the nervous system. These neurons work together with other excitable cells to produce action potentials when they receive electrical or chemical stimuli. Action potentials can be thought of as an “all-or-nothing” event and occur as a large-scale depolarization when sodium and other positive ions rapidly enter the neuron through membrane channel proteins. Once initiated‚ action potentials travel down the length of the axon and when it reaches the end a neurotransmitter is released into the synapse. Neurotransmitters
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activated from the right instead of from the left side and the initial vector (phase 1) is directed to the left. Because of this‚ the normal initial q wave in the left ventricular leads is lost‚ being replaced by a small r wave. Right ventricular depolarization‚ which follows‚ produces an r in V1 and an s in V6. The left ventricle is finally depolarized resulting in an R′ in V6 and a broad S in V1. The QRS duration is increased to 0.12 s or
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Why? Allows completion of atrial contraction before initiation of ventricular systole. 2. Even though cardiac muscle has an inherent ability to beat‚ the nodal system plays a critical role in heart physiology. What is that role? Ensures that depolarization proceeds in an orderly manner from atria to ventricles; accelerates and coordinates heart activity to effectively pump blood. Electrocardiography 3. Define ECG. Recording of electrical changes occurring during heart activity. 4. Draw an ECG
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nerves in turn have the funsion to carry messages from one part of the organism to another‚ so we can understand the action of these drugs. They act in the prevention‚ generation and propagation of the nervous impulse. Acting on the blocking of the depolarization initiation‚ allowing Na + to enter the nerve cell from rest to the trigger threshold (- 50a - 60 mV) would consequently impede the initiation and propagation of the impulse. Therefore‚ in the maintenance of equilibrium‚ Repolarization arises by
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Chapter 1 • Anatomy & Physiology • Gross anatomy – visible to naked eye • Microscopic • Developmental • Pathological anatomy • Radiographic anatomy • Molecular biology • Physiology • Focuses on cellular or molecular level • Principle of Complementarity of Structure and Function • A&P are inseparable • Function reflects structure • Specific form • Levels of organization 1. Chemical level 2
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cells bear taste receptors. Interwoven among the taste cells in a taste bud is a network of dendrites of sensory nerves called "taste nerves". When taste cells are stimulated by binding of chemicals to their receptors‚ they depolarize and this depolarization is transmitted to the taste nerve fibers resulting in an action potential that is ultimately transmitted to the brain. One interesting aspect of this nerve transmission is that it rapidly adapts - after the initial stimulus‚ a strong discharge
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flow back and fourth across the cell membrane Na cl ‚K and Ca ions and they just flow back and fourth without any gate keeper or obstruction‚ When the neuron is at rest its cytoplasm is Negatively charged. That means that it is not going under depolarization‚ we use the term resting potential. Modality gated channels- specific to sensory neurons‚ open in response to mechanical forces (i.e. stretch‚ touch‚ pressure‚ temperature changes or chemicals) Ligand- is a particular molecule that causes
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Cardiovascular Anatomy & Physiology I. Structures and Functions Heart Muscle * Has 3 layers (epicardium‚ myocardium‚ and endocardium) and a surrounding sac called the pericardium * Location: In the mediastinum‚ above the diaphragm‚ and is surrounded on both sides by lung * Shape: Resembling triangle‚ with base parallel to the right edge of the sternum Heart Chambers * The right side of the heart is a low pressure system and the left side is a high pressure system
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Introduction The major function of the heart is to force blood in to a closed system of blood vessels within which the blood is confines and circulated to the entire body. Heart’s activity can be compared to a muscular pump equipped with one way valves. With each heartbeat‚ an electrical impulse travels through the heart and causes the heart muscle to squeeze and pump blood from the heart. These electrical impulses‚ transmitted through the heart‚ are spread throughout the body. This electrical
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E X E R C I S E 3 Neurophysiology of Nerve Impulses O B J E C T I V E S 1. To define the following terms: irritability‚ conductivity‚ resting membrane potential‚ polarized‚ sodium-potassium pump‚ threshold stimulus‚ depolarization‚ action potential‚ repolarization‚ hyperpolarization‚ absolute refractory period‚ relative refractory period‚ nerve impulse‚ compound nerve action potential‚ and conduction velocity. 2. To list at least four different stimuli capable of generating
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