Structure of aNeuron
Types of Neurons and theirbasic structures.
The Neuron
A Neuron is a specialized type of cell thatcarries messages throughout the nervoussystem.
Message are transmitted through anelectrochemical process calledneurotransmission.
Neurons have structures similar to other cells.
They have a cell membrane
They have a nucleus containing DNA
And organelles such as Ribosomes andMitochondria.
Three basic types of Neurons
Sensory Neurons carry signals from the sensoryorgans to the central nervous system alongafferent nerve fibers.
Inter Neurons carry signals from one neuron toanother either within the central nervoussystem or from sensory to motor neurons.
Motor Neurons carry signals from the CentralNervous System to the motor cells or musclesalong efferent nerve fibers.
Basic Structure of a Neuron
File:Neuron-figure-notext.svg
Soma (cellbody)
Dendrites
Axon
TerminalButtons
Myelin Sheath
(Schwann Cells)
Image: Biological NeuronSchema. Wikimedia Commons.Nicolas.Rougier
Parts of a Neuron
Soma or Cell body - contains cytoplasm and thenucleus, which includes the chromosomes.Mitochondria in the cell body performmetabolism. Ribosomes synthesize proteins.
Dendrites – receive input from previous neurons.
Axon – Carries the electrical impulse (actionpotential) to the terminal buttons.
Terminal Buttons – Contains vesicles that releasechemical messengers (neurotransmitters) acrossthe synaptic gap to other neurons.
Image of real neurons
File:Smi32neuron.jpg
Neurotransmission
https://science.education.nih.gov/supplements/nih2/addiction/images/guide/fig2.2.gif
The Synapse
The Synapsedefines theneural pathway.
The type ofneurotransmitterused ensuresthat specificneural functionsoccur.
http://content.answcdn.com/main/content/img/oxford/Oxford_Body/019852403x.synapse.1.jpg
Neurotransmitters
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Specificity ofNeurotransmission
If we only hade a singleneurotransmitter then theonly way to ensurespecificity would bethrough strictlydelineated pathways.
http://what-when-how.com/wp-content/uploads/2012/04/tmp3675_thumb_thumb.jpg
Serotonergic and noradrenergic pathways in depression. Schematic diagrams illustrating the distribution of the: (A) serotonergic pathways that arise from the raphe nuclei, and (B) noradrenergic pathways that arise from the nucleus locus ceruleus and other regions of the brainstem reticular formation. Both of these monoaminergic systems project to all parts of the central nervous system, but in particular, to the forebrain.
Stimulus - Response
A specific stimulus:
Light
Sound
Pressure
Chemical
Yields a specific response:
Color
Pitch
Texture
Odor
Neurotransmission
The complexity of our nervous system allowsus to not only experience the world aroundus, but contemplate it’s meaning even it’svery existence.
“If our brains were simple enough for us tounderstand them, we'd be so simple thatwe couldn't.”
Ian Stewart