Synapses And Reflexes Flashcards
what is a synapse
the connection between two neurones
what are nerve signals transferred by
- chemicals called neurotransmitters
- which diffuse across the gap
how do signals travel from one neurone to the next
the neurotransmitters set off new electrical signal in the next neurone
although the transmission of nervous impulses are fast, what slows them down
- the diffusion of neurotransmitters across synapses
- this takes time
what are reflexes
automatic and rapid responses to stimuli
why do we have reflexes
to reduce our chances of getting injured
what is the passage of information in a reflex, from the receptor to the effector, called
a reflex arc
where do neurones in reflex arcs go through
- the spinal cord
- or through an unconscious part of the brain
what is an examplle of a stimulus
a bee sting or touching a hot pan
what is the first thing that happens when you have touched a hot pan
the stimulus, heat, is detected by pain receptors
what is the response to the heat being detected by the receptors
impulses are sent along sensory neurones to a relay neurone in the central nervous system
what happens when impulses reach a synapse between the sensory neurone and a relay neurone and what does this cause
- they trigger neurotransmitters to be released
- these cause impulses to be sent along the relay neurone
what happens when impulses reach a synapse between the sensory neurone and a motor neurone and what does this cause1
- it triggers neurotransmitters to be released
- which cause impulses to be sent along the motor neurone
where do the impulses travelling through the motor neurone go to
- the effector
- this could be a muscle or a gland for example
what happens when the impulses reach the muscle they wee travelling to
- it causes the muscle to contract
- which moves your hand away from the hot pan
why are reflexes quicker than normal responses and why are they advantageous
- you dont have to spend time thinking about the response
- meaning you can act quicker and get out of danger or injury with the least amount of damage done
what is the whole process of a reflex is a bee were to sting your finger
- the bee stings your finger
- stimulates the pain receptors
- impulses travel along the sensory neurone
- impulses are passed along to the relay neurone in the CNS vis synapses
- impulses travel along a motor neurone via synapses
- when impulses reach the muscle it causes it to contract
why do we have reflexes to protect the eye
because very bright light can damage the eye
what do light receptors in the eye do
- they detect very bright light
- and send a message along the sensory neurone to the brain
what happns after the impulses have reached the brain
- they travel along relay neurones to a motor neurone
- which tells circular muscles in the iris ( the coloured part)
- to contract, making the pupil smaller
