2. Nervous Tissue Flashcards
What are Nissl bodies?
Rough endoplasmic reticulum in the neurons.
What does abudant rough endoplasmic reticulum reflect in a neuron?
High rates of protein synthesis.
Which microtubule is involved in the process of anterograde transport in a neuron?
Kinesins [DR. K.A.]
Which microtubule is involved in the process of retrograde transport in the neuron?
Dynein [DR. K.A.]
What are Schawnn cells?
They are the myelin forming cells fo the peripheral nervous system (PNS). Myelination in the PNS begins during the 4th month of development. Once Schawnn cell myelinate only one axon in peripheral nerves.
What are olygodendrocytes?
Myelin forming cells fo the central nervous system (CNS). Myelination in the CNS begins during the 4th month of development to the second decade of life. An individual oligodendrocytes is able to myelinate many axons.
What are pseudounipolar neurons and where are they found?
They have a single process close to the perikaryon, which divides into 2 branches; one going to the peripheral ending and the other to the CNS. They are found in the dorsal root ganglia and most cranial ganglia.
What are bipolar neurons and where are they found?
They have one axon and one dendrite. They are found in the cochlear and vestibular ganglia as well as in the retina and olfactory mucosa.
What are multipola neuros and where are they found?
They have one axon and multiple dendrite. Most neurons in the body are multipolar (e.g., ventral horn neurons in the spinal cord.)
How long is a synaptic cleft?
20 nm.
What happens tio norepinephrine in the synaptic cleft?
Taken up by the presynaptic cleft; reuptake.
What causes myasthenia gravis?
Autoimmune response to the ACh receptor. Normal half-life of a receptor is 10 days; the disease shortens it to 2 days. Administration of AChE inhibitors is both diagnostic and therapeutic - results are prompt after administration.
What do neuroglia do?
AKA nerve glue, takes care of the nerves without being a nerve itself. In the CNS, it is microliga, astrocytes, oligodentrocytes and ependymall cells. In the PNS, it is Schawnn cells.
What are astrocytes?
Biggest of the neuroglia, they have many processes that attach to walls of blood capillaries; they are involved in the maintanence of the blood-brain barrier.
What does microglia do?
They are small, dense and elongated with origins from the mesoderm, unlike other neuroglia which originate from the neuroectoderm. They are phagocytic and are part of the mononuclear phagocyte system.
