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Nervous System
Revision Notes
Key Points
- The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS)
- There are three types of neurons: sensory, motor, and relay
- Reflex actions are rapid, automatic responses to stimuli
- The cerebrum controls voluntary actions, while the brainstem and hypothalamus control involuntary functions
- The nervous system coordinates and integrates the body's responses to internal and external stimuli
Structure of the Nervous System
- Central Nervous System (CNS): brain and spinal cord
- Peripheral Nervous System (PNS): nerves that connect the CNS to the rest of the body
Types of Neurons
- **Sensory neurons**: carry information from receptors to the CNS
- **Motor neurons**: carry information from the CNS to effectors (muscles and glands)
- **Relay neurons**: connect sensory and motor neurons within the CNS
Reflex Actions
- Rapid, automatic response to a stimulus
- Example: knee-jerk reflex
Voluntary and Involuntary Control
- **Voluntary control**: conscious control of actions, coordinated by the cerebrum
- **Involuntary control**: unconscious control of bodily functions, coordinated by the brainstem and hypothalamus