BSI Lecture 52 Histology/Neurons and Glia Flashcards
Where do dendrites receive information?
Via chemical transmission across synapses
How do the cell body and axons transmit information?
propagating action potentials away from the cell body towards a synapse/synapses
What determines whether or not you get to threshold?
Axon Hillock
How do dendrites receive information?
Via chemical transmission across synapses
How do the cell body and axon transmit information?
By propagating action potentials away from the cell body towards a synapse(s).
What are the transport systems in axons and dendrites?
Microtubules and molecular motors
What does the axon increase?
conduction velocity
What is most the common neuron and where is it located?
Multipolar neuron located in the cerebral cortex, cerebellum, and in multiple dendrites for many inputs.
Where is the bipolar neuron located?
in the back of the eye (retina)
What is a unipolar neuron?
It is the primary sensory neuron that will go into the spinal cord
What is the general way that neurons can be characterized?
according to their processes/dendrites
How are microtubules efficient transport systems?
they relay information quickly
T/F? The physical position of synapses on dendrites is crucial integration.
True
Neurons can and usually have multiple dendrites, but how many axons do they have?
One axon, however, the axon can split to innervate multiple effectors/neurons
What are the variable shapes of the dendrites related to?
function
What are pyramidal cells?
the principal neurons of the cerebral cortices
What are Purkinje cells?
the cerebellar equivalent to pyramidal cells.
What do astrocytes remove?
What do astrocytes remove?
They remove glutamate and terminate its action, which in excess would kill off neurons
What do astrocytes help in the formation of?
They help in forming the vital “blood-brain-barrier” and with neuronal nutrition
What are microglial cells?
immune cells
Why are the glia “forgotten heroes” of the nervous system?
without their support, neurons couldn’t function correctly
What do ependymal cells line?
the ventricular system of the brain and they actually secrete CSF.
What is CSF?
A blood filtrate
How do oligodendrocytes force a faster rate of information transfer?
They are myelinating, which means that they wrap their membranes tightly around the CNS axons, so insulating them
Where do Schwann cells myelinate?
Outside the CNS
By how much does myelination increase speed?
10 times
What occurs at the nodes of Ranvier?
action potentials “hop” between the parts of the axon, which forces an increased rate of action potentials.
What is the outer connective tissue covering a nerve (containing many axons and fascicles) called?
Epineurium
T/F? Axons always start as a single process?
True
Which type of glial cells are involved in neurotransmitter removal and recycling?
Astrocytes
Which type of glial cells are involved in the blood-brain barrier?
Astrocytes
Which type of glial cells are involved in neuronal nutrition?
Astrocytes
Which type of glial cells are involved myelination within the CNS?
Oligodendrocytes
T/F? If individual axons are not myelinated, they will still have enhanced conduction velocities.
FALSE; they will not have enhances conduction velocities
T/F? The nerve has its own blood supply.
True
Where is grey matter located?
dendrites and cell bodies
Where is white matter located?
myelinated axons that transmit data
At the level of the cerebellum, there is an extra outer grey layer. (Grey-White-Grey). What is it composed of?
neurons which migrate from the central grey area often with the help of glia.
What is MS?
An autoimmune condition whereby your own immune system misidentifies the myelin as a pathogen and attacks it so seriously, which compromises data transmission/functions.
What other cells be involved in MS?
Macrophages, microglia, beta-cells/plasma cells
T/F? MS is the most common cause or neural disability in young adults.
True
The disease is characterized by periods of ________ and ________.
remission and relapse
What are some symptoms of MS?
numbness, pain, disrupted vision, poor balance, slurred speech, incontinence, fatigue, depression, and muscle weakness, paralysis
Although the cause of MS is not fully understood, what can it be due to?
Due to the inappropriate targeting of several proteins found in myelin that may resemble certain viral proteins
What are two things that could trigger a relapse for MS?
stress and injury
What has recent research of MS identified an imbalance of?
regulatory T-cells (helpers and suppressors)
T/F? Although remission allows for some repair of myelin sheaths, the accumulative effects can cause a rapid decline in health.
True
What reduces the risk of MS?
Vitamin D
What are some risk factors for MS?
Smoking; changing environment; geographic location
What is a treatment for MS that reduces the severity and duration of relapses?
anti-inflammatory steroids
Although anti-inflammatory steroids reduce severity and duration of relapses, what do they not help?
Frequency
What is interferon Beta-1a thought to strengthen?
the blood-brain barrier
How is an immunomodulator work?
It may “divert” or “decoy” the immune system from attacking myelin as it mimics the structure of myelin basic protein
How has mitoxantrone, a cancer treatment drug had success in MS?
it suppresses lymphocyte activity, which are the primary immune system cells that attack myelin
How does Natalizumab, a monoclonal antibody work?
It blocks the adhesion molecule alpha4-integrin to slow lymphocyte egress into the CNS, but it has been reported to cause/allow other unwanted side effects such as progressive multifocal leukoencephalopathy, which is a viral condition causing progressive damage to myelin
The S-1-P analog Fingolimod (phosphorylated similarly to sphingosine) was approved for the treatment of MS. What does it reduce?
reduces lymphocyte agrees into the CNS, but does so by excessive stimulation of the S1PR (GPR receptor for S-1-P) causing it to be internalized.
