PHIS 206 1st EditionLecture 4Outline of Last Lecture I. OsmosisII. Osmotic PressureIII. Cell MembraneIV. Active TransportOutline of Current Lecture I. Diffusion and Transport ReviewII. Nervous System―UnitsIII. Glial Cells―4 TypesIV. NeuronsV. Electrical Properties of MembranesCurrent LectureI. Diffusion and Transport Review-Metabolic waste products can diffuse across membranes (simple diffusion) carbon dioxide, urea, and water-Nutrients use hectic transport systems (except oxygen) (active transport) glucose transporter different than one for molasses active upon Na+ pumpII. Nervous System―Units-2 Basic Types of CellsThese 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.1. Neurons: “businessman”; info transferred from one place to another (plural: nodes)2. Glia: “glue”; provide environment that allows neurons to do their jobIII. Glial Cells―4 Types1. Oligodendroglia: glial cells that have many branches wrap around axons in neurons insulators in brain + spinal chord2. Schwann Cells: glial cells wrapped around an axon (1 thing wrapped around) are NOT branched in the nerves leading to brain and spinal 3. Astroglia: points will touch nearest capillary and nearest neuron facilitates movement of nutrients/waste products between blood stream and nerve cells4. Microglia: heals damage to nerve cells accumulates site of injury in massesIV. Neurons-2 ways to classify1. Functional: which direction information is travelling sensory neurons/afferent: info towards CNS motor neurons/efferent: info away from CNS (muscles) interneurons: towards each other (neuron to neuron)2. Structural: dendrite (branches), soma (body), axon (exterior of cell membrane), terminals (distilling neurons) Neurons have ONE axon, but MANY dendrites bipolar neuron: dendrite and axon connect to different places of soma uniport: both come from single projection; 1 place where information comes out multiport: single axon; many dendrites; many routes out-Some axons are wrapped in Schwann cells in many ways and so tightly, so almost no cytoplasm is left and lots of cell membrane is -Wrap in segments but always spaces (Nodes of Ranvier) -myelin sheath: coated axon with a substantial layer of liquids -myelinated axons: tightly wrapped Schwann cells V. Electrical Properties of Membranes-Have voltages across them (voltages are driving forces for electrical charges)-Driving force for charged particles (voltages/also known as potential)-Any voltage depends on its diffusion (mobility in solution) and concentration gradients-EVERY cell: (-) on the inside and (+) on the inside-Amplitude: shows the membrane potential-Neurons are relatively non-leaky cells (approx. 75 milliVolts)-Measured potentials are always < actual potential-complete depolarization: no membrane potential-stimuli: gradient responses; mimics: if gradient up, then stimuli up-If voltage exceeds threshold, then single spike (constant #): suprathreshold-Action potential: spike; CAN move; created by stimulating the threshold-Threshold: stationary (measure on soma of cell; nothing on
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