Exercise Physiology

Front 1

1.Muscle fibers can be up to several centimeters long and can branch. True/False

Back 1

True. They do not usually run from one end of muscle to the other. They are bound together by connective tissue.

Front 2

2. Each muscle fiber is made up of what?

Back 2

It is made up of many contractile protein myofibrils, and each myofibril is in turn composed of many overlapping protein threads or filaments known as myofilaments.

Front 3

3. Sarcomeres are the fundamental functional units of muscle. True/False

Back 3

True. The protein myofilaments of the sarcomere are of two main types; thin filaments of actin and thicker filaments of myosin. The overlapping arrangemnt of these filaments gives rise to the striped or striated appearance of the fibers.

Front 4

4. What is meant by the sliding filament mechanism?

Back 4

The sarcomere contracts as a result of these overlapping filaments sliding over each other.

Front 5

5. Regarding the sliding filament mechanism, what happens when stimulated by a motor nerve?

Back 5

The actin filaments which are attached to the Z disks at the end of each sarcomere, are slid between the myosin filaments, drawing the Z discs closer together. Each sarcomere shortens.

Front 6

6. In sliding action, what is the function of "cross bridges"?

Back 6

The sliding action is operated by a series of cross bridges between the filaments. These bridges move the actin filaments actively one way, but not the other on their recovery stroke, explaining why the sarcomere and the whole muscle is only effective in contraction.

Front 7

7. Physiologically, how might a muscle be re stretched?

Back 7

A contracted muscle is restretched by the contraction of an opposing muscle

Front 8

8. Briefly explain the force generated by a muscle.

Back 8

It is related to the degree of overlap of the actin and myosin filaments, which in turn determines the number of cross bridges that can be formed at any one time.

The more a muscle is stretched past an optimum length, the smaller the force that can be exerted as there is less and less overlap between the filaments and fewer cross bridges can be formed.

Front 9

9. When the muscle is at rest the myosin cross bridges are not connected to actin filaments. True/False

Back 9

True. In fact, an ATP molecule is bound to the free end of each cross bridge.

Front 10

10. List two other proteins associated with actin filaments which are involved in control of the contraction mechanism.

Back 10

Tropomyosin and troponin. In the absence of free Ca+ ions tropomyosin and troponin prevent the connection of the cross bridges between the myosin and actin filaments.

Front 11

11. What stimulus is necessary for Ca+ ion release?

Back 11

The spread of an excitatory impulse throughout the muscle fibers causes ther release of calcium ions, from the sarcoplasmic reticulum.

Front 12

12. Troponin has a low affinity for Ca+ ions. True/False

Back 12

False. It has a high affinity for Ca+ ions, and in their presence the inhibitory effect of tropomyosin and troponin is removed and the myosin cross bridges connect with the actin.

Front 13

13. What is the result of the actomyosin complex?

Back 13

The formation of this complex activates an enzyme, myosin ATPase, which causes the breakdown of ATP with the release of energy.

ATP -- ADP + P+ Energy.

This energy is used to move the cross bridges actively in one direction, which in a normal contraction, causes the actin filaments to slide over the myosin towards the center of the sarcomere, thus pulling the Z discs at each end of the sarcomere closer together so that the muscle contracts.

Front 14

14. How is the resulting cross bridge broken?

Back 14

It is broken by the combination of another ATP molecule with the actomyosin.

Front 15

15. Does a cross bridge undergo few reconnections per second?

Back 15

It undergoes many per second.

Front 16

16. What is responsible for the continued coupling and umcoupling of the cross bridges between the myosin and the actin filaments?

Back 16

This process will continue as long as there are sufficient Ca+ ions available to inhibit the troponin-tropomyosin system.

In the absence of ATP, the cross bridges remain coupled and the muscle remains in contraction. (rigor).

Front 17

17. How is the coupling process affected once the nerve impulse stops?

Back 17

The Ca+ ions are actively pumped back into the sarcoplasmic reticulum, and the troponin-tropomyosin system resumes the blocking of the cross bridge connections. ATP is not broken down and energy is not released, and no tension is generated.

Front 18

18. Human skeletal muscles consists of mixtures of each type of this fiber. What are they?

Back 18

Slow twitch and Fast twitch fibers. The relative proportion of each fiber type varies in the same muscles of different people, and in different muscles within the same person.

Elite marathon runners can have a greater proportion of ST fibres in their leg muscles and elite sprinters, more FT fibers, but this is not always the case.

Front 19

19. In the same person it is said that he has a greater proportion of ST fibers. Why?

Back 19

This is so because it is primarily a postural muscle involved in maintaining balance over long periods of time, and the triceps muscle in the arm has a greater proportion of FT fibers.

Front 20

20. Slow twitch fibers have a slower contraction time than fast twitch fibers. True/False

Back 20

True. They are also better adapted to low intensity, and long endurance work.

They have a high capacity for aerobic respiration. They have a better blood supply due to a greater number of capillaries per fibre than fast twitch fibers.

Front 21

21. Do ST fibers have the same quantity of myoglobin as FT fibers?

Back 21

No. They have more (red fibers). MYoglobin has a greater affinity for O2 than Hb. It robs O2 from oxyHb in the blood, and in turn acts as a store of O2 within the muscle releasing it to the mitochondria. ST fibers also have more mitochondria with their associated enzymes for aerobic respiration. They have a greater oxidative potential.

Front 22

22. List some facts about FT fibers.

Back 22

1. They have a fast contraction time. These fibers have a larger diameter due to an increased number of myosin filaments.

2. Their powerful contractions work through a greater rate of Ca+ control for rapid fire activation and relaxation.

3. Their fibers have higher concentrations of the enzyme Myosin ATPase permitting higher rates of energy release from ATP for myosin cross bridge action.

4. They have large stores of phophocreatine, increasing the short term regeneration of ATP.

5. Have fewer capillaries (white fibers) and have larger stores of glycogen and glycolytic enzymes. Sometimes called Anaerobic or fast glycolytic fibers.

Front 23

23. In man, ther number of fibers within a particular muscle appears to be fixed early in life. True/False

Back 23

True. An increase in muscle size as a result of training is due to an increase in the size of the fibers already present, rather than an increase in the number of fibers by longitudinal division. This increase in size is due to an increase in the number and size of myofibrils per fiber

All training gains are rapidly reversible, with periods of restricted muscle use, resulting in loss of muscle fiber mass (atrophy).

Front 24

24. What is a motor unit?

Back 24

Motor neurons must supply more than one muscle fiber. A motor neuron and the muscle fibers it stimulates, act as a unit, and are known together as a motor unit.

The number of fibers stimulated by a single neuron can vary from few(eye muscles) to many (quadaceps).

Front 25

25. Muscle fibers in a particular motor unit are all the same type. True/False

Back 25

True. The fiber type of a motor unit is mainly determined by the nature of the motor neuron supplying it. It might be more correct to refer to slow and fast motor units rather than muscle fibers.

Front 26

26. There are fewer fibers in a ________________

than in a ____________________________ resulting in ______________________________ generating greater force.

Back 26

slow type 1 motor unit (200 units),/ fast type 2 motor unit (up to a thousand), /Type 2 motor units.

Front 27

27. What is a motor end plate?

Back 27

At the point of contact with the muscle fiber, the motor neuron terminates in a motor end plate, or neuromuscular or myoneural junction. Stimulation occurs here.

Front 28

28. What occurs when a nerve impulse arrives at the motor end plate?

Back 28

The presynaptic vesicles release acetylcholine. This diffuses across the gap (synaptic cleft) between the motor end plate and the post synaptic membrane of the muscle and initiates a wave of electrical activity (excitatory post synaptic action potential) EPSP in the post synaptic membrane.

Front 29

29. if nerve impulses are repeated at a high enough frequency, the successive discharges from the presynaptic membrane add up resulting in an increased EPSP which is effective. What is this called?

Back 29

Summation.

Slow twitch fibers are less excitable than fast twitch muscle fibers.

Front 30

30. What happens enzymatically after the action potential is completed?

Back 30

Cholinesterase breaks down the acetylcholine, thus clearing the gap in readiness for the arrival of another impulse at the motor end plate.

Front 31

31. The action potential spreads rapidly over the surface membrane of the fiber and throughout all the myofibrils via the T tubules. True/False

Back 31

True. T tubules are in close contact with the sarcoplasmic reticulum around each myofibril. This action triggers the release of Ca+ ions from the SR vesicles. Contraction occurs. The T tubules penetrate all parts of the fiber.

Front 32

32. What is spatial summation?

Back 32

Also called multiple motor unit summation, in which the number and size of the motor units recruited throughout the muscle as a whole are varied. A staggered spread of activation of the motor units throughout the muscle also enables sustained contractions to be maintained, as some motor units are contracting while others are relaxing. The use of ATP is spread more evenly throughout the muscle.

Front 33

33. What is wave summation?

Back 33

This involves the frequency of motor nerve impulses. If the frequency of impulses is such that the next impulse reaches a muscle before it has completely relaxed after the previous contraction, it begins the second contraction from a higher force level, so that the resulting force is greater than that from a single stimulus. This adding together or wave summation of contractions can lead to a complete fusion of contractions, which will endure as long as the stimuli persist, or until the muscle fatigues.

Front 34

34. Depletion of the neurotransmitter substance acetylcholine, which is released by the motor neurones at the neuromuscular junction reduces the stimulation of the muscles. True/False

Back 34

True. This is likely more common with fast twitch motor units, and this could explain why they fatigue more quickly compared with slow twitch.

Front 35

35. Once the muscle membranes are stimulated, the impulse may not be propagated throughout the muscle. Why might this be?

Back 35

There may be an imbalance between sodium and potassium ions across the muscle membranes.

Once the impulse reaches muscle fibers, there may be a reduced calcium ion release, resulting in a reduced cross bridge formation. There may be T tubule damage or an inhibiting effect of too much lactic acid.

Front 36

36. What causes muscle fatigue?

Back 36

fatigue will result as it becomes increasingly difficult to replenish supplies of ATP.If phosphocreatine stores are depleted, maximum power cannot be maintained.

Front 37

37. Can fatigue result from muscle and liver glycogen depletion?

Back 37

Yes.Glycogen is a readily available source of energy under both aerobic and anaerobic conditions, and as the stores are used up, the same level of activity cannot be maintained.

Also fatty acids from the fat stores cannot be fully oxidized to release all their energy if there is insufficient breakdown of carbohydrates at the same time.

Front 38

38. can carnitine depletion be a cause of muscle fatigue?

Back 38

Yes. The depletion of carnitine, which aids in the transport of the fatty acids into the mitochondria, where they are oxidized, also contributes to fatigue.

Front 39

39. Can an increase in body temperature cause fatigue?

Back 39

Yes. Active muscle rapidly heats up by about 2-3 degrees C. This can be beneficial as it speeds up the rate of enzyme catalyzed reactions involved in muscle contraction. It also increases the amount of O2 liberated from oxyhemaglobin in muscle capillaries. An increase in more than 3 degrees C will disrupt the balance biochemistry of muscle metabolism.

Front 40

40. The oxidation of fat requires more O2 than the oxidation of glucose. True/False

Back 40

True. With insufficient O2 respiration becomes anaerobic and lactic acid accumulates. Increased acidity inhibits resynthesis of creatine phosphate and interferes with actin/myosin cross bridge formation, by interfering with the binding of calcium to troponin.

Front 41

41. What is soda loading?

Back 41

This is an artificial method of trying to overcome the fatigue effects of increasing acidity. One consumes sodium hydrogencarbonate (sodium bicarbonate), an alkali prior to the event. The increased alkalinity of the blood increases the capacity to neutralize the lactic acid.

Front 42

42. What is kinaesthenic feedback?

Back 42

This is accomplished via proprioceptors. Proprioceptors are sense organs in muscles, tendons and joints, which provide information about the position and movement of the body.

Front 43

43. briefly describe the muscle spindle apparatus.

Back 43

Each muscle spindle apparatus consists of several modified muscle fibers (intrafusal fibers), bound in a fine connective tissue sheath. They are supplied with both motor and sensory neurones.

Front 44

44. What are motor spindles physiologically involved in?

Back 44

They are involved in the detection of the state of contraction/extension of a muscle, the anticipation of muscle loading, and in the fine control of muscle contraction.

There may be up to 60 muscle spindles in a skeletal muscle. True/False

Front 45

45. There may be up to 60 muscle spindles in a skeletal muscle. True/False

Back 45

True.

Front 46

46. Briefly describe the gamma loop control in fine muscle action.

Back 46

The first impulse, the gamma motor neurone impulse stimulates stretch of spindle

The second impulse, neurone sends signal back to spinal cord

The third impulse, the alpha motor neurone impulse causes reflex contraction of muscle.

Contraction or stretching of a muscle alters the tension exerted on the muscle spindle apparatus. This is detected by sensory nerve endings in the central part of the spindle.

Sensory feedback of the state of contraction, or stretch of the muscle, is thus relayed to the CNS.

Front 47

47. What is gamma bias?

Back 47

The muscle spindle can be set at a prescribed firing tension, feeding back sensory information when stretched beyond that certain tension. This presetting of muscle spindles is known as gamma bias, and allows the detection of the stretching of a muscle contraction at different degrees of its contraction.

An example is seen when one prepares to lift a load, the weight of which is anticipated as being heavy.

Front 48

48. Stimulation of skeletal muscle can either be direct via the alpha motor neurones, which innervate the muscle fibers, or indirectly via the muscle spindles. True/False

Back 48

True. With indirect control via the muscle spindles, the gamma motor neurones stimulate the contractile ends of the intrafusal fibers within the muscle spindle, thus stretching the sensory stretch receptor endings in the center.

Front 49

49. What is meant by reciprocal inhibition of muscle contraction?

Back 49

Skeletal muscles typically occur in pairs. The biceps and triceps of the upper arm are good examples. The stimulation of a muscle to contract typically leads to the inhibition of the muscle that works in opposition to it, so that it cannot contract at the same time and oppose the intended action which would occur as a result of the stretch reflex.

Front 50

50. What are Golgi tendon organs?

Back 50

These occur at the junction of a tendon and its muscle. They detect the degree of stretch of the tendon. When stretched, they trigger the reflex inhibition of the contracting muscle that is causing the tendon to be stretched, and the reflex contraction of the antagonist (reciprocal activation). This prevents damage to the muscle and tendon.

Front 51

51. Where are joint receptors found?

Back 51

These are sensory nerve endings found in joint capsules and ligaments which can detect movement and position of then joint.

Front 52

52. Briefly describe a fusiform muscle.

Back 52

These have comparatively few long bundles, arranged parallel with the longitudinal axis of the muscles running into flat strap like tendons at each end. This arrangement allows maximal shortening. The biceps brachi is an example.

Front 53

53. Pennate muscles are broad and flat with comparatively more shorter bundles radiating out from a single tendon that extends the length of the muscle. True/False

Back 53

True. The rectus femoris of the thigh, which straightens the leg at the knee is an example.

Front 54

54. regarding muscle contraction, if the force that they generate is greater than the resistance, then they will shorten. True/False

Back 54

True. if they are overcome by the resistance, they can lengthen.

Front 55

55. what are the two types of dynamic muscle actions?

Back 55

Concentric and eccentric.

Front 56

56. Define concentric and eccentric contraction.

Back 56

In this case, the whole muscle shortens as it develops tension. Seen in the biceps muscle of the arm when curling weight.

Eccentric- Here, the muscle develops its active tension while it is being lengthened by stretching. Biceps muscle of the arm as it is lowering a weight after a curl.

Front 57

57. What is an isometric contraction of muscle?

Back 57

This occurs when the muscle is prevented from shortening while it is generating tension, while for example while straining against an immovable resistance. Once a steady state is achieved, the cross bridges hold the filaments steady in one position.

Front 58

58. Isotonic and Isometric contractions are both involved in the typical muscle contraction that results in movement. True/False

Back 58

True. Isometric contraction occurs initially before sufficient force is generated to actually start the movement, and isotonic contraction occurs once the movement is started.

Front 59

59. What are Isokinetic contractions?

Back 59

These occurs when the muscle shortens at constant speed, and exerts maximum tension over the full range of movement at all joint angles, thus stimulating maximum gains over the whole range of joint movement.

The nearest athletic example would be the freestyle swimming armstroke.

Front 60

60. What is Plyometrics?

Back 60

This is a training method which uses both concentric and eccentric contractions.I

Front 61

61. Is there a difference between a prime mover muscle and an agonist muscle?

Back 61

No. they are the same. The biceps brachii flexing the arm at the elbow is an agonist action. The antagonist muscle at the same time, is the triceps is inhibited and relaxes allowing the flexion to occur. Actions are opposite if the triceps becomes the prime mover.

Front 62

62. What is the function of fixator or stabilizer muscles?

Back 62

They hold or fix joints in a stable position, as for example when keeping the wrist stiff during a biceps curl with weights.

Synergist muscles prevent any unwanted movement and help the prime mover to function more efficiently.

Front 63

63. Glycerol and free fatty acids may be used directly as a source of energy. True/False

Back 63

True. They can also be re synthesized into fats and stored in the fatty tissue which have as much as 98% of the body's total energy reserves.

Front 64

64. Can free fatty acids be converted into glucose?

Back 64

No. Glycerol can be converted however. This process is more efficient when body CHO levels are low.

Front 65

65. What is a primary function of amino acids?

Back 65

These are mainly used to synthesize proteins for growth and repair throughout the body.

Excess amino acids cannot be stored in the body, so they are deaminated in the liver, a process in which their nitrogen containing amino groups are removed, producing toxic nitrogen containing waste products such as urea.

Front 66

66. Can the liver efficiently convert excess glucose into glycogen?

Back 66

No. It converts it more readily into fats. Liver glycogen converts it readily into glucose. This is not the case with muscle glycogen.

Front 67

67. The complete oxidation of fats depends readily on the presence of what?

Back 67

Oxygen. Oxygen levels easily affect this process. After about an hour of continuous aerobic exercise the majority of the energy is derived from fats. Training increases the capacity of O2 uptake, and increase the ability to use fats.

Front 68

68. Is much fat stored in muscle fibers?

Back 68

No. Fatty acids and gylcerol must be supplied via the bloodstream.

Front 69

69. Those who exercise aerobically regularly can better spare glycogen. Why is this so?

Back 69

These individuals increase their ability to release fatty acids from their fat stores, and therefore use more fats as an energy source during exercise.

Front 70

70. What are lipoproteins?

Back 70

These are fats that are tightly bound to proteins. These originate from dietary fats absorbed in the small intestine. They are carried to the liver where they are converted to two different types of lipoproteins. Low density lipoproteins and high density lipoproteins.

Front 71

71. Is there a specific function for LDLs and HDLs?

Back 71

LDLs supply cholesterol to the tissues.

HDLs remove cholesterol from the tissues.

Exercise increases the ration of HDLs to LDLs, which is a factor in lowering the risk of atherosclerosis.

Front 72

72. The anerobic breakdown of CHOs (anerobic glycolysis) results in what?

Back 72

It results in the formation of lactic acid. The increased acidity inhibits the mobilization of FFAs and can interfere with their use.

CHOs yield about 12% more energy than fat.

Front 73

73. What is the approximate CHO store in the body?

Back 73

The total CHO store in the body is about 375-475 g. About 3454g are stored as muscle glycogen, 90-100g are stored as liver glycogen, and 15-20 are found in the plasma as blood glucose.

Front 74

74. Blood glucose is the only real source of energy for the brain. True/False

Back 74

True. Most of the glucose released from the liver glycogen stores is used for this purpose.

Front 75

75. The ability of the muscles to absorb glucose from the blood is decreased by the reduction of the level of insulin in the blood, which occurs if blood glucose levels fall. True/False

Back 75

True. If blood glucose levels fall, the muscle fibers are less able to take up glucose and use it as energy. Therefore, muscles will use glucose from their own glycogen stores, rather than from the plasma.

Front 76

76. With respect to energy metabolism five hormones are mainly involved. What are they?

Back 76

Adrenaline

Noradrenaline

Glucagon

Growth hormone

Insulin

Adrenaline, Noradrenaline and glucagon stimulate the conversion of glycogen to glucose, and together with GH they stimulate the conversion of fats to FFAs and glycerol.

Front 77

77. With respect to the hormones mentioned above, they also increase an enzyme that increases the rate of supply of fatty acids. Which enzyme is this?

Back 77

Lipoprotein lipase.

Front 78

78. What effect does Insulin have on adrenaline?

Back 78

It inhibits the effects of adrenaline, and glucagon, and also inhibits the enzyme lipase which catalyzes the breakdown of fats into FFAs and glycerol.

An anabolic effect is also claimed for insulin, and some power athletes attempt to maintain raised insulin levels by continuous CHO snacking during workouts.

Front 79

79. Broadly there are three systems involved in supplying energy to the working muscles. What are they?

Back 79

1. ATP/PC system or phophogen system

2. The lactic anerobic system (anerobic glycolytic)

3. Aerobic system

Each of these is suited to a particular type of exercise.

The end product of all the energy releasing processes of cellular respiration is the energy rich ATP process.

Front 80

80. Is there a biochemical relationship between ATP and phosphocreatine?

Back 80

Yes. To ensure the rapid regeneration of ATP, there is another energy rich phosphate compound in the muscles, namely phosphocreatine, which acts acts as the most immediate energy reserve for the resynthesis of ATP.

ADP+ Phosphocreatine --ATP+ creatine

PC in turn can only be regenerated using energy from ATP. During maximal exercise, PC cannot be replenished, as the ATP is being used continuously in muscle contraction.

Front 81

81. When not enough CHO breakdown occurs, when the glycogen reserves are depleted, the incompletebreakdown of fats can result in toxic ketosis. True/False

Back 81

True.

Front 82

82. What effect does caffeine have on endurance exercise?

Back 82

Caffeine increases the blood levels of FFAs and the ability of the muscles to use them, and thus spares glycogen. Caffeine stimulates the nervous system increasing alertness and reducing pain and fatigue. It increases the heart rate and ventilation.

Front 83

83. Caffeine in excess is considered a form of doping in sporting events. True/False

Back 83

True. It is banned at a level equivalent to 8 strong cups of percolated coffee or 10 cups of strong tea in two hours.

Front 84

84. The initial stages in the breakdown of CHO, occur in the cytoplasm of all cells, including muscle fibers. True/False

Back 84

True. O2 is not involved in these initial stages in the cytoplasm and they are therefore referred to as anaerobic glycolysis.

Anerobic glycolysis generates a net gain of two ATP molecules from each molecule of glucose, which represents about 5% of the total ATP that can be generated from the complete breakdown of the glucose molecule.

Front 85

85. In anaerobic glycolysis an essential part of these stages of anaerobic glycolysis is the removal of hydrogen atoms from the substrate (oxidation). Which molecule accepts these hydrogens?

Back 85

It is accepted by the coenzyme NAD which is thus reduced to NAD2H.

Front 86

86. What is the role of Pyruvic acid in lactic acid metabolism?

Back 86

When the demand of the muscles for O2 exceeds the supply, as for example at the beginning of most types of exercise, an intermediate product (pyruvic acid) of the breakdown of glucose is used to oxidize the NAD2H. The pyruvic acid itself becomes reduced to lactic acid.

Front 87

87. What is meant by "lactate steady state"?

Back 87

A small amount of lactic acid is always formed in the muscles, even at rest. However, if the rate of clearance is more than or equal to the rate of production, lactate levels are held by homeostatic systems at what can be called a lactate steady state. When production does exceed clearance, lactate accumulates increasingly in the muscle and then in the blood.

Front 88

88. What bodily effects are noted with high lactate levels?

Back 88

This can sensitize nerve endings, which create an uncomfortable sensation either locally in the muscle or throughout the whole body.

Front 89

89. What is the difference between lactic and lactate physiologically?

Back 89

An acid id a compound which dissociates in solution to release hydrogen ions (H+). The release of hydrogen ions leaves the rest of the molecule with a net negative charge. This negatively charged part is known as the lactate ion.

Lactic acid---Lactate ion +H+

C3h6o3--C3h5o3 + H+

Front 90

90. How can lactic acid be removed from muscle?

Back 90

Some is lost in sweat and urine, and its reconversion to glycogen in the liver and in muscles.

The major pathway for the removal of Lactic acid is its aerobic oxidation to CO2 and H2O, yielding ATP.

The removal of lactate is such that its concentration is halved about every 15 minutes.

Front 91

91. When enough O2 is delivered to muscles, how does this affect NAD?

Back 91

It can be used to reoxidize the NADH2 produced in the oxidation of glucose to pyruvic acid.

These aerobic stages take place in the cell structures known as mitochondria. Slow twitch fibers have larger numbers of mitochondria containing the enzymes, coenzymes and cytochrome pigments necessary for aerobic processes.

Front 92

92. The complete oxidation of pyruvic acid occurs via a cyclic process known as the_______________________.

Back 92

Krebs cycle. This produces more NADH2. The NADH2 is oxidized back to NAD by the removal of hydrogen atoms which are oxidized by O2.

Front 93

93. This complete oxidation of a glucose molecule results in the production of ____ molecules of ATP.

Back 93

31 molecules of ATP

Front 94

94. What is the Oxygen deficit?

Back 94

It is the difference between, the calculated amount of O2 necessary to supply the energy, for a period of exercise and the actual amount of O2 absorbed during the exercise period in excess of that used in an equivalent period of rest.

(The amount of O2 that the subject was short of during the exercise)

Front 95

95. What is the Oxygen debt?

Back 95

During recovery from exercise, the O2 consumption remains high, above the rate of consumption, for an equal period of rest. Originally, this amount of extra O2 required during recovery was assumed to be that which was needed for the removal of the accumulated lactic acid and was therefore referred to as the O2 debt. Another, perhaps more accurate term is excess post exercise oxygen consumption. (EPOC)

Front 96

96. Regarding excess post exercise oxygen consumption, there is a fast and slow component. Describe the fast component.

Back 96

In the fast component of EPOC, the O2 consumed is used tio regenerate the phosphagen system of ATP and PC and to resaturate the myoglobin and tissue fluids with O2.

Front 97

97. Regarding energy efficiency, the energy released by the oxidation of energy rich substrates in respiration can be estimated indirectly from the net O2 cost of a particular steady state activity. True/False

Back 97

True. However, the energy released for a given volume of O2 varies, depending upon whether CHOs, fats or proteins are oxidized.

The particular substrate being used can be estimated from the RER (respiratory exchange ratio) or respiratory quotient.

The values for CHOs, fats and proteins are 1.0, 0.7 and 0.8 respectively.

Front 98

98. The energy not trapped in ATP, and ultimately even the energy that is released from the ATP in doing work, is all lost as heat. True/False

Back 98

True.

Front 99

99. What is the physiological result if core body temperature rises above 37 C?

Back 99

At this point, the blood vessels in the dermis of the skin shunt more blood towards the surface, increasing the amount of heat lost by radiation, convection, and conduction to the surroundings.

Front 100

100. At what core temperature variation does sweating begin?

Back 100

If the core body temperature rises 0.5 C above normal, sweating is initiated.

Energy is required to change the state of water from liquid to vapor from liquid to vapor and this known as the latent heat of vaporation.

Front 101

101. Can external temperature affect body water loss during exercise?

Back 101

Yes. The volume of water lost depends on external temperature and humidity, the amount of exercise and the volume of water drunk before and during exercise. Losses can vary from 1-3 dm3 (litres) per hour.

Front 102

102. What begins to occur at serious water loss during exercise?

Back 102

There is decreased plasma volume, with circulatory problems, such as diminished stroke volume with an increased heart rate. Reduced blood pressure is a consequence as well. Muscle function is affected as well.

More severe dehydration results in an increased concentration of salts in the plasma, which may interfere with cardiac function.

Front 103

103. How is salt excreted from the body during intense exercise?

Back 103

Salts (sodium chloride) is lost in perspiration. There is a lower sodium concentration in the sweat than in the plasma, therefore sweating does not decrease the plasma sodium concentration. However, if fluid losses are replaced with pure water, the plasma sodium level does decrease, and this is implicated in muscle cramps. Tissues may swell as a result of this decrease in concentration of the fluids which surround the cells, water is drawn via osmosis into the cells, causing tissue swelling.

Front 104

104. Define the cardiac cycle.

Back 104

This is the sequence of events that occurs during the filling and emptying of the heart. At a rate of 70 bpm, the complete cycle takes about 0.86 seconds.

The starting point in the cardiac cycle, is accepted at he point when all heart valves are shut.

Front 105

105. Semilunar valves are sometimes referred to as pocket valves. True/False

Back 105

True.

Front 106

106. When the ventricles relax (diastole), how is bloodflow affected?

Back 106

The blood tends to fall back down the pulmonary artery and main aorta under gravity, thus filling and shutting the pocket valves. The closing of these valves makes the second heart sound.

Front 107

107. What is cardiac muscle histologically composed of?

Back 107

It is composed of short striated fibers interconnected by side branches, which allow for the rapid spread of excitation from fiber throughout the heart wall.

Front 108

108. it is said that cardiac muscle contraction has no merging or summation occurring between successive contractions. Why might this be so?

Back 108

Cardiac muscle has a long refractory or rest period during which it cannot be restimulated. The rest period protects the heart muscle from fatigue.

Front 109

109. Cardiac muscle cannot respire anaerobically to any significant extent. True/False

Back 109

True. True. It being aerobic, it uses glucose, fatty acids and lactic acid, fomed in the exercising muscles, as respiratory substrates or fuels.

Front 110

110. does cardiac muscle have a low concentration of mitochondria?

Back 110

NO. It has a relatively high concentration of mitochondria. These organelles are the center of aerobic respiration, and each fiber is supplied with at least one capillary. It has a high oxidative potential. It can extract up to 80% of O2 from the blood even at rest. Some tissues in comparison have an OP of only 25%.

Front 111

111. Why is there less flow in the coronary arteries during systole?

Back 111

This is so because they are compressed by the contraction of the cardiac muscle.

Front 112

112. As the heart increases during exercise, diastole shortens, more than systole. Why is this so?

Back 112

This would be expected to reduce the diastolic coronary blood flow. However, there is still an increase in coronary flow from about 250cm3 per minute at rest to about 1,000cm3 per minute during exercise as a result of increased dilation of coronary blood vessels which is stimulated by hypoxia, and by increased aortic pressure which forces more blood into the vessels.

Front 113

113. What is the contractual physiological difference between a trained and an untrained heart?

Back 113

Aerobic training increases the stroke volume, and lowers the resting heart rate, thus increasing the period of diastole in each cardiac cycle, and permitting a greater coronary blood flow.

A low heart rate and a high stroke volume is the most efficient way of achieving a given CO. The cardiac muscle of a trained heart needs less O2 and proportionally lower coronary blood supply at rest than the untrained heart.

Front 114

114. As a result of the special properties of cardiac muscle, the heart cannot develop an O2 debt to any real extent, nor can it devlop cramp as can occur in skeletal muscle tissue. True/False

Back 114

True.

Front 115

115. Can a healthy heart be damaged or strained by high exercise levels?

Back 115

It is generaslly agreed that it is difficult to strain a healthy heart. However,if cardiac muscle is deprived of O2 for several minutes, it will die. Should coronary vessels become blocked, O2 distribution suffers. Fatty deposits or coronary plaques of cholesterol on coronary wall arteries can narrow vessel lumens, and roughen the internal surface. Blood clots or thrombi can form.

regular aerobic exercise tends to reduce the possibility of these events, but not as much for those who are more naturally at risk.

Front 116

116. Define Cardiac output.

Back 116

This is the amount of blood pumped into the arteries by contraction of the ventricles in a given time. At rest it may be 5,000cm3 (5 litres) per minute from each ventricle in an untrained individual, rising to a possible 30,000 cm3 (30 litres) per minute in a trained individual undergoing maximal exercise.

CO= HR X Stroke volume. Typical stroke volume is about 75cm3 (75ml)

Front 117

117. Define Cardiac reserve.

Back 117

The CR is the difference between the CO at rest (Q rest) and the maximum cardiac output (Q max). It gives a measure of the increase in blood supply available during exercise..

Front 118

118. What is meant when stated that cardiac muscle is myogenic?

Back 118

This means that the heart can contract without nervous stimulation.

Coordinating waves of electrical activity originate in a mass of specialized cardiac muscle in the right atrium (S-A node or pacemaker). This provides the basic rhythm of cardiac contraction.

Front 119

119. When the SA node is stimulated how does a typical cardiac wave distribute itself?

Back 119

The wave of excitation spreads rapidly throughout the interconnected cardiac muscle fibers of the atria. However, a band of fibrous connective tissue between the atria and ventricles prevents the excitation wave spreading down into the ventricles. Both atria and ventricles cannot contract simultaneously, as blood would not move from atria to ventricles.

Front 120

120. What is the A-V node?

Back 120

This is another mass of specialized tissue, the AV node at the bottom of the atria. When stimulated from the SA wave, impulses are transmitted to the base of the ventricles in a tract of conducting tissue, from where the impulses radiate upwards through cardiac muscle of the ventricles.

Front 121

121. The spread of the wave of the excitation throughout the heart can be detected by electrodes attached to the skin of the chest and displayed as an EKG. True/False

Back 121

True. In fact, the onset of strenuous activity can result in EKG abnormalities due to insufficient blood flow to the heart muscle in the first few seconds. A two-three minute warmup period before can prevent this abnormality.

Front 122

122. During exercise, alterations in cardiac nerve stimulation are the results of changes associated with exercise acting either directly or indirectly on the cardiovascular control center in the brain. List some notable changes.

Back 122

An accumulation of CO2 and lactic acid.

A decrease in the amount of O2 in the blood

An increase in temperature, which speeds up metabolism in general, and also reduces the viscosity of the blood making pumping easier.

Front 123

123. The heart rate increases very rapidly at the onset of exercise. True/False

Back 123

True. In a trained athlete it can trble within a minute of starting. Thgis increase is too rapid to be the result of activities of the metabolic mechanisms concerned with cardiac acceleration. The exact cause of this is not clear.

Connections exist between the higher centers of the cerebral cortex, and the CV center of the brain (from which the sympathetic and parasympathetic impulses to the heart originate), which can result in anticipatory increases in heart rate prior to exercising.

Front 124

124. What is ejection fraction?

Back 124

When the body is not exercising, the ventricles do not empty completely, when they contract, they only expel about 40-70% of the blood they contain. This is ejection fraction.

With the onset of exercise, adrenaline and noradrenaline increase tyhe contractility of the cardiac muscle. This increases the force of contraction and the ejection fraction.

Front 125

125. In regard to contraction, what does Starling's law state?

Back 125

It states that the force of contraction of the ventricles is proportional to the degree of stretch of the cardiac muscle fibers during filling.

The reduced heart rate in the trained individual allows a greater filling during the longer diastole, so the degree of stretch of the fibers will be greater. This increases the ejection fraction.

Front 126

126. Heart rate has been shown to increase proportionally with increasing workload, whereas stroke volume does not. True/False

Back 126

True. it has been demonstrated that stroke volume increases to a maximum plateau between 40-60% of VO2 max, In highly trained athletes stroke volume continues to increase beyond this level to maximum effort.

Front 127

127. What is cardiovascular drift?

Back 127

Endurance trained athletes initially increase their CO in response to demands of exercise mainly by an increase in their ejection fraction, whereas untrained athletes respons mainly with an increase in heart rate. Thus in trained athletes the heart rate increases more slowly during exercise. For periods of more than 30 minutes of submaximal work, the cardiac output is maintained, but due to loss of fluid as sweat tere is a reduced plasma volume and therefore reduced venous return to the heart, therefore the SV gradually decreases and the heart rate slowly increases in a process called cardiovascular drift.

Front 128

128, During upright exercise such as running there are difficulties in increasing venous return against the force of gravity, so the central blood volume is decreased reducing the venous return and the SV. True/False

Back 128

True. In the horizontal position, such as swimming, there are fewer resistances.

Front 129

129. What is athletes heart?

Back 129

The adaptations that the heart shows to aerobic exercise over a period of time, can lead to athlete's heart.There is an enlargement (hypertrophy) of the heart giving an increased SV and a reduced resting rate which is often irregular and associated with some abnormal EKG findings. Physicians should be made aware of one's exercising regimen, so as not to misdiagnose the finding.

Front 130

130. What occurs in a well trained heart to cardiac myofibrils?

Back 130

The individual myofibrils in the cardiac muscle fibers thicken and increase in number, and there is an increase in the size and number of the mitochondria. It should be noted that a healthy untrained heart does not experience insufficient O2 supply even during maximum exercise, but the changes seen in the trained heart are an advantage, as they enable the heart to function at a lower percentage of its total oxidative capacity during exercise.

Front 131

131. Are enlarged athletic hearts likely to diminish if exercise regimens are stopped?

Back 131

Yes.Functional changes such as an increase in contractility of the cardiac muscle are rapid and occur within weeks, but structural changes, such as ventricular enlargement may take months to years. These changes are reversed over time once the training load is decreased.

Front 132

132. Define mean blood pressure.

Back 132

The average of the systolic and diastolic pressures during a complete cardiac cycle is the mean blood pressure. Blood pressure drops as blood moves further away from the heart.

Front 133

133. What are some typical figures for mean blood pressure?

Back 133

In mm/Hg at rest:

arteries- 100

arterioles- 60

capillaries- 18

veins- 7

entrance to right atrium- 3

Front 134

134. What is peripheral resistance?

Back 134

Blood pressure is determined by CO and the resistance to flow of the blood. Resistance is called peripheral resistance.

The resistance to flow is due to the friction between the blood and the walls of the blood vessels. The friction is determined by the length, diameter, and the smoothness of the lining of the vessel, as well as the viscosity of the blood.

Plaque and loss of elasticity of vessels are examples of resistance risks.

Front 135

135. The viscosity of the blood is increased if the plasma volume is decreased. True/False

Back 135

True. This could be due to dehydration. Replacement of fluid by drinking regularly during exercise is important to maintain water and salt balance, and temperature regulation.

The viscosity of the blood also increases if the number of RBCs in a given volume of blood (hematocrit value) is increased.

Front 136

136. The viscosity of the blood is reduced after taking aspirin. True/False

Back 136

True. The practice of taking aspirin as an ergogenic aid (one that improves the ability to do work) is not banned.

Endurance training can increase the overall blood volume by up to 10% mainly as a result of an increase in the amount of plasma, and this would also tend to reduce the blood's viscosity. This increase in plasma in endurance trained athletes reduces the concentration of hemoglobin in the blood, a condition known as athletic pseudo-anemia, even though the RBC number is increased.

Front 137

137. During rhythmic exercise, the CO rises, and there is a rise in systolic blood pressure perhaps by as much as 30%. True/False

Back 137

True. The diastolic pressure tends to remain relatively stable.

Front 138

138. Does pulmonary circulation operate at a lower pressure relative to the general circulation?

Back 138

Yes. The pulmonary arterial systolic blood pressure is between 19 and 26mm/Hg. The resistance is lowered by the thin elastic walls of the pulmonary arteries and the thinness of the muscle walls of the arterioles.

This lower pressure is necessary to prevent the exudation of fluid into the alveoli, which could flood the lungs, and interfere with O2 uptake.

Front 139

139. The systolic and diastolic blood pressures are raised considerably during static (isometric) straining type exercises as in weight training. True/False

Back 139

True. This is caused by compression of peripheral blood vessels, resulting in an increase in resistance to blood flow.

Front 140

140. Regarding blood vessels, how is blood pressure generally monitored?

Back 140

Pressure receptors in the aorta, carotid arteries and the heart monitor the blood pressure at all times. Reflex actions occur to oppose any move away from the optimum. A drop in blood pressure is opposed by sympathetic stimulation.

Front 141

141. What effect does adrenaline have on blood vessels?

Back 141

It causes arteriolar constriction in the skin and the gut, but dilation of the vessels in the skeletal muscles, the liver and the coronary circulation of the heart.

Noradrenaline causes a net vasoconstriction overall, even in skeletal muscles. Noradrenaline (norepinephrine) has a stronger effect in raising blood pressure than adrenaline.

Front 142

142. The adrenal glands secrete which substance which results in the kidneys to retain sodium and water?

Back 142

Aldosterone. (mineralcorticoid) TRhis will increase blood volume.

Front 143

143. The arteries close to the heart have large cross sectional area. True/False

Back 143

True. The large elastic arteries are stretched by the large cardiac output of ventricular syndrome. Pressure tends to drop during diastolic phases.

Front 144

144. Give an example of how blood is shunted during muscular exercise?

Back 144

When the body is at rest, about 45 percent of CO passes through the capillaries of the gut wall and associated glands and the kidneys. During maximum exercise this can be reduced to about three percent of the CO, as old is redirected to working muscles.

Front 145

145. Considering the above question, does this haunting lead to a reduction in O2 supply to the gut?

Back 145

Nor really. These regions use about 10-25% of the O2 , available in their normal blood supply.

Front 146

146. How is the shunting of blood between competing tissues achieved?

Back 146

This is achieved by constriction and dilation of the arteries and of the arteriovenous beads which are direct connections between the arteries and juveniles from which the capillary beds arise. The entrances to the capillary beds are controlled by circular capillary sphincter muscles, which when contracted shut off the capillaries, and when ralaxed, open them.

Front 147

147. How are arteries and precapillary sphincter controlled?

Back 147

These are controlled and supplied with vasoconstrictor nerves from the sympathetic nervous system. These local factors within the working muscle include a drop in the O2 , and a rise in the CO2 levels, a decrease in oN, an increase in temperature, an increase in the amount of ASP present in muscle fibers, and an increase in potassium and Mg ions in the muscles.

Front 148

148. Capillaries have the smallest diameters of all blood vessels. True/False

Back 148

True. They are about 7 micrometers (0.007 mm) which is about the same.e as that of RBCs. Capillary walls are about 1 cell thick, which further aids exchanges by diffusion between the blood and the tissues. Theatre number of capillaries provide a very large surface area across which changes occur.

Front 149

149. As a result of the positive pressure of the blood, plasma is forced out through the walls of th capillaries to form tissue fluid. This is also known as ____________________ pressure.

Back 149

Hydrostatic. This tissue fluid carries O2' nutrients, hormones and antibodies from the capillaries out into direct contact with the cells of the tissues. During g heavy exercise as chief as 10-20 percent of the plasma volume can as tissue fluid in the working muscles.

Front 150

150. How does most of the water in the tissue fluid return to capillaries?

Back 150

This is done via osmosis. This movement occurs closer to the juveniles, where the blood pressure is lower. The 'remainder of the fluid is drained away from the tissues in the blind ending lymphatic capillaries of the lymphatic system, in which the fluid is known lymph. Waste products are carried away as well.

Front 151

151. What is muscle water logging?

Back 151

Obe cause of muscle pain and stiffness after unaccustomed exercise is the water logging of the muscles by excess tissue his which was not drained away efficiently during exercise by the lymphatic system. The muscles swell, which stimulates pain receptors. Increased training can increase fluid clearance efficiency.

Front 152

152. Individual veins have a larger cross section than the comparable arteries. True/False

Back 152

True. There are more veins than arteries, the veins also have a greater total cross sectional area. The was of veins are thinner and less elastic than those of arteries.

Front 153

153. Do veins have valves?

Back 153

In the veins of the legs and arms there are semi l or pocket valves at intervals ing their length. Valves oppose any backfire of blood under gravity and ensure a k e way flow old to the heart.

Front 154

154. What is meant by the respiratory pump?

Back 154

These are breathing movements which typically become more exaggerated during exercise, and assist the return of blood in the veins to the heart.

Front 155

155. At rest the veins act as a large reservoir of blood for use when circulatory demands increase. True/False

Back 155

True. During exercise when the cardiac output increases, the muscle fibers in the walls of the veins assimilated to contract (venous tone), the veins constrict a d Sather portion blood is shunted back to the heart. This is I.important in preventing g blood from looking in the legs u Der the force of gravity during upright exercise.

Front 156

156 In reference to blood flow, the smaller the cross sectional area the faster the flow, and vice versa. True/False

Back 156

True. The capillaries are the smallest vessels, their total cross sectional area is about 800 times greater than the aorta leaving the heart. ( has diameter of about 25mm). Blood flow slows in the capillaries so efficient exchange can take place.

Front 157

157. Is pulmonary circulation as fast as general circulation?

Back 157

No. This is because the total cross sectional area of the vessels in the pulmonary circulation is less than that in the systemic circulation.

Front 158

158. Are lymphatic vessels thick or thin walled?

Back 158

They are thin walled, with numerous one way pocket valves. Respiratory and muscle pumps move the lymph.

Front 159

159. What is the function of lymph nodes?

Back 159

LNd have special cells and antibodies, which prevent infective agents, which may have e n trees the tissues vulnerable points ( lining of the gut, the upper , or the lungs from entering the circulation.

Front 160

160. What is another function of lymph?

Back 160

t also important for returning plasma proteins to the blood. Some proteins pass into the tissue fluid, and these proteins cannot pass back I to blood capillaries. They can be removed by lymphatic capillaries. If these into tissues, they would cause a detention of water.

Front 161

161. The thorax is divided into two separate halves by a membrane, so that if one is punctured only one lung will collapse. True/False

Back 161

True. Inspiration I on is to be process, and expiration is a passive one. However, in exceptional activity, expiration be active.

Front 162

162. Which portion of the brain controls normal breathing?

Back 162

This is controlled by involuntary, automatic rhythmic discharges of nerve impulses from of the brain known as the respiratory control centers.

Front 163

163. How does the respiratory control center send impulse signals?

Back 163

It sends motor nerve impulses to the external intercourse muscles of the ribs, and the muscles of the diaphragm, causing cram, and inspiration to occur. This phase lasts for about two seconds. Impulses will stop being sent for about three seconds.

Front 164

164. How do pH changes affect respiration?

Back 164

Any increase in the acidity of the blood results in quickened respiration. A decreAse in pH results mainly increase in the production of lactic acid and CO2(acid gas) due to the increase in the respiratory rate.

Front 165

165. How is the level of acidity monitored?

Back 165

It is monitored by chemoreceptors in the main aorta and in the carotid bodies in the arteries of the neck.

Front 166

166. Does the blood have a certain ability?

Back 166

Yas. It can resist changes in its oN to between 7.2-7.45. As the lactate accumulates in the blood it is buffered by combination with hydrogen carbonate ions present in the plasma, of CO2 in the blood. (H+ (+) HCO 3 yields H2CO3 yields H2O + CO2). An increase in CO2 simulates the chemoreceptors in the carotid bodies and the respiratory control center. In strenuous the oH within the muscles can drop to 6.4' and the arterial blood oN to about 7.0 or slightly below as a result of lactic acid accumulation.

Front 167

167. What is the ventilation break point?

Back 167

Dduring exercise at a certain point, the rate of ventilation of the lungs increases rapidly that's heart rate and the O2 uptake. This point at which ventilation from the heart rate is the ventilation break point. It is used invasive estimates of the lactate threshold.

Front 168

168. Stretch receptors in the bronchitis and the bronchioles are stimulated by the expansion of the lungs. True/False

Back 168

True. Nerve impulses pass from these along sensory nerves to the respiratory control center , causing the reflection inhibition of the respiratory motor nerve impulses. It operates to protect the lungs from overinflatiln.

Front 169

169. Other sensory receptors(proprietors) in the skeleton and muscles, back information to increase breathing movements during exercise. True/False

Back 169

True.

Front 170

170. What is tidal volume?

Back 170

During quiet breathing , when at rest, about 500cm3 of air can be breathed. This is tidal volume. Of this 500cm, about 350cm3 reaches the alveolar where gaseous exchange occurs. The remaining 150 fills the pharmacy, larynx, trachea, bronchitis and bronchioles. No e cha n he takes place here. It is effectively a dead space zone. The alveolar air consists of about 350cm3 of fresh air that has undergone gaseous e x with

the blood.

Front 171

171. What is the inspiration reserve volume?

Back 171

By breathing in as deeply aS possible an extra volume of air, in addition to the tidal volume a d the stationary air can be taken into the lungs. The IRV can be up to 2'000cm3. The exploratory reserve volume can be up to 1500cm3. The lungs cannot emptied completely or they would collapse. Residual volume can be up to 1500cm3.

Front 172

172. The ________________________ ( up to 2500cm3) is the sum of the tidal volume and the inspiratory reserve volume.

Back 172

The inspiratory capacity.

The vital capacity (up to 4,000 cm3) is the sum of the IRV, the TV and the ERV,

Front 173

173. What does the vital capacity represent?

Back 173

It represents the maximum total amount of air that can be moved into and out of the lungs by one inhalation and one exhalation.

Front 174

174. The total lung capacity is the sum of all lung capacities. True/False

Back 174

True. It is about 5500cm3.

Front 175

175. It is believed that high intensity aerobic training does not have as much effect on the lungs as might be expected. True/False

Back 175

True. Lung capacities might be increased a little, and forced exhalation may increase in power, but overall increased respiratory efficiency is not terribly significant. True improvements are likely due to cardiac improvements.

Lung capacities are measured via spirometers.

In fact, with increasing age the residual volume increase from about 20% of total lung volume to more than 30%.

Front 176

176. What is Minute expiratory ventilation?

Back 176

This is the volume of air breathed in one minute. That is the tidal volume multiplied by the breathing rate per minute.

500cm3 X 16 =8,000 cm3

The tidal volume increases from about 12% of the vital capacity at rest, to about 50-60% of the vital capacity during exercise, and the breathing rate can increase to up to 50 per minute.

Ve max = 3,000cm3 X 50 = 150,000cm3

Front 177

177. What is the maximum Voluntary Ventilation?

Back 177

The MVV is the volume of air that can be breathed in 15 seconds of forced rapid and deep breathing, multiplied by four, to give a one minute result, It can be up to 200,000 cm3 in males.

Front 178

178. What is FEV1?

Back 178

Also known as timed vital capacity is that volume of air in dm3 (litres) that can be expired in one second. It is an indicator of the power of the lungs to breathe out. It actually measures resistance to air flow. Its normal value is about 85%, below 65% in patients with pulmonary disorders.

Front 179

179. Resistance to air flow in the air tubes accounts for up to 80% of the total resistance of the lungs to ventilation. True/False

Back 179

True. This is true especially during expiration when airways tend to collapse. The remainder of resistance is due to the elasticity or compliance of lung tissues.

Front 180

180. In the lungs, where does gas exchange occur?

Back 180

It occurs between the air in the alveoli of the lungs and the blood in the capillaries present in the walls of the alveoli of the lungs.

Front 181

181. In gas diffusion, what is mea nt by moving down a concentration gradient?

Back 181

It goes from a higher concentration to a lower concentration until an equilibrium is reached. An increase in temperature increases the speed of diffusion.

Front 182

182. What is meant by partial pressure of a solution?

Back 182

The continuous random movement of particles of a gas means that the particles will occasionally collide with each other and with the walls of any structure enclosing them within a space, thus exerting a pressure.

The number of such collisions and therefore the pressure is proportional to the amount of substance present.

Front 183

183. In mixtures of gases, e.g. air, each substance exerts a partial pressure in that mixture proportional to the amount of that substance in the mixture. True/False

Back 183

True.

Front 184

184. The partial pressure of a gas is a better measure of the amount of gas present than quoting its concentration as a percentage (21% of O2 in air). Why is this so?

Back 184

This is true, because, although the percentage of O2 remains the same in air under different conditions, the amount of O2 does not.

At atmospheric pressures less than at sea level, at altitude, there is still 21% O2 in air, but as the air is less dense, there is a smaller amount of O2.

The normal barometric pressure of dry atmospheric air at sea level is 760 mm/Hg (101.3 kPa)

Front 185

185. So at normal atmospheric pressure at sea level the pO2 is what as expressed in an equation?

Back 185

pO2 = 760 X 21/100 = 159.6 mm/Hg. (percentage in air is 21%)

The pCO2 = 760 X 0.04/100 = 0.3 mm /Hg (CO2 is 0.04% in air)

Front 186

186. Blood entering the capillaries of the alveoli from the pulmonary arteries has a lower O2 and a higher carbon dioxide content, than the air in the alveoli. True/False

Back 186

True. CO2 diffuses out of the blood into the alveoli, and O2 diffuses into the blood from the alveoli, down their partial pressure gradients.

Front 187

187. What is the route of entry once oxygen is diffusing into the blood?

Back 187

O2 diffusing into the blood dissolves in and diffuses through the srface film of moisture on the surface of the alveoli, through the thin walls of thenalveoli, through the thin wall of thecapillaries, through the plasma, and through the red blood cell membrane to combine with the hemoglobin to form oxyhemoglobin.

Front 188

188. About how much O2 per minute diffuses in over the lungs at rest?

Back 188

About 250cm3 of O2. This can be increased up to about 20X this amount during exercise. The CO2 diffuses in the opposite direction to the O2 from the blood plasma into the alveoli.

Front 189

189. CO2 molecules diffuse more slowly in the gas phase than O2. Why is this so?

Back 189

CO2 molecules are larger than O2 and diffuse more slowly, but CO2 is more soluble than O2 and diffuses about 20X more readily than O2 across the capillary-alveolar barrier.

This explains why, although the pressure gradient of carbon dioxide is only 6mm Hg compared to 60 mm/Hg for O2, sufficient exchange of CO2 still occurs.

Front 190

190. Expired air is a mixture of what?

Back 190

It is a mixture of the alveolar air and the air that occupied the dead space. The inspired air becomes saturated with water vapor, and this has the effect of decreasing the partial pressure of o2 or pO2 by about 10mmm/Hg.

Front 191

191. Does nitrogen play a part in respiratory metabolism?

Back 191

Not really. However, its percentage increases by +1.7% in alveolar air, in proportion to the decrease in volume caused by more O2 being absorbed (7.2%) than CO2 being given out (5.5%) a difference of about -1.7%)

Front 192

192. Can fats and proteins affect O2 absorption?

Back 192

Yes. More O2 is absorbed than CO2 is given out as a result of the oxidation of fats and proteins, which consume more o2 than they gave out CO2.

Front 193

193. Regarding alveolar gas diffusion, surface area and thickness can affect diffusion. True/False

Back 193

True. The surface area of the lungs is about 70m3 and the walls are made up of very thin flat lining cells (epithelium). It is estimated that there are about 300 million alveoli in each lung.

Front 194

194. Why are the alveoli surfaces ridged and corrugated?

Back 194

The capillaries of the pulmonary circulation are sandwiched between the thin walls of adjacent alveoli, resulting in the surfaces to be ridged and corrugated, which further increases their surface area.

The capillaries have thin walls, so that the total thickness of cells between the air and blood can be as little as 0.001 mm.

Front 195

195. At rest, are all parts of the lungs equally ventilated?

Back 195

No. The upper regions are generally undersupplied with blood (standing position). These regions make up the physiological dead space, as little gas exchange occurs.

Front 196

196. At rest , briefly explain the speed of circulation of the blood through the lungs.

Back 196

It is such, that the contact between the blood and the wall of an alveolus is about 0.75 seconds. During exercise this time is reduced to about 0.35 seconds.

Front 197

197. regarding the utilization of O2, what is meant by the arterioi-venous difference?

Back 197

The absorption and utilization of O2 from the blood by the tissues, especially in working muscles, leads to a difference in the O2 content of arterial and venous blood. This is the arterio-venous difference or also known as the vO2 diff per 100cm3 of blood.

Front 198

198. What does vO2 refer to?

Back 198

The vO2 refers to the O2 content of mixed venous blood, that is blood returning from both active muscles and other less active tissues.

What is VO2 Max in Athletic Training? VO2 max, or maximal oxygen uptake, is one factor that can determine an athlete's capacity to perform sustained exercise and is linked to aerobic endurance. VO2 max refers to the maximum amount of oxygen that an individual can utilize during intense or maximal exercise. It is measured as "milliliters of oxygen used in one minute per kilogram of body weight."

Front 199

199. The vO2 diff is larger in trained individuals as a result of the adaptations to greater O2 usage in the muscles. True/False

Back 199

True. This increase in the vO2 difference increases gaseous exchange by diffusion in the alveoli.

During exercise, O2 uptake can increase up to 5,000 cm3 per minute, as a result of the increase in ventilation of the lungs, the increased blood flow through the pulmonary circulation, and increased rates of diffusion.

Front 200

200. Why can breathing in too much O2 be harmful?

Back 200

If pure O2 is breathed under high pressure, so much O2 may dissolve in the plasma that the needs of the tissues may be supplied in this way, and the oxyhemoglobin does not give up its O2. This can interfere with the transport of CO2.

Front 201

201. What is blood doping?

Back 201

In blood doping, a volume of blood, about 1 litre, (dm3) is withdrawn, from the athlete and stored for about a month. When the body has replaced the lost blood, the extracted red blood cells are re infused prior to the event, thus increasing the O2 carrying capacity of the blood.

Front 202

202. What is an important substance in blood, that tends to deteriorate in stored blood?

Back 202

A substance, 2,3 DPG levels of which are increased with training in RBCs, which increases the unloading of O2 from oxyhemoglobin to the tissues, deteriorates in stored blood, and the reinfused blood may not be a seffective as supposed.

Front 203

203. What is phosphate loading?

Back 203

Phosphate loading is when one takes in sodium phosphate to increase the levels of 2,3 DPG, increasing the aerobic capacity and lowering blood lactate levels.

Front 204

204. Are there side effects to blood doping?

Back 204

Increases blood viscosity can interfere with proper blood flow. High blood pressure can result with decreased cardiac output. Blood doping is very difficult to detect.

Front 205

205. What is altitude training?

Back 205

This is based on the same principle of increasing the RBC count and the amount of hemoglobin in a given volume of blood, and therefore increasing the amount of O2.

RBC volume (hematocrit) can increase from 40-45% at sea level to 59% after 6 weeks at 4500 meters. This mode of training may be half as efficient as EPO blood doping. Altitude training is considered by some to be a form of natural blood doping. The legality of this method is questionable. Some countries consider any hypobaric-hypoxic method in violation to fair competition ruling. The train high-live low approach is still practiced by many athletes.

Front 206

206. What happens to O2 levels as one gains in altitude?

Back 206

As altitude increases, the pO2 in air decreases as air becomes less dense, so that an altitude of about 5500m, the amount of O2 in a given volume of air is half that at sea level.

In altitude training, about 3-4 weeks of training are considered to be necessary to achieve the gains one hopes for. It could take as well, 7-10 days to re acclimatize at sea level. Individual variations do occur.

Front 207

207. An increase in temperature, and a decrease in pH decrease the affinity of hemoglobin for O2. True/False

Back 207

True. It is recommended to restudy the association and dissociation curves of hemoglobin.

Remember, that as blood gains CO2 from the tissues, the functional curve gradually moves to the right, that is in the presence of CO2, more O2 is liberated to the tissues.

The release of oxyhemoglobin is further encouraged during exercise by an increase in temperature, and a decrease in pH as a result of lactic acid and CO2 production, both of which occur in working muscles.

Front 208

208. Describe slow twitch muscle fibers and how they utilize O2 during exercise.

Back 208

Muscle fibers, especially the slow twitch types, have the pigment myoglobin, which has a higher affinity for O2 than hemoglobin, and increases the uptake of O2 by the muscle fibers.

Front 209

209. At rest, only about 25% of the O2 transported in the blood is used> True/False

Back 209

True. This is the case so that even venous blood is still approximately 75% saturated with O2. During intense exercise, up to 85% of the transported O2 may be used.

Front 210

210. Endurance training increases the capillary supply and the amount of myoglobin in the muscles, especially those of the slow twitch type. True/False

Back 210

True. There is also an increase in the number, size and enzyme activity of the mitochondria, which increases the potential of the muscles to use O2 (oxidative potential).

Front 211

211. What is meant by the "economy of exercise"?

Back 211

This is measured as the O2 cost of performing, eg, running at a certain pace. Over a period of training, the economy of running can be improved by up to 5%.

Front 212

212. What is a metabolic equivalent?

Back 212

The O2 cost of the resting metabolic rate is on average about 3.5 cm3 of O2 per kg-1 per minute. This is a metabolic equivalent (MET) and can be used a s a unit of O2 cost of various activities, walking at 4mph= 6.5 METS and running at 10mph = 15.0 METS.

Front 213

213. What occurs with CO2 when it is produced as a waste product?

Back 213

CO2, produced as a waste product of aerobic respiration in the mitochondria, diffuses in solution down its concentration gradient, from the high pCO2 in the mitochondria, to the lower pCO2 in the blood.

Front 214

214. About 5% of the total CO2 carried away by the blood is in simple solution in the plasma. True/False

Back 214

True. Up to another 5% may be combined with water to form carbonic acid:

CO2 + H2O--- H2CO3

This is a weak acid and only dissociates slightly into hydrogen and hydrogencarbonate ions:

H2CO3--H+ + HCO3.

Less than 1% of the CO2 combines with plasma proteins to form carbamino compounds.

Some CO2 is also carried in combination with hemoglobin, as carbaminohemoglobin in the RBCs.

Front 215

215. How is the greatest proportion of CO2 carried?

Back 215

It is carried as hydrogen carbonate ions (HCO3) in the plasma. These are formed from CO2 that diffuses into the RBCs. The hydrogencarbonate ions are then released into the plasma.

Front 216

216. What is carbonic anhydrase?

Back 216

RBCs contain this enzyme (as do many other cells in the body) that catalyzes this reaction and accelerates the formation of carbonic acid.

O2 is released from oxyhemoglobin at the same time, and the deoxygenated hemoglobin acts as a hydrogen acceptor, encouraging the dissociation of carbonic acid into hydrogen ions and hydrogencarbonate ions.

Front 217

217. Do the hydrogen ions continue to be absorbed by the hemoglobin?

Back 217

Yes. The hydrogencarbonate ions diffuse out into the plasma, in exchange for chloride ions which diffuse into the RBCs from the plasma. This is known as the chloride shift.

At the lungs, these reactions are reversed.

Front 218

218. What is meany by maximum O2 consumption?

Back 218

During extreme exercise, there is a level of work beyond which the O2 uptake of an individual shows no further increase with additional effort. This is the VO2 max, or maximum aerobic capacity.

Front 219

219. The maximum O2 consumption or uptake is the greatest rate of O2 uptake an individual can achieve during exercise. True/False

Back 219

True. It is expressed as an absolute value, i.e. dm3 per minute or in relation to body mass in cm3 per kg of body mass per minute.

If an athlete can consume an absolute level of 3.5 dm3 per minute and body mass is 70 kg, the VO2 max can be expressed as:

3.5/70 X 1,000 = 50cm3 per kg per minute.

Front 220

220. VO2 max is commonly expressed in relation to the body mass. Why is this so?

Back 220

THis is believed because most sporting activities are weight bearing in nature. However, in these cases, a distrinction is not easily, nor often made between lean body mass (muscle) where most of the O2 is used, and fat mass, where little O2 is used.

Front 221

221. What effect does aging have on the heart?

Back 221

Extra collagen fibers are laid down between muscle fibers of the heart, resulting in a decrease in elasticity and contractility, which reduces the stroke volume and the cardiac output.

It is believed that the maximum heart rate decreases at a rate of about 1-2 beats per year.

Front 222

222. What effect does aging have on the lungs?

Back 222

As well, extra collagen fibers are laid down in the lungs reducing elasticity which reduces lung volumes and gas exchange capacities.

There is also an increase in cross linkages that form between collagen fibers, so that collagen throughout the body, including tendons and muscle sheaths becomes stiffer.

Front 223

223. How is muscle mass affected in the aging process?

Back 223

A general reduction in the ability to synthesize proteins results in a loss of lean muscle mass, which is reflected in a 1% loss of strength per year. BMR is reduced as well.

Front 224

224. What are ergogenic aids?

Back 224

These are substances, other than naturally occurring foods, that when taken orally or by injection, will increase the potential for exercise performance,ex. anabolic steroids.

Front 225

225. Define glucose.

Back 225

This is the simplest carbohydrate in the body. It is a monosaccharide or single sugar. It can be oxidized aerobically to CO2 or anaerobically to lactic acid. It is the sole source of energy for the nervous system. It can be converted into glycogen or fat.