the nervous system Flashcards
reflex actions
are automatic and unconscious (you don’t think about it)
describe a reflex arc
goes from:
- stimulus triggers response
- receptor detects stimulus and sends as messengers via electrical impulses
- sensory neurone carries the electrical impulses
- to the central nervous system eg brain and spinal cord
- CNS coordinates response
- the information is sent via motor neurone to an effector
- the effector responds - the response happens eg muscle contraction or hormones are secreted by a a gland
what is the point of a reflex arc?
to prevent injuries/play a protective role eg snatching back your hand after you touch a burning plate
how does the effector respond?
- the effector responds - the response happens eg muscle contraction or hormones are secreted by a a gland
neurones transmit information as
electrical impulses
the connection between two neurons is called a
synapse
how do you travel across a synapse?
- the electrical impulse triggers the release of transmitter chemicals
- these diffuse across the gap
- the chemicals bind to receptors
- the chemicals are messengers to the membrane of the next neurone
- sets off a new electrical impulse
what is the eye?
a sense organ
what is a neuron?
a nerve cell
the reflex of the iris (not a part of the nervous system but does reflex actions)
- adjusts to respond to the amount of light (via muscle contraction)
- larger in low light
- smaller in high light
- this is a REFLEX ACTION
what is a receptor?
where are they found?
- receptors detect stimuli
- they are in the sense organs e.g. skin and eyes
what is an effector?
what is an example of one?
- they cause a response
- eg glands excrete hormones or muscles contract
a synapse has nerve signals called…. that diffuse across the gap
neurotransmitters
how do receptors and effectors communicate?
- hormone system (through the bloodstream)
- the nervous system (neurones)
what are the three types of neuron?
- sensory neuron
- relay neuron
- motor neuron
