Nervous Tissue/ANS Flashcards
In the brain, Gray matter occupies the ___territory whereas, the white matter occupies the ___ territory
peripheral; internal
gray matter =
neuronal soma and synapses
white matter =
tracts of neuronal processes
what is the organization of the spical cord.
Gray matter occupies the central region, white matter occupies the periphery.
meninges =
dense irregular connective tissue
dura mater consists of ____CT, whereas, arachnoid and pia mater consist of ____ CT
dense irregular; loose
What are the connective tissues of the PNS
Epineurium: the most external nerve fibers
Perinerium: middle nerve fiber(directly surrounds fascicle)
Endoneurium: innermost nerve (around each ind nerve/myelin sheath)
epineurium consists of
dense irregular CT
endonerium is a ___CT
loose CT
perinerium consists of ___CT
in between fibers of dense irregular and loose CT
What are the parts of a typical neuron
- soma (cell body): contains nucleus and nucleolus, & nissl bodies
- Dendritic process
- Axon: axon hillock, axon terminal
soma means
cell body; large eukaromatic nuclueus, nucleoulus, and granules called nissl bodes; rough collections of rough ER. We see them everywhere EXCEPT axon hillock.
what are dendrites and its features
- Neuronal processes that transmit signal toward soma.
- Unmyelinated
- arborize into dendritic trees
- dentdritic spines inc area for synapses to form.
Describe axon and its features
- Transmits signal AWAY from soma
- Arises from soma at axon hillock
- Terminates in synaptic bulb
- may be myelinated
- few branches
- may synapse on soma, dendrite, or synaptic bulb of another neuron
what are the basic neuron types
- Bipolar: sensory neuron ( 1 dendrite and 1 axon)
- Pseudounipolar: sensory; acts as single axon. may have free endings for sensation.
- Multipolar; motor neurons; multiple dendrites coming off and single axon.
- Pyrimidal cell: dendritic processes come off as a tree; cell body also has triangular appearance in cross section.
Where do you find bipolar and psuedounipolar neurons?
look this up
What are the PNS support cells
- Schwann cells: support axons; produce myelin
2. satellite cells: support soma
Even unmyelinated nerve fibers have :
schwann cells
of times it wraps around is determined by:
the nerve fiber with its surface proteins telling the schwann cell how to interact. ; determines the thickness of the myelin sheath.
what are nodes of ranvier
provides site where we could have branching of axons and also axo-axonal synapses. Has to happen in these gaps.
What are the support cells of the CNS
neuroglia
What are the types of neuroglia
- Oligodendrocytes: produce myelin; assoc with multiple axons.
- Astrocytes: provide neurons with nutrients, removes wastes; forms blood brain barrier.
- Microglia: phagocytose debris in nervous tissue
- Ependymal cells: line ventricles; produce CSF (choroid plexus)
What happens if damage is too great
- Portion of nerve fiber distal to injury degenerates, myelin sheath also fragments
- Within the neuronal cell body, the nucleus moves peripherally instead of centrally and Nissl bodies degenerate. If damage is too great and neuron cant regenerate cell will die.
What if damage is not that bad
The basal lamina of the schwann cell remains and guides repair if possible. Scar forms, produces by CT within basal lamina skeleton. Schwann cells divide and create a tube around the CT. Neuronal process will regenerate within the tube of schwann cells.
Neuronal cell bodies loc in the PNS are clustered in
ganglia
What are the neuronal cell bodies in the PNS
- sensory
- sympathetic
- parasympathetic
Describe parasympathetic ganglia
- Based on size
- On walls of organs
- Cluster of a dozen of neurons
- cell bodies of post ganglionic autonimc neurons
- Have a lot of smooth muscle tissue (dark pink staining )
- motor neurons; multipolar shaped
describe sympathetic ganglia
- Cells are more dense in tissue
- nucleus of Cell body are located in the periphery.
- post ganglionic cell bodies
- motor neurons; multipolar shaped
Describe sensory (dorsal) root ganglia
- Nucleus are located centrally
- contain cell bodies of affarent neurons
- Can see nuclei of satellite cells around it
- psudounipolar shaped
Describe features of synpases and what they are
Includes synaptic bulb, synaptic cleft, postsynaptic membrane
What are the three types of synapses
Axodendritic: Between axon and dendrite.
Axosomatic: Directly on cell body.
Axoaxonal: Directly to axons
