NeuroScience Mid Term 1

• Descartes (1595-1650) believed that the mind is spiritual and receives sensations and command movements by communication from the Pineal gland.

  
• Histology: the microscopic study of the structure of tissues.
• Nissl Stain: It distinguishes between neurons and glia, and it enables histologists to study the arrangement or (cytoarchitecture) of neurons in different parts of the brain.
• Golgi Stain: Soaking brain tissue in a silver chromate solution makes a small percentage of neurons become darkly colored in their entirety.

  This revealed that the neuronal cell body, the region of the

  neuron around the nucleus that is shown with the Nissl stain, is actually

  only a small fraction of the total structure of the neuron.
• The Golgi stain shows that neurons have at least two distinguishable

  parts: a central region that contains the cell nucleus and numerous thin

  tubes that radiate away from the central region.
• Glia or glial cells: contribute to brain function mainly by insulating, supporting, and nourishing neighboring neurons.
• Cytolsol: The watery fluid inside the cell, is a salty, potassium-rich

  solution that is separated from the outside by the neuronal membrane.

  Within the soma are several membrane-enclosed structures

  called organelles.
• Golgi Apparatus: The stack of membrane-enclosed disks in the soma that lies farthest from the nucleus which sorts certain proteins that are destined for delivery to different parts of the neuron, such as the axon and the dendrites.
• Adenosine triphosphate (ATP): The cell's energy source. The chemical energy stored in ATP fuels most of the biochemical reactions of the neuron.
• Electrostatic or electric force: When ions of a similar charge repel each other and thus move in certain directions in a solution
• sodium potassium pumps are correcting those rouge ions that go across the membrane.
• • If the brain is deprived of oxygen, the Mitochondria within neurons cease producing ATP and the resting membrane potential would be compromised because the sodium-potassium pumps do not work. 
• No energy is required for the voltage-dependent ion channels, energy is only required for pumps.
• • Volted-gated ions: They are proteins that do not require energy to operate because of the charged polar segments of the subunits they will just move. When there's a change in the membrane potential it does not require ATP to make them move It's automatic and the movement of ions across the membrane requires no energy to make that happen.
• Equilibrium is -80mV, especially potassium
• The action potential is trigged once the resting membrane potential is depolarized to at least the threshold level. If it doesn’t travel it will slightly depolarize and dissipate but once there becomes an action potential it lasts about 2 milliseconds. It propagated or conducted down the axon membrane by depolarizing to threshold successive. 
• Cytoskeleton: This is what gives the neuron its characteristic shape. The "bones" of the cytoskeleton are the microtubules, microfilaments, and neurofilaments.
• Microtubule-Associated Proteins (MAPs): A class of proteins that participate in the regulation of microtubule assembly and function.

  • Pathological changes in an axonal MAP are called "Tau" Which have been implicated in the dementia that accompanies Alzheimer's disease.
• Axon Hillock: The beginning of the axon and specialized for the transfer of information over distances in the nervous system.
• Axon Terminal: The end of the axon where the axon comes in contact with other neurons and passes information on to them.
• Axoplasmic transport: The degeneration of axons that occurs when they are cut is now (Wallerian degeneration) which occurs because the normal flow of materials from the soma to the axon terminal is interrupted.
• Fast axoplasmic transport: Material is enclosed within vesicles which then "walk down" the microtubules of the axon. The "legs" are provided by a protein called Kinesin and the process is fueled by ATP.
• Anterograde Transport: Kinesin moves material only from the soma to the terminal.
• Retrograde Transport: Movement from the terminal to the soma. The "legs" for retrograde transport are provided by dynein.
• Astrocytes: fill most of the space between neurons which regulate the chemical content of this extracellular space. They also have a special protein in their membrane that actively removes Neurotransmitters from the synaptic cleft.
• Oligodendroglial Cells: Provide layers of membrane that insulate axons with wrappings that are called myelin.
• Oligodendrolia are found only in the central nervous system and contribute myelin to several axons.

  Schwann Cells are found only in the peripheral nervous system and this myelinates only a single axon.
• The electrical charge in the cytosol of the axon is carried by electrical charge atoms (ions) instead of free electrons
• Action Potential: the axonal membrane has properties that enable it to conduct a special type of signal.
• Organelles: membrane-enclosed structures within the

  soma
• Agonist: Drug that attaches to certain neurochemical receptors and mimics or modulates the activity of the endogenous neurochemical.
• Antagonist: a drug that attaches to a certain neurochemical receptor and blocks or hinders the action of the endogenous neurochemical
• Ligand: Substance that binds to a postsynaptic receptor or an ion channel. (Transmitter, hormone, drug)
• Receptor: Binding location for neurochemicals so that they can exert their effect on specific neurons; most are specific, genetically encoded, specialized proteins.
• Precursor: Substance that, on entering the CNS, serves as a foundational ingredient for the subsequent formation of a neurochemical. Tryptophan, found in bananas, turkey, and milk, crosses the blood-brain barrier, interacts with certain enzymes, and results in the formation of the Neurotransmitter serotonin.
• Autorecpetor: Receptor located in the membrane of the presynaptic neuron that is sensitive to the neurochemical being released by the neuron so that it can monitor the neurochemical activity of the neuron.
• Reuptake: Reabsorption of a neurochemical that is activating a receptor into the cell that secreted it, usually so that it can be repackaged and used again.
• Modulation: Synaptic transmission that modifies effectiveness of EPSPs generates by other synapses with transmitter-gated ion channels.
• Types of synapses

  Axodendritic: Axon to dendrite

  Axosomatic: Axon to the cell body

  Axoaxonie: Axon to Axon

  Dendrodendritic: Dendrite to Dendrite
• Sodium potassium pumps are correcting those rouge ions that go across the membrane.