Module 1.3: Neuron, Neural Firing, Neurotransmitters, and Psychoactive Drugs Flashcards
(101 cards)
What is a neuron?
It is a nerve cell that is the basic building block of the nervous system
What are the parts of a neuron?
- Dendrites
- Cell body
- Axon
- Myelin Sheaths
- Terminal branches of axon
What are dendrites?
Branching extensions of neurons that receive messages from other neurons
What is the soma?
AKA cell body - contains the nucleus, the cell’s life-support center
What is the axon?
it passes electrical messages from the cell body to the axon terminals; attached to the soma
What is the myelin sheath?
It is a fatty layer that protects the axons of certain neurons and makes messages within a neuron travel faster
When does the myelin sheath begin to develop?
Before birth and continues into adulthood
What is myelination? When does it occur?
Myelination is the process of formation of myelin sheath - it helps with planning, logic, decision-making, and impulse control
It occurs during preteen years in the brain’s frontal lobes (which fully develop around age 25)
What is Multiple Sclerosis?
It is an autoimmune disease that results from myelin sheath deterioration, causing muscle control loss
What do terminal branches of the neuron do?
Contain terminal buttons, which hold vesicles ; found at the ends of each axon
What are vesicles?
The sacs that hold neurotransmitters
What do glial cells do?
Support, nourish and protect neurons; provide nutrients and myelin, guide neuron connections, and clean up ions and neurotransmitters
Why do glial cells provide nutrients to neurons?
Because neurons cannot feed themselves or do these functions for themselves
What is the synapse?
It is the gap or space between the tip of the sending (presynaptic) neuron and the dendrite of the receiving (postsynaptic) neuron
What is the synapse also known as?
Synaptic gap - synaptic cleft
What is a neurotransmitter?
It is the chemical messenger of the nervous system; it travels across the synapse and binds to receptor sites on the receiving (postsynaptic) neuron
What is a neural impulse?
It is the influx of the +ve ions moving like falling dominos in the axon of the neuron
How is a neural impulse generated?
If the combination of chemical signals received by a neuron’s dendrites exceed a minimum strength or threshold, the neuron fires, transmitting an action potential down its axon in a chemical-to-electrical process
What is a threshold?
It is the level of stimulation required to trigger a neural impulse
When is a threshold reached?
When the excitatory “go” messages overwhelm the inhibitory “stop” messages
What is the threshold value?
-55 mV (millivolts)
What is an all-or-none response mean?
Neural impulses are not “strong” or “weak” = action potentials have the same strength
therefore, neural firing happens at full response or not at all
What does a “strong” sensation equate to?
A large quantity of action potentials
What are neurotransmitters divided into?
Excitatory and Inhibitory Signals