receptors and neurones Flashcards
what is an action potential
a nerve impulse
what are the 3 types of neurones
1) sensory neurones
2) motor neurones
3) relay neurones
what does a sensory neurone do
transmits nerve impulses from receptors to the CNS( the brain and spinal cord)
what does a motor neurone do
transmits nerve impulses from CNS to effectors
what does a relay neurone do
transmits nerve impulses between sensory and motor neurones
what type of energy does a sensory receptor convert a stimulus into?
Electrical energy
sensory receptors act as transducers as they convert one energy from into another
what is the potential difference when the cell is resting
resting potential
what happens when a stimulus is detected:
- The cell membrane is excited and becomes more permeable, allowing more ions to move in and out of the cell which changes the potential difference.
what potential is it ,when there is a change in potential difference due to stimulus
Generator potential:
greater stimulus= more permeable membrane as it gets more excited
this means bigger movement of ions which= bigger change in potential difference
WHICH MEANS GREATER GENERATOR POTENTIALPRODUCED
IF generator potential is big enough, an action potential is fired along the neurone, but its only fired if the generator potential reaches a certain level called threshold.
what carries nerve impulses towards the cell body
The dendrites and dendrons
what carries nerve impulses away from the cell body
axons
Direction of impulse in a sensory neurone:
They have short dendrites and one long dendron
that carry nerve impulses from receptor cells to the cell body.
They have one short axon that carries nerve impulses from the cell body to the CNS.
are motor neurones mylinated or non-mylinated
non-mylinated
Direction of impulse in a motor neurone
motor neurones have dendrites that carry nerve impulses from the CNS to the cell body
There is one axon that carries nerve impulses from the cell body to the effector cells
Direction of impulse in a relay neurone
Relay neurones have many short dendrites that carry nerve impulses from sensory neurones to the cell body
Then the axon carries nerve impulses from the cell body to the motor neurones
when is the outside of the cell membrane positively charged
When the neurone is in its resting state
As there are more positive ions outside the cell than inside the cell
what is the voltage of the membrane at resting potential
-70mV
what does the sodium potassium pump do to the charge of the membrane
- Is found in the membrane of a neurone
Creates a resting potential and maintains it
sodium potassium pumps… ( Na+) ACTIVE TRANSPORT
pump sodium ions out of the neurone
- sodium ions cant diffuse back into the neurone as the membrane isn’t permeable.
THIS CREATES a sodium ion electrochemical gradient
sodium potassium pumps…(K+) FACILLITATED DIFFUSION
Pumps potassium ions into the neurone,
HOWEVER membrane of the neurone is permeable,
- so potassium ions diffuse back OUT through the potassium ion channel
which makes the outside of the cell more positively charged.
