Functional Histology of Nervous Tissue Flashcards
Glia types
astrocytes
microglia
oligodendrocytes
schwann cells
astrocytes
sustain neurons metabolically and tropically
support them physically - structural function
maintain extracellular fluid composition
microglia
scavenger immune cells in CNS
oligodendrocytes
myelination of CNS axons (spinal cord and brain)
schwann cells
myelination of PNS axons (nerves throughout the body
demyelination disease
no much is clear, genetic? environmental?
effects oligodendrocytes and schwann cells
cancerous diseases
glia keep dividing and they stop helping the neurons
effects astrocytes
triads
basic template for the brain
principle neuron
interneurons
afferents
principle neurons
axon leaves the region most are excitatory (glutamate) only 1 type present dendrites are extensive integration of inputs ex: sensory neurons
interneurons
axons stay within the region
most are inhibitory (GABA)
many varieties
dendrites are radically arranged
afferents
axons enter from other brain regions
different parts of the dendritic tree synapse on different locations on the principle neurons
often excitatory
general function of triads
two general circuits
purpose is to autoregulate
feed forward pathway
afferents -> (+) principle neurons -> (+) out or region
afferents excite the principle neuron the principle neuron in turn conveys action potentials out fo the region to another
ex: alpha motor neurons in the ventral horn of the spinal cord
feedback pathway
afferents -> (+) interneurons ->(-) principle neuron
afferents excite local interneurons, interneurons inhibit the principle neuron
general function here is to limit the number of action potentials the principle neuron can send from the region
