Mam Phys Chaptr 6neuro

Mam Phys Chaptr 6neuro - Mam Phys Chaptr 6 Neural phys...

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Mam Phys Chaptr 6 Neural phys SECTION A: Neural tissues. CNS STRUCTURES AND CELLS V. PNS STRUCTURES AND CELLS. Anatomy of a neuron includes: dendrites, soma, axon collateral, axon, axon hillock, myelin, Node of Ranvier. Neurons can be divided into three functional classes: afferent neurons, efferent neurons, and interneurons. 1. Afferent neurons: These send information to the CNS, the cell body and most of the peripheral process of the axon are in the pns while the short central process of the axon enters the CNS. These neurons have no dendrites as they receive no input from other neurons. 2. Efferent neurons: transmit info from cns to effectors ie. Muscles, glands and other neurons. Soma, dendrite and small seg of axon in cns most of axon in pns. 3. Interneurons: integrate both efferent and afferent into reflex circuits, all are in cns. SYNAPSES are junctions between two neurons where one alters the electrical/chemical activity of another. This is usually accomplished by release of a neurotransmitter, chemicals by which neurons communicate either with each other or with their effectors. A neuron that conducts a signal toward a synapse is a PRESYNAPTIC NEURON while a neuron conducting signals away from a synapse is a POSTSYNAPTIC NEURON. GLIAL CELLS; are the support cells for the neurons. Microglia cells are a macrophage like cell performing immune functions, Schwann cells and Oligodendritic cells produce myeline, astroglia cells help in metabolic support. SECTION B: Membrane Potentials. 1. The Resting Membrane Potential: The inside of the neural membrane is negative with respect to the outside during normal resting conditions in the absence of an action potential. In the neuron, that resting potential is around -70mV. This is measured using a milivoltmeter, inserting a recording intracellular microelectrode and a reference extracellular electrode and recording the potential difference between the two. Muscle cells and other cells will show different values for resting potential. During this time sodium and chloride concentrations are low inside the cell while potassium concentration is low outside the cell. It is the differences in the ion concentrations and differences in the membranes permeability to these ions that will determine the membrane potential and finally the action potential, if there is one. 2.
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This note was uploaded on 04/14/2008 for the course BIOLOGY 346 taught by Professor Frischmann during the Spring '08 term at Rutgers.

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Mam Phys Chaptr 6neuro - Mam Phys Chaptr 6 Neural phys...

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