Cells of the Nervous System Flashcards
Neurons
building blocks of the nervous system
discrete, metabolic units
Golgi Method
“the black method”
- used to visualize individual neurons
Input zone
where neurons collect and process info, either from the environment or from other cells
- dendrites
Integration Zone
where the decision to produce a neural signal is made
- inputs are combined here
Conduction zone
where info can be electrically transmitted over great distances
- info as electrical signal goes down axon
Output zone
axon terminals transfer info to other cells
what kind of signals flow info through neuron
electric signal -> chem signal -> electric signal
sensory neurons
respond to environmental stimuli (light, touch, etc.)
interneurons
receive input from a neuron and send input to another neuron
motor neuron
stimulate muscles or glands
unipolar neuron
has a single extension from the cell body (axon that extends into dendrites)
- make up most neurons in CNS of invertebrates
- helps with direct signaling bc it is quicker
- not found in humans
pseudounipolar neurons
single extension from cell body and axon splits into two branches
- are exclusively sensory neurons (dorsal root ganglia and cranial nerves)
- carry info about touch, vibration, pain, temp, etc.
- branches are axons, there are no dendrites
bipolar neuron
one axon, one dendrite
- ex: form the middle layer of the retina
multipolar neuron
only has one axon extending from the cell body, but multiple dendrites grow out of it, making transmitting information easier
- also helpful to gather lots of information
dendritic arborization
the branching out of dendrites
- more of it means more complexity bc there are more synaptic connections possible
dendritic spines
- form functional contacts with neighboring axons of other neurons
- are very plastic and their size and shape are constantly changing in response to neuronal activity
axon hillock
part of the cell body that acts as an administrator (integration zone)
- sums up inhibitory and excitatory signals to see if it is enough to trigger an action potential
- if so, an electrical signal is sent down the axon
anterograde transport
help move info to and from the neuron
- ex: anterograde motor proteins: kinesin
retrograde transport
shuttles molecules/organelles away from axon termini toward the cell body
- ex: cytoplasmic dynein is used to send chemical messages and endocytosis products headed to endolysosomes from the axon back to the cell
what cargo might anterograde vs. retrograde proteins carry?
- neurotransmitters/precursors to axon terminal
- movement of nutrients
synaptic transmission
synaptic vesicles in presynaptic axon terminals contain a chemical neurotransmitter (nt)
- nt are released in response to electrical activity in the axon
- receptors in the postsynaptic membrane are specialized proteins that react when a nt molecule binds to them
glia
- communicate with each other and neurons
- influence neural structure and excitability
- important for neural repair and signaling
microglia
- functions: surveillance, pruning, and plasticity
- are the primary immune system of the nervous system
- patrol the cerebral microenvironment to respond to pathogens and damage
- release inflammatory factors like cytokines
- make up 10% of cells in the brain
- can change morphology depending on what it needs to do
cytokines
proteins that, when released, signal the immune system to do its job
- affect the growth of all blood cells and activity of immune cells
aberrations (abnormalities) in microglia functioning can lead to
excessive synapse loss and cognitive dysfunction
- ex: Alzheimer’s Disease, Schizophrenia (excessive synaptic pruning)
macroglia
- oligodendrocytes
- schwann cells
- both have similar function (form myelin sheath) but occur in different parts
oligodendrocytes
in the CNS and form myelin sheaths in brain and spinal cord
schwann cells
in the PNS and form myelin sheath for cells outside of the brain
insulation of axons (myelin sheath) help to
transmit electrical impulses quickly and efficiently
myelination in cells over time
- more myelination occurs as neuron cell grows older (baby has none and adult is longer with more myelin)
- increases rapidly during first 6 months of life bc there is a lot of info coming in and is learning a lot
- locations near back and top of brain get myelinated fastest (vision/motion)
Multiple Sclerosis
- immune system mistakenly attacks brain and nerves
- causes a loss in myelination
- leads to sclerosis (abnormal hardening of body tissue)
astrocytes
help transmit info from neurons and blood
- monitor and support neurons
- regulate cerebral blood flow in adjacent capillaries to coordinate oxygen and glucose delivery with the energy demands of neurons
- can receive neuronal input and release transmitters (gliotransmission)
can glia “talk”?
glia tune signal and amplify it
- regulate how neurons communicate
- release additional glutamate in return (can activate glutamate receptors on cerebellum neurons to amplify neural function - important for motor learning)
