Neurons + Synaptic Transmission Flashcards
What are neurons?
Neurons are the building blocks of the nervous system, they are never cells
Where are neurons located?
Neurons are located within the brain
How many types of neurons are there? What are the different types called?
There are three types of neurons: sensory neuron, motor neuron relay neuron
What is the function of the relay neuron?
The relay neuron connects sensory neurons to motor neurons or other neurons. Essentially a connector neuron
What is the function of the sensory neuron?
The sensory neuron carry messages from the peripheral nervous system to the central nervous system
How would the sensory neuron, motor neuron and relay neuron work together?
For example the body receives a stimulus (touching something hot) this stimulus will be picked up by a sensory neuron and passed onto a relay neuron which will pass the information directly onto a motor neuron. This information is passed onto an effector (muscle gland) to receive a response
What is the function of the motor neuron?
The motor neuron carries nerve impulses from the central nerv ous system to an effector (muscle/gland)
Where is the neuron located: RELAY? SENSORY? MOTOR?
RELAY: located within the brain and the visual system
SENSORY: located in the peripheral nervous system
MOTOR: located in the central nervous system
What is the structure of the: RELAY? SENSORY? MOTOR?
RELAY: has short dendrites and short axons
SENSORY: long dendrites and short axons
MOTOR: has short dendrites and long axons
In clusters xx
What form is the sensory neuron found in when located in the peripheral nervous system?
In clusters called ganglias
What is the function of dendrites?
Dendrites carry impulses from neighbouring neurons towards the cell body
What is the function of axons?
Axons carry impulses away from the cell body down the length of the neuron towards the axon terminals
What is the axon covered in? How is this cover described? What is the function of the cover
The axon is covered in a fatty layer called the myelin sheath which protects the axon and speeds up the electrical transmission of the impulse
The myelin sheath has gaps within it, what are these gaps called?
The gaps are called the nodes of Ranvier
What is the function of the node of Ranvier
The nodes of Ranvier speed up the transmission of the electrical transmission by forcing the impulse to jump across the gaps down the axon
What is a synapse?
A synapse is the very small gap between neurons that act as a bridge for communications between two neurons
When neurons are at rest, what does this refer to?
When neurons are at rest, it means they are not sending any signals to one another. When at rest neurons are negatively charged inwardly relative to their outside
Action potential is also known as the neuron doing what? During action potential, what is created?
Action potential is also known as a neuron firing. During action potential an electrical impulse is created
When a neuron is activated by a stimulus, what occurs?
When a neuron is activated by a stimulus it becomes positively charged for a small amount of time, this causes what is known as action potential
Where does this electrical impulse travel to?
The electrical impulse created travels through the axon to the end of the neuron (terminal buttons)
How does a signal get from one neuron to another neuron?
Neurons do not make direct contact, they cross the synapse to continue their to/from the CNS. This is done through the use of chemicals which diffuse across the gap between two neurons
How are signals transmitted within neurons? How are signals transmitted between neurons?
Signals are transmitted within neurons electrically. Signals are transmitted between neuron chemcially
What is the process of neuron communication
- The nerve impulse reaches axon terminal (the presynaptic terminal)
- This triggers the release of neurotransmitters
- neurotransmitters cross synaptic gap taken up by postsynaptic gap on dendrites of next neuron
- Chemical message is then converted back into electrical impulse and the whole process begins again
How do neurotransmitters travel?
In one direction
Why do neurotransmitter travel in one direction?
Neurotransmitters are released from. the presynaptic neuron terminal and received by the postsynaptic neuron
Neurotransmitters have two effects on neighbouring neurons, what are these called?
Excitatory effect and inhibitory effect
What is the inhibitory effect neurotransmitters have on other neurons? What is an example of a neurotransmitter having an inhibitory effect?
Neurotransmitter act by making the neuron more negatively charged so they are less likely to fire. For example low levels of serotonin have been linked to depression
What is the excitatory effect neurotransmitters have on other neurons?
Other neurotransmitters increase the positive charge to make the neuron more likely to fire. For example caffeine encourages dopamine to be released into synapses. This makes the erpson feel more alert and able to focus
What is the process of stimulation?
The process of stimulation is the process whereby the sum of excitatory and inhibitory signals at any one time has to reach the threshold in order to trigger the action potential of the postsynaptic neuron
What is the difference between a neuron and a neurotransmitter?
Neurons are nerve cells whereas neurotransmitters ae chemicals that communicate signals from one neuron to another across the synapse
Give one difference between the autonomic nervous system and the somatic nervous system? (responsibilities)
The autonomic nervous system is responsible for functions like stress response and the somatic nervous system is in control of muscle movement
