Download THE NEURON (Slides 4 to 14) • Based on the PowerPoint attached

THE NEURON (Slides 4 to 14)
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Based on the PowerPoint attached/ your notes, explain the three stages a neuron takes
when it fires
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Stage 1: The neuron is at rest
A neuron is resting when its membrane forms a partial barrier between the inside and
outside of the neuron. The solution contains electrically charged particles called ions.
When the neuron is at rest, there are more negative ions on the outside which is called the
resting potential. A resting neuron is similar to a guitar string which is pulled and not
released. The release of tension is needed to generate the neurons potential.
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Stage 2: The neuron is stimulated & depolarized
An incoming message stimulates the neuron and the inflow of sodium coming from the
pores in the cell membrane depolarizes the neuron and the inside becomes positively
charged which in turn, sets out a chain reaction. More sodium begins to flow in, and an
electrical charge, called a neural impulse or action potential travels down the axon. This
can be compared to a fuse burning from one end to the other.
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Stage 3: The neuron fires
The firing is caused by an influx of sodium. It takes a few milliseconds to ‘fire’ sending
an electrical impulse to the synapse, the threshold of excitation must be exceeded for the
neuron to fire. The connections of the neurons to other neurons determine whether the
neuron is likely to fire or not as its receiving messages from these neurons. This is a
constant interplay of excitatory or inhibitory messages.
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What are the nerve cells of the brain called? How many of these does the average human
have?
The nerve cells of the brain are called neurons. The average brain has 100 billion neurons.
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What makes the neuron different from other cells?
Neurons are different from other cells because fibers that extend out from the cell body,
allowing it to receive and transmit messages – this are called dendrites.
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What is an axon?
An axon is a single long fiber extending out from the cells body—its job is to pick up
incoming messages from other neurons.
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What is the white fatty covering that covers the axon? What's its function?
The white fatty covering that covers the axon is the myelin sheath. Its function is to
provide insulation, and ensure that signals from adjacent neurons don’t interfere with
each other. Myelin also increases the speed of transmission.
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What are neurons that collect messages from the sense organs and carry them to the brain
called?
Neurons that collect messages from the sense organs and carry them to the brain are
called sensory neurons.
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What are neurons that carry messages from the spinal cord or the brain are called?
Neurons that carry messages from the spinal cord or the brain are called motor neurons.
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What do glial cells do?
Glial cells hold the neurons in place. Also, glial cells remove waste and prevent harmful
substances from passing from the bloodstream to the brain.
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How do neurons ‘talk to each other’?
Neurons ‘talk to each other’ through electrochemical impulses.
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What happens to the membrane of the neuron when it is resting?
When a neuron is resting, its membrane forms a partial barrier between the inside and the
outside of the neuron – the solution contains electrically charged particles called ions.
When the neuron is at rest – where are there more negative ions, on the inside or the
outside?
The more negative ions are on the inside
What does an inflow of sodium from the pores in the cell membrane do?
The cell membrane depolarizes the neuron and the inside becomes positively charged.
THE SYNAPSE (Slides 15 -20)
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In your notes packet, label the synapse using the information on slide 18 of the attached
PowerPoint.
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What is the name of the gap between neurons?
The gap between the neurons is called the synapse.
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What is at the end of each axon?
At the end of each axon is a synaptic button.
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What must the neuronal impulses do to travel to the next neuron?
The neuronal impulse reaches the end of an axon and must cross the synaptic gap to
travel to the next neuron.
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What is the transfer between neurons made by
This transfer is made by chemicals called neurotransmitters.
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What do the synaptic vesicles release when the neural impulse reaches the terminals?
Synaptic vesicles release neurotransmitters when the neural impulse reaches the
terminals in which neurotransmitters travel across the synaptic space and affect the
next neuron.
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Why is this described as a ‘lock & key’ process?
Each neurotransmitter has its own specific receptor cite as a key fits into a lock.
NEUROTRANSMITTERS AND THEIR EFFECTS (Slides 21-28)
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What is at the end of each axon?
At the end of each axon is a synaptic button.
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Neurotransmitters need to cross the synaptic gap and bind onto receptor cites.
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Give four clinical characteristics of depression
Characteristics of depression include loss of weight, sadness, suicidal thoughts, and disordered
sleep patterns.
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What did Kravitz (1988) find out about serotonin?
When Kravitz injected lobsters with serotonin, he found that they heaved like a dominant animal,
thus strengthening his research that serotonin has a role in social behavior.
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What is serotonin? What role does it play in humans and animals?
Serotonin is a neurotransmitter and it has a connection with depression. It functions in humans
through the regulation of intestinal movements, the regulation of mood and sleep, and cognitive
functions including memory. Therefore, it affects humans and animals by having a role in their
social behavior.
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What is the monoamine hypothesis?
The monoamine hypothesis states that low levels of neurotransmitters such as serotonin in the
synaptic gap between neurons in the brain are associated with depression.
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What does SSRI stand for?
SSRI stands for Selective serotonin reuptake inhibitors.
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How do these work?
They are psychoactive drugs that work by increasing the amount of the levels of monoamines at
the synapse to affect human behavior.