What is the order of events in a response?

Stimulus, receptor, coordinator, effector, response.

A muscle or gland that carries out the response.

What does a sensory neurone do?

Carries impulses from a receptor to the CNS.

What does a relay neurone do?

Connects sensory and motor neurones in the CNS.

What does a motor neurone do?

Carries impulses from the CNS to an effector.

A gap between two neurones. A chemical diffuses across it to pass the signal on.

A fast, automatic response that does not involve conscious thought.

Why is a reflex fast?

The pathway is short and does not involve the brain's decision-making.

Give an example of a reflex.

Pulling a hand away from a hot object; blinking; the knee jerk.

Which stimuli do the eye, ear, nose, tongue and skin detect?

Light; sound and balance; chemicals in the air; chemicals in food; touch, pressure, temperature and pain.

In the ruler-drop test, what does a shorter distance mean?

A shorter reaction time (a faster reaction).

The nervous systemIB MYP Biology: Flashcards

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What is the CNS?

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What is the CNS?: The central nervous system: the brain and spinal cord.
What is a stimulus?: A change in the environment that is detected by a receptor.
What does a receptor do?: Detects a stimulus.
What is the order of events in a response?: Stimulus, receptor, coordinator, effector, response.
What is an effector?: A muscle or gland that carries out the response.
What does a sensory neurone do?: Carries impulses from a receptor to the CNS.
What does a relay neurone do?: Connects sensory and motor neurones in the CNS.
What does a motor neurone do?: Carries impulses from the CNS to an effector.
What is a synapse?: A gap between two neurones. A chemical diffuses across it to pass the signal on.
What is a reflex?: A fast, automatic response that does not involve conscious thought.
Why is a reflex fast?: The pathway is short and does not involve the brain's decision-making.
Give an example of a reflex.: Pulling a hand away from a hot object; blinking; the knee jerk.
Which stimuli do the eye, ear, nose, tongue and skin detect?: Light; sound and balance; chemicals in the air; chemicals in food; touch, pressure, temperature and pain.
In the ruler-drop test, what does a shorter distance mean?: A shorter reaction time (a faster reaction).

Exam questions on The nervous system

A chef accidentally touches a hot pan with her hand. She pulls her hand away before she feels any pain, and only a moment later does she notice the burn.
Explain why the reflex pulls the chef's hand away faster than a decision made by her brain.2 marks
At a food festival in Mumbai, judges assess a new snack. They look at its colour, smell it, taste it, feel its texture in the mouth and listen to how loudly it crunches.
Suggest why food seems to have less flavour when you have a blocked nose.2 marks
A class investigates whether reaction time is different for the dominant hand and the non-dominant hand, using the ruler-drop test. One student holds a 30 cm ruler vertically above the open fingers of a partner and drops it without warning. The partner closes the fingers as fast as possible, and the distance the ruler fell is read from the top of the thumb. Each student does five drops with each hand. One student's distances for the dominant hand were 14, 12, 13, 25 and 13 cm. For the non-dominant hand they were 18, 20, 19, 17 and 21 cm.
Identify the independent variable, the dependent variable and one control variable in this investigation.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).