PHIS 206 1st Edition Lecture 4 Outline of Last Lecture I Osmosis II Osmotic Pressure III Cell Membrane IV Active Transport Outline of Current Lecture I Diffusion and Transport Review II Nervous System Units III Glial Cells 4 Types IV Neurons V Electrical Properties of Membranes Current Lecture I 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 pump II Nervous System Units 2 Basic Types of Cells 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 1 Neurons businessman info transferred from one place to another plural nodes 2 Glia glue provide environment that allows neurons to do their job III Glial Cells 4 Types 1 Oligodendroglia glial cells that have many branches wrap around axons in neurons insulators in brain spinal chord 2 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 cells 4 Microglia heals damage to nerve cells accumulates site of injury in masses IV Neurons 2 ways to classify 1 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 axon
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