Introduction to Axon
If we compared the human body to a computer, then the nervous system would be the motherboard. It is the main control unit for the body, and through the nervous system, other functions in the body are regulated. Therefore, the nervous system is one of the most important systems in the human body as its effects can be seen in all other systems.
The nervous system communicates through the use of cells, called neurons. These cells participate in cell-to-cell communication for the purposes of regulating bodily processes. This is done through the generation of electrochemical stimulation that relays from neurons to other neurons and effector (target) cell. The delivery of this stimulation is going to be mediated by a portion of the neuron known as the axon.
Structures of Axons
Axons are extended regions of the neuron cell membrane. It starts from a portion of the cell body, known as the axon hillock. From there, the axon extends towards the target cell to what is known as the terminal. Along the cell membrane of the axon will be ion channels and ATP-driven pumps that will regulate ion concentrations within the axon. These ion concentrations will establish the resting membrane potential, which is the electrochemical charge of the membrane when the neuron is at rest.
Some axons will also have additional structures to assist with communications. In areas of the nervous system that require faster communication, the axons will contain insulation, known as myelin sheaths. This insulation speeds up the transmission of cell-to-cell communication and stimulation. Not all axons will have these sheaths, but the ones that do function quicker.
Communication via Axons
At rest, the membrane potential of an axon is typically -70 millivolts. This charge is established by ATP-driven pumps in the membrane known as sodium/potassium pumps. This pump ensures that more positive ions are outside of the membrane compared to inside of the cell. When the neuron depolarizes, or becomes positively charged, it will transmit this communication down the axon by way of voltage-gated, which means electrically controlled, ion channels that open up to allow for the charge to relay along the axon. This takes place until the charge reaches for the axon terminal.
The axon terminal is the site of neurotransmitter release. Neurotransmitters are chemical messengers that are released from the axon and received by effector cells. This process is critical for delivery of the message to the cells and tissues that are being controlled. The terminal, then, is the final point of stimulation in the axon before the charge is delivered.
The axon is an extended region of the neuron cell membrane and the portion of the cell responsible for delivering cell-to-cell communication. Neurons are the cells that communicate and the axons are merely a smaller part of the larger story. This is sometimes sped up by myelin sheaths, which are a type of insulation that speeds up the transmission of cell-to-cell communication and stimulation. Through transmission of electrical charges and the release of neurotransmitters, axons are able to control target cells in order to regulate bodily processes. Beginning at the axon hillock, this process is completed through the movement of ions. Ion concentration will establish the resting membrane potential, which is the electrochemical charge of the membrane when the neuron is at rest and is approximately -70 millivolts. Axons are the key components of neuronal function for the nervous system and other systems under nervous control.
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