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 processinga. Unipolar, bipolar, multipolar neuronsIII. Neurons can be divided functionallya. Collecting informationb. Integrating informationc. Sending informationIV. Nodes of Ranvier are located between myelinated segments of axons and allow for salutatory conduction in neuronsOutline of Current Lecture I. Schwann cells function in creating a healthful environment for axons and can provide myelination when necessaryII. Astrocytes function in maintaining extracellular concentrations, providing structural support, and linking neurons to the circulatory systemIII. Microglia are responsible for inflammatory responses in the brain and migrate to injuredbrain areasIV. Transmembrane protein channels allow passage of certain moleculesa. Leak channels b. Gated channelsc. Pumps Current LectureI. Schwann cells are responsible for creating a healthful environment for an axona. Provide optimal conditions to conduct action potentialb. Schwann cells can surround unmyelinated axonsi. Extracellular fluid fills the space between the axons and Schwann cell, allowing free movement of substancesc. What causes a Schwann cell to function as myelin rather than having astrocytic/microglial functions?i. Local cues within the cellii. Growth factors and nutrients are provided in this extracellular environment, promoting the neuron’s healthiii. This is referred to as “nonmyelinated sheathing”II. Astrocytes sit adjacent to synapses/presynaptic terminalsa. Control extracellular ion concentrationsThese 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.b. Also provide structural supporti. Maintained throughout the life of an organismii. Are involved in neurodevelopment by acting as a scaffold when cortical layers are being formedc. Fibrous astrocytes form end-feet with capillaries so that materials go through a “filtering” system before arriving at a neuroni. These end-feet may connect anywhere on the neuron ii. Provides a pathway through which substances travel from the blood to neuronsd. Also form the blood-brain barrierIII. Microglia (<10% of nervous system cells)a. Mostly derived from hematopoietic precursor cellsi. Some reside in the central nervous systemb. Secrete signaling molecules (cytokines)i. Involved in inflammatory responsesc. Carry out apoptosisd. Help to respond to damaged brain tissuei. Migrate to injury from compromised vascular system/other brain areasii. Proliferationiii. May perform phagocytosis to destroy foreign bodiesIV. Neurolemmal/Schwann cells share functions with other glial cells in the nervous systema. Myelinationb. Health, nutrition, regeneration, support of neurons (astrocytic function)c. Phagocytosis (microglial function)V. Satellite cells are located in the dorsal root gangliaa. Surround unipolar cells and help them maintain normal healthVI. Transmembrane protein channels in the central nervous systema. Leak channels contribute to resting membrane potentiali. Constantly openii. Allow for passive transport of ions such as sodium and potassiumb. Gated channels are selective but also allow for passive transporti. Voltage-gated channels contribute to action potential in a neuronii. Change shape to allow passage but can prevent passage under the correct electrochemical conditionsiii. Also allow transport of sodium and potassiumc. Pumps change shape to allow passage of moleculesi. Involve cotransporters ii. Allow active transport (requires energy input)iii. Sodium/potassium pumpVII. Some relevant terminology:a. Voltage is the force exerted on a charged particlei. The potential difference between two locationsii. Measured in volts/millivolts iii. Vm = membrane potentialb. Current is the rate, amount, or number of charged particles that flow from one point to anotheri. Measured in amperes (amps) or milliamps ii. Can refer to the slow of a specific ion as wellc. Resistance is the difficulty that a charged particle has in moving from one point to anotheri. Measured in ohmsd. Conductance (G or g) is the ease with which an ion moves from one point to anotheri. 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
View Full Document
Unlocking...