Nervous Tissue Histology Flashcards
what are the 3 functions of the nervous system
1 - sensory input
2 - motor output
3 - processing and integration
what is a collection of axons called in the nervous system
nerve
what are the 2 basic types of cells found in nervous tissue
- neurons/nerve cells
- glia/neuroglia/supporting cells
which basic cells of the nervous system are the excitable cells
neurons
which are more abundant in the nervous system, neurons or glia cells
glia cells (can divide/multiply)
what are the 3 special characteritics of neurons
longevity
amitotic
high metabolic rate
clumps of rough ER and ribosomes found in the cell body
Nissl bodies
what is a perikaryon and what is its main function
neuron cell body, its the biosynthetic control center of nuueron
in a neuron, what parts of the basic structure is/are myelinated
axon =myelin
dentrite and cell body = unmyelinated
what is a axon terminal
storage area of nerve transmitters, its the secretory portion of the cell that can then signal the next neuron
where is the AP generated in a neuron
axon hillock
difference b/w anterograde and retrograde movement in a neuron
anterograde - AP goes from cell body to axon terminal
retrograde - AP goes form axon terminal to cell body
what are the 3 types of neurons based upon structure
Multipolar(most) , bipolar (rare) , unipolar
what are the 3 types of neurons based on function
afferent (sensory), efferent (motor), interneurons
multipolar neurons carry out what neuron function
motor(efferent) or internuerons
bipolar neurons carry out what function
special sensory neurons
unipolar neurons carry out what function
general sensory neurons
what are the 2 most common types of synapses
axodentritic (axon terminal and dendrite)
axosomatic (axon terminal and cell body)
what is the difference b/w presynaptic and postsynaptic neurons
pre is signal carrier before synapse
post is carrying signal after synapse
what is the difference b/w electrical and chemical synapses
electrical - neurons can touch and exchange AP via gap junctions, rapid communication
chemical - slower cuz must transfer AP to a chemical signal to diffuse across synaptic cleft, then back to electrical AP
explain the process of transferring information across a chemical synapse
1- impulse arrives at synaptic cleft
2- depolarization opens voltage gated Ca channels
3 - Ca signals release of neurotransmitter
4- neurotransmitter diffuses across synaptic cleft
5-neurotransmitter binds and opens ligand gate channel
6 - ions flow across postsynaptic membrane = AP
what are the 3 ways a neurotransmitter can be removed from a postsynaptic receptor in a chemical synapse
1 - enzymatic degradation
2 - recycled by presynaptic terminal for later use
3 - diffusion out
what are the 4 neuroglia cells found in the CNS
astrocyte, microglial, ependymal, oligodendrocyte
what are the 2 neuroglia cells found in the PNS
schwann cells, satellite cells
what neuroglia cells in the CNS are predominant in the white matter
oligodendrocytes
what neuroglial cell in CNS is predominant in the gray matter ?
astrocytes (largest of all glial cells)
what is the difference b/w oligodendrocytes and schwann cells
oligodendrocytes - in CNS, wrap many axons
schwann cells - in PNS, wrap 1 axon
what neuroglia cells would be found lining ventricular spaces of the brain, and what are their function
ependymal cells - regulate blood-CSF barrier of choroid plexus
which glial cell can be recognized by its elongated nucleus, what is the cells role ?
microgli cells - immune defense for CNS (originate from monocytes)
what makes the white matter in the CNS white ?
myelin sheath made form oligodendrocytes
what makes the gray matter in the CNS actually gray
lack of myelin and numerous Nissl bodies
what is a cluster of nerve cell bodies in the CNS called
nucleus
what is a cluster of nerve cell bodies found in the PNS called
ganglion
what is a bundle of neuronal axons in the CNS called
tract
what is a bundle of neuronal cell bodies found in the PNS called
nerve
what are the 3 connective tissue coverings around nerve from largest to smallest
epineurium, perineurium, endoneurium
how many pairs of cranial nerves are there and where do the originate from
12 pairs at the brain
how many pairs of spinal nerves are there and where do they originate from
31 and originate at the spinal cord
what is the function of a myelin sheath
protect and insulate axons from others increase speed (more myelin=faster impulse conduction)
what is the neurilemma in PNS
area outside of myelin sheath in a nerve fibers that contains the organellses and nucleus of schwann cells
the rate of impulse propagation down an axon depends on what two things
axon diameter, presence of myelin
what is the difference b/w continuous vs. salutatory conduction
continuous is for unmyelinated axons
salutatory is for myelinated axons and regenerates AP at every node of ranvier
