Co-ordination & Response Flashcards
All 15 cards in this deck
What two organs make up the central nervous system (CNS)?
The brain and the spinal cord.
What is the role of a sensory receptor?
To detect a stimulus (e.g. a pin pricking the skin).
In a motor neurone, what is the long fibre that carries the impulse away from the cell body called, and what is the fatty layer around it called?
The axon; the myelin sheath.
What is the function of the myelin sheath on a neurone?
It insulates the axon so the electrical impulse travels faster.
What is a synapse?
The gap between two neurones.
What are the steps by which an impulse passes from one neurone to the next across a synapse?
e.g. relay neurone to motor neurone
- The impulse triggers release of a chemical (neurotransmitter) from the relay neurone.
- The neurotransmitter diffuses across the synapse (the gap).
- A new impulse is triggered in the motor neurone.
What name is given to the chemical released at a synapse?
A neurotransmitter (chemical messenger / chemical transmitter).
In a reflex arc, what is the order of the three neurones the impulse travels through?
Sensory neurone → relay neurone → motor neurone.
Where in the body is the relay neurone of a reflex arc found?
In the spinal cord (the CNS).
Why is a reflex action very fast and automatic?
The impulses bypass the conscious (thinking) part of the brain, so it is an involuntary (subconscious) process — this protects the body from harm.
In a reaction-time test, a student presses a key as soon as a blue square turns yellow. What is the stimulus and what is the response?
Stimulus: the square changing colour. Response: pressing the key.
What is the job of a sensory neurone?
It carries electrical impulses from a sensory receptor to the central nervous system (brain and spinal cord).
Which type of neurone carries electrical impulses from the central nervous system to an effector?
A motor neurone.
What is an effector?
A muscle or gland that carries out the response to a stimulus: a muscle contracts, or a gland releases a substance such as a hormone.
In which direction does a dendron carry electrical impulses?
Towards the neurone's cell body (the axon carries them away from it).