# Human Brain and Nervous System

- Link: https://psychologyforeveryone.com/chapter/3-human-brain-and-nervous-system/
- Published: 2026-10-24T07:45:03+00:00
- Author: myadvisorfriend@gmail.com

![(Illustration created with AI tools.)](/wp-content/uploads/pfe-book/image10.webp)

## 3.1 Overview

The brain and nervous system control thinking, emotions, memory,
 movement, senses,
hormones, and automatic body functions like breathing and heartbeat. Understanding
brain structure helps us understand mental health.

#### In more depth

This is why a new temper after a head injury is not only ‘attitude,’
 and why a 
first week of no sleep is not only ‘stress.’ The organ that thinks can be tired,
inflamed, concussed, or starved of thyroid hormone. Mental wellbeing lives in this
wiring. It is not only a story.

## 3.2 Major brain regions

![Figure 3.1 Three regions you will meet often: thinking brain, alarm and memory.(
Illustration created with AI tools.)](/wp-content/uploads/pfe-book/image11.webp)

**Figure 3.1** _Three regions you will meet often:
 thinking brain, alarm and memory.

![Figure 3.2 The lobes of the brain and what each is mainly responsible for. (Illustration
created with AI tools.)](/wp-content/uploads/pfe-book/image12.webp)

**Figure 3.2** _The lobes of the brain and what each
 is mainly responsible for.

### Frontal lobe (front of brain)

 * Planning and organisation.
 * Decision-making.
 * Self-control and impulse control.
 * Personality expression.
 * Speech production (Broca’s area).
 * Problem-solving.
 * Judgment.

working memory and social judgement.

Clinic note. Damage or exhaustion here looks like poor planning,
 blunt speech, 
or a person who cannot stop a harmful impulse. That can be injury, mania, substance
use, or sleep loss — not always ‘bad character.’

### Parietal lobe (top-middle of⏎  brain)

 * Touch sensation.
 * Spatial awareness.
 * Body position (proprioception).
 * Navigation and movement coordination.
 * Processing sensory information.

spatial attention.

### Temporal lobe (sides of⏎  brain, near ears)

 * Hearing and auditory processing.
 * Memory formation and retrieval.
 * Language comprehension (Wernicke’s area).
 * Emotion processing.
 * Face recognition.

The temporal lobe also helps us recognise objects and faces. A person
 who suddenly
cannot name familiar faces needs a medical door, not a motivation speech.

### Occipital lobe (back of⏎  brain)

 * Vision and visual processing.
 * Color recognition.
 * Object recognition.
 * Visual memory.

### Limbic system (deep inside⏎  brain)

 * Emotions (fear, anger, pleasure).
 * Memory formation (hippocampus).
 * Motivation and reward (amygdala, nucleus accumbens).
 * Survival behaviours.
 * Emotional memories.

The pieces are separate: hippocampus — new episodic memories and
 spatial maps; 
amygdala — salience and threat, emotional memory.

Clinic note. Trauma and panic use this neighbourhood heavily. The
 alarm can fire
after the danger has gone. Therapy and, when needed, medicine work here as well 
as in the frontal lobe that tries to talk the alarm down.

### Cerebellum (back-bottom of⏎  brain)

 * Balance and coordination.
 * Fine motor control.
 * Motor learning.
 * Some cognitive functions.

timing and coordination.

### Brainstem (base⏎  of brain, connects to spinal cord)

 * Breathing control.
 * Heart rate regulation.
 * Sleep-wake cycles.
 * Consciousness.
 * Vital automatic functions.

The brainstem keeps the basics running: breathing, heart rate and
 alertness. This
is the landlord who does not negotiate. If consciousness or breathing is failing,
this is casualty, not counselling.

## 3.3 The nervous system

![Figure 3.3 How the nervous system is organised. (Illustration created with AI 
tools.)](/wp-content/uploads/pfe-book/image13.webp)

**Figure 3.3** _How the nervous system is
 organised.

### Central nervous system (CNS)

 * Brain.
 * Spinal cord.
 * Processes and coordinates information.

### Peripheral nervous system⏎  (PNS)

 * Nerves throughout the body.
 * Carries information to and from the CNS.
 * Two divisions:
 * Somatic nervous system: voluntary movements.
 * Autonomic nervous system: automatic functions.

In short, the central nervous system is the brain and spinal cord.
 Everything else
is peripheral. Somatic nerves move the limbs you can point to. Autonomic nerves 
run the interior.

### Autonomic nervous system:⏎  two branches

#### Sympathetic nervous⏎  system (fight-or-flight)

 * Activates during stress or danger.
 * Increases heart rate.
 * Dilates pupils.
 * Redirects blood to muscles.
 * Prepares body for action.

#### Parasympathetic⏎  nervous system (rest-and-digest)

 * Activates during rest.
 * Slows heart rate.
 * Promotes digestion.
 * Supports healing and recovery.
 * Conserves energy.

The two branches work as a balance, not a light switch. The
 hypothalamus sits on
the border of neural and hormonal control and aims the pituitary at the rest of 
the endocrine system — including the HPA stress axis and cortisol.

Clinic note. Anxiety often feels like a sympathetic system that will
 not stand 
down. Depression and exhaustion often feel like a system that will not stand up.

## 3.4 Brain plasticity

Neuroplasticity is the brain’s ability to change and adapt throughout
 life. This
means:

 * New neural connections can form.
 * The brain can recover from injury.
 * Learning changes brain structure.
 * Therapy can rewire thought patterns.
 * Habits can be changed with practice.

This is why treatment, therapy, and lifestyle changes can improve
 mental health.

#### In more depth

The brain can change, but it takes time and practice. Sleep,
 movement, practice,
and sometimes medicine are how maps are redrawn. A stroke rehab plan and a CBT homework
sheet are both plasticity projects.

## 3.5 Messengers

A neuron receives on dendrites, sums in the soma, and sends an
 all-or-none action
potential down the axon. At the synapse, chemicals speak. No single chemical is 
a mood.

![Figure 3.4 A neuron and its synapse. (Illustration created with AI tools.)](/wp-
content/uploads/pfe-book/image14.webp)

**Figure 3.4** _A neuron and its synapse._

 * > Neuron structure: dendrites, soma, axon, synapse.
 * Action potential.
 * Glutamate (excitatory).
 * GABA (inhibitory).
 * Acetylcholine (movement, attention, memory).
 * Dopamine (movement, motivation, reward).
 * Serotonin (mood, sleep, appetite, impulse).
 * Norepinephrine (arousal, vigilance).

They are listed here because they belong with the living brain.

## 3.6 Taking care of your brain

You can look after your brain with ordinary, free habits:

 1.  **Move.** Regular physical activity increases blood
      flow, supports new connections,
     and lifts mood.
 2.  **Sleep.** Keep regular hours and protect your
      sleep.
 3.  **Eat well.** Fruits, vegetables, whole grains, nuts,
      fish, and plenty of water
     support brain health.
 4.  **Stay mentally active.** Reading, puzzles, learning new
      skills, and conversation
     keep the brain flexible.
 5.  **Stay connected.** Social contact is good for the brain
      at every age.
 6.  **Manage stress.** Relaxation, hobbies, and breaks lower
      the load.
 7.  **Protect your head.** Wear helmets and seat belts.
 8.  **Limit alcohol and avoid drugs.** They damage brain
      function.
 9.  **Get medical check-ups.** Blood pressure, blood sugar,
      and hearing all effect
     brain health.

**TRY THIS: THE 4-6 BREATH**

Sit comfortably. Breathe in gently through your nose for a count of
 four. Breathe
out slowly through your mouth for a count of six. Repeat for two minutes. A longer
outbreath activates the body’s calming system and settles the stress response. Practice
daily when calm, so that it is easy to use when stressed.

## 3.7 One story

A STORY FROM ORDINARY LIFE — THE STROKE THAT TAUGHT A FAMILY ANATOMY

After a left-sided stroke, a grandmother lost speech but not song.
 Relatives said
she was being stubborn. A doctor named Broca’s area. Naming did not heal her. It
stopped the insult. Rehab was slow. The family learned that language and song do
not live in one drawer — and that a new ‘personality’ can be an injured lobe.

A STORY FROM ORDINARY LIFE — THE HELMET ARGUMENT

A teenager’s new rudeness followed a scooter fall without a helmet.
 Uncles planned
a lecture on respect. An emergency doctor planned a scan. The scan was respect for
the frontal lobe.

## 3.8 One companion verse

One old picture of the same chapter: body as chariot, mind as reins,
 intellect 
as driver. If the horses bolt, inspect the chariot — sleep, injury, thyroid — not
only the rider’s morals.

SHLOKA / VERSE

**Sanskrit Text:**

आत्मानं रथिनं विद्धि शरीरं रथमेव च ।

बुद्धिं तु सारथिं विद्धि मनः प्रग्रहमेव च ॥

**Pronunciation:**

_atmanam rathinam viddhi sariram ratham eva ca |_

_buddhim tu sarathim viddhi manah pragraham eva ca ||_

**Translation:** Know the self as the rider, the body as
 the chariot, the intellect
as the driver, and the mind as the reins.

**Practical Meaning for Daily Health:** Mental health
 work includes the chariot.
A lecture to the rider is not enough if the axle is broken.

_Reference — Katha Upanishad 1.3.3–4_

![Figure 3.5 The chariot of the Kaṭha Upaniṣad: the self rides, the body is the 
chariot, the intellect drives, the mind is the reins and the senses are the horses.(
Illustration created with AI tools.)](/wp-content/uploads/pfe-book/image15.webp)

**Figure 3.5** _The chariot of the Katha Upanishad:
 the self rides, the body is
the chariot, the intellect drives, the mind is the reins and the senses are the 
horses.

### Reflection

 1. Which region in this chapter best matches a problem you have seen in
     a relative—
    impulse, memory, vision, alarm, or sleep?
 2. When did someone in your house blame ‘attitude’ for what might have
     been a body
    event?
 3. What one sleep or safety habit this week would help the chariot, not
     only the 
    rider?