what is the enteric neural system?
innervation of the gut
what is the autonomic nervous system?
having to do with the sympathetic and parasympathetic system
what is the somatic nervous system?
having to do with the somatic motor neurons
what is the soma?
cell body of the neuron
what is the telodendria?
branching of the axon with the end-bulb
what is an axon collateral?
axon that juts off the major axon
what is the axon helliock, initial segment or trigger zone?
area where the first action potential will be generated
-where body of neuron and axon meet
what is the graded potential?
areas on the dendrites
what is the myelin sheath?
surrounds the axon
what do Schwann cells do?
lay down myelin only located in the peripheral nervous system
-one Schwann cell: one node of myelin
what do oligodendrocytes do?
lay down myelin in CNS
-can coat many cells
what are the nodes of Ranvier
spaces in between Schwann cells where action potentials jump to
-sodium and potassium voltage gated channels are here (not underneath the myelin)
what kind of ion channels do nerve cells have?
voltage-gated sodium and potassium channels
what is the axolemma?
the plasma membrane of an axon
what is the neurolemma?
the plasma membrane of the Schwann cells
what are missile substance?
ribosomes within neuron cells
do CNS neurons regrow?
no other cells have to take over their function
-don’t have centrioles (they don’t divide)
what is a neuroglial cell?
small, tiny cell, more abundant
what are the 4 types of CNS neural cells?
astrocytes
oligodendrocyte
ependymal
microglial
what are the 2 types of PNS neural cells?
Schwann cell
satellite cell
what are the 3 types of ligands in the body? (substance that binds to a receptor to initiate change)
neurotransmitters
hormones
drugs
what kind of ion channels do dendrites have?
ligand (chemically) gated
what kind of ion channels do axons have?
voltage gated
what is special about neurons?
multitude of neuron transmitters
multitude of ion channels
what ion channels are present on the axon?
sodium and potassium exlusively
what is the normal picture of neurons
hundreds and thousands of neural cells touching one another
what is the main purpose of the dendrite?
increase receptive surface area of the neural cell
what does anterograde mean?
moving neurotransmitter from cell body to synaptic end ball
- uses kinesin
- nutrients
- enzymes
- mitochondria
which type of protein moves neurotransmitter from synaptic ball to cell body (retrograde)?
dynein
- may send recycled membrane vesicles
- growth factors
- other chemicals
- some diseases
alzheimers mechanism
microtubules within neurons get tangles up and stop working
what is afferent?
into the CNS (sensory)
what is efferent?
away from the CNS (motor)
what type of neurons are unipolar?
sensory neurons (most sensory are unipolar) -cell body is offset from axon
what are interneurons?
transfer sensory information to CNS (have short axons)
what is important about motor neurons?
cell body is located inside the CNS
usually multipolar
where are bipolar neurons?
special senses (retina, olfactory)
where in the brain are the Purkinge cells?
cerebellum
largest neuron in the entire CNS
where are pyramidal cells found?
frontal lobe of brain in the precentral gyrus
corticospinal pathway
from frontal lobe to body
nociceptor
pain sensor
spinothalamic track
in spinal cord, cross and receives information on the opposite side of brain where injury occurs
-parietal, post sensory cortex
what does the astrocyte do?
it is the most abundant of the glial cells
helps the neuron get the nutrients that it needs
-good extracellular environment
-remove waste
-caretaker
-BBB
-fetal development
components of BBB
- tight junctions
- thick basement membrane in capillaries
- foot processes of astrocytes sitting on top of the capillaries
BBB works against us in which situations?
chemo
antibiotics
where do primary brain tumors originate from?
glial cells (neurons can’t divide)
most common type of brain tumor
astrocytoma
what are the two types of astrocytes?
protoplasmic -present in gray matter -many short branching processes fibrous -present in white matter -many long unbranched processes
what is the pia mater?
inner layer of meninges sitting right on the brain
what does a microglia do (spider-like cells)?
phagocytic function (remove cellular debris) (brain has no lymphatic system other than these cells)
what do ependymal cells do?
line the ventricular system of brain and central canal of the spinal cord
- cuboidal/columnar have microvilli, cilia and tight junctions
- produces and maintain the circulation of the CSF
what do oligodendrocytes do?
synthesize and maintain the myelin sheath of axons in the CNS
what is white matter?
nervous tissue that is myelinated
what is gray matter?
nervous tissue that is non-myelinated
how does myelin impact speed of conduction?
unmyelinated = slower myelinated = faster
how does size of neural cell impact speed?
wider = faster thinner = slower
ganglion
collection of nerve cell bodies in the PNS
what type of cell sits on top of the ganglion?
satellite cells
what do satellite cells do?
regulate the exchange of materials between the neurons and the interstital fluid
how much myelin do Schwann cells lay down?
specific ratio of axon diameter: myelin diameter
how much do axons regrow if peripheral nerve is damaged?
1mm/day
how many neurons are killed off when a fetus develops?
50-70% of the original ones
where do motor neurons exit SC?
ventral root
where do sensory neurons enter SC?
dorsal root
