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Mock paper 3 > 17 Metabolism and exercise > Flashcards

17 Metabolism and exercise Flashcards

1
Q

how many minutes per week should a healthy adult be active?

A

150 mins (at least 10 mins per day)

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2
Q

why does heart rate increase immediately with exercise?

A

incr. in adrenaline secretion
incr. in stimulation of the sympathetic NS
incr. anticipatory response –> release of NT (e.g. adrenaline and noradrenaline)

–> increases proportional to exercise until plateau/max h.r. reached

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3
Q

how does vasodilation of arterioles in skeletal muscles occur?

A

secretion of nitric oxide by arteriolar endothelium

in response to fall in O(2) levels

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4
Q

why does stroke volume increase with exercise?

A

more blood returns to left atrium

∴ larger volume of blood filling ventricle in diastole

∴ greater volume of blood pumped out in systole

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5
Q

why does breathing rate + tidal volume increase with exercise?

A

more air into alveoli –> incr. in concentration gradient ∴ O(2) can diffuse into the blood more easily

∴ incr. rate of aerobic respiration ∴ more CO(2) produced ∴ more H(2)CO(3) produced

incr. in blood acidity detected by chemoreceptors - sends impulses to respiratory centre in medulla
incr. in rate and extent of contractions of diaphragm and intercostal muscles

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6
Q

what are the long term effects of exercise on the circulatory system?

A

incr. VO2 max
incr. heart size (hypertrophy of cardiac muscle –> incr. in wall thickness)
decr. resting h.r.
incr. stroke volume
decr. recovery time

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7
Q

what are the long term effects of exercise on the respiratory system?

A

incr. max b.r.
incr. tidal volume
incr. vital capacity
incr. capillary density –> decr. b.r. at rest

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8
Q

what are the long term effects of exercise on the skeletal system?

A

incr. in cross-sectional area of slow twitch muscle fibres
incr. in size/number of mitochondria in muscle fibres
incr. capillary network surrounding muscle fibres
incr. efficiency of lipid metabolism
incr. Mb and glycogen stores

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9
Q

what is the definition of aerobic fitness?

A

a measure of the ability of the heart and lungs to respond to the demands of aerobic exercise

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10
Q

what are three indicators of aerobic fitness?

A

efficiency of GES/CVS

extent of aerobic respiration without fatigue

efficiency of respiration

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11
Q

how is aerobic fitness achieved?

A

20 mins of exercise

3 x per week

increasing in intensity to 50-55% of VO2 max

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12
Q

give four factors that affect aerobic fitness

A

age

gender

smoking

malnutrition

motivation

programme

alcohol consumption

stimulants

depression

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13
Q

give four health benefits of regular aerobic exercise

A

strengthened skeletal muscle

improved circulatory efficiency

reduced blood pressure

improved mental health

reduced risk of diabetes

stimulate bone growth

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14
Q

how can aerobic exercise be improved?

A

increase:

  • Frequency
  • Intensity
  • Type
  • Time (i.e. duration)
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15
Q

how is aerobic fitness measured?

A

decr. resting h.r.
decr. recovery time
incr. VO2 max

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16
Q

how does a successful training programme bring improved aerobic fitness?

A

successful training = stressor

body adapts

progressive overload –> prevents plateau

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17
Q

what is the definition of VO2 max?

A

the maximum rate at which oxygen can be taken in, transported and utilised, as measured by/during incremental exercise

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18
Q

what units is VO2 max measured in?

A

absolute rate = dm^3 min-1

relative rate = ml kg-1 min-1

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19
Q

what is the function of the Bruce treadmill test?

A

to check the development of general endurance

can check nerve impulses from SAN if coronary heart disease is suspected

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20
Q

how is VO2 max calculated for men and women?

A

men: VO2 max = 14.8 - (1.379 x T(1)) + (0.451 x T(2)) - (0.012 x T(3))
women: VO2 max = 4.38 x T - 3.9

{where T = minutes on treadmill}

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21
Q

what is directly measured in the Bruce treadmill test?

A

ventilation rate

oxygen concentration of inhaled air

CO(2) concentration of exhaled air

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22
Q

when is VO2 max reached?

A

when O(2) consumption remains steady despite increased workload

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23
Q

what is excessive post-exercise oxygen consumption (EPOC)?

A

the increased volume of oxygen consumed following vigorous exercise

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24
Q

how is EPOC calculated?

A

oxygen consumed during recovery period - total oxygen consumed

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25
why is oxygen required after exercise?
reoxygenate Hb and Mb balance hormones replenish glycogen stores in skeletal muscles carry out cell repairs regenerate ATP convert lactate to glucose/glycogen meet demands of incr. metabolic rate
26
what are the advantages of high intensity interval training?
incr. resting metabolic rate improved VO2 max
27
how does erythropoietin enhance athletic performance?
recombinant human erythropoietin (RhEPO) EPO normally secreted from cells in renal cortex of kidneys incr. erythrocyte production in bone marrow incr. RBC count
28
how is RhEPO produce?
GE bacteria detectable ∴ random tests given
29
what are the advantages of RhEPO and blood doping?
incr. RBC count incr. Hb concentration incr. oxygen-carrying capability of the blood incr. VO2 max incr. performance
30
what are the disadvantages of RhEPO?
unethical illegal can cause severe cardiovascular problems can lead to renal failure
31
how does blood doping enhance athletic performance?
remove ~ 1 dm^3 several months before competition extra EPO secreted naturally RBC count increases to normal blood reintroduced a few days before the competition
32
what are the disadvantages of blood doping?
unethical illegal dangerous - incr. blood viscosity --> clotting/pulmonary embolism difficult to detect
33
how do steroids enhance athletic performance?
stimulate anabolic reactions cause transcription of specific genes artificial anabolic steroids can be used to increase muscle mass
34
what are the advantages of steroids?
incr. muscle size and strength more aggressive
35
what are the disadvantages of steroids?
unethical can cause liver damage decr. natural testosterone production decr. immune response
36
how does carbohydrate loading enhance athletic performance?
incr. stored glycogen in skeletal muscles (more a. glucose) carbodepletion - CBH intake reduced carbloading - high CBH diet for days before competition --> incr. a. glucose
37
what is the advantage of carbohydrate loading?
more a. glucose ∴ more aerobic respiration ∴ can work for longer
38
what are the disadvantages of carbohydrate loading?
weight gain digestive issues + bloating
39
around how many molecules of haemoglobin (Hb) are there per RBC?
~ 280 million
40
how many O(2) molecules can each Hb molecule transport?
4 {accounts for 98% of O(2) in blood)
41
what is the prosthetic group of a Hb molecule?
haem (Fe2+) binds cooperatively (allosteric conformational change makes it easier for the next O(2) to bind)
42
what is the definition of a respiratory pigment?
a specialised molecule that is capable of binding reversibly with oxygen
43
what is the function of Hb?
to transport O(2) as oxyHb to all respiring cells, where is acts as the final e- acceptor in the eTC
44
what is association?
the binding uptake of O(2) by Hb to form oxyHb
45
what is dissociation?
the ability of oxyHb to release O(2) from haem groups
46
what is the oxygen dissociation curve (ODC)?
a graph that shows the relationship between the partial pressure of oxygen (PO(2)) and % saturation of Hb
47
how is PO(2) calculated?
volume of gas/total volume = pressure of gas/total pressure
48
what is the oxygen binding capacity?
1.34 cm^3 of O(2) per g-1 of Hb
49
what is the appearance of the ODC for adult Hb (aHb)?
{sigmoidal curve - coop binding} at high PO(2), little/no change in % saturation of Hb (i.e. plateau) ∴ O(2) is still taken up by Hb in capillaries steep part = active skeletal muscles ∴ small changes in PO(2) --> large change in % saturation
50
what is the appearance of the ODC for foetal Hb (fHb)?
fHb has higher affinity for O(2) than aHb ∴ at any PO(2), fHb has higher % saturation than aHb ∴ fHb can obtain (O(2)) from maternal Hb via placenta
51
what is the quaternary structure of fHb?
2 alpha and two gamma p.p.c. haem prosthetic groups
52
what is the quaternary structure of myoglobin (Mb)?
1 a. helix p.p.c. 1 haem prosthetic group
53
when does Mb release O(2)?
at low PO(2) ~ 0.5 kPa
54
why can Mb not bind cooperatively?
only 1 prosthetic group Mb + O(2) MbO(2)
55
what is the appearance of the ODC for Mb?
a hyperbolic curve
56
what are the three ways in which CO(2) is transported in the blood?
dissolved in the blood plasma (5%) reacts with terminal amine groups in haem p.p.c. to form carbaminohaemoglobin (10%) reacts with water to form carbonic acid (85%)
57
which enzyme is required to turn CO(2) and H(2)O into carbonic acid (H(2)CO(3))?
carbonic anhydrase can also catalyse the reverse reaction
58
how does the reaction between CO(2) and H(2)O in the blood decrease blood pH?
dissociation of H(2)CO(3) into H+ and HCO(3)- H+ combines with Hb to form haemoglobinic acid (H.Hb)
59
what is the Bohr shift?
an decrease in blood pH due to the presence of CO(2) causes more O(2) to dissociate from Hb in erythrocytes respiring tissues require more oxygen for more aerobic respiration to produce more ATP more CO(2) is produced ∴ less Hb can combine with O(2) ∴ it is released more easily
60
what does the Bohr shift look like on a graph?
shift of ODC to right at same PO(2)
61
what happens to the HCO(3)- ions produced? what is their effect?
diffuse out of RBCs into plasma Cl- diffuse in to balance change in charge
62
how is CO(2) reformed from H(2)CO(3) in the lungs and exhaled?
carbonic anhydrase catalyses the reverse reaction releasing CO(2) and H(2)O CO(2) diffuses down concentration gradient into the alveolar space and is exhaled
63
give three features of cardiac muscle
striated myogenic has intercalated discs
64
what is the purpose of intercalated discs?
cells membranes fuse and form gap junctions free diffusion of ions for action potential movement
65
give three types of cardiac muscle
walls of atria walls of ventricles specialised conductive and excitatory muscle fibres
66
give three features of smooth muscle
tires easily not under conscious control has circular and longitundinal bundles for peristalsis
67
how is smooth muscle used in the iris?
circular bundles: contraction --> constriction of pupil radial bundles: contraction --> dilation of pupil
68
give three features of skeletal muscle
multinucleated striated under conscious control of motor cortex
69
muscle --> ......... --> sarcomere
muscle muscle bundle fascicle muscle fibre (cell) myofibril sarcomere
70
name the three proteins that make up actin
troponin (globular) tropomyosin ('string') G-actin (where myosin binds)
71
what enzyme can a myosin head function as?
ATPase
72
sliding filament theory: outline the formation of the cross bridge
myosin head has ADP + P(i) bound to it E from hydrolysis of ATP activates myosin to 'cocked' position Ca2+ released from sarcoplasmic reticulum and bind to tropomyosin troponin undergoes allostery causing tropomyosin to move and expose mysosin binding sites on G-actin myosin binds, forming cross bridge P(i) released --> bridge strengthened
73
sliding filament theory: outline the power stroke
ADP is released from myosin head head pivots and slides actin filament towards centre of sarcomere
74
sliding filament theory: outline the cross bridge detachment
another ATP binds to the myosin head cross bridge weakens and myosin detaches
75
sliding filament theory: outline the reactivation of the myosin head
ATP is hydrolysed by myosin kinase E released activates myosin head to 'cocked' position
76
why is Ca2+ required in muscle contraction?
causes troponin to undergo an allosteric change which moves tropomyosin exposing actin binding sites for the myosin heads
77
how is a nerve impulse converted into a muscle contraction?
a.p. arrives at synaptic end bulb of axon synaptic transmission of ACh (see chap. 26) ACh binds to receptors on motor end plate, opening Na+ channels t tubules carry Na+ to centre of muscle fibre, spreading a.p. through the muscle Ca2+ released and spread to actin filaments
78
outline the differences between slow and fast-twitch muscle fibres
slow: - ATP production in aerobic respiration - lots of mitochondria for KC and OP - high Mb conc. - small diameter - high capillary density fast: - anaerobic respiration - few mitochondria - low Mb conc. - large diameter - low capillary density

Mock paper 3 (8 decks)

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