Biopsych: Neurons And Synaptic Transmission Flashcards
How many neurons are in the nervous system?
100 billion
What percentage of neurons are located in the brain?
80%
What is the primary function of neurons?
Transmit electrical and chemical signals
What are the three types of neurons?
- Sensory neurons
- Relay neurons
- Motor neurons
What do sensory neurons do?
Carry messages from PNS to CNS
What is the structure of sensory neurons?
Long dendrites and short axons
What do relay neurons connect?
Connect sensory to motor and other relay neurons
What is the structure of relay neurons?
Short dendrites and long axons
What do motor neurons connect?
Connect CNS to effectors (muscles and glands)
What is the structure of motor neurons?
Short dendrites and long axons
What is the maximum length a neuron can vary?
Up to a metre
What is the basic structure of all neurons?
Cell body, dendrites, axon, terminal buttons
What does the cell body of a neuron contain?
Nucleus with genetic material
What are dendrites and their function?
Branches that carry nerve impulses to the cell body
What does the axon do?
Carries impulse away from the cell body
What covers the axon?
Myelin sheath
What is the function of the myelin sheath?
Protects axon and speeds up electrical transmission
What are nodes of Ranvier?
Separate the myelin sheath
What are terminal buttons?
Communicate with the next neuron
Where are motor neuron located?
Cell body: In the CNS
Axon: form part of PNS
Where are sensory neurons found?
In the PNS in clusters (ganglia)
Where are most relay neurons found?
Within the brain and visual system
What is the charge of a neuron in a resting state?
Negatively charged
What happens when a neuron is activated by a stimulus?
Inside becomes positively charged for a split second, causing action potential
What does action potential create?
An electrical impulse that travels down the neuron
What is synaptic transmission?
An electrical signal reaches the end of one nerve cell and releases neurotransmitters
What are neurotransmitters?
Chemicals that carry signals between neurons
What happens when neurotransmitters reach the next neuron?
Triggers an electrical signal in the next nerve cell
How do neurons communicate with each other?
In groups (neural network)
What are synapses?
Tiny gaps that separate neurons
What type of transmission occurs WITHIN neurons?
Electrical transmission
What type of transmission occurs BETWEEN neurons?
Chemical transmission
What triggers the release of neurotransmitters?
An electrical impulse reaching the presynaptic terminal
presynaptic terminal: end of neuron
Where are neurotransmitters released from?
Tiny sacs called Synaptic Vesicles
What effect can neurotransmitters have on neighboring neurons?
- Excitatory effect
- Inhibitory effect
What does the neurotransmitter serotonin cause?
Inhibition in the receiving neuron
Leads to a negative charge making it less likely to fire
What does the neurotransmitter adrenaline cause?
Excitation in the receiving neuron
Leads to a positive charge making it more likely to fire
Fill in the blank: Neurotransmitters diffuse across the synapse to the next neuron and are received by _______.
[postsynaptic receptor site]
On the dendrite of the next neuron
What happens to the chemical message after a neurotransmitter crosses the gap?
Converted back into an electrical impulse and the process beings again with the next neuron
