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APHY 9.1
NEURAL CELLULAR PHYSIOLOGY
| Question | Answer |
|---|---|
| ______ _____ surround all axons in the peripheral nervous system | Schwann Cells |
| Schwann cells create a layer called ______ that protects axons | neurolemma |
| A _______ ______ is formed by ________ when and axon in the PNS is cut. | Regeneration tube Schwann Cells |
| If the regeneration tube is disrupted ________ will fail. | Regeneration |
| Which glial cell does not develop from the embryonic neural tube, and where does it develop? | Microglia Originates as monocytes in embryo and migrate to neural tube |
| Microglia function as _________ cells and are responsible for _______ axons | phagocytic cells pruning |
| ______ are the most abundant glial cell | Astrocytes |
| What are the 4 main functions of astrocytes | Regulate the environment of the CNS Supply neurons with lactate Recycle neurotransmitters Participate directly in cognition |
| Since neurons in the CNS require constant moving of K+ inside of the cell to the outside of the cell, it is critical that astrocytes do what? | Uptake K+ from extracellular fluid to maintain the proper ionic environment of neurons. |
| Astrocytes form the ______ ______ ______ to prevent exchanging of substances through filtration | Blood brain barrier |
| End-feet around capillaries take up ______ from the blood and convert it to _________ via _______ | Glucose Lactate Anerobic glycolysis |
| ______-______ build up and store glycogen to allow creation of more lactate on demand | End-Feet |
| Neurons are dependent on the supply of lactate from ________ to survive | Astrocytes |
| CNS neurons lack the ________ for the glycolytic pathway or to catabolize proteins/fatty acids for energy | Enzymes |
| CNS neurons derive all of their ATP by converting _______ to _______ where it enters the ________ pathway. | Lactate Pyruvate Aerobic |
| By converting lactate to pyruvate where it enters the aerobic pathways, the neurons are able to make ATP more _________ during bursts of activity. | Quickly |
| Astrocytes take up ______ and _______ | K+ and Glutamate |
| ________ is the major excitatory neurotransmitter released in the CNS (so it ends up everywhere) | Glutamate |
| Glutamate is converted to _______ by the astrocytes | Glutamine |
| The conversion of Glutamate to Glutamine prevents __________ | Cross-Talk |
| Astrocytes return glutamine back to the excitatory neurons which use it as raw material to make more _________ | Glutamate |
| Inhibitory neurons convert glutamine to _______, (the major inhibitory neurotransmitter of the CNS) | gamma-aminobutyric acid (GABA) |
| Astrocytes do not produce ______ ______ | action potentials |
| Astrocytes are depolarized by changes in the intracellular ______ concentration, and become active participants in brain circuitry as a result | Ca++ |
| True or false Neurons communicate with astrocytes in the cerebellum to aid in coordinating motor activity | True |
| Astrocytes respond to glutamate and other signals from neurons by releasing ___________. | Gliotransmitters |
| When gliotransmitters stimulate or inhibit surrounding neurons it is called _____-_____ _______ | neuron-glia crosstalk |
| Astrocytes play an essential role in regulating the formation of new _____ and _______ | synapses and neurogenesis |
| The nucleus and machinery for protein synthesis is confined to the ______ ______ | cell body |
| _________ proteins carry materials anterograde | Kinesin |
| Some kinesins are a part of the fast system (_____mm/day) which carries vesicles with neurotransmitter to resupply the _____ ______ | 400mm/day terminal button |
| Some kinesins are a part of the slow system (_____mm/day) and resupply the ______ with more than 200 critical proteins | 0.2mm/day axon |
| _______ proteins transport materials retrograde, and carry used lysosomes and other organs and molecules back to the _____ ____ | Dynein Cell body |
| A build-up of ions on one side of the membrane creates a ______ _____ and an _____ _____ | charge imbalance electric field |
| The combined electric effect of all ions on both sides of the membrane sets up an electric field called the ________ ________ | membrane potential |
| The ______ ______ pushes or pulls ions across the membrane | membrane potential |
| The force from the membrane potential and the force of the chemical concentration sum together to drive diffusion of charged particles. This overall force is known as ________ ________ | electrochemical gradient |
| Electric potential is measured in _______. | Volts |
| ______(+/-) membrane potential pushes cations out and pulls anions in | positive (+) |
| ______(+/-) membrane potential pulls cations in and pushes anions out | negative (-) |
| What is the normal molarities (higher concentration inside/outside of cell) of the 4 most important ions inside of the cell? | Na+ higher concentration outside of cell K+ higher concentration inside of cell Cl- higher concentration outside of cell Ca++ higher concentration outside of cell |
| Na+/K+ pumps move ___ (#) Na+ outward and ___ (#) K+ inward | 3 Na+ out 2 K+ in |
| Plasma membrane Ca++ pumps move ___(#) Ca++ outward per ATP | 1 Ca++ out |
| What two forms of active transport are responsible for maintaining the normal molarities of intracellular and extracellular fluid? | Na+/K+ pumps Plasma membrane Ca++ pumps |
| True or False Charged ions can readily cross the phospholipid bilayer. | False |
| Charge ions need specific _______ channels in order to cross the phospholipid bilayer | protein |
| When the gated channel for one type of ion opens, the increased permeability allows the ion to diffuse until the membrane potential reaches a specific level called an _________ _________ | Equilibrium potential |
| The K+ equilibrium potential is ______mV | -90mV |
| The Na+ equilibrium potential is ______ mV | +66mV |
| When Na+ channels open, does Na+ diffuse in or out of the cell | In |
| When K+ channels open, does K+ diffuse in or out of the cell | Out |
| Normal membrane potential of a cell is known as _____ _____ _____ and is typically ______ mV | Resting membrane potential -70mV |
| Negative resting membrane potential is a result of which non-gated, passive channels. | K+ leak channels |
| K+ leak channels are always _______(open/closed) just enough to keep the cell close to the K+ equilibrium potential of ______mV | Open -90mV |
| A cell is considered _________ (polarized/depolarized) when at resting membrane potential | Polarized |
| Rise in membrane potential due to the inflow of positive charge is described as _________ (polarized/depolarized), because the potential moves toward 0mV. | Depolarized |
| Depolarization has an ________ (excitatory/inhibitory) effect | excitatory |
| Movement of the membrane potential back downward is known as _______ | Repolarization |
| If membrane potential becomes more negative than resting potential it is known as __________ | Hyperpolarization |
| In the axon, relevant ion channels are ________-gated, meaning that the membrane potential itself opens them | Voltage |
| Voltage-gated channels have two mechanisms in order to ______/_______ them | open/close |
| Voltage-gated Na+ channels open at a threshold of ________mV | -55mV |
| Voltage-gated K+ channels open at a threshold of ______mV | +30mV |
| Open voltage-gated channels do not close by a threshold, instead they close by ________________ | N-Type inactivation |
| During N-Type inactivation channels are ____________ to membrane potential and will not reopen until fully reset | insensitive |
| The interaction between Na+ and K+ voltage-gated channels creates a phenomenon called an ______ ________ | action potential |
| The entire purpose of an axon is to transmit an electrical signal called an _______, quickly from the cell body to the terminal button | impulse |
| The measure of how much a voltage attenuates (gets smaller) from one part of an axon to another is called the ______ _______ | Cable Property |
| With an average axon, a change in potential will lose about ____% of its magnitude after traveling a millimeter | 85% |
| True or False No axons have sufficient cable property to carry an impulse the entire length | True |
| The All-or-None Law causes a problem with how to encode information about intensity, but this is solved by ______ _______ | Frequency modulation |
| Action potentials have periods of rest called ________ ________ | Refractory periods |
| The __________ refractory period is where ion channels will not respond to voltage due to N-Type inactivation | Absolute |
| The absolute refractory period gives the impulse time to propagate far enough away to prevent retriggering the same area which would cause a _______ | Bounce |
| The ________ refractory period is where it is possible for another action potential to occur, but harder than normal because the membrane is hyperpolarized. | Relative |
| In relative refractory periods a larger ________ stimulus is required to reach -55mV | depolarizing |
| Relative refractory period sets up ________ ______ since progressively stronger stimuli are required to trigger more frequent action potential | frequency encoding |
| ______ is an insulating roll of 20-40 layers of plasma membrane wrapped around axons | Myelin |
| Myelin is produced by _______ in the PNS and _________ in the CNS | Schwann Cells Oligodendrocytes |
| What is the purpose of Myelin? | To block movements of ions across the membrane (prevent leakage) to significantly speed up nerve conduction by further improving cable property. |
| Unmyelinated gaps are called _________? | Nodes of Ranvier |
| True or False Nodes of Ranvier do not allow ion channels to function | False |
| Action potentials can only occur in the nodes of Ranvier and "jump" to the next, this is known as _________ _________ | saltatory conduction |
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