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phty251 > exercise/thermoregulation > Flashcards

exercise/thermoregulation Flashcards

1
Q

what is human core body temp?

A

37 C

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2
Q

what is an endotherm and what is a homeotherm? why are humans both?

A

an endotherm = don’t need to rely on the environment to maintain body temperature
a homeotherm = maintain body temp in a range of environments

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3
Q

what is the thermoneutral zone?

A

28-30 C, when body temperature is easily maintained/no change in heat gain or loss

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4
Q

what is the circadian rhythm of body temp?

A

circadian rhythm of body temp is an average of 37 C, there is a high in body temp at approx. 4pm and a low at approx. 4am. this rhythm is large;y atttribited to melatonin (secreted by pineal gland)

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5
Q

maintaining heat balance - 3 x mechanisms?

A
  • conduction
  • convection
  • radiation
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6
Q

how does evaporation help with heat loss?

A

sweat glands secrete sweat onto the skin, and body heat evaporates the moisture on our skin to cool us down.

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7
Q

how does humidity affect evaporation for heat loss?

A

low humidity = sweat evaporates easily as air water vapour is less than skin water vapour conc.
high humidity = sweat doesn’t evaporate as easily as water vapour conc. is greater than water vapour in skin

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8
Q

what is shivering thermogenesis?

A

shivering thermogenesis is muscle activity to generate heat (more muscle = larger rate of heat production)

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9
Q

why do infants have brown adipose tissue and what is it used for?

A

brown adipoe tissue has a high density of mitochondria, and thus metabolism generates large amount of heat. this is important for infants to generate heat as shivering reflex is not yet developed

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10
Q

which part of the brain contains the thermoregulatory centre?

A

the hypothalamus is the location of the thermoregulatory centre

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11
Q

describe the 4 methods of heat loss

A

the 4 methods of heat loss are:
conduction - when the heat energy of a substance is directly transferred down a conc. gradient
convection - when the air immediately surrounding the body warms up, warm air rises, cooler air lowers
radiation - gaining heat from the sun
evaporation - moisture in the form of sweat evaporates from the skin and cools it.

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12
Q

how does thermoregulation occur during exercise?

A
  • rapid incr. in heat production
  • incr. core body temp
  • reflex stimulates heat loss mechanism
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13
Q

what is fever?

A

fever = hyperthermia, when the ‘set point’ for thermoregulation is changed

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14
Q

how does fever from infection occur?

A

macrophages release chemical messengers which activate hypothalamic thermoreceptors, stimulate vagal afferents and result in local release of prostaglandins within hypothalamus. incr. body temp = incr. immune activity

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15
Q

what are the 4 steps of ATP synthesis?

A
  • phosphorylation of ADP by creatine phosphate
  • glycolysis
  • oxidative phosphorylation
  • fatty acid oxidation
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16
Q

what is phosphorylation of ADP by creatine phosphate in ATP synthesis (seconds)

A
  • rapid efficient ATP cycle, but short lived.
  • within muscle fibres there is a store if creatine phosphate, donates a p to ADP to make ATP + creatine.
  • once p is cleaved off ATP to become ADP again, it combines with c to make creatine phosphate once again
  • this system is limited by the amount of creatine phosphate in the system
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17
Q

what is glycolysis in ATP synthesis (1-2 mins)

A

glycolysis uses circulatory glucose and doesnt require O2

  • glucose - (glycolysis/pyruvate as intermediate) - ATP
  • still relatively inefficient + production of lactic acid
  • 2 ATP produced per 1 glucose used
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18
Q

what is oxidative phosphorylation of ADP in the mitochondria (1-2 hours)

A

oxidative phosphorylation:

  • occurs in the mitochondria and requires O2
  • is a multistep process therefore needs other rapid system until it kicks in
  • aerobic mechanism = 36 ATP: 1 glucose
  • sustainable
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19
Q

what is fatty acid oxidation (many hours)

A

fatty acid oxidation:

  • uses free fatty acids as fuel
  • slow ATP generation but very efficient
  • some FFA make up to 100 ATP: 1 FFA
20
Q

what is anaerobic threshhold?

A

anaerobic threshold s when oxidative phosphorylation is not capable of making enough ATP to maintain exercise, when exercise exceeds 70% max intensity.

21
Q

what is lactate threshold?

A

when anaerobic threshold is reached and ATP synthesis begins to bypass oxidative phosphorylation and instead occur through anaerobic glycolytic pathway thus rate of lactate production sharply incr.

22
Q

explain how we normalise after exercise with restoring stores and clearing metabolites?

A

restoring stores = regeneration of creatine phospahte, need to invest ATP in order to regenerate creatine phosphate
clearing metabolites = lactic acid/cori cycle, invest ATP to convert lactate back to glucose, clears lactic acid from muscles

23
Q

what is oxygen debt?

A

oxygen debt occurs post exercise when ATP is needed to recover creatine phosphate and process lactic acid thus still using oxidative phosphorylation to restore O2 levels

24
Q

how does exercise affect arterial and venous PCO2 and PO2?

A

affect of exercise on arterial/venous PO2/PCO2:

  • arterial PO2 remains constant
  • venous PO2 will decr. (as muscles extract more)
  • arterial PCO2 stable at ‘moderate’ exercise, falls w intense exercise (ventilation higher than CO2 production)
  • venous PCO2 will incr. as muscles produce more CO2
25
Q

how does an increased core temp act as a stimulus for ventilation?

A

takes a while for increased core temp to increase ventilation, when it does, stimulates increased ventilation

26
Q

how does an increased arterial H+ conc. act as a stimulus for ventilation?

A
  • generation of lactic acid incr. H+ in arterial system
  • peripheral chemoreceptors are activated by metabolic acidosis
  • this causes a reflex incr. in ventilation
27
Q

how do K+ and adrenaline act as a stimulus for ventilation?

A
  • exercise = muscle damage, thus K+ is released from the muscles and activates peripheral chemoreceptors to incr. ventilation (small effect)
  • exercise = release of adrenaline from the adrenal glands, thus incr. cardiac and respiratory activity (incr. HR/BR)
28
Q

what is the role of muscle mechanoreceptors in skeletal muscle feedback for ventilation?

A
  • muscle mechanoreceptors are embedded in muscle detect mechanical forces.
  • act as a FEEDFORWARD mechanism to the CNS
  • sends a signal that muscle needs more O2 for incr. oxidative phosphorylation
29
Q

what is the role of muscle chemoreceptors in skeletal muscle feedback for ventilation?

A
  • muscle chemoreceptors are sensitive to metabolites (lactic acid)
  • acts as FEEDBACK mechanism
30
Q

explain the 4 major methods of ATP production, their yields, and their locations

A

4 methods of ATP production
Glycolysis - 2 ATP, in cytosol
oxidative phosphorylation - 36 ATP, mitochondria
fatty acid oxidation - lots ATP, in mitochondrion
phosphorylation of ADP by creatine phospahte

31
Q

describe the temporal profile of aerobic metabolism during endurance exercise . explain the effect of increasing exercise intensity over 70% of maximal

A
  1. energy source in seconds = ATP = creatine phosphate. creatine phosphate store in muscle fibres (therefore limited by the amount of creatine phosphate in system)
  2. energy source in 1-2 minutes = anaerobic glycolysis, using glucose stored in muscles (side effect = lactic acid production)
  3. aerobic oxidation: oxidative phosphorylation of ADP in mitochondria (using muscle/liver glycogen, plasma glucose)
  4. aerobic oxidation: fatty acid oxidation, using plasma FFA, adipose tissue triglycerides.
    oxidative phosphorylation not enough when exercise exceeds 70% max intensity, therefore anaerobic glycolysis contributes proportionally more ATP (lactic generation) (bypasses pathway 3 once at pathway 4)
32
Q

what is anaerobic/lactate threshhold?

A

anaerobic threshhold is the level where rate of lactate production increases (measure of overall fitness, when curve becomes steep)

33
Q

explain the generation and recovery of ‘oxygen debt’ and explain the size of the debt in relation to exercise intensity

A

generation/recovery of oxygen debt = need to use ATP to recover creatine stores and clear lactic acid from muscles, therefore, still using oxidative phosphorylation to restore O2 levels. low intensity exercise = small O2 debt, high intensity exercise = big O2 debt.

34
Q

describe the profile of respiratory responses to exercise and relate this to the control mechanisms

A

temporal profile of ventilatory response to exercise:

  1. (from rest) sudden increase in ventilation at exercise onset
  2. gradual increase during exercise period
  3. sudden decrease at cessation of exercise
  4. sustained increase after exercise due to O2 debt.
35
Q

outline the characteristics and fatigue resistance of the three main skeletal muscle fibre types

A

type 1a = slow oxidative
- F production/glycolytic enzymes/contraction speed = low
- fatigue resistance/mitochondria/capillary density = high
type 2a= fast oxidative glycolytic
- F production/fatigue resistance/glycolytic enzymes = moderate
- mitochondria/capillary density/contraction speed = high
type 2x = fast glycolytic
- fatigue resistance/mitochondria/capillary density = low
- F production/contraction speed/ glycolytic enzymes = high

36
Q

describe the cardiovascular adaptations to exercise

A

cardiovascular adaptations to exercise:

  • training incr. CO and changes HR
  • decr. resting HR
  • incr. range (of rest to max)
  • incr. SV
  • remodel of ventricle walls
  • moderate hypertrophy
  • incr. chamber size
37
Q

what are the cardiovascular and cellular adaptations to anaerobic exercise?

A

anaerobic training (strength)

  • myofibrillar hypertrophy: incr. size NOT number of fibres CS incr. = incr. contractile strength, incr. protein synthesis)
  • sarcoplasmic hypertrophy (incr. volume of sarcoplasm, no change in contractile strength, increased anaerobic metabolism)
  • incr. lactate threshhold
38
Q

what are the cardiovascular and cellular adaptations to aerobic exercise?

A

aerobic training = incr. aerobic capacity
- cardiovascular adaptations
+ further adaptations that will support but may not incr, VO2 max:
- angiogenesis of alveoli and sk. muscle (incr. SA and decr. diffusion distance)
- incr. respiratory strength of diaphragm, intercostals, more effective ventilation

39
Q

what is microtrauma theory in strength training?

A

microtrauma theory
microdamage = activates satellite cells in skeletal muscle which travels to site of tear and fills in gap, therefore incr. contractile strength and decr. risk of future damage

40
Q

what is VO2 max and how does aerobic training affect this capacity?

A

VO2 max is the maximum rate of O2 the body is able to use during exercise. aerobic exercise incr. the efficiency of O2 transport in the body, by incr. SV and decr. HR.

41
Q

what are some metabolic adaptations to aerobic training ?

A

metabolic adaptations to training

  • myoglobin increase (incr. store of O2)
  • incr. glycolytic and oxidative enzymes (incr. ATP synthesis capacity)
  • mitochondrial biogenesis (more mitochondria = incr. oxidative phosphorylation)
42
Q

describe the distribution of blood flow during exercise and explain the mechanism by which this is achieved

A

….

43
Q

how is the baroreceptor reflex modified during exercise?

A

modifying the baroreceptor reflex:

central command increases and prevents a decrease in sympathetic nerve activity

44
Q

what are some factors that contribute to increased cardiac output during exercise ?

A
  • increased cardiac contractility
  • increased sympathetic nervous activity
  • increased circulating adrenaline
  • increased HR
45
Q

describe some common performance enhancement techniques and how they may enhance exercise capacity?

A

Blood doping= incr. RBC concentration (incr. arterial O2 = incr. VO2……)

phty251 (6 decks)

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