Exercise 15: Histology of Nervous Tissue
What are the six types of neuroglia (glial cells), and what nervous system are they apart of?
1. Astrocytes: Central 2. microglial cells: Central 3. ependymal cells: Central 4. Oligodendrocytes: Central 5. Satellite cells: Peripheral 6. Schwann cells: Peripheral
Describe how the Schwann cells form the myelin sheath encasing the nerve fibers.
A Schwann cell becomes apposed to an axon and envelopes it in a trough. It then begins to rotate around the axon, wrapping it loosely in successive layers of its plasma membrane.
efferent neuron
Neuron that conducts impulses away from the CNS to muscles and glands.
afferent neuron
Neuron that conducts impulses toward the CNS from the body periphery.
What is a nerve?
a bundle of axons wrapped in connective tissue
interneuron
a neuron serving as part of the conduction pathway between sensory and motor neurons
Amyotrophic lateral sclerosis is a neurodegenerative disease in which motor neurons are progressively destroyed. Excess levels of the neurotransmitter glutamate have been implicated in this process. Which type of neuroglia would play a role in controlling glutamate levels in the chemical environment of neurons?
astrocytes because they control the chemical environment of neurons.
nerve
bundle of axons in PNS
tract
bundle of axons in the CNS
Neurotransmitters
chemicals released by neurons that stimulate or inhibit other neurons or effectors
ganglion
collection of nerve cell bodies in the PNS
Nucleus
collection of neuron cell bodies found within the CNS
chromatophilic substance
essentially rough endoplasmic reticulum, important metabolically
peripheral nervous system
ganglia and spinal and cranial nerves
Axon
impulse generator and transmitter
myelin sheath
insulates the nerve fibers
neurofibril
involved in the transport of substances within the neuron
snaptic cleft
junction or point of close contact between neurons
What type of neuron is multipolar?
motor neuron
Peripheral neuropathy has a variety of causes. Worldwide, the most common cause is leprosy, also known as Hansen's disease. Would you expect peripheral neuropathy to cause damage to tracts or to nerves? Why?
nerves because leprosy affects the skin and skin is part of the PNS
What substance is found in synaptic vesicles of the axon terminal?
neurotransmitters
Where is the endoneurium located?
on the outside of the myelin
Dendrite
receptive region of a neuron
axon hillock
region of the cell body from which the axon originates
axon terminal
secretes neurotransmitters
What type of neuron is unipolar?
sensory neuron
cell body
site of the nucleus and most important metabolic area
Neuroglia
specialized supporting cells in the nervous system
Where is the perineurium located?
surrounds a bundle of axons
central nervous system
term for the brain and spinal cord collectively
what anatomical characteristic determines whether a particular neuron is classified as unipolar, bipolar, or multipolar?
the number of processes that extend from the cell body
What is the function of the connective tissue wrappings found in a nerve?
to protect and insulate nerve fibers
The basic functional unit of the nervous system is the neuron. What is the major function of this cell type?
to send messages from one part of the body to another
microglial cells
type of neuroglia that act as a phagocyte in the CNS
Astrocytes
type of neuroglia that controls the chemical environment around neurons in the CNS
Oligodendrocytes
type of neuroglia that forms the myelin sheath in the CNS
Schwann cells
type of neuroglia that forms the myelin sheath in the PNS
ependymal cells
type of neuroglia that lines CSF-filled cavities
sattelite cells
type of neuroglia that surrounds the cell body of a neuron found in the PNS
