5.1.3 Neuronal communication Flashcards
What are the 3 main types of neurons?
1- Sensory
2- Relay
3- Motor
What do sensory neurons do?
transmit nerve impulses from receptors to the CNS - (the brain and the spinal cord)
What do motor neurons do?
Transmit nerve impulses from the CNS to the effectors
What do relay neurons do?
Transmit nerve impulses between sensory neurons and motor neurons
What happens when a stimulus is detected by receptor cells?
A stimulus is detected by receptor cells and a nerve impulse is sent along a sensory neuron
When a nerve impulse reaches the end of the neuron, chemicals called neurotransmitters take the information across to the next neuron which then send a nerve impulse
The CNS then processes the information , decides what to do about it and sends impulses along motor neurons to an effector
Order of this neuronal system
Stimulus , receptor, sensory neuron, CNS, motor neurons , effectors , response
What role does the CNS play?
CNS processes information and decides what to do with it
What do sensory receptors do?
Convert stimulus energy into nerve impulses
What do sensory receptors act as ?
Transducers
What is a transducer?
Something that converts one form of energy into another.
Why are sensory neurons known as transducers?
Different stimuli have different forms of energy EG: light energy or chemical energy
BUT your nervous system only sends information in the form of nerve impulses (electrical impulses)
Sensory neurons convert the energy of a stimulus into electrical energy
so , sensory receptors act as transducers
What is a resting potential?
The potential difference when a cell is at rest
What is a generator potential?
The change in potential difference due to a stimulus
What potential do we need for a neve impulse o take place?
We need our generator potential to be big enough to reach the threshold so that the action potential (nerve impulse ) can be triggered , if the stimulus is too weak, the generator potential wont reach the threshold so there will be no action potential
What is potential difference also known as ?
Voltage
Is there a potential difference / voltage across a cell membrane when the nervous system receptor is at rest (not being stimulated)?
There is a difference in charge between the inside and the outside of the cell, this is generated by ion pumps and ion channels . This means that there is a voltage/ potential difference across the membrane
What happens to a potential difference when a stimulus is detected?
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 altering the potential difference , The change in the potential difference is called generator potential
What happens to the membrane when there is an even bigger stimulus?
A bigger stimulus excited the membrane more meaning the membrane gets more permeable . This causes a bigger movement of ions and a bigger change in potential difference so a bigger generator potential is made / produced
Example of a sensory receptor and what type of receptor it is
Pacinian corpuscle, it is an example of a mechanoreceptor
What does mechanoreceptors mean?
They detect mechanical stimuli EG: pressure and vibrations
Where are Pacinian corpuscles found?
in your skin
What do Pacinian corpuscles contain?
The end of a sensory neuron
What is the end of a sensory neurone called?
A sensory nerve ending
What are the sensory nerve endings surrounded by?
The sensory nerve ending is wrapped in lots of layers of connective tissue
What are they layers of connective tissue surrounding the sensory nerve endings called?
lamellae
Example of how a Pacinian corpuscle can be stimulated?
EG: By a tap on the arm
What happens when a Pacinian corpuscle is stimulated?
the lamellae gets deformed and press on the sensory nerve ending
When the lamellae gets deformed due to pressure, the sensory nerve ending gets pressed , what does this cause?
This causes a deformation on the stretch-mediated sodium ion channels in the sensory neurone
Where in the Pacinian corpuscle are the stretch mediated sodium ion channels found?
Cell surface membrane of the sensory neurone
What happens when the stretch mediated sodium ion channels are deformed?
The sodium ion channels open and sodium diffuses inside te cell creating a generator potential, if the generator potential reaches threshold then the action potential will be triggered
What do all three of the neurons have?
A cell body which contains a nucleus and all the other organelles you usually get in a cell
What neuron has a dendron?
Sensory
dendrites in neurons
Sensory - short dendrites
relay - many shot dendrites
Motor- Many short dendrites
What do dendrites and dendrons do?
Carry nerve impulses towards the cell body
What do axons do?
Carry nerve impulses away from the cell body
What does the dendron and the dendrites in the sensory neuron do?
Carry impulses from the receptor cells to the cell body
What does the axon in the sensory neurone do?
Carries impulses from the cell body to the CNS
What do they dendrites in the relay neuron do?
Carry impulses from the sensory neuron to the cell body
What does the axon in the relay neurone do
carries impulses from the cell body to the motor neurones
What do the dendrities do in the motor neurone
Carry nerve impulses from the CNS to the cell body
What does the axon do in the motor neuron?
Carry nerve impulses from the cell body to the effector cells
