Neurotransmitters and Synapses and How They Communicate

There are 3 types of neurons, the motor neurons, sensory neurons, and interneurons but we will be focusing on the neuron in the first picture, the motor neuron.

The dendrites are what collect signals from the other neurons, the nucleus gives it energy so it may function, the cell body is the life support of the neuron, the axon allows signals to go through it. the axon terminals allow the signals to be sent to another cell, and the myelin sheath (although not shown on this picture) is a cover the surrounds the axon to help speed the neural impulses.

Neurons communicate by sending electrochemical signals called action potential. An action potential is a brief spark that moves down the axon and is caused by the moving of positive ions from inside the axon to outside of them. The charge must reach a certain level of stimulation if it wants to trigger a neural impulse. When a neuron is in resting potential, it means that there are more positive neurons on the outside of the axon and more negative ions inside the axon. When a neuron is stimulated by an incoming message, the neuron starts to depolarize. Depolarizatoin is when the channels of the axon open up to allow sodium (NA+) ions to enter the axon. Repolarization is when the channels open up and allow potassium (K+) ions to leave but make the other nearby segment to depolarize. This chain of events is called the Flow of Depolarization, making it so action potential moves down the axon at a continuous rate.

 

The synapse is the end of the axon and the beginning of another neuron’s dendrites. This is how neurons send signals to each other. There is always a small microscopic gap between the two, which is called the synaptic gap/cleft. (number 3 on the synapse picture) Within the axon of sending neuron (number 7)  are synaptic vesicles which contain neuro transmitters. When action potential goes through the axon of sending neurons, the synaptic vesicles are relaesed and allow the neurotransmmitters out of them. The neurotransmitters proceed to open the receptors on the dendrites of the receiving neuron (number 8) which allow postive ions into the dendrites, allowing the action potential to continue onward.

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