CBSE  Class 12 Physical Education Chapter 8 Physiology and Sports

1 Mark Questions
Question.1. Calculate how much blood is pumped by the heart in one minute.
Answer. Blood pumped by the heart in one minute is
Cardiac output =‘heart rate x stroke volume’
=72 beats/min x 70 mL approximately
= 5 L approximately.

Question.2. Define physiology and sports.
Answer. Physiology is the study of how the human body functions. Sports physiology is derived from exercise physiology. It applies the concept of exercise physiology to training the athlete and enhancing the athlete’s sports performance.

Question.3. How much blood is found in a normal human being?
Answer. The body of an adult contains about 5 to 7 L of blood which weighs 1/3 rd of the total body weight.

Question.4. What is the systolic pressure exert by the blood?
Answer. The pressure exerted by the blood on the walls of the blood vessels is called ‘blood pressure’. It has two limits, i.e. the upper limit called ‘systolic pressure’ and the lower limit called the ‘diastolic pressure’. Systolic pressure is recorded when the blood is ejected into the arteries during ventricular contraction.

Question.5. State the amount of blood pumped in one ventricle beat.
Answer. The amount of blood pumped into the aorta with every heart beat is known as the stroke volume. In an untrained male, it is 70 mL/beat to 90 mL/beat.

Question.6. What is tidal volume?
Answer. Tidal volume is the amount of air inspired or expired per breath. This can be increased with the help of endurance training. In untrained individuals, tidal volume is about 500 mL/breath, whereas in trained persons, it is increased to 600-700 mL/breath.

Question.7. What is the size of the heart and resting heart rate?
Answer. Heart Size is approximately the size of the fist of an athlete. Weight of the normal adult heart is 250-300 gm.
The resting heart rate of a normal adult is approximately 72 beats/min.

3 Marks Questions
Question.8. Explain the effects of ageing on fat, lean body weight and BMR.
Answer. With advancing age, there is an increasing trend to accumulate fat because the ability to release stored fatty acids from adipose tissues for energy decreases. Similarly, lean body weight also decreases due to decrease in muscle size and decline in calcium and phosphorous content of the bones. BMR or Basal Metabolic Rate also reduces with ageing due to the decline in lean body weight.

Question.9. Explain the effects of ageing on muscle size and strength.
Answer. As an individual gets older, there is a decline in muscle size. It is believed that this decline is due, in . part, to a reduced amount of protein as well as a decline in the number and size of muscle fibres, which may be due to degenerative diseases generally associated with advancing age affecting the. nerve fibres. Increases in strength are related to muscle fibre hypertrophy, meaning that strength increases parallel to increases in muscle size. As people get old and the muscle size decreases, there is a parallel decrease in muscular strength.

Question.10. Specify the role of physiology in exercise and sports.
Answer. Exercise physiology is the study of how exercise alters the function and structure of the body. A sports physiologist ^examines the acute responses and chronic adaptations to athletic performance in a variety of environments. While a sports physiologist can test the effect of exercises in a laboratory, which has a controlled environment, it is not always possible to simulate sporting activity in a lab. So physiologists use field based testing as much as possible.
Physiology can improve an athlete’s performance by giving important objective information which can help coaches to adapt training programmes to maximise their desired outcome. This will depend on many factors including the environment, diet, gender, age and health.

Question.11. Describe the role of regular exercise on ageing process.
Answer. Regular exercise keeps the human body livelier, fitter and in better condition, thus delaying the ageing processes, as given below:

  1.  Exercise reduces the loss of elasticity from the lungs and chest wall.
  2.  Exercise increases muscle strength and hypertrophy by increasing the cross-sectional area of the Slow Twitch Fibres (STF) and Fast Twitch Fibres (FTF)., This slows down ageing.
  3.  The body composition changes due to exercise by reducing the fat coment of the body, thus slowing down the ageing process.
  4. Exercise improves flexibility by strengthening the musculoskeletal systems, thereby preventing the stiffening of joints. This also slows the ageing process.

Question.12. Explain the redistribution of blood flow in our body during rest and during exercise.
Answer. During exercise, the active muscles demand a greater supply of oxygen. The consumption of the skeletal muscle during exhaustive exercise is increased by 10 to 12 times. Such an increased demand is accomplished through an increased cardiac output (which results in a greater blood supply) and redistribution of the blood flow from the inactive areas towards the active muscles. The redistribution of blood flow at rest and during exercise is given below :

5 Marks Questions
Question.13. What is the the effect of exercise on the cardiovascular system?
Answer. The effects of exercise on the cardiovascular system are

  1.  Cardiac output is the amount of blood pumped by the heart in 1 min. This increases directly with increasing exercise intensity.
  2.  The heart rate increases from a resting rate of 72 beats / min to 150 beats / min or even more.
  3.  The stroke volume, meaning the amount of blood pumped into the Aorta with every heartbeat, increases from a resting volume of 70 – 90 mL to 100 – 120 mL per beat.
  4. Exercise increases the plasma volume of blood by 12%, but total blood volume may reduce slightly.
  5. Blood flow is redistributed with more blood going to the muscles, heart and skin, while blood in the kidneys and abdomen is reduced.
  6.  Blood pressure increases due to exercise because there is more blood flowing in the blood vessels.
  7. Cardiac hypertrophy occurs, meaning that the heart size increases to take care of the larger requirement of blood during exercise.

Question.14. Describe physiological factors determining component of physical fitness.
Answer. Physiological factors determining components of physical fitness are

  1. Muscular strength This is the maximum force or tension a muscle or a muscle group can exert against a resistance; Physiologically the muscle will increase in strength only if it has to increase its workload beyond what is ordinarily required of it.
  2.  Power This is the ability’ of the body to release maximum muscle contraction in the shortest possible time.
  3.  Speed This is the rapidity with which one can repeat successive movements of the same pattern.
  4.  Muscular endurance This is the ability of a muscle or muscle group to perform repeated contractions against a resistance / load or to sustain contraction for an extended period of time with less discomfort and more rapid recovery.
  5. Agility This is the ability of a person to change direction or body position as quickly as possible and regain body control to proceed with another movement.
  6.  Flexibility This is a quality of the muscles, ligaments and tendons that enables the joints of the body to move easily through a complete range of movements.

Question.15. “Most people say that as you get old, you have to give up things. I think you get old because you give up things.” Give your opinion what you think about this with the help of physiological changes due to ageing.
Answer. The saying is correct because, by giving up your usual activities, you speed up the ageing process. In fact, the ageing process can be slowed down by continuing your usual activities. Regular exercise keeps the human body livelier, fitter and in better condition, thus delaying the ageing processes like loss of elasticity from the lungs and chest wall, reduction in muscle strength and hypertrophy, increase in the fat content of the body, reducing flexibility by weakening of the musculoskeletal systems, thereby causing the stiffening of joints and soon. So we should not reduce our normal activities, if we want to slow down our ageing.

Question.16. Recall the adaptive effects that take place in our cardiovascular system after engaging in exercise for a longer period.
Answer. The adaptive effects that take place in our cardiovascular system after engaging in exercise for a longer period are

  1. Increase in heart size We cannot do the exercise on our heart directly, but when we perform any exercise regularly, our heart size increases. Exercising develops the muscles of the heart.
  2.  Increase in heart rate Generally an adult has a heart rate of 72 beats per minute while resting, but when he exercises, his heart rate increases as per the intensity and duration of the exercise.
  3.  Increase in stroke volume Stroke volume is the quantity of blood which the heart pumps out in a single stroke. Due to the heart’s size increasing, the stroke volume increases.
  4.  Decrease in cholesterol level Regular exercise reduces the cholesterol level in our blood, which has a direct link with the blood pressure.
  5.  Increase in number and efficiency of capillaries Regular exercise increases the number of capillaries and their efficiency.
  6.  Reduced risk of heart diseases Regular exercise gradually reduces stress related hormones from circulating in the blood. This results in increase of blood flow in the blood vessels, which in turn, lowers the risk of building up of plaque which affects the heart. Hence, regular exercise . reduces the risk of heart diseases.

Question.17. A trainer can improve the respiratory system with the help of exercise. Justify this statement.
Answer. The respiration system consists of organs responsible for taking in oxygen for respiration and releasing carbon dioxide and water vapour, which are the waste products formed during respiration. The passages in the nose, windpipe (trachea), bronchi, lungs and air sacs are the main organs of the respiratory system. A trainer can improve the respiratory system with the help of exercise by :

  1. Increasing the lung volume and capacity Vital capacity, which is the maximal volume of air forcefully expired after a maximal inspiration, in a normal untrained person may be 3-4 litres, but in a trained athlete this goes up to 5-6 litres.
  2. Reducing the breathing frequency In a normal untrained individual, the resting breathing frequency is about 12-20 breaths/min, whereas in trained athletes, it comes down to 7-8 breaths/min.
  3. Maximising the minute ventilation Maximum minute ventilation in an untrained individual is about 100 L/min, whereas in trained athletes it increases to more than 150-160 L/min.
  4. Increasing the tidal volume In an untrained individual, tidal volume is about 500 mL/breath, whereas in trained persons, it increases to more than 600-700 mL/breath.
  5. Increasing the ventilatory efficiency Normally, 15 L of air is required to get 1 L of oxygen but a trained individual gets the same amount of oxygen, i.e. one litre, from less air i.e. 12 L.
  6. Increasing the pulmonary diffusion During maximal level of exercise, more alveoli become active for diffusion. The size of the alveoli is also increased, which provides more space for diffusion of gases such as oxygen (o2) and carbon dioxide(co2).

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