l>BIOL 237 Class Notes - Neurology
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Click on imeras or hypermessage for a bigger see. Click on
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for histologymodule.Links to
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The Nervous System - Neurology
Functions of the nervous system:1) Control of effectors, both voluntary and autonomic - muscles (skeletal, smooth, cardiac),glands.2) Response to stimuli3) Integration of processes4) Responsible for conscious thought and also perception, emovements, personality, the mind.Structural Divisions of the nervous system:1) Central Nervous System (CNS) - the brain and spinal cord.2) Peripheral Nervous System (PNS) - the nerves, ganglia, receptors, and so on.Functional Divisions of the Nervous System:1) The Voluntary Nervous System - (a.k.a. somatic division) regulate ofwillful control ofeffectors (skeletal muscles) and also aware perception. Mediates voluntary reflexes.2) The Autonomic Nervous System - control of autonomic effectors - smooth muscles,cardiac muscle, glands. Responsible for "visceral" reflexes.

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Nervous System Histology - cell types: (See Figure 11.3)1) Neurons - the sensible cells of the nervous system. See listed below.2) Neuroglia (glial cells) - Long explained as supporting cells of thenervous mechanism, tbelow islikewise a practical interdependence of neuroglial cells and neurons. a) astrocytes - these cells anchor neurons to blood vessels, regulate themicro-environmentof neurons, and control deliver of nutrients and wastes to and also from neurons. b) microglia - these cells are phagocytic to defend against pathogens. Theymight alsomonitor the condition of neurons. c) ependymal cells - these cells line the fluid-filled cavities of the brain andspinal cord.They play a function in manufacturing, move, and also circulation of the cerebrospinal liquid. d) oligodendrocyte - develop the myelin sheath in the CNS which insulatesand also protectsaxons and also providing for saltatory conduction. e) Schwann cells - develop the myelin sheath in the PNS. The myelinsheath protects andinsulates axons, maintains their micro-setting, and enables them to regeneprice andre-develop link via receptors or effectors. Enables saltatory conduction.f) satellite cells - surround cell bodies of neurons in ganglia. Their function is topreserve themicro-environment and administer insulation for the ganglion cells.
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Neuron Structure:In order to attach to various other cells, receptors, and also effectors, neurons havecytoplasmic extensions which affix to an enlarged area known as thecell body or cyton. Within the cell body is the nucleus andthe neuron"sbiosynthetic machinery, the unstable endoplasmic reticulum and the Golgibodies. These organelles are so extremely concentrated they have the right to bevisualized with a light microscope as soon as stained with a details strategy.Called Nissl substance after the scientist that created the stainingtechnique, they manufacture the neurotransmitters which the neuronneed to secrete in large amounts. The neurotransmitter molecules aretransported to the axon terminus by microfilaments and microtubules.There are 2 basic kinds of cytoplasmic extensions: the dendrites andthe axon. Dendrites are brief branching processes which receive stimulifrom receptors or other neurons. They can perform this feature becausethey, choose the exposed membrane of the cell body, possess chemicallyregulated ion gates (chemically gated ion channels) which respond tostimulation by neurotransmitters. So the dendrites rise the area onwhich a neuron have the right to be engendered and along with the remainder of themembrane of the cell body constitute the neuron"s receptive region (SeeTable 11.1).A neuron will certainly commonly have actually only one axon, although it might branchextensively. The axon has actually voltage regulated ion gates (voltage gatedion channels) and therefor is responsible for transporting an impulse toone more neuron or effector. The axon represents the neuron"s conductingregion. At the finish of the axon, the axon terminus, is the secretoryregion where the neurotransmitters are released right into the synapse.The create zone is where the location via chemically regulated entrances andthe area with voltage regulated gates satisfy, normally at the junction of theaxon and also cell body, the axon hillock. In this area summation ofdepolarization and hyperpolarization (described later) deserve to producesufficient depolarization to open up the voltage regulated gates and producean action potential.
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Types of neurons based upon structure:The neuron pictured in Figure 11.4 and also linked above is a multipolarneuron bereason it has actually many poles or procedures, the dendrites and also theaxon. Multipolar neurons are found as motor neurons andinterneurons(see below). Tbelow are also bipolar neurons through twoprocesses, a dendrite and also an axon, and unipolar neurons, which haveonly one procedure, classified as an axon. (See Table 11.1). Unipolarneurons are discovered as the majority of of the body"s sensory neurons. Their dendritesare the exposed branches linked to receptors, the axon carries theaction potential in to the main nervous device.
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Types of neurons based upon function:motor neurons - these bring a message to a muscle, gland also, or othereffector. They are sassist to be efferent, i.e. they carry the messageawayfrom the central nervous mechanism.sensory neurons - these carry a message in to the CNS. They areafferent, i.e. going toward the brain or spinal cord.interneuron (a.k.a. association neuron, connecting neuron) - theseneurons attach one neuron through an additional. For example in many type of reflexesinterneurons attach the sensory neurons through the motor neurons.

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A straightforward Reflex Arc illustrates how these 3 types of neurons mightwork together. We will certainly comment on forms of reflexes in a later on section. Thereflex shown has actually its facility in the spinal cord our nexttopic.
NEXT: The Spinal Cord and Peripheral Nerves