Neurons and Neuroglia Flashcards
these are the signaling units of the NS
neurons
these are the support cells
neruoglia
what is the function of a neuron
excitable cells for reception of stimuli and conduction of nerve impulses
where are neurons found
brain and SC
can neurons replicate ?
does not undergo cell division
what are the 4 regions of a neuron
cell body or soma
dendrites
axon
presynaptic terminals
what is the function of the cell body
metabolic center and contains the nucleus sa cytoplasm bounded by PM
what are the 2 kinds of processes a cell body gives rise to
axon and dendrite
describe the structure of dendrites
several and short and they branch out like trees
function of dendrites
receives incoming signals from other cells; TOWARDS the cell body
function of axons
carries signal to other neurons; AWAY from cell body
0.1 mm to 2m
describe structure of axons
single, long and tubular
what is the significance of the initial segment of an axon
first 50-100 um; specialized trigger region near origin where AP are initiated then propagated down the axon
how are neurons classified
number, length, mode of branching neurites and size
structure of pseudounipolar neuron
spherical body with single process that bifurcates into central and peripheral branches
branches have same structure and function of an axon
example of pseudounipolar
posterior root ganglion
structure of bipolar
elongated, spindle cell body with single emerging neurites on each end
example of bipolar
retinal cells, vestibular and cochlear ganglion cells
structure of multipolar
one long axon and multiple dendrites
most of the cells in CNS
where are multipolar found
most of the cells in CNS
structure of golgi type 1
long axons that can stretch 1m or more
examples of golgi type 1
pyramidal cells of cerebral cortex, purkinje of cerebellar cortex and motor cells of SC
structure of golgi type 2
short axons that terminate in the vicinity of the cell body or absent
star shaped - multiple short dendrites
function of golgi type 2
often inhibitory and mas madami sha sa type 1
function of nucleus
metabolic center of neuron and stores DNA
can mature neurons replicate?
nope only functions in gene expression
function of nucleolus
synthesizes rRNA and assists in ribosome subunit assembly; large due to high rate of protein synthesis
function of nuclear envelope
continuous w cytoplasmic RER; double layered w nuclear pores
what is the the PM
continuous external boundary of the cell and its processes
in EM how does the PM appear as
2 dark lines with light line in between
what is the structure of the PM
inner and outer layer very loosely arranged protein molecules separated by a middle lipid layer
discuss the structure of the lipid layer
rows of phospholipid molecules with hydrophobic ends in contact with protein layers
function of hydrophilic channels
allows ions to pass through
significance of carbohydrates to the PM
attached to the outside of plasma membrane and are linked to the proteins or lipids
what is formed through the attachment of carbohydrates in the PM
forming a cell coat or glycocalyx
what are the 2 confrontational states of sodium and potassium channels
open and closed
what is gating and when does it occur
twisting of channel widening the lumen - response to voltage change, ligand, stretch or pressure
