Structure of a Typical Neuron
Myelin
-A mixture of proteins and phospholipids forming a whitish insulating sheath around many nerve fibers -Function: increasing the speed at which impulses are conducted.
Soma or Cell Body
-Contains nucleus, nucleolus and usual organelles surrounded by cytoplasm -Nissl Bodies (made up of rough endoplasmic reticulum (RER) are e.g. organelles -What is the function of RER: protein synthesis -Function of Nissl Bodies: Neurotransmitter production
Synaptic End Bulb
-Found at end of axon terminal & contain synaptic vesicles that are filled with neurotransmitters
Axon
-One axon per neuron -Transports information away from the cell body of a neuron
Projections (Nerve Fibers)
-Projections are attached to soma -Two types of projections: +Dendrites +Axons
Typical Neurons
-Their size and shape vary -Are made up of two parts: +Soma (Cell Body) +Projections (Nerve Fibers) -Cluster of cell bodies of neurons in CNS are called Nucleus and in PNS are called Ganglion (Ganglia)
Dendrites
-Usually short and multiple in number -Profuse branching -Unmyelinated: Lacking a myelin sheath -Transports information towards the cell body of a neuron
Axon Hillock
-Wide area (cone shape) -Atom is attached to the cell body of the neuron -Unmyelinated: lacks myelin sheath
Nodes of Ranvier
Gaps in the myelin sheath
Myelinated Nerve Fibers
Matter that surrounds a nerve fiber
Axon Collaterals
Side branches of the axon
Axon Terminal (Telodendira)
The endpoint of a neuron where neurotransmitters are stored
Schwann Cell
a cell in the peripheral nervous system that is wrapped around a myelinated axon, providing one segment of its myelin sheath
Unmyelinated Nerve Fiber
lacks myelin sheath; Schwann cells are not wound around the axons but simply form a groove or valley in which the axon sits; appear GRAY in color.