Histology (1)

Question 1

What are the basic components of a neuron?

Answer 1

apical dendrites, cell body (nucleus and perikaryon), basal dendrites, axon hillock (primary node of ranvier), myelin sheath, nodes of ranvier, axon, terminal button, synaptic cleft

Question 2

What are the different kinds of neurons? example of location?

Answer 2

bipolar, pseudounipolar, pyramidal, projection, neurosecretory, purkinje cell and granule cell, inter neuron, alpha and gamma motor neuron, pre-gang and post-gang motor

Question 3

How are dendrites specialized?

Answer 3

for receiving stimuli, apical from apex of body away from axon, basal emerge at base of soma, dendritic spines increase SA for additional synapses

Question 4

What are the characteristics of a neuronal cell body?

Answer 4

contains nucleus with a prominent nucleolus and perikaryon with abundant RER (aka Nissl body)-cresyl violet and thionin used to stain these

Question 5

What myelinates axons? How does this differ throughout the nervous system?

Answer 5

Schwann in the PNS, oligodendrocytes in the CNS

Question 6

What cellular changes are associated with Alzheimer’s?

Answer 6

neurofibrillary tangles of tau protein, beta amyloid plaques outside neurons; roll of involvement of both in disease hotly debated

Question 7

What is a pseudounipolar neurons? Examples

Answer 7

single process connected to cell body, begins as bipolar; Dorsal root ganglion and trigeminal ganglia

Question 8

What is a bipolar neurons? Examples

Answer 8

two processes connected to a cell body, found in the vestibular ganglion, olfactory epithelium and the retina

Question 9

What is a multipolar neurons? Examples

Answer 9

more than two processes connected to the cell body; almost all neurons in CNS just in different shapes; Purkinje in cerebellum, Pyramidal in Cerebral Cortex,

Question 10

What are projection neurons? examples

Answer 10

have long axons that extend beyond the cell group their bodies are found in; most of what we will study

Question 11

What are interneurons? examples

Answer 11

neurons with short axons, transmit locally within same cell group in which their bodies are found; most neurons in CNS are interneurons

Question 12

How are pathways named?

Answer 12

from a to b, so spinal cord to thalamus is the spinothalamic tract

Question 13

What types of signals in synapses are there?

Answer 13

chemical- use a NT (NE, Dopa, Serotonin, ACh, GABA, and Glutamate), or electrical- pass current through gap junctions

Question 14

What are the components of a chemical synapse?

Answer 14

Presynaptic terminal with synaptic vesicles containing NT and neuropeptides close to presynaptic membrane, synaptic cleft, and post synaptic membrane with NT receptors

Question 15

What types of synapses are there?

Answer 15

axodendritic (axon term to dendrite, most common), axosomatic (axon terminal to cell body), dendrodendritic (dendrite on dendrite, most rare)

Question 16

What mechanisms of axonal transport are there?

Answer 16

anterograde- synaptic vesicles to axon terminal vie microtubules and molecular motor kinesin or retrograde- signaling molecules back to cell body and nucleus via microtubules and molecular dynein

Question 17

What are microglia and where are they found? What role do they potentially play in Alzheimers?

Answer 17

mesodermally derived, invade during development, phagocytotic cell; stimulated by B amyloid plaques and possibly contribute to neuronal loss

Question 18

What are ependymal cells and where are they found?

Answer 18

along ventricle walls, this zone gives rise to new neurons in embryos and may be source of quiescent stem cells in adults, their cilia beat and appear to move CSF; modified versions make up choroid plexus

Question 19

What are astrocytes derived from? What causes their differentiation?

Answer 19

neural tube multipotential stem cells will differentiate into astrocyte precursors after exposure to CNTF (ciliary neurotrophic growth factor)

Question 20

What is the function of astrocytes?

Answer 20

maintain extracellular milieu, work as a buffer for potassium by taking it in (during APs), also take up excess NT

Question 21

What are the two types of astrocytes and where are they found?

Answer 21

protoplasmic found primarily in gray matter but some in white, and fibrous astrocytes found in the white matter

Question 22

What are radial and bergmann glia? Where are they found?

Answer 22

radial are transitory and aid in neuronal migration in cortex and other areas of the brain; Bergmann aid in migration of granule cells in the cerebellum

Question 23

What are oligodendrocytes derived from and what do they do?

Answer 23

derived from neural tube, found in white matter, responsible for myelination of CNS, multiple processes myelinating multiple axons (50)

Question 24

What are the glia in the PNS? What are they derived from?

Answer 24

Schwann cells and satellite cells, neural crest

Question 25

What do the Schwann cells do?

Answer 25

myelinate PNS axons (500 per axon), important in axonal regeneration, release nerve growth factor and produce the basal lamina

Question 26

What is a neurofibromatosis type I?

Answer 26

often contains tumors of schwann cells along with other types, these cells are also often found in acoustic neuromas

Question 27

What is the composition of myelin?

Answer 27

cytoplasmic membranes of either Schwann cells (PNS) or oligodendrocytes (CNS) wrapped around axons, it makes the white matter, unmyelinated nerves are gray, when stained myelin is black

Question 28

What happens during myelination?

Answer 28

cytoplasm is squeezed out co the cytoplasmic surfaces of the membrane become closely opposed, myelin basic protein and proteolytic protein play a role in this process

Question 29

What is MS?

Answer 29

chronic demyelinating disease of CNS, common in temperate regions, symptoms include visual defects and ataxia, immune system attacks myelin specific proteins (possibly MBP)

Question 30

What is Guillian-Barre syndrome?

Answer 30

acute demyelinating disease of PNS, schwann affected, symptoms include sudden weakness which can be severe, also thought to be autoimmune

Question 31

What is the makeup of a peripheral nerve?

Answer 31

axons, schwann cells (neuralemma cells), and connective tissue (endoneurium, perineurium, and epineurium)

Question 32

Where is the endoneurium?

Answer 32

adjacent to each shcwann cell

Question 33

Where is the perineurium?

Answer 33

surrounds groups of axons (fascicles), exterior portions continuous with the dura mater

Question 34

Where is the epineurium?

Answer 34

surrounds the fascicles within a peripheral nerve, continuous with the dura mater