Quiz2 Flashcards
label the parts of a neuron
on paper
give the basic description of what parts of the neuron do
dendrites: receive neurological information
cell body: contains nucleus and other organelles to support cell function
axon hillock: location a large electrical signal is generated
axon: transmits electrical/chemical signal
myelin: controls speed of signal
what is resting potential
difference in electrical charge between the inside and outside of a neuron
-the resting potential of a neuron is -70mV
why is the resting potential of a neuron negative
- neurons have semi-permeable membrane, ions can move through but not easily
- positively charged ions: K+ and Na+
- inside of cell is negatively charged so K+ in cell is content
- outside of cell is positively charged so Na+ wants to go in because inside is negative
- there are more sodium ions on the outside of the cell than there are more potassium ions on the inside of cell*
what is the sodium potassium pump
pumps 2 K+ into cell and 3 Na+ ions out
explain the Na+ ion in neurons (relative concentration, electrostatic pressure, concentration gradient)
relative concentration: more outside of cell
electrostatic pressure: move in (to negative)
concentration gradient pressure: move inward
explain K+ ion in neurons (relative concentration, electrostatic pressure, concentration gradient)
relative concentration: more inside of cell
electrostatic pressure: move inward (towards negative)
concentration gradient pressure: move outward
explain Cl- ion in neurons (relative concentration, electrostatic pressure, concentration gradient)
relative concentration: more outside of cell
electrostatic pressure: move outward (toward positive)
concentration gradient pressure: move inward
what is an action potential
when cells become stimulated enough to reach -55mV, they reach a threshhold which starts an action potential
what are the four properties of action potential
1) all or nothing: either the cell fires or it doesn’t
2) propagation: once it is in motion nothing else needs to be done and its strength doesn’t decrease with the distance it travels down the neuron
3) threshold: resting potential must meet a certain number for the AP to occur
4) refractory: two periods absolute and relative, there is an upper limit to the firing rate of an AP
what is myelin
- wraps around axons of neurons and it insulates the neuron
- increases the speed of potential
- myelin is “fat” but it is technically glial cells
what are glia cells and the types of glial cells
glia cells are nervous system support cells
- oligodendrocytes myelinate axons in the brain and spine
- schwann cells myelinate axons in the periphery of the body
what are postsynaptic potentials
local changes in electrical potential that occur near the receptor sites can make the charge of a cell more negative or positive
- action potential leads to neurotransmitter release
- postsynaptic receptors bind to neurotransmitters
- binding leads to postsynaptic potentials
- can be either excitatory or inhibitory
what are the differences between post-synaptic and action potentials
- can be excitatory or inhibitory (not just excitatory)
- much smaller in magnitude/ electrical charge
- can be graded
- lose energy over time/space
what is excitatory spatial summation
- if multiple postsynaptic potentials come in at the same time from different spaces
- can maybe provide enough power for AP
what is excitatory temporal summation
one postsynaptic potential occurring again and again quickly and summing enough to start the AP
if APs are all or none how can we tell difference in a strong stimulus? (poke v stab)
- more APs fire off in a smaller period of time
- or a given neuron can fire off quickly or slowly (not stronger)
what are the mechanisms of eliminating neurotransmitters in synaptic cleft
1) reputake: neurotransmitter taken up by the presynaptic neurons
2) enzymatic deactivation: breaking them down
3) glial cell degradation: glial cells destroy neurotransmitter
4) autoreceptors: neurotransmitters bind to them
5) diffusion: neurotransmitters diffuse away from synapse
when the threshold is reached and an action potential starts, what channels open first
the sodium channels open first, sodium rushes in
what are the parts of a synapse
synapse: region of contact between the neuron containing the terminal bouton, the synaptic cleft, and the postsynaptic region
what are the synaptic vesicles
small balloon like structures in and on the neuron that are filled with neurotransmitter
what is the synaptic cleft
space between adjacent neurons
what are receptors
specially configured proteins embedded within the post synaptic membrane that create binding sites for neurotransmitter
what are the types of neurons
interneurons: transmits impulses between neurons
motor neurons
sensory neurons
what is a node of Ranvier
gaps between myelinated sections of an axon
explain depolarization, repolarization and hyperpolarization
depolarization: cell fires and charge goes from -55 to 40, reaching the peak
repolarization: after reaching the peak the electrical charge then retreats to baseline resting potential
hyperpolarization: the voltage becomes briefly more negative than the resting potential
presynaptic v postsynaptic side
presynaptic: side of cleft that releases neurotransmitter
postsynaptic: opposite side containing the outside edge of the neighboring neuron
what are neurotransmitters
molecules released from neuron that enable transmission of signals
what is the difference between absolute and relative refractory periods
absolute: action potential cannot be initiated
relative: more stimulation than normal is needed to initiate an action potential (hyperpolarization)
explain the pump throughout the phase of the action potential
1) sodium channels open and Na goes in (at start of AP)
2) potassium channels open and K leaves cell (during AP)
3) Na channels close (at peak of absolute refractory period)
4) K channels close (at hyperpolarization)
what are the three functions of glial cells
nourishment in neurons
mylenation
breaking down neurotransmitters
