the message jumps from one neuron to another across the synapse, but sometimes the message gets through and sometimes it doesn't.
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Hormones and the Fight-or-Flight Response
Your endocrine system is like your body's chemical messaging service. Hormones are powerful chemical messengers produced by glands that travel through your bloodstream to target specific organs.
When you face danger, your body launches the fight-or-flight response - an automatic survival mechanism that's been keeping humans alive for thousands of years. This isn't something you control; it's completely innate.
Here's how it works: your hypothalamus detects threat and activates the sympathetic branch of your nervous system. This triggers your adrenal glands to pump out adrenaline, which supercharges your body for action - faster heartbeat, sharper focus, and more energy.
The beauty of this system is its speed. Whilst your nervous system uses electrical signals for instant responses, your endocrine system provides the chemical backup that keeps you going during stressful situations.
Key Point: Your adrenal glands are your body's emergency broadcasters - when they release adrenaline, every cell with the right receptor gets the "danger alert" message instantly.
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Psychology98 views·Updated May 24, 2026·3 pagesComprehensive Biological Approach Study Notes
annabelle @annabelle_styles
The biological approach examines how our physical makeup shapes behaviour, exploring everything from our genes to our nervous system. It's the foundation for understanding why we act the way we do - from inherited traits to our body's automatic responses... Show more
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Understanding Biological Behaviour
Your behaviour isn't just random - it all starts with biology. The biological approach assumes that everything we do has a physical cause, meaning our biological structure directly influences how we behave.
Scientists use twin studies to figure out what's inherited versus what's learned. Monozygotic twins (identical) share 100% of their genes, whilst dizygotic twins share about 50%. When researchers compare concordance rates between these twins, they can work out how much genetics influences specific traits.
Adoption studies offer another piece of the puzzle. By comparing adopted children to both their biological and adoptive parents, researchers can separate nature from nurture influences.
Your genotype is your complete set of genes, but your phenotype (what you actually look like and how you behave) equals your genotype plus your environment. Remember that dominant genes always show up, even with just one copy, whilst recessive genes need two copies to appear.
Key Point: Charles Darwin's theory of natural selection explains how behaviours that help survival and reproduction get passed down through generations, even if some traits become maladaptive in our modern environment due to genome lag.
2
of 3Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
The Nervous System in Action
Your nervous system is basically your body's electrical wiring, split into two main parts. The CNS (brain and spinal cord) is mission control, whilst the peripheral nervous system carries messages back and forth.
The peripheral system has two branches you need to know. The somatic nervous system handles voluntary movements like raising your hand. The autonomic nervous system runs the automatic stuff you don't think about, like your heartbeat.
Within the autonomic system, sympathetic arousal kicks in during stress - speeding up your heart, dilating your pupils, and prepping you for action. Parasympathetic arousal does the opposite, slowing things down and helping you relax.
Neurons are the messenger cells that make it all work. Sensory neurons carry information from your senses to your brain, motor neurons control muscle movement, and relay neurons pass messages within the CNS. Synaptic transmission happens when neurotransmitters jump across the tiny gaps between neurons, either causing excitation (firing the next neuron) or inhibition (stopping the signal).
Key Point: Think of synaptic transmission like passing notes in class - the message jumps from one neuron to another across the synapse, but sometimes the message gets through and sometimes it doesn't.
3
of 3Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Hormones and the Fight-or-Flight Response
Your endocrine system is like your body's chemical messaging service. Hormones are powerful chemical messengers produced by glands that travel through your bloodstream to target specific organs.
When you face danger, your body launches the fight-or-flight response - an automatic survival mechanism that's been keeping humans alive for thousands of years. This isn't something you control; it's completely innate.
Here's how it works: your hypothalamus detects threat and activates the sympathetic branch of your nervous system. This triggers your adrenal glands to pump out adrenaline, which supercharges your body for action - faster heartbeat, sharper focus, and more energy.
The beauty of this system is its speed. Whilst your nervous system uses electrical signals for instant responses, your endocrine system provides the chemical backup that keeps you going during stressful situations.
Key Point: Your adrenal glands are your body's emergency broadcasters - when they release adrenaline, every cell with the right receptor gets the "danger alert" message instantly.
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.
Most popular content in Psychology
9Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google 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 SiOS 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 KlichAndroid 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.
AnnaiOS user