Anatomy of Peripheral Nerves Peripheral nerves consist of fascicles that contain myelinated and unmyelinated axons. Endoneurium is the small amount of matrix that is present between individual axons. The perineurium is a sheath of special‚ fiber-like cells that ties the axons of each fascicle together. Epineurium is the connective tissue that surrounds the entire nerve trunk and gives off vascular connective tissue septa that traverse the nerve and separate fascicles from one another. | | Single
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are unable to pass across the axon membrane. Since the only place sodium is located and freely moving on the axon is at the nodes of Ranvier‚ the action potential hops from node to node‚ which is called saltatory conduction. This is the first reason that myelinated axons have a higher conduction velocity than non-myelinated axons. Since the action potential goes from one node of Ranvier to another‚ it is able to travel a greater distance in a shorter time than it would on a non-myelinated axon
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sodium ions is higher on the outside of its membrane and potassium ions is higher on the inside. Answer: D 4. Saltatory conduction a. occurs only if the myelin sheath is continuous. b. occurs only if nodes of Ranvier are lacking. c. is faster than conduction on an unmyelinated fiber. d. is slower than conduction on an unmyelinated fiber. Answer: C 5. The most rapid nerve impulses are conducted on fibers that are a. thick and myelinated. b. thick and unmyelinated. c. thin and myelinated
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REVIEW SHEET EXERCISE 3 Neurophysiology of Nerve Impulses NAME: 1. Match each of the definitions in Column A with the appropriate term in Column B. Column A Column B __D__ term that refers to a membrane potential of about -70 mv __F__ reversal of membrane potential due to influx of sodium ions __B__ major cation found outside of a cell __A__ minimal stimulus needed to elicit an action potential __E__ period when cell membrane is totally insensitive to additional stimuli‚ regardless
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follows: Red: Sodium ion channels and sodium ions Blue: Potassium ion channels and potassium ions Page 1. Introduction • Neurons communicate over long distances by generating and sending an electrical signal called a nerve impulse‚ or action potential. Page 2. Goals • To understand that rapid changes in permeability of the neuronal membrane produce the action potential. • To recognize
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excitability‚ conductivity‚ and contractility) enable the conduction system to start an electrical impulse‚ send it through the cardiac tissue‚ and stimulate the myocardial tissue to contract. • The autonomic nervous system plays an important role in the rate of impulse formation‚ the speed of conduction‚ and the strength of cardiac contraction. Electrocardiogram Monitoring • The electrocardiogram (ECG) is a graphic tracing of the electrical impulses produced in the heart. • ECG waveforms are produced
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Topic 2 Explain why comparing the G.D.P. of various nations might not tell you which nation is better off. Use information from the World Bank website to support your answers. In your explanation refer to the limitations of using G.D.P. as a measure of economic welfare and where possible‚ refer to the countries in your table above. Due to the very complex methods used in estimating gross domestic product and the sheer enormity of the task‚ gross domestic product is very necessarily a less than
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main intracellular anions Back phophates protein anions Front these gates are found on the dendrites and cell body of neurons Back ligand gates mechanical gates Front this conduction type is faster and more energy efficient and involves myelinated neurons Back saltatory Front this is the name for a bundle of axons in the PNS Back nerve Page 5
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3. Why don’t the terms depolarization and action potential mean the same thing? The terms depolarization and action potential differ because are excitable cells that communicate by transmitting electrical impulses that are capable of producing rapid electrical signals and depolarization in the interior surface of the membrane which becomes less negative and the exterior surface becomes less positive. Additionally‚ when depolarization reaches a certain threshold‚ an action potential is initiated
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Question: Explain how human activities can interrupt or modify the nutrient cycles in the coniferous forest. Refer in detail to examples you have studied. Attempt to show as annotated diagrams the altered minerals nutrient cycle. Essay: The coniferous forest occurs in cold climates to the poleward side of 60 N in Eurasia and North America as well as high attitudes in more temperate latitudes and in Southern Chile. It has an average NPP of 800g/m/yr. There is usually only one layer of vegetation
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