NSCI 110 1st Edition Lecture 7 Outline of Last Lecture I Dermatomes are body segments that correspond with a specific spinal cord segment II Neurons are specialized in information processing a Unipolar bipolar multipolar neurons III Neurons can be divided functionally a Collecting information b Integrating information c Sending information IV Nodes of Ranvier are located between myelinated segments of axons and allow for salutatory conduction in neurons Outline of Current Lecture I Schwann cells function in creating a healthful environment for axons and can provide myelination when necessary II Astrocytes function in maintaining extracellular concentrations providing structural support and linking neurons to the circulatory system III Microglia are responsible for inflammatory responses in the brain and migrate to injured brain areas IV Transmembrane protein channels allow passage of certain molecules a Leak channels b Gated channels c Pumps Current Lecture I Schwann cells are responsible for creating a healthful environment for an axon a Provide optimal conditions to conduct action potential b Schwann cells can surround unmyelinated axons i Extracellular fluid fills the space between the axons and Schwann cell allowing free movement of substances c What causes a Schwann cell to function as myelin rather than having astrocytic microglial functions i Local cues within the cell ii Growth factors and nutrients are provided in this extracellular environment promoting the neuron s health iii This is referred to as nonmyelinated sheathing II Astrocytes sit adjacent to synapses presynaptic terminals a Control extracellular ion concentrations These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute III IV V VI VII b Also provide structural support i Maintained throughout the life of an organism ii Are involved in neurodevelopment by acting as a scaffold when cortical layers are being formed c Fibrous astrocytes form end feet with capillaries so that materials go through a filtering system before arriving at a neuron i These end feet may connect anywhere on the neuron ii Provides a pathway through which substances travel from the blood to neurons d Also form the blood brain barrier Microglia 10 of nervous system cells a Mostly derived from hematopoietic precursor cells i Some reside in the central nervous system b Secrete signaling molecules cytokines i Involved in inflammatory responses c Carry out apoptosis d Help to respond to damaged brain tissue i Migrate to injury from compromised vascular system other brain areas ii Proliferation iii May perform phagocytosis to destroy foreign bodies Neurolemmal Schwann cells share functions with other glial cells in the nervous system a Myelination b Health nutrition regeneration support of neurons astrocytic function c Phagocytosis microglial function Satellite cells are located in the dorsal root ganglia a Surround unipolar cells and help them maintain normal health Transmembrane protein channels in the central nervous system a Leak channels contribute to resting membrane potential i Constantly open ii Allow for passive transport of ions such as sodium and potassium b Gated channels are selective but also allow for passive transport i Voltage gated channels contribute to action potential in a neuron ii Change shape to allow passage but can prevent passage under the correct electrochemical conditions iii Also allow transport of sodium and potassium c Pumps change shape to allow passage of molecules i Involve cotransporters ii Allow active transport requires energy input iii Sodium potassium pump Some relevant terminology a Voltage is the force exerted on a charged particle i The potential difference between two locations ii Measured in volts millivolts iii Vm membrane potential b Current is the rate amount or number of charged particles that flow from one point to another i Measured in amperes amps or milliamps ii Can refer to the slow of a specific ion as well c Resistance is the difficulty that a charged particle has in moving from one point to another i Measured in ohms d Conductance G or g is the ease with which an ion moves from one point to another i Measured is siemens s ii Can also refer to the number of membrane channels open gK for example when referring to the amount of potassium channels open
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