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53 Cards in this Set
- Front
- Back
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Are there more glia or neurons in the nervous system?
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Glia outnumber neurons 10-fold
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How large are most neurons?
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0.01-0.05 mm in diameter
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Since the consistency of the brain is like Jello, what did the anatomy of the study of the anatomy of the brain cellls have to await?
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The development of a method to harden the without disturbing it structure and an instrument that could produce very thin slices
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What is the microscopic study of the structure of tissues called?
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Histology
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Why are Nissl stains useful?
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1. Distinguish neurons and glia from one another
2. Enables histologists to study the arrangement or cytoarchitecture of neurons in different parts of the brain |
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What are two other words for cell body?
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Soma and perikaryon
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What view did Golgi take regarding the organization of the brain?
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Neurites of different cells are fused together to form a continuous reticulum; brain is an exception to cell theory, which states that the individual cell is the elementary functional unit ofall animal tissue.
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What view did Gajal take regarding the organization of the brain?
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Neurites of different neuronsare not continuous with one another and must communicate by contact, not continuity; neuron doctrine
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What is teh reading of the DNA known as?
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Gene expression
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What is the structure of messenger RNA?
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Four different nucleic acids strung together in various sequences to form a chain
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Structurally describe RNA.
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At one end of the gene is at the promoter, where NRNA-synthesizing enzyme , RNA polymerase, binds to initiate transcription. The binding of ht epolymerase to the promoter is tightly regulated by othe rproteins called trasncription factors. At the other end is a sequences of DNA called the terminator that the RNA polymerase recognizes at the point of transcription.
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What is RNa splicing?
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Introns are removed and axons remaining exons are fused together
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All all ribosomes attached to the rough ER?
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No; many are freely floating and are caled free ribosomes
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When are free ribosomes preferred?
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If a protein is destined to reside within the cytosol of the neuron, then protein's mRNA transcript shuns ribosomes of rough ER and gravitates toward free ribosomes.
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What do smooth ERs do?
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Performs different functions at different locations; site where proteins that jut out from teh membrane are carefully folded, giving them their three-dimensional structure; regulate internal concentrations of substances, such as calcium
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Which organelle lies farther from the nucleus?
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Golgi appartus
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What are the multiple folds of the inner membrane of mitochondria called?
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Cristae
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What are the inner spaces of the mitochondria called?
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Matrix
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How does the mitochondria create ATP?
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Pulls in pyruvic acid and axygen; converts to ATP through Krebs Cycle
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What are MAPs?
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Microtubule-associated proteins that anchor the microtubulues to one another and to tther parts of hte neuron
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What can disrupting the function of MAPs lead to?
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Pathological changes in an axonal MAP, called tau, have been implicated in the dementia that accompanies Alzheimer's disease
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Describe microfilaments.
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Particularly numerous in the neurites; strands are polymers of the protein actin
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Describe neurofilaments.
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Intermediate in size between microtubules and microfilaments.; called intermediate filament in every other cell type besides the neuron; consist of individual long protien molecules
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What are 2 structural differences between the axon and the soma?
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1. No rough ER extends into the axon (few if any free ribosomes)
2. Protein composition of the axon membrane is fundamentally different from that of the soma membrane |
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What are branchings of axons called?
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Axon collaterals; those that return to communicate with the same cell are called recurrent collaterals
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What are 5 ways to classify neurons?
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1. Number of neurites
2. Dendrites 3. Connections (motor, sensory, & interneuron) 4. Axon length 5. Neurotransmitters |
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Describe how one classifies based on dendrites.
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Stellate cells are star-shaped and can be either spiny or aspinous; pyramidal cells are pyramid-shaped and are spiny
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What are the two classification based on axon length?
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Golgi type I neurons (long axons, such as pyramidal cells) and Golgi type II neurons (short axons, such as stellate cells)
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What are 4 functions of astrocytes?
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1. Influences whether a neurite can grow or retract
2. Envelop synaptic junctions in the brain, thereby restricting the spread of neurotransmitter molecules that have been released 3. Posses neurotransmitter receptors that can trigger electrical and biochemical events inside the glia 4. Regulate the concentration of potassium ions in the extracellular fluid |
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What are the two types of myelinating glia?
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Oligodendrocytes in the CNS (myelinate several axons) and Schwann cells in the PNS (myelinate one axon)
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What are ependymal cells?
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Provide the lining of fluid-filled ventricles within the brain and play a role in directing cell migration during the brain development
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What are microglia?
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function as phagocytes to remove debris left by dead or degenerating neurons and glia
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Do action potentials diminish over distance?
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NO, they are signals of fixed size and duration
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How is information encoded by action potentials?
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Encoded in the and distribution/# of neurons firing action potentials
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What are the 3 'main players' in the establishment of membrane potential?
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1. Salty fluids on either side of the membrane
2. Membrane itself 3. Proteins that span membrane |
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What is the center carbon of amino acids called?
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The alpha carbon
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Describe the primary, secondary, tert
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Primary: chain
Secondary: beta or alpha Tertiary: globular shape Quaternary: different polypeptide chains bond together to form a larger molecule |
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In addition to ion channels, what are the other type of protein openings in the membrane?
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Ion pumps
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Ionic movement through channels are influenced by which two factors?
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Diffusion and electricity
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How can Vm be measured?
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Micropoelectrodes (extremely fine tip that penetrate the membrane potential; filled with electrically conductive salt solution adn connected to voltmeter that measures the electrical potential difference between the tip of microelectrode and wire placed outside the cell
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What is the membrane's ability to store electrical charge called?
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Capacitance
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What is the ionic driving force?
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The difference between the real membrane potential and the equilibrium potential
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How can the equilibrium potential be calculated?
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Using the Nerst equation
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What is the Nerst equation used to calculate?
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The equilibrium potential
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Is Ca+ more concentrated inside or outside of the cell at equilibrium potential?
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Outside
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How does the sodium-potassium pump work?
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Breaks down ATP in the presence of internal NA+; exchanges internal NA+ for external K+ ~ maintains higher concentration of K+ inside and Na+ outside of the cell
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What is the resting membrane potential?
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-65 mV
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How can the resting membrane potential be calculated?
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Goldman equation
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What is the Goldman equation used to calculate?
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The resting membrane potential
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What region of the potassium channels are of particular interest?
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Pore loop, which contributes to the selectivity filter that makes the channel permeable mostly to K+ ions
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How does scorpion toxin work?
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Blocks the potassium channel by binding tightly to a site within thh channel pore
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What does the blood-brain barrier do?
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Limits the movement of potassium into the extracellular fluid of the brain
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What is potassium spatial buffering?
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The regulation of K+ outside of the cell by astrocytes; increase of K+ inside the cell is dissipated over a large area by astrocytic processes
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