Neurons First Test Flashcards
neuron
sense changes in brain environment, communicate changes to other neurons, and commands body’s responses to changes
excitable
amitotic
glial cell
insulate, support, and nourish neurons glue non excitable 10x more numerous than neurons mitotic
histology
the microscopic study of the structure of tissues
nissl stain
a class of basic dyes that stains the nucleus of all cells and also stains clumps of material surrounding the nuclei of neurons distinguishes neurons and glia from one another enables histologists to study arrangement of neurons in different parts of the brain
cytoarchitecture
the arrangement of neurons in different parts of the brain
study of cytoarchitecture led to realization that brain consists of many specialized regions
golgi stain
golgi soak brain tissue in silver chromate solution
small percentage of neurons become darkly colored in entirety
revealed that neuronal cell body (region of neuron around the nucleus that is shown with the nissl stain) is only small fraction of total structure of neuron
cell body
swollen region containing organelles and cell nucleus
aka soma aka perikaryon
neurite
the thin tubes that radiate away from the soma
two types: axons and dendrites
axon
wires that carry the output of the neurons
dendrite
come in contact with axons
act as antennae of neuron to receive incoming signals or input
neuron doctrine
the idea that the neuron adhered to the cell theory
golgi said neurons continuous, cajal said neurites of different neurons are not continuous and communicate by contact not continuity
canal/neuron doctrine correct
cytosol
the watery fluid inside the cell
contanis organelles
organelle
membrane-enclosed structures inside the cell
cytoplasm
everything contained within the confines of the cell membrane, including the organelles but excluding the nucleus
nucleus
spherical, centrally located
contained within nuclear envelope
contains DNA and genetic material for the cell
chromosome
contain genetic material DNA
double strands
DNA
genetic material passed on by parents
codes for identity
huge amount
gene
segments of DNA that code for specific parts of identity
gene expression
the reading of the DNA
final product of this is the synthesis of proteins
the process by which information from a gene is used in the synthesis of a functional gene product
protein
exist in a wide variety of shapes and sizes, perform many different functions, and bestow upon neurons virtually all of their unique characteristics
protein synthesis
assembly of protein molecules
occurs in cytoplasm
mRNA
the intermediary that carries the genetic message to the sites of protein synthesis in the cytoplasm
consists of four different nucleic acids strung together in various sequences to form a chain
detailed sequence of nucleic acids represents the information in the gene
transcription
process of assembling mRNA from DNA
occurs in nucleus
microglial cell
function as phagocytes to remove debris left by dead or degenerating neurons and glia
translation
assembling of proteins from amino acids under direction mRNA
occurs in cytoplasm
ribosome
take raw material in the form of amino acids and manufacture proteins using the blueprint provided by the mRNA
attached to rough ER and free
rough go into membranes
proteins synthesized on free ribosomes are destined to reside within the cytosol of the neuron
rough endoplasmic reticulum
nissl bodies
major site of protein synthesis
proteins synthesized here are destined to be inserted into the membrane of the cell or an organelle
smooth ER
performs different functions
site where proteins that just out from the membrane are folded
regulate internal concentrations of substances in the cell
golgi apparatus
site of extensive post translation chemical processing of proteins
sorts certain products that are destined for delivery to different parts of the neuron
mitochondrion
site of cellular respiration
energy of cell
makes ATP
powerhouse of the cell
ATP
cell’s energy source
energy currency of the cell
used to fuel most of the biochemical reactions of the neuron
neuronal membrane
barrier to enclose the cytoplasm inside the neuron
excludes certain substances that float in the fluid that bathes the neuron
cytoskeleton
scaffolding of the cell
gives neuron characteristic shape
microtubules, microfilaments, and neurofilaments
elements of it are dynamically regulated and in continual motion
microtubule
big and run longitudinally down neurons
straight, thick-walled hollow pipe
biggest
microfilament
smallest numerous in neuritis brain of two thin strands actin filaments run longitudinally down the core of the neuritis anchored to the membrane
neurofilament
middle size
exist as intermediate filaments
closely resemble bones and ligaments of the skeleton
very strong
axon hillock
beginning of axon
tapers to form initial segment of axon proper
differences between axons and soma:
1. no rough ER extends into the axon and there are few if any free ribosomes
2. protein composition of the axon membrane is fundamentally different from that of the soma membrane
axon collateral
branches of axons
vary in size
thicker axon means faster impulse
axon terminal
aka terminal button
site where axon comes in contact with other neurons and passes information on to them
terminal button
same as axon terminal
synapse
point of contact of axon and dendrite of other cell
synaptic vesicle
axon terminal contains numerous small bubbles of membrane
store various neurotransmitters that are released at the synapse
neurotransmitter
the chemical signals that cross the synaptic cleft
stored in and released from the synaptic vesicles
different neurotransmitters have different functions
axoplasmic transport
movement of material down the axon
anterograde and retrograde
anterograde transport
movement of materials from the soma to the axon terminal
receptor
specialized protein molecules in the dendritic membrane that detect the neurotransmitters in the synaptic cleft
dendritic spine
specialized structures that cover the dendrites of some neurons
receive some types of synaptic input
unipolar neuron
neuron that has a single neurite
bipolar neuron
neuron that has two neurites
multipolar neuron
neuron that has multiple neuritis
most neurons are multipolar
stellate cell
star shaped cell/dendritic tree
pyramidal cell
pyramid shaped cell/dendritic tree
spiny neuron
neuron whose dendrites have spines
spinous neuron
neuron whose dendrites don’t have spines
primary sensory neuron
cells with connections
information delivered to nervous system by neurons that have neuritis in the sensory surfaces of the body
motor neuron
have axons that form synapses with the muscles and command movements
interneuron
most neurons
form connections only with other neurons
astrocyte
most numerous glia
fill spaces between neurons
influence growth
regulate chemical content of extracellular space
actively remove many neurotransmitters from the synaptic cleft
oligodendroglial cell
provide layers of membrane that insulate axons
found in CNS
contribute myelin to several axons
schwann cell
provide layers of membrane that insulate axons
found in PNS
contribute myelin to only one axon
myelin
the insulation around axons
myelin sheath is the entire covering
speeds up propagation of nerve impulses down axon
node of ranvier
periodic interruptions of the myelin sheath
short lengths where the axonal membrane is exposed
speed up nerve impulses transport
ependymal cell
provide lining of fluid filled ventricles within the brain
play role in directing cell migration during brain development
help make CSF
differences between cytoplasm of axon terminal and that of axon
- microtubules don’t extend into the terminal
- terminal contains numerous synaptic vesicles
- inside surface of membrane that faces synapse has particularly dense covering of proteins
- numerous mitochondria indicating high energy demand
retrograde transport
movement of material from axon terminal to soma
