📚 Section 1 — Classroom Notes
Real-World Connection: When you accidentally touch a hot pan and pull your hand away before you even think about it, that is your reflex arc in action — your spinal cord made the decision in milliseconds to protect you. Hormones work like slow text messages through your blood, while nerves work like instant phone calls at high speed. Every blink, heartbeat, and even your mood is coordinated by your nervous and endocrine systems working together!
🧠 Topic 1: What Is the Nervous System?
- The nervous system controls our body.
- It sends messages very fast.
- The brain is the main control part.
- Nerves carry messages to all body parts.
- It helps us think, feel, and move.
🔬 Topic 2: Parts of a Neuron
- A neuron is a nerve cell.
- The cell body has the nucleus inside.
- Dendrites receive messages from other cells.
- The axon is a long wire-like part.
- Messages travel as electrical signals.
⚡ Topic 3: How Nerves Send Messages
- A signal starts at the dendrite tip.
- It moves through the cell body next.
- Then it goes along the axon.
- A small gap is between two neurons.
- Chemicals cross the gap to the next cell.
🔥 Topic 4: What Is a Reflex Action?
- A reflex is a very fast response.
- You pull your hand from a hot pot.
- The message goes to the spinal cord.
- It does not go to the brain first.
- This path is called a reflex arc.
🏛️ Topic 5: Parts of the Human Brain
- The cerebrum is the biggest brain part.
- It helps us think and remember things.
- The cerebellum keeps our body balanced.
- The medulla controls breathing and heartbeat.
- The brain is safe inside the skull.
🌱 Topic 6: How Plants Respond
- Plants move but very slowly.
- Roots grow towards water in the soil.
- Stems grow towards sunlight above.
- This slow growth movement is called tropism.
- Touch-me-not plant folds leaves when touched.
🌿 Topic 7: Types of Plant Movements
- Phototropism is growth towards light.
- Geotropism is growth towards the ground.
- Hydrotropism is growth towards water.
- Nastic movements do not need a direction.
- Plant hormones control these movements.
💉 Topic 8: Hormones in Animals
- Hormones are chemical messengers in blood.
- Adrenaline makes your heart beat fast.
- Thyroxine controls how fast body works.
- Insulin controls sugar level in blood.
- Hormones are made by glands in the body.
🧬 Topic 9: Growth and Sex Hormones
- Growth hormone helps children grow tall.
- Testosterone is the male sex hormone.
- Estrogen is the female sex hormone.
- These hormones cause body changes at puberty.
- The pituitary gland controls other glands.
🔄 Topic 10: Feedback Mechanism
- Feedback keeps hormone levels just right.
- Too much sugar makes the body release insulin.
- Insulin brings the sugar level down.
- When sugar is low, insulin release stops.
- This is like a thermostat in a room.
✏️ Section 3 — Worked Examples
📝 Example 1: Trace the Reflex Arc
You touch a hot cup. What happens step by step?
1
Your skin feels the heat. Skin is the receptor.
2
A sensory nerve sends a signal to the spinal cord.
3
The spinal cord quickly decides what to do.
4
A motor nerve sends a signal to your hand muscle.
5
Your hand pulls back from the hot cup.
Answer: Receptor → Sensory nerve → Spinal cord → Motor nerve → Muscle. The brain is not used.
📝 Example 2: Name the Brain Part
Which brain part keeps you balanced when you ride a bike?
1
Balance means keeping the body steady.
2
The cerebellum controls balance and posture.
3
So riding a bike needs the cerebellum.
Answer: The cerebellum helps you balance on a bike.
📝 Example 3: Identify the Hormone
A person has too much sugar in blood. Which hormone helps?
1
Blood sugar is too high. Body needs to lower it.
2
Insulin is the hormone that lowers blood sugar.
3
Insulin is made by the pancreas gland.
4
If insulin is low, the person gets diabetes.
Answer: Insulin lowers blood sugar. It is made by the pancreas.
🏠 Section 5 — Take-Home Handout
Part A: Fill in the Blanks
1. A nerve cell is called a ________.
2. The longest part of a neuron is the ________.
3. A very fast body response is a ________ action.
4. The biggest part of the brain is the ________.
5. ________ controls sugar level in the blood.
Part B: True or False
1. The brain controls all reflex actions. ________
2. Roots grow towards water. ________
3. Adrenaline makes the heart beat slowly. ________
4. The medulla controls breathing. ________
5. Plants cannot move at all. ________
Part C: Solve
1. Write the five steps of a reflex arc in order.
2. Name three types of tropism in plants.
Part D: Match the Columns
| Column A | Column B |
|---|
| 1. Cerebrum | a. Balance and posture |
| 2. Cerebellum | b. Lowers blood sugar |
| 3. Insulin | c. Thinking and memory |
| 4. Adrenaline | d. Fight or flight response |
Part E: Draw and Label
Draw a neuron and label its four main parts.
✅ Detailed Solutions — Section 5 Take-Home Handout
Part A: Fill in the Blanks
1. A nerve cell is called a neuron.
2. The longest part of a neuron is the axon.
3. A very fast body response is a reflex action.
4. The biggest part of the brain is the cerebrum.
5. Insulin controls sugar level in the blood.
Part B: True or False
1. The brain controls all reflex actions. → False — Reflex actions are controlled by the spinal cord, not the brain, so the response is faster.
2. Roots grow towards water. → True — This is called hydrotropism (positive hydrotropism in roots).
3. Adrenaline makes the heart beat slowly. → False — Adrenaline (the “fight or flight” hormone) increases heart rate, preparing the body for danger.
4. The medulla controls breathing. → True — The medulla oblongata in the hindbrain controls involuntary actions like breathing and heartbeat.
5. Plants cannot move at all. → False — Plants show movement through tropisms (e.g. sunflowers turn towards sunlight).
Part C: Solve
1. Write the five steps of a reflex arc in order.
1
Stimulus — a trigger (e.g. touching a hot pan)
2
Receptor — sensory cells in skin detect the stimulus
3
Sensory neuron — carries the nerve impulse to the spinal cord
4
Motor neuron — spinal cord sends a signal to the muscle (effector)
5
Effector (muscle/gland) — produces the response (e.g. hand pulls away)
2. Name three types of tropism in plants.
1
Phototropism — growth in response to light (stems grow towards light; roots away)
2
Geotropism — growth in response to gravity (roots grow downward; shoots upward)
3
Hydrotropism — growth in response to water (roots grow towards moisture in soil)
Part D: Match the Columns
1. Cerebrum → c. Thinking and memory (the largest part of the brain; controls voluntary actions)
2. Cerebellum → a. Balance and posture (coordinates movement and maintains equilibrium)
3. Insulin → b. Lowers blood sugar (secreted by the pancreas when blood glucose rises)
4. Adrenaline → d. Fight or flight response (secreted by adrenal glands in stressful situations)
Part E: Draw and Label — A Neuron
Your diagram should show:
- Cell body (soma) — contains the nucleus; round shape in the centre
- Dendrites — short branching extensions coming off the cell body; receive signals
- Axon — one long fibre extending from the cell body; carries signals away
- Myelin sheath — protective coating around the axon (segmented sections)
- Axon terminals (synaptic knobs) — at the end of the axon; pass signals to the next cell
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