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level: 14.3 A reflex arc

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level questions: 14.3 A reflex arc

QuestionAnswer
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