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Worksheet 8.1
Chapter 8: Physiology of exercise – fifteen summary facts
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Joints of the body include bones, muscles, nerves, ligaments, and tendons. The elbow is a synovial
joint because of the presence of a synovial cavity which contains synovial fluid. Synovial joints
are freely movable. Hinge joints include the elbow and knee. The hip is a ball-and-socket joint.
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Muscles are of three major types:
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skeletal or striated
cardiac
smooth or non-striated.
Muscle cells are called muscle fibres and contain multiple nuclei. Muscle fibres contain large
numbers of glycosomes that store glycogen and mitochondria for ATP production. Also present in
the muscle fibres are large amounts of myoglobin; myoglobin has the ability to store oxygen.
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Muscle fibres are made up of myofibrils. Myofibrils are composed of sarcomeres. Sarcomeres are
the units that allow movement. Sarcomeres include Z lines, actin, myosin, H zone, A band, I band,
and M line.
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Muscle contraction involves the neurotransmitter acetylcholine, the enzyme acetylcholinesterase,
T-tubules, calcium ions, ATP, troponin, and tropomyosin. When the muscle is contracted, the H
zone disappears, the Z lines move closer together, the I bands are no longer present and the A
bands appear to run the complete length of the sarcomeres.
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The pulmonary system provides an adequate flow of oxygen to the cells of the body as well as
removing the waste gas carbon dioxide from the body cells. To perform these tasks four distinct
processes are necessary. They are:
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pulmonary ventilation
external respiration
transport of respiratory gases
internal respiration.
The last two processes require the assistance of the cardiovascular system.
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Measuring lung volumes requires the use of spirometer or respirometer.
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Tidal volume is the amount of air that passes in and out with each inhalation or exhalation at
rest.
Vital capacity is the maximum volume of air that can be exhaled after maximum inhalation.
Total lung capacity includes the vital capacity and the residual volume.
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When muscles receive an inadequate supply of oxygen due to intense exercise, they enter into
anaerobic exercise. The result of anaerobic exercise is the production of lactic acid which
ultimately limits muscle action.
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Regular physical activity or training that is aerobic will create larger vital capacity, decrease
ventilation rate at rest, and increase maximum ventilation rate during exercise.
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Cardiac muscle responds to training just as skeletal muscle does, it increases in size, efficiency,
and strength. Heart rate can be used to assess the fitness of one’s cardiovascular system.
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Stroke volume is the amount of blood pumped out by the heart with each contraction.
Cardiac output is defined as the volume of blood pumped out of the heart per minute.
10 The SA (sinoatrial) node is known as the pacemaker of the heart and gives the heart myogenic
properties. However, the function of the node is affected by neuro-endocrine factors. During
exercise, blood flow to the skeletal muscle, skin and heart is increased while flood flow to the
abdominal organs and kidneys is decreased. Blood flow to the brain remains the same.
11 Aerobic training has a number of effects on the heart. They include hypertrophy (especially of the
left ventricular myocardium) greater stroke volume, greater cardiac output, and often there will be
decreased heart rate.
12 VO2 max is defined as a person’s maximal rate of oxygen consumption and it represents an
individual’s ability to generate the energy required for endurance activities that last longer than 4–
5 minutes. VO2 simply demonstrates the effectiveness of the relationship between oxygen delivery
and tissue metabolic demands. As VO2 max is reached during aerobic exercise, carbohydrates
account for 100% of the energy source in mitochondria. Before this stage, fats are often the source
of energy in cellular respiration.
13 Myoglobin provides oxygen and creatine phosphate provides energy for muscle activity during
activities. Lactic acid build-up results in the build-up of the oxygen debt. To overcome the oxygen
debt, the lactate must be sent to the liver via the bloodstream so it can be broken down into
pyruvate. This requires large amounts of oxygen that must be provided by increased breathing rate.
14 Muscle fibres may be slow or fast muscle fibres. Slow fibres have a high capacity for generating
ATP and are used in aerobic activities. Fast fibres have little capacity for generating ATP and are
used in anaerobic activities.
15 Disagreements often arise over performance-enhancing substances such as erythropoietin, creatine
phosphate, and anabolic steroids. Many question the use of these substances because of their rather
severe side-effects. Others question their use on ethical grounds.
© Pearson Education Ltd 2010. For more information about the Pearson Baccalaureate series please visit
www.pearsonbacc.com
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