🧠 THE NERVOUS SYSTEM
PAGE 1 OF 5 · THE COMMAND CENTRE
BRAIN
86 BILLION NEURONS
Your brain is the busiest control room you will ever own. It weighs about as much as a small laptop yet uses roughly a fifth of your daily fuel. Every thought, giggle, balance correction, and memory search runs on networks of cells that chatter using electricity and chemistry at once.
⚡ POWER FACT
The brain is only about two percent of body weight but can use around twenty percent of resting energy, mostly to keep neurons ready to fire.
THINK!
CEREBRUM
🧩 Largest part: thinking, language, planning, voluntary movement.
↔️ Left and right hemispheres specialise a bit yet talk through thick cable bridges.
↔️ Left and right hemispheres specialise a bit yet talk through thick cable bridges.
CEREBELLUM
⚖️ Fine tunes balance, timing, and smooth motion.
🚴 Lets you ride a bike or play music without staring at every muscle.
🚴 Lets you ride a bike or play music without staring at every muscle.
PAGE 2 OF 5 · NEURONS AND SIGNALS
SPEED
FASTER THAN YOU CAN BLINK
Some nerve fibres conduct impulses over a hundred metres per second. That speed lets you jerk your hand from heat before the conscious story catches up. Each neuron receives branches called dendrites, sums the chatter in its cell body, then fires an action potential down a long axon. At the tip, chemical messengers called neurotransmitters leap across microscopic gaps called synapses to the next cell.
ZIP!
SENSORY
👂 Carry sight, sound, touch, taste, smell toward the brain.
📡 First step in turning world into data.
📡 First step in turning world into data.
MOTOR
💪 Carry commands from brain and cord to muscles and glands.
🎯 The final output stage for movement.
🎯 The final output stage for movement.
INTERNEURON
🔗 Link neurons inside brain and spinal cord.
🧠 Most of your neurons are this type.
🧠 Most of your neurons are this type.
PAGE 3 OF 5 · REFLEXES AND THE SPINAL CORD
HOT!
🔥 Touch something painful and your hand leaps back.
⚡ The spinal cord can command the muscle before the brain finishes the thought.
⚡ The spinal cord can command the muscle before the brain finishes the thought.
CNS
🧠 Brain plus spinal cord form the central nervous system.
📍 Headquarters for most decisions.
📍 Headquarters for most decisions.
REFLEX ARC
SHORTCUT THROUGH THE SPINE
A sensory neuron reports damage, interneurons in the grey matter of the spinal cord decide, and motor neurons fire in a tiny fraction of a second. Only afterward does the brain receive the full story. Peripheral nerves branch through the body like highways, while autonomic branches handle silent jobs like heart rate using sympathetic and parasympathetic balances.
FAST!
PAGE 4 OF 5 · MEMORY AND LEARNING
SYNAPSE
NEURONS THAT FIRE TOGETHER, WIRE TOGETHER
Learning physically strengthens busy synapses through processes like long term potentiation. Short term memory holds a handful of items for moments, while long term storage can last years if rehearsed. Procedural memory keeps skills like typing automatic, and emotional tagging makes some lessons stick louder than others.
LEARN!
SHORT
📌 Working memory juggles what you are doing right now.
⏱️ Limited slots, so focus matters.
⏱️ Limited slots, so focus matters.
LONG
🗄️ Names, facts, and stories can last decades.
🔁 Sleep helps move lessons from temporary to stable.
🔁 Sleep helps move lessons from temporary to stable.
SLEEP
🌙 Brain cleans waste and replays patterns during deep rest.
😴 Skimping on sleep slows attention and memory the next day.
😴 Skimping on sleep slows attention and memory the next day.
PAGE 5 OF 5 · CARE FOR YOUR NETWORK
HABITS
FUEL, AIR, AND KINDNESS
Movement boosts blood flow to neurons. Hydration and steady meals keep salt balances right for electrical signals. Helmets and seat belts protect the soft tissue inside hard bone. Stress management and sleep give synapses room to reset. Your nervous system is plastic, meaning practice reshapes it, so choose skills and stories you want to grow.
GROW!
PNS
🌐 Cranial and spinal nerves reach organs and skin.
🔄 Autonomic fibres adjust heart and digestion without asking.
🔄 Autonomic fibres adjust heart and digestion without asking.
REMEMBER
⚡ KEY FACTS
Brain, cerebellum, brain stem roles. Sensory, motor, interneurons. Reflex arc through cord. CNS vs PNS. Synapses strengthen with learning. Sleep consolidates memory.
✅ Signals are both electrical and chemical.
✅ Protection and rest are part of performance.
✅ Curiosity keeps your map of the world expanding.
✅ Protection and rest are part of performance.
✅ Curiosity keeps your map of the world expanding.
🧠 QUIZ TIME!
THE NERVOUS SYSTEM · 5 QUESTIONS
QUESTION 01
About how many neurons are in the human brain?
QUESTION 02
Which part of the brain is most tied to balance and smooth coordination?
QUESTION 03
Roughly how fast can some nerve signals travel?
QUESTION 04
What is a reflex arc best known for?
QUESTION 05
About what share of resting body energy does the brain use?
0/5
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