2.4: Neural Firing Flashcards
Neurons
Our body’s nerve cells which make up the nervous system.
How Does a Neuron Fire?
For a neuron to fire, or communicate with another neuron, information must first be gathered in by the dendrites of the receiving neuron. From there, the information passes through the cell body to the axon.
Dendrite
Receives information and transfers it to the cell body.
Cell Body/Soma
The neuron’s support center.
Axon
Passes messages to its terminal branches.
The neural impulse goes through the axon and is an electrical signal.
Myelin Sheath
A layer of tissue that covers the axon and speeds up neural impulses.
Without a myelin sheath, there is a loss of muscle control.
Terminal Branches
Pass on chemical messages to other cells and parts of the body.
Action potential
Must occur for the message to continue to travel down the axon.
Threshold Being Met
Meaning it has received enough stimulation from the original sending neuron.
What Would Happen If The Threshold is Met?
If this threshold is met, the action potential occurs and the message travels down the axon via a process of depolarization.
Depolarization
The process that carries the neural impulse through the axon, action potential is what must happen for the process to occur.
What Would Happen If The Threshold is Not Met?
If the threshold is not met, nothing happens.
All-Or-None Response
Neurons either fire, or they don’t.
Two Types of Signals/Neurotransmitters
Excitatory Signals/Neurotransmitters & Inhibitory Signals/Neurotransmitters.
Excitatory Signals/Neurotransmitters
Pushes neuron’s “accelerator”; makes a neuron more likely to reach action potential and fire.
Inhibitory Signals/Neurotransmitters
Pushes a neuron’s “brake”; makes it less likely for a neuron to reach action potential.
What does Terminal Branches Contain?
The terminal branches of a neuron contain neurotransmitters which are then released.
These neurotransmitters cross the synaptic gaps between neurons and are gathered in by dendrites of a new neuron, continuing the communication process.
Synapse
Where two neurons meet and neurotransmitters are released into it.
Types of Synapses
Electrical & Chemical Synapses.
Electrical Synapse
Relays quick messages to another cell.
Chemical Synapse
Sends messages slowly to another cell.
Where are Neurotransmitters Stored in?
Neurotransmitters are stored in vesicles in the axon terminal.
What Happens When There is a Neural Impulse?
When there is a neural impulse, the vesicle binds with the edge of the axon terminal and the neurotransmitters are released into the synaptic cleft.
What Happens When There is a Neural Impulse?
When there is a neural impulse, the vesicle binds with the edge of the axon terminal and the neurotransmitters are released into the synaptic cleft.
What Happens When There is a Neural Impulse?
When there is a neural impulse, the vesicle binds with the edge of the axon terminal and the neurotransmitters are released into the synaptic cleft.
Reuptake
A process in which the neurotransmitters are absorbed back into the original neuron, if they do not find a home on the dendrites of another neuron.
Neurotransmitters
Act as agonists or antagonists in our body.
Antagonist Neurotransmitter
Binds to the dendrites of a neuron and prevents or blocks its response.
Agonists
Bind to receptor sites and mimic the effects of a specific neurotransmitter.
Opiates are an example of an agonist as they mimic the effects of endorphins in our body (which is why they produce a morphine-like effect).
Acetylcholine (ACh)
Function: Enables muscle action, learning, and memory.
Examples of Malfunctions: With Alzheimer’s disease, ACh-producing neurons deteriorate.
Dopamine
Function: Influences movement, learning, attention, and emotion.
Examples of Malfunctions: Oversupply –> schizophrenia Undersupply –> tremors and decreased mobility in Parkinson’s disease.
Serotonin
Function: Affects mood, hunger, sleep, and arousal.
Examples of Malfunctions: Undersupply –> depression. Antidepressant drugs raise serotonin levels.
Norepinephrine
Function: Helps control alertness and arousal.
Examples of Malfunctions: Undersupply can depress mood.
GABA
Function: A major inhibitory neurotransmitter.
Examples of Malfunctions: Undersupply –> seizures, tremors, and insomnia.
Glutamate
Function: A major excitatory neurotransmitter; involved in memory.
Examples of Malfunctions:
Oversupply –> over stimulates the brain –> migraines and seizures (why lots of people avoid MSG in their food).
Endorphins
Function: Diminishes the perception of pain and acts as a natural sedative.
Examples of Malfunctions: Undersupply –> can cause depression, anxiety and moodiness.
What Happens After Firing?
After a neuron fires and reaches action potential, it goes into its refractory period, where it cannot fire.
Refractory Period
This period of rest prevents one signal from combining with another.
