Welcome to Topic C: Biological Psychology!

Hello future psychologists! This is one of the most exciting and fundamental areas of study. Biological psychology, often called biopsychology, looks at how your biological makeup – your genes, your brain structure, and your nervous system – influences your behaviour, thoughts, and emotions.

If you sometimes find this topic challenging, don't worry! We will break down the 'hardware' (the body) and the 'software' (the thoughts) into simple, manageable pieces using analogies you already know. By the end of this section, you'll understand why you react the way you do when stressed, and how your genetics play a role in shaping your personality.

Section 1: The Blueprint – Genetics and Evolution

Every single one of your traits, from your eye colour to your temperament, is influenced by the instructions contained within your genes. This section explores how we inherit these instructions and how they developed over millions of years.

1.1 Genotype, Phenotype, and Heritability

When studying genetics in psychology, we need to understand the difference between the instructions you carry and the traits you actually express.

  • Genotype: This is your complete, unique genetic make-up; the potential you inherited from your parents. Think of the Genotype as the full recipe book you own.

  • Phenotype: This is the observable characteristics of an individual, which result from the interaction between your genotype and your environment. Think of the Phenotype as the actual cake that gets baked – the recipe (genotype) is followed, but the final result is affected by factors like the oven temperature or altitude (environment).

Heritability is a measure of how much variation of a trait in a population is due to genetic factors. For example, if intelligence has a high heritability, it means that genetic differences explain a large proportion of the differences in IQ scores among people.

1.2 The Evolutionary Basis of Behaviour

The evolutionary approach suggests that many behaviours we see today developed because they helped our ancestors survive and reproduce. This process is called Natural Selection.

Step-by-Step: How Natural Selection Works

  1. Variation: Individuals in a species are all slightly different (e.g., some are faster runners, some are better problem-solvers).
  2. Inheritance: These advantageous traits are passed down genetically to offspring.
  3. Survival Advantage: In the environment, individuals with the advantageous traits are more likely to survive challenges (like predators or limited food).
  4. Reproduction: Because they survive, they live long enough to reproduce and pass on those useful genes.

Example: Early humans who developed attachment behaviours (caring for their young) were more likely to have offspring who survived, meaning the genes for attachment were 'selected' and passed down through generations.

Key Takeaway: We are complex products of both our inherited genetic code (Genotype) and the environments we grow up in (shaping the Phenotype). Our most basic behaviours exist because they offered a survival advantage.

Section 2: The Command Centre – The Nervous System

The nervous system is the body’s speedy, electrochemical communication network. It controls everything you do, from breathing to solving complex physics problems.

2.1 Divisions of the Nervous System (CNS vs. PNS)

Imagine the nervous system is a national railway network:

  • The Central Nervous System (CNS): This is the 'main hub' or the control room. It consists of the Brain and the Spinal Cord. It processes information and makes decisions.

  • The Peripheral Nervous System (PNS): This is the network of tracks and local lines that carries messages to and from the CNS. It connects the CNS to the rest of the body (muscles, organs, glands).

The PNS is further divided:

  • Somatic Nervous System (SNS): Controls voluntary movements (like kicking a football). Think of 'Soma' as 'body' – you control your body movements.

  • Autonomic Nervous System (ANS): Controls involuntary life functions (like heartbeat, breathing, digestion). This happens automatically, without you thinking about it.

2.2 The Autonomic Nervous System: Fight or Flight

The ANS is crucial for responding to threats. It has two opposing sub-systems:

1. Sympathetic Nervous System (SNS - Activation)

This is the body’s emergency response. When you perceive danger, the Sympathetic system speeds things up to prepare you to Fight or take Flight (run away).

  • Heart rate increases.
  • Breathing rate increases.
  • Digestion slows down (no time for food!).
  • Adrenaline is released.

Memory Tip: Sympathetic = Stress/Speed up.

2. Parasympathetic Nervous System (PNS - Deactivation)

This is the 'rest and digest' system. Once the threat is over, the Parasympathetic system works to calm the body down and conserve energy.

  • Heart rate decreases.
  • Digestion restarts.
  • Muscle tension decreases.

Memory Tip: Parasympathetic = Peace/Pause.

Key Takeaway: The CNS makes the big decisions, while the PNS carries the messages. The Sympathetic and Parasympathetic systems work in opposition to manage the body’s emergency and resting states.

Section 3: Biological Communication – Neurons and Synaptic Transmission

Messages within the nervous system travel via specialised cells called Neurons (nerve cells). Neurons communicate chemically across tiny gaps.

3.1 The Structure of a Neuron

A neuron has three main parts:

  1. Dendrites: Receive incoming electrical signals from other neurons. (Like the antennae of a radio).
  2. Axon: A long fibre that carries the electrical impulse away from the cell body towards the end of the neuron. (Like the main cable wire).
  3. Myelin Sheath: A fatty layer that protects the axon and speeds up the electrical transmission. (Like the plastic insulation around a wire).
  4. Axon Terminals/Terminal Buttons: Found at the end of the axon, these release chemical messengers.
3.2 Synaptic Transmission (The Chemical Handshake)

Neurons don't actually touch. They are separated by a tiny gap called the Synapse.

Step-by-Step: The Synaptic Process

  1. An electrical impulse (called the action potential) reaches the end of the pre-synaptic neuron (the one sending the message).
  2. This triggers the release of tiny chemical messengers called Neurotransmitters (e.g., serotonin, dopamine) from the terminal buttons into the synaptic gap.
  3. The neurotransmitters diffuse across the gap and bind to specific receptor sites on the post-synaptic neuron (the one receiving the message).
  4. If enough neurotransmitter is absorbed, it triggers a new electrical impulse in the post-synaptic neuron, and the message continues.
  5. The remaining neurotransmitter is either broken down or reabsorbed by the sending neuron (reuptake) to clear the space for the next message.

Did you know? Different neurotransmitters have different effects. Serotonin is often linked to mood and sleep, while Dopamine is linked to reward, motivation, and motor control.

Key Takeaway: Neurons transmit signals electrically along the axon, but they communicate with each other chemically across the synapse using neurotransmitters.

Section 4: The Brain – Structure and Localisation of Function

The brain is arguably the most complex organ in the universe. Psychology is focused on the idea of localisation of function: the belief that specific parts of the brain are responsible for specific behaviours.

4.1 The Cerebral Cortex and Hemispheric Lateralisation

The brain is divided into two halves, the Cerebral Hemispheres (left and right), which are covered by the wrinkled outer layer called the Cerebral Cortex.

Hemispheric Lateralisation: The idea that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other.

  • The Left Hemisphere controls the right side of the body and is generally associated with language, logic, and analytical tasks.
  • The Right Hemisphere controls the left side of the body and is generally associated with creativity, spatial reasoning, and visual-motor tasks.
4.2 The Four Lobes of the Cortex

Each hemisphere is divided into four main lobes, each specialised for different tasks:

1. Frontal Lobe (The Planner)
Associated with higher-level thinking, decision-making, personality, planning, and speaking.

2. Parietal Lobe (The Sensor)
Processes sensory information like touch, temperature, pain, and spatial awareness.

3. Temporal Lobe (The Listener)
Associated with hearing, memory, and understanding language.

4. Occipital Lobe (The Viewer)
Dedicated almost exclusively to processing visual information.

Mnemonic: Think of a person trying to keep their eyes, touch, thinking, and hearing straight. Over Planet France Tonight.

4.3 Key Language Centres (Broca’s and Wernicke’s Areas)

These are classic examples of strict localisation:

  • Broca’s Area: Located in the posterior part of the frontal lobe (usually left hemisphere). Responsible for speech production (forming the words). Damage here leads to Broca's aphasia – difficulty speaking fluently, though comprehension remains good.

  • Wernicke’s Area: Located in the posterior part of the temporal lobe (usually left hemisphere). Responsible for speech comprehension (understanding language). Damage here leads to Wernicke's aphasia – ability to speak fluently, but the speech is meaningless, and comprehension is severely impaired.

Quick Review Box: Common Confusion
It helps to remember the functions by the sounds: Broca = Blow out the words (Production). Wernicke = Words and Wondering (Comprehension).

Key Takeaway: The brain demonstrates strict localisation, meaning damage to a specific area (like Broca's) causes a predictable loss of function (like speech production).

Section 5: Slow Communication – The Endocrine System

While the nervous system communicates quickly via electrical impulses, the Endocrine System communicates slowly but powerfully using chemical messengers called Hormones, which travel through the bloodstream.

5.1 Glands and Hormones

The Endocrine System is made up of various glands across the body. The main control centre is the Pituitary Gland (often called the 'Master Gland') in the brain, which regulates the release of hormones from other glands.

Hormones affect target organs by stimulating them into action. This system is essential for regulating mood, metabolism, sleep, and our stress response.

5.2 Example: The Stress Response (Adrenaline)

The Adrenal Glands (located above the kidneys) are crucial for the stress response.

  1. When a threat is perceived, the CNS signals the Adrenal Medulla.
  2. The Adrenal Medulla releases the hormone Adrenaline into the bloodstream.
  3. Adrenaline travels quickly around the body, causing the immediate physical changes associated with the fight or flight response (increased heart rate, oxygen flow to muscles, etc.).

This shows how the nervous system (quick response) and the endocrine system (sustaining the response chemically) work together.

Key Takeaway: The Endocrine system uses slower, blood-borne chemical signals (hormones) to regulate long-term processes, often working alongside the faster nervous system to manage key biological functions.