Neurons And Synaptic Transmission Flashcards
Add pictures of neurones
Dendrites function
Carry nerve impulses from neighbouring neurons towards the cell body
Axon
Carries the nerve impulse away form the cell body
Myelin Sheath
A fatty layer around the axon which protects and insulates the axon and speeds up electrical transmission of the impulse.
Nodes of Ranvier
Gaps in the myelin sheath which speed up the transmission by forcing it to “jump” across gaps in the axon.
What are the three types of neurons?
Motor, relay and sensory
What is the role of the sensory neuron?
To carry messages from the PNS to the CNS. found in receptors such as the eyes, ears, tongue and skin
What is the role of the motor neuron?
To connect the CNS to effectors such as muscles and glands. They have short dendrites and long axons.
What is the role of the relay neuron?
To connect the sensory neurons to the motor neurons or other relay neurons. They have short dendrites and short axons. NO MYELIN SHEATH
What is synaptic transmission?
The process by which a nerve impulse passes across the synaptic cleft from the presynaptic neuron to the postsynaptic neuron
What is excitation?
When a neurotransmitter increases the positive charge of the postsynaptic neuron, increasing the likelihood that the neuron will fire. E.g. adrenaline
they are the nervous system’s “on switches”.
What is inhibition?
When a neurotransmitter makes the charge of the postsynaptic neuron more negative, decreasing the likelihood that the neuron will fire. E.g. Serotonin
Inhibitory neurotransmitters are like the nervous system’s “off switches” and are generally responsible for calming the mind and body inducing sleep and filtering out unnecessary excitatory signals
What is a neurotransmitter?
A chemical messenger that helps transfer the electrical impulse across the synapse from the presynaptic to the postsynaptic neuron
What is summation?
The net result of adding up the excitatory and inhibitory neurotransmitters binding to the receptors- determines whether or not the neuron fires
Describe the process of synaptic transmission
x Nerve impulse travels down axon of presynaptic neuron and then reaches the terminal button.
x At the end of the axon, there are a number of sacs known as synaptic vesicles. These contain neurotransmitters.
x The synaptic vesicles release neurotransmitters which transfer electrical impulses into chemical messages.
The neurotransmitters diffuse across the synapse and bind to receptors on surface of postsynaptic neuron- has either inhibitory or excitatory effect
x Likelihood of cell firing determined by summation
What are neurons?
Neurons are the information processing units of the brain responsible for sending, receiving, and transmitting electrochemical signals throughout the body.
