neurohistology Flashcards
synapse
space between 2 neurons where communication occurs
gap junctions
connect two neurons together; allow electrical signal to pass from 1 to another without a synapse
categories of nerve cells
- conducting elements
- supportive cell types
conducting elements
excitable cells; neurons; typically conduct electrical signals over long distances
supportive cell types
glial cells (neuroglia, glia); do not generate/conduct electrical signals but facilitate the transmission of these signals in conductive elements
cell body
contains the nucleus, surrounded by cytoplasm
nucleus
contains chromosomes (DNA)
nucleolus
produces ribosomes (important for growth and development of neuron)
ribosomes
site of protein synthesis or translation in all cells
mitochondria
powerhouse of the cell
Golgi apparatus
type of endoplasmic reticulum
- role in making sure proteins are created
axon
carries the electrical signal; typically single axon but can have branches
axon hillock
where the axon initiates from the cell body (electrical signal starts here)
dendrites
- Arise from the cell body; multiple branches
- primary targets for synaptic inputs from other neurons
- contain a lot of ribosomes; contain specialized cytoskeletal proteins
nissl bodies
clusters of rough endoplasmic reticulum
- make proteins and replace growth and regenerating
neurofibrils
cell shape and support
microtubules
allow movement of materials to/from cell body
transport
organelles can be moved along the neuron
slow axonal transport
1-5 mm/day; unidirectional; axoplasm supply
- away from cell body
fast axonal transport
200-400 mm/day; to and from cell body
- bidirectional
- bring garbage cells up to be recycled and bring down new
convergence
reflects the number of inputs to a single neuron
- coming in
- receive input from more than one location
divergence
reflects the number of targets that 1 neuron innervates
- going out
bipolar
2 ends (1 axon, 1 dendrite)
unipolar
1 axon, no dendrites
multipolar
several dendrites, 1 primary axon
receptors
sense something (sensory)
afferents
carry single away from periphery to CNS (dorsal)
integrating centers
integrate/figure out what info means
internuncial neurons (interneurons)
connect neurons (relay point)
efferents
carry info away from CNS to periphery
effectors
target cells, number of types of tissue (endocrine glands, muscles, etc)
presynaptic neuron
sending the message
postsynaptic neuron
receiving the message
synaptic cleft
space between the presynaptic and postsynaptic neurons
- support cells within space that help neurotransmitter across
interneurons
short neurons that connect other neurons
- only found in CNS
projection neurons
longer neurons that carry signals over significant distances
- travel long distance
glial cells
- supportive cells
- still vital
- only stem cells in the adult brain
glial cells function
- regulate ions in the nervous system
- influence signal transduction in nerve cells
- control neurotransmitter reuptake and processing at / near synaptic cleft
- provide framework for growth of neural tissue during development
- play a role in neural recovery from injury
- brain-immune system interface
- cycles interstitial fluid through the brain during sleep
primary types of glial cells
- astrocytes
- oligodendrocytes
- microglial cells
glial stem cells
- subset of astrocytes
- polydendrocytes
astrocytes
found in the CNS
astrocytes function
- blood brain barrier
- ensure appropriate chemical environment for neuronal signaling
- formation of new synapses
oligodendrocytes
only found in CNS
oligodendrocytes function
- produce myelin - stops electrical signal from leaking out
- speeds up transmission of electrical signals
Schwann cells
the cells in the PNS that produce myelin
microglial cells
- important when injury / damage occurs
- signal to other cells to modulate inflammatory response
subset of astrocytes
- mostly located near the ventricles of the brain or near the blood vessels around the ventricles
polydendrocytes
- produce mature oligodendrocytes and some astrocytes
ganglia
group of nerve cell bodies and supporting cells
nerves
groups of peripheral axons
sensory systems
- receive and process internal (movement) and external (touch, vibration, pain, temp) stimuli
- peripheral and central nervous system components
motor systems
- generate movement
- usually, but not always, in response to sensory stimuli
association systems
- “relay” center
- process/integrate signals from sensory and motor systems, send them on to the appropriate area
somatic motor division
connect brain/spinal cord to skeletal muscle
visceral/autonomic motor divison
innervates smooth muscle, cardiac muscle, glands (involuntary)
autonomic ganglia
site of synapses between CNS visceral motor neurons and peripheral motor neurons
sympathetic division
ganglia located near the spinal column
parasympathetic divison
ganglia located near the organs they innervate
enteric system
gut innervation
