CNS Components
Brain and Spinal Cord; “President”
Peripheral Nervous System Components
Cranial Nerves, Spinal Nerves, Ganglia; “Workers”
Ganglion
Group of neuron cell bodies located outside CNS
Sensory Division
Receives information FROM body and transmits it TO the CNS for processing
Somatic Sensory Component
Receives sensory information from skin, joints, muscle, and special senses (Vision, Hearing, Balance)
Visceral Sensory Component
Receives sensory information from blood vessels and viscera (Organs)
Motor Division
Transmits information FROM the CNS TO muscles and glands
Somatic Motor Component
Innervates Skeletal System; “Voluntary”
Autonomic Motor Component
Innervates smooth muscle, cardiac muscle, and glands of viscera (organs)
Neurons
Respond to stimuli and conduct nerve impulses. Primarily Amniotic, not undergoing cell division
Glial Cells
Support and Protect Neurons, Numerous more of these and divide by Mitosis.
Cell Body Function
Is the neurons “Control Center” or “Head”
Nucleus Function
Contains Nucleolus , while also containing nucleolus for protein synthesis
Chromatophilic Substances (Nissl Bodies) Function: Rough ER
Look like dark clumps within Cytoplasm
Responsible for Protein Synthesis
Dendrites Function
Short Nerve Cell Processes. Receives input and send nerve impulses to cell. Neuron can have one or many dendrites
Axon Function
Long Nerve Cell Process: Sends the Output
Multipolar Neuron
One Axon with Many Dendrites
Most Common
Example; Motor Neurons, Interneurons
Bipolar Neuron
Two Processes: One Axon and One Dendrite
Limited In Location (Rare)
Example: Retina of Eye, Olfactory Neurons in Nose
Unipolar Neuron
Common
Single Process comes off of the cell body and divides into two branches. One process attaches to Cell Body, the other to Axon.
Example: Sensory Neurons of PNS, Rare
Sensory Neurons Functions
Brings Information TO the CNS
Example: Unipolar and Bipolar Neurons
Motor Neurons Functions
Takes information FROM CNS to other parts of the body
Example: All are Multipolar Form
Interneuron Function
Helps coordinate and integrate information between sensory and motor neurons.
Example: CNS, the ‘translator/mediator’. Multipolar in form
Satellite Cells
Surround neuron cell bodies in spinal ganglia
Protect Cell Bodies; Regulate nutrient exchange and waste removal.
Located in PNS
Neurolemmocytes
Myelinate axons in PNS
Myelination
Myelin is a protective covering around axon; insulates axon and helps produce faster nerve impulses. Can also regenerate damaged PNS axons
Astrocytes
Regulate transfer of material from blood to the brain - helps the workings of “blood-brain barrier”
Helps make blood vessels less leaky and keeps harmful substances away from the brain. Chemotherapy can’t pass this barrier. Dopamine can’t pass barrier but L-Dope can. So can cocaine.
Astrocytes Disease
Parkinson Disease. It is caused by a decrease of neurotransmitter called Dopamine
Oligodendrocytes
Myelinate axons in CNS
Microglia
Phagocytize damaged neurons
Replicate when there is CNS damage and need to clean up
Ependymal Cells
Line central canal and ventricles - Help circulate cerebrospinal fluid (CSF)
Myelination (2)
Dendrites are not myelinated. Only axons larger than two micrometers are myelinated as well.
Myelination Procedure in PNS (1)
Neurolemmocyte wraps around a 1 mm portion of an axon successively
Myelination Procedure in PNS (2)
Cytoplasm and nucleus of neurolemmocyte gets “squeezed” to the outside
Myelination Procedure in PNS (3)
Inner successive layers of cell membrane make up the myelin sheath
Neuolemmocytes Seperation
Separated by neurofibril nodes. These are gaps between two adjacent neurolemmocytes. Unmyelinated axons located here.
Oligodenrocytes in CNS
Myelinated 1mm portions of many axons
