Components of the Nervous System - Neurons

What is Neuron/Nerve Cell

• The basic structural unit or building block of the nervous system
• The smallest nerve cell is less than a millimeter in size while the largest may be more than a meter in length
• Nerve cell holds the secret how the brain works
• Nerve cell has two specialized functions: [1] to receive signal [2] the longer extension is for transmitting signals

Acethylcholine – is a neurotransmitter or chemical substance that travels across synaptic gap, stimulates the next neuron, carrying the impulse from one neuron to another

Glial cells – are non-neural cells that hold the neurons in place

Myelin Sheath – is the covering on the axons of neurons, which insulate them, making the transmission of impulses faster

Parts of a Neuron

• Dendrites – receive impulses and carry them toward the cell bodies. These are short branches of fibers branching out like roots from the cell body
• Axon – carries impulses away from the cell body toward other neurons. These are the longer branches / fibers at the end of a cell body
• Synaptic Terminals / End Brushes – are fine collaterals at the end of the axon which have small swellings. It does not actually touch the neuron it stimulates. It has a slight space or synaptic gap between the synaptic terminal and the dendrites of the receiving neuron

Types of Neuron

• Sensory Neurons /Afferent Neurons – transmit impulses received by the receptors to the CNS.
• Motor Neurons / Efferent Neurons – carry outgoing signals from the brain to the spinal cord to the muscles and glands
• Interneurons / connector Neurons / Association Neurons – connect neurons between sensory and motor neurons. These also receive signals from the sensory neurons and send impulses to the other neuron. These are found in the brain, eyes and spinal cord only.