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64 Cards in this Set
- Front
- Back
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What are the 2 basic types of cells in the CNS?
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-information carriers (neurons or nerve cells)
-support cells (glia) |
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Describe neurons.
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-nerve cell
-the info-processing and transmitting element in the nervous system -billions in nervous system |
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What do neuroglia ("glue") provide?
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-physical support
-regulate nutrient flow -nerve "housekeeping" |
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What are the 3 primary types of glial cells?
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-astrocytes (CNS)
-oligodendroglia (CNS) -schwann cells (PNS) |
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Describe astrocytes.
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-clean up local debris including dead neurons (phagocytosis)
-provide nutrients -regulate chemical composition of extra cellular fluid -in CNS |
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What is phagocytosis?
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the process of cleaning up
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Describe oligodendroglia.
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-in CNS
-provide support for axons -produce myelin sheath |
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What is myelin composed of?
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80% lipid and 20% protein
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What surrounds axons in a series of segments approximately 1 mm long, with small bare portions between segments?
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myelin
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What are the Nodes of Ranvier?
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the 1 mm gaps between myelin
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What are microglia?
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-smallest glial cells
-phagocytes -protect brain from invading microorganisms |
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What are schwann cells?
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-in the PNS
-support cells -produce myelin -each cell provides myelin for one neuron (unlike oligodendroglia) |
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What are the 4 different neuron classification schemes?
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-number of neurites (axons and dendrites) that extend from soma (unipolar, bipolar, multipolar)
-connections (sensory, motor, interneurons) -neurotransmitter (NT) used by neuron -effects of NT (excitatory vs. inhibatory) |
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What are unipolar neurities?
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-have one primary process
-no dendrites emerging from soma -appear in some ganglia |
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What are bipolar neurons?
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-have 2 processes extending from the cell body
-one extension is peripheral and the other is central, which carries info to the CNS -egs. retinal cells, olfactory epithelium cells |
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What are pseudounipolar cells?
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-have 2 axons
-one axon extends centrally toward the spinal cord, the other extends toward the skin or muscle -eg. dorsal root ganglion cells |
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What are multipolar neurons?
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-have a single axon and one or more dendritic branches that emerge the soma
-egs. spinal motor neurons, pyramidal neurons, Purkinje cells |
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What are the different neuron connection types?
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-sensory (afferent)
-motor (efferent) -interneurons |
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What are interneurons?
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a neuron located entirely within the CNS
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True or false: Protein is produced outside the nucleus.
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True
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Why are proteins important for cell function?
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-provide structure
-serve as enzymes that control chemical reactions |
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Genes in cells nucleus produce ______ which is a copy of a portion of _______.
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-mRNA
-DNA |
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When the mRNA leaves the nucleus what does it attach to?
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ribosomes
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What do ribosomes produce?
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the particular protein
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Chromosomes are strands of?
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DNA
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What is a specific segment of DNA on a chromosome?
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gene
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What is mRNA?
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a molecule that delivers genetic instructions from a portion of a chromosome to a ribosome for protein synthesis
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Where are receptor proteins located?
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on the dendrites
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What is the function of the mitochondria?
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breakdown nutrients and produce ATP (adenosine triphosphate), which is used as an immediate source of energy
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What are endoplasmic reticulum?
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-a channel for transporting chemicals through cytoplasm
-segregates proteins destined for export from the cell or for intracellular use -stores ribosomes, which produce proteins |
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What is cytoplasm?
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intracellular fluid
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What is the golgi apparatus? AND what does it produce?
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-a special form of smooth endoplasmic reticulum
-it produces lysosomes |
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What are lysosomes?
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-serve as a cleaning process
-small sacs that contain enzymes that break down substances no longer needed by the cell -recycle the cell's organic material |
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What is axoplasmic transportation?
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because some neurons are long (4-5 ft.), a transportation system is necessary to deliver substances that are manufactures in the soma to the terminal button
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What are microtubles?
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-long strands of protein filaments
-substances are propelled along microtubules that run the length of the axon |
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What is anterograde?
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movement of substance from soma to button
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What is retrograde?
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movement of substance from button to soma
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What does the semi permeable cell membrane play a role in?
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the maintenance of resting membrane potential (has a certain charge/voltage at rest)
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What are the selected particles that can get inside the cell's membrane?
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by diffusion or active transport:
-ions -nutrients -molecules |
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What is diffusion?
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molecules want to go from a high concentration to a low concentration (passive)
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How do neurons communicate?
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via synapses
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What do synapses result from?
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one neuron transmitting a chemical message (NT) to another neuron
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Neurons send messages thru what process?
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electrochemical process
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What are ions?
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chemicals in the body that contain an electrical charge
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What ions play important roles in the nervous system?
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-sodium (Na) and potassium (K) have a positive charge
-chloride has a negative charge -negatively charged protein molecules |
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What are action potentials (AP)?
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the fundamental units of neural communication
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What are the properties of AP?
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-"all or none" event
-actively propagated down the axon on successive patches of membrane -reflects the property of the membrane |
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What is resting membrane potential?
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-pre-action potential conditions in the cell (before anything has happened)
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True or false: Neurons do not always have a charge.
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False: Neurons always have a charge.
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True or false: At rest the cell has a positive charge.
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False: negative charge at rest
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What charge do cells have at rest?
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-70 mV (millivolt) - means that the charge inside of is 70 mV less than the outside
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When the depolarization of a cell reaches _______, a neuron will fire at AP.
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-55 mV <--Threshold of excitation
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What is depolarization?
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when the cell becomes activated (because at rest it is polarized)
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True or false: AP is a stereotyped change in membrane potential.
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True - happens the same way each time
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What happens in a cell when RMP moves past threshold (-55 mV)?
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the membrane quickly moves to +40 mV and then returns to resting
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What is hyperpolarization?
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when charge in cell is below -70 mV
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Why does the cell have a negative charge at rest?
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because if it were equal the ions wouldn't want to go anywhere and nothing would occur
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What 2 sources cause the cell to be negative inside?
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-electrostatic
-diffusion |
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What is electrostatic?
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electrical gradients (differences in charge- when they're negative they want to repell, when they're opposite they want to attract)
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What actively transport ions to establish a concentration gradient?
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sodium-potassium pump
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Why does Na+ really like to go inside the cell?
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because there is a low concentration inside and at rest inside the cell is negative (opposites attract)
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What does the sodium-potassium pump do?
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-sets RMP charge to -70 mV
-moves 3 Na+ out of for every 2 K+ that is pumps into cell -creates a concentration gradient that triggers a negative electrical gradient |
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What is ionic basis of AP?
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Na+ in
K+ out |
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Describe the propagation of AP down the axon.
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-action potentials typically originate at the axon hillock because it has a lower threshold than the rest of the plasma membrane
-once the AP is initiated it travels across the soma and down the axon -the AP only changes the voltage on the surface near the membrane, it doesn't occur within the whole cell |
