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B1 Part 1 B1 Lesson 12 Nervous System B1 Lesson 14 Control in the human body
Year 9

Learning outcomes and Specification referenceEdit

B1.2.1 The nervous system B1 Lesson 13 Reflex actions
d Pathway of nerve impulses and reflex actions. Explain the importance of reflex actions and be able to give examples.
e Describe the pathway of a nerve impulse in a reflex response and explain the roles of the structures involved.
stimulus→receptor→sensory neurone→relay neurone→motor neurone→effector→response
Explain the role of chemicals at synapses.
Describe different ways of measuring reaction time.

Full Specification TextEdit

d) Information from receptors passes along cells (neurones) in nerves to the brain. The brain coordinates the response. Reflex actions are automatic and rapid. They often involve sensory, relay and motor neurones.

e) Candidates should understand the role of receptors, sensory neurones, motor neurones, relay neurones,
synapses and effectors in simple reflex actions.

In a simple reflex action:
■ impulses from a receptor pass along a sensory neurone to the central nervous system
■ at a junction (synapse) between a sensory neurone and a relay neurone in the central nervous system, a chemical is released that causes an impulse to be sent along a relay neurone
■ a chemical is then released at the synapse between a relay neurone and motor neurone in the central nervous system, causing impulses to be sent along a motor neurone to the organ (the effector) that brings about the response
■ the effector is either a muscle or a gland, a muscle responds by contracting and a gland responds by releasing (secreting) chemical substances.

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References to lessons and resources in commercial schemesEdit

Nelson ThornesEdit


Harper CollinsEdit