A nerve cell along which electrical impulses pass.

What two parts make up the human nervous system?

Central nervous system (CNS) — the brain and spinal cord Peripheral nervous system (PNS) — all the nerves in the body

How is information sent through the nervous system?

As electrical impulses passing along neurones.

What is the role of the CNS?

It acts as a central coordinating centre for impulses coming in from, or sent out to, any part of the body.

What is the function of the myelin sheath on an axon?

It insulates the axon; the impulse jumps from one node to the next, speeding up transmission.

State the functions of sensory, relay and motor neurones.

Sensory: carry impulses from sense organs to the CNS Relay: found in the CNS, connect sensory and motor neurones Motor: carry impulses from the CNS to effectors

What is the nervous pathway from stimulus to response?

stimulus → sensory neurone → relay neurone → motor neurone → effector → response

What does an effector do, and what may it be?

It carries out the response. It may be a muscle or a gland.

A junction between two neurones where there is a very small gap.

Chemical signalling molecules used to transfer the signal between neurones at a synapse.

The very small gap between two neurones at a synapse.

Why can't electrical impulses travel directly across a synapse?

Because of the synaptic cleft — electricity cannot 'jump' the gap.

How is the signal carried across the synaptic cleft?

The electrical signal is briefly converted to a chemical signal (neurotransmitters) that can cross the gap, then converted back into an electrical impulse.

Describe how an impulse is passed across a synapse.

The impulse triggers vesicles in the presynaptic neurone to release neurotransmitters The neurotransmitters diffuse across the synaptic cleft They bind to receptor molecules on the postsynaptic membrane, stimulating a new electrical impulse

How do neurotransmitters move across the synaptic cleft?

By diffusion — a passive process requiring a concentration gradient.

Why are neurotransmitters destroyed after they act?

To prevent continued stimulation of the second neurone, which would otherwise cause repeated impulses.

Why do synapses ensure impulses travel in only one direction?

Receptors are only on the postsynaptic membrane, so the signal can only pass one way, avoiding confusion in the nervous system.

An involuntary, automatic and rapid response that does not involve the conscious part of the brain.

The pathway taken by electrical impulses along neurones during a reflex response.

Why are reflex responses important?

They are automatic and rapid, which helps minimise damage to the body and aids survival.

Give three examples of reflex responses that help avoid injury.

Pain-withdrawal, blinking and coughing.

In the pain-withdrawal reflex, what detects the stimulus?

A receptor in the skin (a pain/pressure/touch receptor).

What acts as the coordinator in the pain-withdrawal reflex arc?

The spinal cord (part of the CNS).

Put the reflex arc in order from stimulus to response.

Stimulus detected by receptor Sensory neurone Relay neurone Motor neurone Effector carries out response

What is the effector in the pain-withdrawal reflex, and what does it do?

A muscle in the leg; it contracts to pull the foot up and away from the sharp object.

Which neurone connects the sensory and motor neurones in the reflex arc?

The relay neurone, found in the CNS.

GCSEScienceEdexcelCombined ScienceBiologyFlashcardsCells & ControlCo-ordination & Response

Co-ordination & Response (Edexcel GCSE Combined Science: Biology): Flashcards

Exam code: 1SC0

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FrontThe Human Nervous System
Central nervous system (CNS)

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Cards in this collection (34)

Central nervous system (CNS)
The brain and spinal cord.
Neurone
A nerve cell along which electrical impulses pass.
What two parts make up the human nervous system?
Central nervous system (CNS) — the brain and spinal cord
Peripheral nervous system (PNS) — all the nerves in the body
What is a nerve?
A bundle of neurones.
How is information sent through the nervous system?
As electrical impulses passing along neurones.
What is the role of the CNS?
It acts as a central coordinating centre for impulses coming in from, or sent out to, any part of the body.
What is the function of the myelin sheath on an axon?
It insulates the axon; the impulse jumps from one node to the next, speeding up transmission.
State the functions of sensory, relay and motor neurones.
Sensory: carry impulses from sense organs to the CNS
Relay: found in the CNS, connect sensory and motor neurones
Motor: carry impulses from the CNS to effectors
What is the nervous pathway from stimulus to response?
stimulus → sensory neurone → relay neurone → motor neurone → effector → response
What does an effector do, and what may it be?
It carries out the response. It may be a muscle or a gland.
The central nervous system consists of the brain and the .
spinal cord
A neurone carries impulses from sense organs to the CNS.
sensory
Synapse
A junction between two neurones where there is a very small gap.
Neurotransmitters
Chemical signalling molecules used to transfer the signal between neurones at a synapse.
Synaptic cleft
The very small gap between two neurones at a synapse.
Why can't electrical impulses travel directly across a synapse?
Because of the synaptic cleft — electricity cannot 'jump' the gap.
How is the signal carried across the synaptic cleft?
The electrical signal is briefly converted to a chemical signal (neurotransmitters) that can cross the gap, then converted back into an electrical impulse.
Describe how an impulse is passed across a synapse.
The impulse triggers vesicles in the presynaptic neurone to release neurotransmitters
The neurotransmitters diffuse across the synaptic cleft
They bind to receptor molecules on the postsynaptic membrane, stimulating a new electrical impulse
How do neurotransmitters move across the synaptic cleft?
By diffusion — a passive process requiring a concentration gradient.
Why are neurotransmitters destroyed after they act?
To prevent continued stimulation of the second neurone, which would otherwise cause repeated impulses.
Why do synapses ensure impulses travel in only one direction?
Receptors are only on the postsynaptic membrane, so the signal can only pass one way, avoiding confusion in the nervous system.
Neurotransmitters are released from at the end of the presynaptic neurone.
vesicles
Neurotransmitters cross the synaptic cleft by and bind to receptors on the postsynaptic membrane.
diffusion
Reflex response
An involuntary, automatic and rapid response that does not involve the conscious part of the brain.
Reflex arc
The pathway taken by electrical impulses along neurones during a reflex response.
Why are reflex responses important?
They are automatic and rapid, which helps minimise damage to the body and aids survival.
Give three examples of reflex responses that help avoid injury.
Pain-withdrawal, blinking and coughing.
In the pain-withdrawal reflex, what detects the stimulus?
A receptor in the skin (a pain/pressure/touch receptor).
What acts as the coordinator in the pain-withdrawal reflex arc?
The spinal cord (part of the CNS).
Put the reflex arc in order from stimulus to response.
Stimulus detected by receptor
Sensory neurone
Relay neurone
Motor neurone
Effector carries out response
What is the effector in the pain-withdrawal reflex, and what does it do?
A muscle in the leg; it contracts to pull the foot up and away from the sharp object.
Which neurone connects the sensory and motor neurones in the reflex arc?
The relay neurone, found in the CNS.
In a reflex arc, a neurone carries impulses from the receptor to the spinal cord.
sensory
A neurone carries the impulse from the CNS to the effector.
motor

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