| The two major divisions of the nervous system | - Central nervous system (CNS)
- Peripheral nervous system (PNS) |
| Central nervous system (CNS) | - Made up of brain + spinal chord |
| Peripheral nervous system (PNS) | - Made up of pairs of nerves that originate from either the brain or the spinal chord |
| What the peripheral nervous system is divided into | - Sensory neurons
- Motor neurons |
| Sensory neurons | - Carry nerve impulses (electrical signals) from the receptors towards the CNS |
| Motor neurons | - Carry nerve impulses away from the CNS to effectors |
| What the motor nervous system can be further subdivided into | - Voluntary nervous system
- Autonomic nervous system |
| Voluntary nervous system | - Carries nerve impulses to body muscles
- Under voluntary (conscious) control |
| Autonomic nervous system | - Carries nerve impulses to glands, smooth muscle + cardiac muscle
- Not under voluntary control, involuntary (unconscious) |
| The spinal cord | - Column of nervous tissue that runs along the back
- Lies inside the vertebral column for protection
- Pairs of nerves emerge at intervals along spinal chord |
| A reflex | - Automatic response to a stimulus
- Where the body responds to a stimulus without making a conscious decision to respond
- Because you don't have to spend time deciding how to respond, info travels very fast from receptors to effectors
- Helps to protect organism |
| A reflex arc | - Pathway of neurones linking receptors to effectors in a reflex |
| Flow diagram of reflex arc (aka spinal reflex arc) | - Stimulus
- Receptor
- Sensory neuron
- Coordinator
- Motor neuron
- Effector
- Response |
| Importance of reflex arcs | - Involuntary, do not require decision making powers of the brain, leaving it free to carry out more complex responses
- Protect body from harm, effective from birth, do not have to be learnt
- Fast, because the neuron pathway is short with very few synapses |
