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61 Cards in this Set
- Front
- Back
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peripheral nervous system
central nervous system |
the part of the NS outside of the brain and spinal cord
brain and spinal cord |
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dendrite
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-RECEIVES info from the terminal buttons of other neurons
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synapse
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junction between the terminal button of an axon and the membrane of another nueron
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unipolar and bipolar neurons are ______ types of neurons
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sensory
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terminal buttons
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-bud at the end of a branch of an axon
-forms synapses with other neurons and SENDS info to that neuron -release neurotransmitters |
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neurotransmitter
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chemical released by the terminal buttons that either has excitatory or inhibitory effects on neuron
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mitochondria
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provide energy by producing ATP
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chromosome
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-a strand of DNA that carries genetic makeup (found in the nucleus)
-contain recipe for making proteins |
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enzymes
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cause molecules to either join together or split apart
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microtubules
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bundle of protein filaments that transport substances within the cell
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glia
3 types |
supporting cells of the CNS
astrocytes oligodendrocytes microglia |
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astrocyte
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-provide physical support
-provide nutrients -regulates chemicals |
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oligodendrocyte
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make myelin
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phagocytosis
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when cells engulf and digest other cells or debris caused by cellular degeneration
*performed by astrocyte glia cells |
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microglia
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-act as phagocytes
-protect the brain |
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node of Ranvier
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-unmyelinated sections on axon
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myelin sheath
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-surrounds axons
-preevents messages from spreading btw adjacent axons -increases speed of AP |
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schwann cells
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support axons and produce myelin in the PNS
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blood brain barrier
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semi-permeable barrer between the blood and brain produced by the cells in the walls of the brain's capillaries
-regualtes the composition of extracellular fluid -capillaries of the CNS lack the gaps between the cells |
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membrane potential
*caused by... *potential means |
the electrical charge across a cell membrane, the difference in electrical potential inside and outside the cell
forces of diffusion and electrostatic pressure stored up energy |
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resting potential
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the membrane potential of a neuron when it is not being altered by postsynaptic potentials (-70mV)
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depolarization
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reduction (toward zero) of a membrane potential of a cell from its normal resting potential
*decrase in the difference of electrical charge inside and outside of the cell |
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hyperpolarization
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an increase in the membrane potential of a cell (becomes MORE negative)
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action potential
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-brief electrical impulse that provides the basis for conduction of info along an axon
-70 (resting) , +40 (depolarized), -80 (hyperpolarized), -70 (resting) |
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threshold of excitation
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the voltage level that triggers an action potential
-the value of the membrane potential that must be reached to spark depolarization and trigger an AP |
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diffusion
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*equal distribution of molecules
movement of molecules from regions of high concentration to regions of low concentration |
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ion
cation anion |
a charged molecule
positive charge negative charge |
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electrostatic pressure
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the attractive force between particles charged with opposite signs OR
the opposing force between ions charged with the same sign |
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Na+ (positive charge) outside the cell is attracted to the inside of the cell but another force pushes Na+ out via molecules called ___________
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sodium-potassium transporters
3 Na+ OUT 2 K+ IN |
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INSIDE THE CELL
A- is ______ K+ _______ OUTSIDE THE CELL Na+ _______ Cl-_______ |
-impermeable
-opposes positive charge outside the cell -attracts to negative charge inside the cell -opposes negative charge inside the cell |
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if the membrane became permeable to Na+ then....
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Na+ would rush into the cell which would change the membrane potential and cause an action potential
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ion channels
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provides an opening that permits certain ions to enter or leave the cell
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permeability of a membrane to an ion depends on...
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the number of ion channels that are open
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sequence of an action potential
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1. sodium channels open Na+ enters the cell (triggered by depolarization)
2. potassium channels open next K+ leaves the cell (K+ requires greater depolarization b/c their ion channels are less sensitive 3. when AP reaches its peak, sodium channels become refractory (channels become blocked and no more Na+ enters the cell until resting potential is acheived again) 4. the cell is now + inside due to the influx of Na+ and the K+ continues to leave the cell (driven out by ES pressure) 5.outflow of K+ causes membrane potential to retun to normal, K+ channels close and Na+ channels reset |
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conduction of action potential
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movement of AP down the axon
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all or none law
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the principle that once AP is triggered it is transmitted down the axon to its end
*remains the same size, even when it splits down 2 branches |
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rate of firing, firing means
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rate of production of APs
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rate law
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variations in the intensity of a stimulus being transmitted in an axon are represented by variations in the rate at which an axon fires
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saltatory conduction
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conduction of APs by meylinated axons
*AP is retriggered at each node and jumps from one node to the next |
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advantages to myeling
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1. spend less time maintaining Na+ balance b/c Na+ can not permeate through myelin
2. increased speed of APs down the axon |
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postsynaptic potentials
*produced by? |
change in membrane potential (brief depolarizations or hyperpolarizations) of a post-synaptic membrane
*PPs increase or decrase the rate of firing of the axon of the post-synpatic neuron *NTs in the synapse |
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binding site
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the location on a receptor molecule where ligands (Ex:NTs) attach and exert their effects
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ligand
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chemical that attaches to a binding site
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synaptic cleft
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gap between the presynaptic membrane and the postsynaptic membrane
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synaptic vesicles
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bead like structure found in terminal buttons that carry NTs down the microtubules to the terminal button to disperse NTs into the synaptic cleft
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as APs are conducted down an axon...
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synaptic vesicles fuse with the presynaptic membrane, spilling the NTs into the synaptic cleft
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postsynaptic receptor
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receptor molecule in the post-synaptic membrane of a synapse that contains a binding site for NTs
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once NTs bind with the postsynaptic receptors of the PS membrane...
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post-synaptic receptors open NT-dependent ion channels which permit the passage of certain ions in or out of the cell
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the presence of NTs in the synaptic cleft allows for....
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certain ions to pass through the membrane, changing the membrane potential producing either a depolarization or hyperpolarization in the post-synaptic membrane
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a potential is either depolarizing or hyperpolarizing depending on...
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the characteristics of the post-synaptic receptors and the type of ion channels that they open
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three types of NT dependent ion channels
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sodium
potassium chloride |
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open sodium channels leads to Na+ entering the cells which leads to deplorazation called...
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excitatory postsynaptic potential (EPSP)
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inhibitory postsynaptic potential (IPSP)
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open potassium channels --> K+ leaves the cell OR Cl- enteres the cell --> becomes hyperporlized
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reuptake
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the re-entry of a NT that was recently released from its terminal button back through its membrane
removes NT from synaptic cleft eliminating post-synaptic potential |
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autoreceptor
purpose? |
receptor molecule located on a neuron that responds to the NT released by that neuron
*regulate internal processes |
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type of post-synaptic potential depends on...
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the type of ion channel that is opened by the post-synaptic receptors at a particular synapse
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when are NTs released into the synaptic cleft?
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when the action potential reaches the terminal buttons
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what does a stimulus do to the membrane potential?
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• A stimulus changes the permeability of the cell membrane to sodium and potassium ions which alters the distribution of charge in the cell body and if the change is great enough it triggers an action potential
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what causes the cell to return to resting potential
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when K+ leaves the cell
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what causes an action potential?
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when a stimulus triggers depolarization causing sodium ion channels to open and Na+ rushes into the cell
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what do NTs do in the synaptic cleft
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attach to binding sites of post synaptic receptors which allows ion channels of the post-synaptic membrane to open
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