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Action Potential - By the Nutty Neurons!
Transcript of Action Potential - By the Nutty Neurons!
Neurons and The Action Potential Explanation of Terms By: Leah Benz, Sajni Vora, and Anna Johnson A neuron is a nerve cell that passes information electrically and chemically throughout the body Neuron An axon is the longest part of the neuron,
attached to the cell body.
It passes the message from the dendrites to the
terminal branches of the axon.
The axon and its membrane are
what determines whether an action potential
is fired or not! Axons Action Potential Action potential is a short electrical impulse fired by a neuron to a neighboring neuron. This is how neurons communicate chemical messages to each other!
The signal flows through neuron to neuron until it reaches the brain, and then the brain sends instructions back telling the body how to respond. If the signal reaches the threshold, the neuron fires an action potential. If the neuron does not reach the threshold, it will not fire. It doesn't matter how strong the stimulus is as long as it at least reaches the threshold. Like a gun, the neuron either fires or it doesn't. This is known as the all-or-nothing response!* All or Nothing Response An event causes the resting potential to move and
when the depolarization reaches -55 mV a neuron
will fire an action potential of a fixed size.
If the neuron doesn’t reach this threshold level,
then no action potential will fire. Threshold Refractory Period Neurotransmitters are chemicals that are released
from neuron at the presynaptic nerve terminal.
They cross synapses in order to transmit signals
between neurons. At the end of axon endings of
motor neurons, these chemicals may stimulate
muscle fibers. Neurotransmitters http://webspace.ship.edu/cgboer/genpsyneurotransmitters.html
http://tinyurl.com/8lhybcf Works Cited So..Why did Dr. Nottoobrite's patient slap him when he attached the wires to his arm? When Dr. Nottoobrite attached the wires to the patient’s arm, he felt it and it triggered him to move his arm in response. So, here's a recap! This happened because
the wires stimulated
the arm with
electrical signals. These electrical signals then traveled up the arm to the spinal cord and into the brain via the neurons. The brain interpreted that stimulation and told the patient, “HEY! YOU’RE BEING ELECTROCUTED!” This caused the patient’s arm to twitch and knock Dr. Nootrobrite to the floor Before Dr. Nottoobrite attached the wires to the arm of his patient, the neurons located in the patient's arm were at resting potential.
At resting potential, the outside of the neuron has positively charged sodium ions and the inside of the neuron has negatively charged potassium ions. When the Doctor attached the two wires to the patient's arm, hooked to the battery, the battery sent a charge to the neurons in the patient's arm. This electrical charge created a stimulus at the beginning of the neuron's axon. From there, the action potential traveled along the axon of the nerve
The action potential caused the next section of the axon to reach the threshold, triggering it to open its channels and allowing sodium ions to rush in Now the next portion of the axon reached the threshold and created an action potential!
This pattern continued down the axon until the action potential reached the axon terminal When an electrical signal stimulates the sodium channels to open, sodium ions flow in and increase the axon's positive charge, producing an action potential
so during the refractory period, or resting pause, the sodium channels pump the excess positive ions back outside the membrane so it can return to resting potential and get ready for another action potential to fire! The stimulus caused the voltage-gated channels of the first section of the axon to open, allowing positively charged sodium ions to rush in. This created a greater positive charge (from the sodium ions) than negative charge (from the potassium ions) inside the axon. When there were enough sodium ions in the axon, the stimulus reached the threshold and depolarization occurred, firing an action potential! Now that an action potential has been fired, that section of the axon can return to resting potential. The sodium channels that let the positively charged ions in now forced them back outside the membrane during the refractory period, returning the axon to its negative-inside positive-outside state. *The strength of the stimulus can trigger more neurons to fire faster, but it does not affect the action potential's strength or speed! ...Before we jump right in to what happened chemically inside the patient's body, let's explain the concepts that are involved! This is where the neurotransmitters got in the game! When the action potential reached the end of the axon, it triggered the release of a neurotransmitter, which crossed the synaptic gap and binded to receptor sites on the next neuron! The neurotransmitter stimulated the receptor sites, causing the channels in the receiving neuron's axon to open, exciting a new action potential. This process continued until the signal reached the brain and it sent a message back to the body, making it aware of the stimulation and causing the patient's arm to jerk and knock Dr. Nottoobrite to the floor! There were three different types of neurons involved in this communication process:
1. Sensory neurons carried the message from the arm's muscle tissues inward toward the spinal cord and brain for processing
2. Interneurons acted as a middle ground between the sensory input and motor output, carrying information to be processed within the brain
2. Motor neurons carried instructions from the brain and spinal cord to the muscle tissues in the patient's arm, telling it to jerk and slap Dr. Nottoobrite! ...and thus the Curious Case of Dr. Nottoobrite is solved! Thanks for watching!