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64 Cards in this Set

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