refractory period. b. During the relative refractory period‚ the cell can generate another action potential but only if the membrane more depolarized. 7. a. Conduction velocity along the axon is increased by what two characteristics? 1. increased diameter 2. presence of myelin b. Conduction along a myelinated axon is called saltatory conduction. 8. a. Name the disease whose symptoms include loss of vision and increasing muscle weakness: Multiple sclerosis (from the quiz section) b. What does
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Chapter 11 – Fundamentals of the Nervous System and Nervous Tissue I. The 3 Overlapping Functions: a. Sensory Input: b. Integration: c. Motor Output: II. Levels of Organization in the Nervous System: a. Central Nervous System (CNS): b. Peripheral Nervous System (PNS): i. Sensory (afferent) Division: ii. Motor (efferent) Division: 1. Somatic Nervous System: 2. Autonomic Nervous System (ANS): a. Sympathetic Division: b. Parasympathetic
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The formation of an action potential can be divided into five steps. (1) A stimulus from a sensory cell or another neuron causes the target cell to depolarize toward the threshold potential. (2) If the threshold of excitation is reached‚ all Na+ channels open and the membrane depolarizes. (3) At the peak action potential‚ K+ channels open and K+ begins to leave the cell. At the same time‚ Na+ channels close. (4) The membrane becomes hyperpolarized as K+ ions continue to leave the cell. The
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muscle contraction Introduction For a skeletal muscle fiber to contract‚ a stimulus must be applied to it. The stimulus is delivered by a nerve cell‚ or neuron. A neuron has a threadlike process called and axon that my run 91 cm or more to a muscle. A bundle of such fibers from man different neurons composes a nerve. A neuron that stimulates muscle tissue is called a motor neuron. The motor neuron branches into terminal structures called telodendria that come into close approximation with
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At the end of the play‚ Malcolm‚ the newly crowned King of Scotland describes Lady Macbeth as a ’fiend-like queen. ’ To a certain extent this judgement is true‚ yet Lady Macbeth has to actually evoke evil spirits to help prevent her from feeling any compassion or warmth. The evil spirits ’unsex ’ Lady Macbeth and remove all feminine qualities from her‚ trading them for evil‚ proving that deep down there must be some good in her if she has to call for some outside help to aid her with her deeds
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innovation and economic development. What role do creativity and problem solving play in this relationship? Refer to both theory and examples from the business world to support your discussion. Entrepreneurship‚ innovation and economic development are linked to one another through different factors and characteristics of each other. Entrepreneurship “is the result of what entrepreneurs do and refers to events and their economic impact” (Lumsdaine E‚ Binks M 2007 P11). This definition demonstrates that
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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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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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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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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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