Nerve tissue II Flashcards
What are the three divisions of gray matter in the brain?
- cerebral cortex
- cerebellar cortex
- nuclei
What is the cerebral cortex? Cerebellar?
multiple layers of nerve cell
bodies that form a folded sheet on brain surface
Cerebellar is the same, just on the cerebellum
What is the nuclei of the brain?
collections of nerve cell bodies and neuroglia embedded deep within the brain
What is the white matter of the brain?
myelinated nerve cell axons with some unmyelinated axons and neuroglia
Where does the myelin in the CNS come from (which type of cell)?
Oligodendrocytes
Why is white matter white?
Myelin content of axons
Where are cell bodies located in the CNS?
In the gray matter
Where are axons located in the CNS?
In the white matter
Where are neuroglia located in the CNS?
In both white and gray matter, but mostly gray
What are cell bodies called inside the CNS? In the PNS?
CNS = nucleus PNS = ganglia
Where are cell bodies located in the PNS?
ganglia
Where are axons located in the PNS?
in the nerves
What are the six different types of axon bundles found in the CNS? What type of matter are these found in?
- Tracts
- Fasciculi
- Lemnisci
- Commissures
- Brachii
- Peduncles
All are white matter (axons)
What are the three major components of the PNS?
Nerves (CN and spinal)
Plexuses
Ganglia
What are the five plexuses?
- Cervical
- Brachial
- Lumbar
- Sacral
- Periarterial
Is the dorsal root ganglia motor or sensory?
Sensory
What are the two functional subdivisions o the nervous system?
Voluntary and involuntary
Which subdivision of the NS is the ANS apart of?
the involuntary
What is the enteric division of the ANS?
Controls peristalsis, gland secretions, blood flow through GI
What is the thoracolumbar outflow?
Sympathetic ANS
What is the craniosacral outflow?
parasymp ANS
Which part of the ANS is responsible for homeostasis?
Parasymp
What are the spinal nerves that are in the parasympathetic nervous system?
S2-4 keeps the penis off the floor
True or false: the enteric division functions independent of the CNS
True
What are the three classifications of synapses?
- Axodendritic
- Axosomatic
- Axoaxonic
What is an axoaxonic synapse?
Synapse between one axon and another AXON
What are the two ways that synapses can transmit a signal?
Electrical or chemical
Where are electrical synapses found in the human body?
human brain stem, retina and cerebral cortex
How are electrical synapses connected?
Via gap junctions
Which is more rapid, electrical or chemical synapses?
Electrical
What is the presynaptic density?
consists of cone-shaped
structures that represent the active site of the synapse
What is the post synaptic density?
complex of proteins, binding neurotransmitter receptors
What type of channels are at the post synaptic membrane?
Ligand-gated Na channels
What are the two models of synaptic transmission/
Kiss and run (porocytosis)
Collapse fusion (exocytosis)
What are the histological characteristics of a presynapse?
Has tons of vesicles
What are the cells that line the choroid plexus?
Ependymal cells
Where is the choroid plexus located?
In the ventricles of the brain
What type of junction is between the ependymal cells of the choroid plexus?
Zonulae occludentes
Does the brain have lymphatic vessels?
No
What are arachnoid villi?
The villi that compose an arachnoid granulation
Where does nerve injury and regeneration occur?
In the PNS
What is Wallerian degeneration?
Anterograde degeneration of damaged axons
What are the aterograde steps of axon regeneration?
- Distal segment of axon degenerates
- The segment is eliminated by phagocytic cells from Schwann cells
- Schwann cells proliferate with basal lamina
What are the retrograde changes that occur during axon regeneration?
- Cell body swells and nissl bodies+nucleus move to periphery
- free ribos
- axon sprouts and reconnects with target
A summation of arachnoid vili form what structure?
Arachnoid granulations
What are the four things needed for regeneration of an axon?
macrophages, fibroblasts, basal lamina, and Schwann cells
