Coordination: neurones GCSE

What are the three main types of neurones in the human nervous system?

Sensory neurones, relay neurones, motor neurones

Describe the function of sensory neurones

Sensory neurones transmit electrical impulses from receptors to the central nervous system (CNS).

What role do relay neurones play in the nervous system?

Relay neurones connect sensory neurones to motor neurones within the CNS.

Explain the function of motor neurones

Motor neurones carry electrical impulses from the CNS to effectors, such as muscles or glands.

What is a synapse?

A synapse is a small gap between two neurones where nerve signals are transmitted chemically via neurotransmitters.

Outline the process of neurotransmitter release at a synapse

• An electrical impulse travels along the first neurone.

• This triggers the release of neurotransmitters from vesicles into the synaptic gap.

• Neurotransmitters diffuse across the synapse and bind to receptor molecules on the membrane of the second neurone.

• This stimulates the second neurone to generate a new electrical impulse.

Define a reflex action

A reflex action is an automatic and rapid response to a stimulus that does not involve the conscious part of the brain, helping to protect the body from harm.

List the components of a reflex arc in the correct sequence

• Stimulus

• Receptor

• Sensory neurone

• Relay neurone (in the spinal cord)

• Motor neurone

• Effector

• Response

Provide an example of a reflex action and explain its pathway

• Heat (stimulus) is detected by temperature receptors in the skin.

• Sensory neurones transmit the impulse to the spinal cord.

• The impulse is passed to a relay neurone and then to a motor neurone.

• Motor neurones carry the impulse to the muscles in the hand (effectors).

• The muscles contract, resulting in the withdrawal of the hand (response).

Why are reflex actions important for survival?

Reflex actions provide rapid responses to potentially harmful stimuli, minimizing damage to the body and increasing chances of survival.