just flashcards from week one idk
what does the anterior cerebral artery supply
medial surface of cortex
what does the middle cerebral artery supply
lateral side of cortex
what does the posterior cerebral artery supply
occipital lobe, bottom of temporal lobes (ventral cortex)
what does the middle cerebral artery become when it enters the circle of willis/CNS
corotid artery
what did golgi discover
golgi stains, silver nitrate stains around 1% of cells (but not the axon), thought that all neurons were connected (reticularis doctrine), golgi stain is yello
what is the reticularis doctrine
golgi thought that all neurons were connected like a web
who was the person who discovered the yellow staining technique
camillo golgi
who was the person who discovered the purple staining technique
franz nissl (nissl stain)
who came up with the neuronal doctrine
ramon santiago y cajal
what did ramon santiago y cajal discover/think
neurons are not connected but have spaces between them through which they communicate
how many neurons are in the human brain
around 86 billion
name the three types of neurons
sensory, motor, interneurons
name four zones of a neuron from dendrites to terminal
input zone, integration zone, conduction zone, output zone
what is a neurite
the branches (axon or dendrites) which come off the cell body of a neuronwhat
what makes a neuron unipolar
one neurite
cell body—————–dendrites
what makes a neuron bipolar
two neurites
dendrite——-cellbody——————-sensoryreceptor
what makes a neuron pseudopolar
one axon that splits into two branches
where are pseudopolar neurons found
in dorsal root ganglia
what makes a neuron multipolar
more than two neurites
what type of neurons are typically multipolar
motor neurons, cortical neurons
what type of neurons are typically uni and bipolar
sensory neurons
what is the advantage/point of multipolar neurons
receive multiple inputs
what is the advantage/point of uni and bipolar neurons
rapid transmission (not really needing to do integration of stimulus)
what and where is the axon hillock
where the neuron integrates info + makes signaling decision (right before axon on cell body)
are chemical synapses or gap junctions/electrical synapses faster
electric/gap junction synapses are faster
name all 7 shapes of neurons
pyramidal cell, basket cell, chandelier cell, arachniform cell, spiny stellate cell, bitufted cell, double boquet cell
what is the main dendrite of a pyramidal cell called
apical dendrite
name the parts of a pyramidal cell
cell body, axon, apical dendrite, basilar dendrite, oblique dendrite
what is the name of a dendrite that branches from the apical dendrite of a pyramidal cell
oblique
what is the name of a dendrite that branches from the cell body (sort of bunchy) in a pyramidal cell
basilar dendrite
how much of the axon can you see in a golgi stain of a neuron
barely any, bc myelin doesnt stain in golgi stains
name the 5 types of glial cells
microglia, astrocytes, oligodendrocytes, shwann cells, satellite cells
what is the function of microglia cells
activated in response to injury, infection, etc. can cause swelling, too much = bad
what is the function of astrocytes
regulates local bloodflow, nourishment to blood vessels, and maintains the BBB
how do astrocytes help maintain the BBB
astrocytes wrap all around capilaries forming tight junctions so anything cant enter the brain
what do astrocytes have to do with cerebral spinal fluid
CSF can travel through the ‘feet’ of the astrocytes. metabolic waste is carried away through this cerebral spinal fluid mostly as you sleep (slow wave sleep before REM)
what does an oligodendrocyte do
provides myelin to neurons in CNS
what do shwann cells do
provides myelin to neurons in PNS
what is a main difference between oligodendrocytes and shwann cells (beside CNS/PNS)
oligodendrocytes can myelenate MANY axons while shwann cells can only do a little (like one essentially)
what can be a problem with glial cells
continue dividing (unlike neurons) and are susceptible to cause tumor
what are ependymal cells
found inside of brain ventricles and produce + secrete CSF
where are ependymal cells found
inside of brain ventricles
what structure do ependymal cells have that many others do not
cilia to create current in the CSF
what are nine words for a group of axons
bundle, peduncle, nerve, commisure, fasiculus, funiculus, tract, lemniscus, corpus callosum
definition of membrane potential
the difference in electrical charge across the cell membrain (charge inside cell vs charge outside)
depolorization definiton
membran potential moves toward zero (more positive)
hyperpolarization definition
membrain potential moves away from zero (more negative)
equilibrium potential
when the electrical and chemical gradients for a particular ion ‘ballance out’ and there is no net movement of ions across the membrain
which equation do you use to calculate an ions equilibrium potential
nerst equation
which equation do you use to predict which direction/where an ion is going to move
goldman equation
what does the sodium potasium pump do (specific)
uses ATP to move 3 sodium ions out and 2 potassium ions in, maintaining the negative intracellular charge
what does a positive result in the goldman equation mean
ion wants to move OUT of cell
what does a negative result from the goldman equation mean
ion wants to move INTO the cell
is depolorization excitatory or inhibitory
excitatory
is hyperpolarization excitatory or inhibitory
inhibitory
when the mp becomes more positive (closer to zero) this is BLANK which is a INHIBIOTORY/EXCITATORY signal
this is DEPOLARIZATION which is EXCITATORY
what the mp becomes more negative, this is BLANK which is an INHIBITORY/EXCITATORY signal
this is HYPERPOLARIZATION which is INHIBITORY
where do chemical/ligand gated ion chanels exist on a neuron
soma + dendrites
where do voltage gated ion channels exist on a neuron
axon
what is the space between myelinated sections of an axon called
nodes of ranvier
what is a post-synaptic potential
small, brief changes in membane poential
what causes a post-synaptic potential
the opening of CHEMICALLY gated ion channels
what is an EPSP
excitatory post-synaptic potential
increase chances of generating an action potential (depolorization)
what is an IPSP
inhibitory post-synaptic potential
decreases the chances of generating an action potential (hyperpolarization)
what does it mean the post-synaptic potentials are graded
have varying strengths
3 types of membrane potentials
resting mp, post-synaptic/graded potentials, action potentials
what ion channels open to cause depolarization
sodium channels open and sodium rushes into the cell bringing positive charge, making the mp more positive (depolorized)
what ion channels open to cause hyperpolarization
chloride channels open and chloride enters the cell making the membaine potential more negative (hyperpolarization)
ALSO CAN OCCUR WHEN:
potassium chanels are opened and potassium exits the cell making the cell more negative
what is summation
if EPSP is followed by addition EPSPs, sodium chanels will remain open or more will open increasing the sodium conductance and the EPSPs summate (are all added up)
what is threshold mp
each neuron has a threshold mp at which cell will fire an action potential if the summation of EPSPs causes a cell’s mp to reach threshold
name the two types of summation
temporal and spacial
what is temporal summation
when one presynaptic input stimulates a postsynaptic neuron multiple times in a row
what is spacial summation
when multiple presynaptic inputs stimulate one post-synaptic neuron at the same time
can EPSPs summate with IPSPs?
yes, will result in either weaker deplarization (compared to EPSP(s) alone) or no depolarization (depends on strength of IPSP)
what is propogation
the action potential traveling from the axon hillock down the axon to the presynaptic terminal resulting in the release of neurotransmitters
what opens voltage-gated ion channels
when the cell reaches the threshold membane potential
name the 5 phases of an action potential
depolarization, overshoot (rising phase), falling phase, undershoot, return to rest
what causes the rising phase of an action potential
opening of voltage-gated sodium channels which open immediatly once cell reaches threshold mp. sodium rushes in depolarizing the cell
what causes the falling phase of an action potential
caused by the inactivation of sodium channels + the opening of potassium channels.
(abt one milisecond after sodium ion channels open, the sodium channels close and potassium channels open. potassium (+) rushes out of the cell repolarizing the mp + returns mp to rest)
what is the voltage trigger for the opening of potassium channels (during action potential)
also the threshold mp but sodium channels open immediatly and potassium channels have a short delay
what causes the undershoot of an action potential
caused by potassium channels remaining open just long enough to cause hyperpolarization as potassium moves toward its equilibrium potential
what causes the return to rest phase of an action potential
voltage gated ion channels close + sodium/potassium pump reestablishes proper ion concentrations (return to resting mp)
what is a refractory period
neurons can only fire so fast, the refractory period is the time during and right after an action potential is fired in which a neuron cannot fire another action potential
what are the two types of refractory periods
absolute refractory periods and relitive refractory periods
absolute refractory period (def)
during rising + falling phases. during absolute rf a second action potential cannot be fired reguardless of stimulus strength
relative refractory period (def)
during the undershoot. neuron CAN still fire but need a larger-than-normal stimulus to make cell reach threshold again
what causes the absolute refractory period, why physically can the neuron not fire?
the voltage-gated ion channels are either open (rising phase) or inactivated (falling phase)
how does the nervous system know the strength of a stimulus
frequency of action potential firing (weak stimuli cause less frequent action potentials that strong stimuli)
what keeps an action potential from going backwards/the wrong way
the refractory period.
as an action potential moves from one node of ranvier to the next, the sodium channels inactivate once the action potential has ‘passed’ and the inactivated channels on the previous axon segment make it impossible for the membane to depolarize again
what effects speed of action potential propogation/movement
myelination and axon diameter
how does myelin make the propogation of axon potentials faster
action potential ‘jumps/skips’ over myelinated segments (from one node of ranvier to the next), making the distance traveled much shorter
what is saltatory conduction
conduction of action potential on a myelinated axon (jumping from one node of ranvier to the next)
how does axon diameter effect conduction speed
larger the axon diameter, faster the propogation of action potentials
