organization of the nervous system Flashcards
3 subdivisions of the nervous system
- central
- peripheral
- autonomic
2 parts of CNS
- brain
- spinal cord
3 meninges of CNS
- dura mater (outer membrane)
- arachnoid (middle membrane)
- pia mater (inner membrane)
nuclei
aggregations of neurons that share similar functions
gray matter
contains neuron cell bodies
white matter
rich in myelin
peripheral nervous system (PNS)
those parts of the nervous system that lie outside the dura mater
afferent nerves
sensory nerves that carry messages from the periphery to the CNS
efferent nerves
peripheral motor nerves that carry messages from the CNS to peripheral tissues
peripheral ganglia
groups of nerve cells concentrated into small knots or clumps that are located outside the CNS
autonomic nervous system (ANS)
portion of the nervous system that regulates and controls visceral functions
2 parts of nervous tissue
- neurons
- neuroglial cells (glia)
purpose of neurons
electrical communication
what did the neuron doctrine say
neurons are entirely separate from one another, even though their processes come into very close contact
4 domains of structure of a neuron
- cell body (soma, perikaryon)
- dendrites
- axon
- presynaptic terminals
3 fibrillary structures of the cytoskeleton
- neurofilaments
- microtubules
- thin filaments
cell body
the portion of the cell surrounding the nucleus
function of dendrites
receiving information (their membranes are endowed with receptors that bind and respond to the neurotransmitters released by neighbouring cells)
axon hillock
point of origin of axon
initial segment (spike initiation zone)
distal to hillock, untapered, unmyelinated region
axoplasm
cytoplasm of the axon, packed with parallel arrays of microtubules and neurofilaments
function of axons
message-sending
myelin
coiled cell membranes of glial cells
continuous propagation
way of traveling of action potential if axon is not covered with myelin
saltatory conduction
way of traveling of action potential if axon is myelinated
node of Ranvier
space between adjacent myelin segments
function of presynaptic terminals
rapid conversion of the neuron’s electrical signal into a chemical signal
synaptic transmission
release of chemical signaling molecules when the action potential reaches the presynaptic terminal
chemical synapse
junction formed between the presynaptic terminal and its target
3 parts of synapse
- presynaptic terminal
- postsynaptic membrane
- synaptic cleft
dendritic spine
small membranous protrusion from a neuron’s dendrite
what’s MAPs the abbreviation for?
microtubule-associated proteins
2 major classes of MAPs
- high-molecular-weight protein (MAP-1, MAP-2)
- lower-molecular-weight tau proteins
neurofibrilarry tangles
abnormal accumulations of a protein called tau that collect inside neurons
caused by hyperphosphorylated tau proteins
orientation of microtubules in axons
with plus ends pointed away from the cell body
anterograde direction
mechanism for moving material to the presynaptic terminals
to + end
retrogade direction
moving material from the presynaptic terminals
to - end
3 ways of axoplasmic transport
- fast anterograde
- fast retrograde
- slow anterograde
direction in which kinesin moves
toward the plus end of microtubules (away from the cell body)
how does anterograde movement work
- proteins synthesized in the ‘secretory pathway’ are packaged by budding off in the
membrane-enclosed vesicles from the Golgi - the vesicles and mitochondria are carried down the axon on microtubule ‘tracks’ by
kinesin motors that are energized by ATP
synonym for MAP-1C (used in retrograde movement)
brain dynein
kinesin
microtubule-dependent motor protein (used in anterograde movement)
consequence of loss of ATP production in axons
failure of axonal transport in both the anterograde and retrograde directions
2 types of neurons based on axonal projection
- projection neuron (principal neurons, golgi type I cells)
(connect with other parts of the nervous system) - interneurons (intrinsic neurons, golgi type II cells)
(all processes confined to one region of the brain)
2 types of neuron based on dendritic geometry
- pyramidal cells (spiny)
- stellate cells (spiny or aspiny)
3 types of neurons based on number of processes
- unipolar (dorsal root ganglion cell)
- bipolar (retinal bipolar cell)
- multipolar
what 3 elements do glial cells lack
- axons
- action potentials
- synaptic potentials
3 main types of CNS glial cells
- oligodendrocytes
- astrocytes
- microglial cells
3 main types of glial cells in PNS
- satellite cells
- Schwann cells
- enteric glial cells
what do oligodendrocytes form
the myelin sheaths of CNS axons
function of Schwann cells
to myelinate peripheral nerves
2 types of neurons based on direction
- afferent (sensory)
- efferent (motor)
2 types of neurons based on the anatomical distribution of the information flow
- visceral
- somatic
2 types of neurons based on the information flow on the basis of the embryological origin of the structure being innervated
- special (for example: from the branchial arch region of the embryo)
- general
