Question

A child is frightened by a loud noise and shouts for help. In which order the different types of neurons in neurons involved will act?
A. Motor neurone → relay neurone → sensory neurone
B. Motor neurone → sensory neurone → relay neurone
C. Sensory neurone → motor neurone → relay neurone
D. Sensory neurone → relay neurone → motor neurone

Answer 1

Answer:

D

Explanation:

Sensor Neurone⇒relay Neurone⇒motor neurone.

Receptor in the skin detects a stimulus (the change in temperature).

Sensory neurone sends electrical impulses to relay neurone, which are located in the spinal cord. They connect sensory neurones to motor neurones.

Motor neurone sends electrical impulses to an effector.

Effector produces a response (muscle contracts to move hand away).

Where two neurones meet there is a small gap, a synapse.

An electrical impulse travels along the first axon.

This triggers the nerve-ending of a neurone to release chemical messengers called neurotransmitters.

These chemicals diffuse across the synapse (the gap) and bind with receptor molecules on the membrane of the second neurone.

The receptor molecules on the second neurone bind only to the specific neurotransmitters released from the first neurone. This stimulates the second neurone to transmit the electrical impulse.

Answer 2

Explanation:

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option a