The Nervous System
What Is the Nervous System?
The nervous system detects and responds to stimuli using electrical impulses. It allows us to react quickly to changes in the environment.
💡 Key Concept: It is made up of the central nervous system (CNS) and peripheral nerves, working together to coordinate responses.
Key Parts of the Nervous System
Part | Function |
Receptors | Detect stimuli (e.g. light, sound, pressure, temperature). |
Sensory Neurones | Carry signals from receptors to the CNS. |
Central Nervous System (CNS) | Brain and spinal cord – coordinates response. |
Motor Neurones | Carry signals from the CNS to effectors. |
Effectors | Muscles (contract) or glands (secrete hormones) – carry out a response. |
The Pathway of a Nervous Response
1️⃣ Stimulus (e.g. hot object) is detected by a receptor.
2️⃣ An electrical impulse is sent along a sensory neurone.
3️⃣ The signal is passed to a relay neurone in the spinal cord or brain (CNS).
4️⃣ Then to a motor neurone.
5️⃣ The effector carries out a response (e.g. muscle contracts to move hand away).
💡 This process is extremely fast and helps protect the body.
Synapses
At the junction between neurones, the signal is passed by chemicals called neurotransmitters.
✔ The chemicals diffuse across the gap and trigger a new electrical impulse in the next neurone.
Why Is the Nervous System Important?
✔ Allows fast communication and coordination.
✔ Protects the body via reflex actions.
✔ Controls complex behaviours like movement, memory, and learning.
Questions
- What does the CNS consist of?
- What is the function of a sensory neurone?
- What is an effector?
- How do signals cross a synapse?
- What type of response is fast and automatic?
Summary
- The nervous system allows quick responses to changes (stimuli).
- It includes receptors, neurones, the CNS, and effectors.
- Signals travel as electrical impulses, and cross synapses using neurotransmitters.
- Reflex actions are fast, automatic responses that help protect the body.