Chapter 8: Physiology of Exercise Fifteen Summary Facts

Worksheet 8.1

Chapter 8: Physiology of exercise – fifteen summary facts

1Joints 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.

2Muscles are of three major types:

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.

3Muscle 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.

4Muscle 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.

5The 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:

pulmonary ventilation
external respiration
transport of respiratory gases
internal respiration.

The last two processes require the assistance of the cardiovascular system.

6Measuring lung volumes requires the use of spirometer or respirometer.

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.

7When 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.

8Regular physical activity or training that is aerobic will create larger vital capacity, decrease ventilation rate at rest, and increase maximum ventilation rate during exercise.

9Cardiac 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.

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.

10The 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.

11Aerobic 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.

12VO2 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.

13Myoglobin 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.

14Muscle 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.

15Disagreements 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.