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Exercise Physiology > Exam 2- Lecture 7 > Flashcards

Exam 2- Lecture 7 Flashcards

1
Q

Primary functions of the respiratory response to exercise

A
  1. increase oxygen uptake to support accelerated cellular metabolism
  2. remove carbon dioxide produced as a result of accelerated cellular metabolism and as a result of buffering metabolic acids (lactic acid)
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2
Q

What components of the respiratory response to exercise should you consider?

A
  • mechanics of ventilatory response
  • gas exchange at the alveolus
  • oxygen transport in the blood
  • oxygen extraction at the muscle capillary/tissue interface
  • regulation of the ventilatory response
  • does Ve limit max aerobic capacity?
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3
Q

Inspiration during exercise

A
  • diaphragm flattens
  • active contraction of external intercostals and scaleni to move rib case upward
  • net effect is to increase volume of thoracic cavity, “sucking” air into lungs
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4
Q

expiration during rest and light exercise

A

passive recoil and relaxation of inspiratory muscles

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5
Q

expiration during increased intensity of exercise

A

active expiration

internal intercostals and abdominal muscles contribute to expiration by reducing thoracic volume

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6
Q

airway resistance during exercise

A
  • resistance in the airways affects the rate of airflow

- with exercise, airway resistance decreases due to bronchodilation

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7
Q

what is a very important determinant of airway resistance?

A

airway diameter

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8
Q

how does bronchodilation occur during exercise?

A

sympathetic NS –> release NE and circulating E from adrenals –> these catacholemines relax bronchial smooth muscle via beta-2 receptors

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9
Q

3 phases of exercise hyperpnea

A
  • there is a step increase in Ve at the onset of exercise (phase I; 0-15 s)
  • Phase I is followed by a slower, exponential rise in Ve (phase II, about 3 mins for submaximal exercise)
  • phase III occurs after 3 mins
  • if submaximal exercise is being performed, Ve will stabilize
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10
Q

ventilatory response to a graded exercise test

A
  • ventilation will continue to rise as workload increases
  • response is linear up to a point called the ventilatory threshold, at which point further increases in workload are accompanied by a disproportional increase in Ve
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11
Q

Components of Ve response

A

Ve=Vt x f
At rest, ventilation = 500 ml x 12 = 6 L/m
With maximal exercise, Vt is about 2 L or greater; f= 35-45 breaths/min or higher

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12
Q

maximal exercise Ve

A

about 100-120 L/min

17-20x resting

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13
Q

does exercise Vt ever exceed 60% of FVC?

A

rarely

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14
Q

at moderate levels of exercise, what causes most of the rise in Ve?

A

increase in Vt

some smaller contribution from f

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15
Q

what occurs once Vt = 50-60% of FVC?

A

Ve can only increase further by f

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16
Q

what regulates the combination of Vt and f necessary for a given Ve?

A

the brainstem

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17
Q

Why does tidal volume increase at the expense of IRV and ERV?

A

during exercise, you are inspiring to a greater volume and expiring to a small lung volume so that tidal volume increases
there is a greater dependence on changes in inspiratory volume

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18
Q

Ve = ?

A

Ve= Vd + Va

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19
Q

What is alveolar ventilation?

A

the portion of the insured air (Ve) that participated in gas exchange

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20
Q

at the same Ve, what provides more effective alveolar ventilation?

A

deeper breathing and lower f

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21
Q

what does deeper breath cause?

A

a larger portion of the tidal volume to enter and mix with alveolar air

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22
Q

FEV1% =

A

% of FVC expelled in 1 second

inversely related to airway resistance

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23
Q

what can FEV1% be used to detect?

A

exercise-induced bronchospasm

10-15% fall in FEV1% suggests airway obstruction due to bronchospasm

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24
Q

Gas exchange in the alveolus

A
  • Diffusion of O2 and CO2 across alveolar membrane and capillary walls is a function of the partial pressure differential, surface area for exchange, and thickness of membranes
  • Most healthy individuals maintain adequate gas exchange during heavy exercise
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25
What occurs to PaO2, even in heavy exercise?
it is well-maintained
26
what occurs to PaCO2 as intensity increases past moderate exercise?
decreases
27
Diffusion of CO2 across alveolar membrane and capillary walls are a function of what?
pressure differential membrane thickness surface area
28
Why is there a fall in PaCO2 at higher intensities of exercise?
look up recording
29
why does mixed venous PCO2 increase with increasing intensity?
look up recording
30
What is exercise-induced arterial hypoxemia associated with?
- Increased ventilation/perfusion (V/Q) mismatch - Diffusion limitation: the high pulmonary blood flow decreases time available for gas transfer (AKA diffusion disequilibrium)
31
Mild EIAH
SaO2: 93-95%
32
Moderate EIAH
SaO2: 88-93%
33
Severe EIAH
SaO2 < 88%
34
when is supplemental O2 during exercise indicated?
in patients with pulmonary disease who have a rising SaO2 < 88%
35
why might elite endurance athletes may experience arterial desaturation during maximal exercise
- Most likely due to diffusion limitation due to an exceptionally fast transit-time of red blood cells through the pulmonary capillaries (incomplete gas exchange), secondary to extremely high cardiac output - Other factors: mechanical constraints on airflow and a less than maximal ventilatory response
36
When is VO2 measurably affected?
- When SaO2 reaches 3% below resting levels (1.5-2% decrease in VO2max for every 1% reduction in SaO2)
37
how much can EIAH decrease VO2 max?
up to 15%
38
What is the relevance of EIAH?
- It can limit VO2max in healthy, active individuals, and this effect will be magnified in hypoxic environments, like altitude
39
Who is most affected by altitude?
Those with higher VO2max
40
When do person with pulmonary disease show EIAH?
- At low work rates | - They require supplemental O2 during exercise
41
What occurs to PO2 during exercise?
it is well maintained
42
when does PaCO2 decrease?
when the lactate or ventilatory threshold is reached because ventilation increases out of proportion to the CO2 production
43
when might arterial O2 desaturation occur?
At high work rates in some well-trained persons (especially at high altitudes) and at lower work rates in persons with pulmonary disease
44
How is oxygen transported in the blood?
Hemoglobin
45
O2 content =
(Hb concentration x 1.34 ml O2/g Hb x SaO2) + 0.003 PaO2
46
a-v O2 difference =
CaO2 - CvO2
47
What is the difference of Hb concentration between men and women?
- Hb concentration is 5-10% lower in women | - This lower Hb contributes to lower aerobic capacity in women
48
What does alterations in Hb concentration affect?
``` O2 content (iron-deficiency anemia) ```
49
What does interference of binding of O2 to Hb affect?
O2 content | smoking--carbon dioxide
50
what drives unloading of O2 from Hb?
Low tissue PO2
51
what is the a-v O2 difference at rest?
4-5 ml O2/100ml at rest
52
what does exercise do to a-v O2 difference?
increases it up to 15-16 ml/100 ml
53
What does decrease in tissue PO2 from 40 at rest to 15 mmhm during exercise do?
increases the pressure gradient, favoring release of oxygen from Hb
54
What factor facilitate unloading of oxygen/shift O2 dissociation curve to the right?
- lower pH - increase body temperature - increase carbon dioxide concentration
55
what is 2,3 DPG and what does it do?
it is produced in red blood cells during glycolysis and facilitates unloading of oxygen from Hb (reduces affinity of Hb for O2)
56
what results in chronically increased levels of 2,3 DPG?
altitude or chronic cardiopulmonary disease
57
do males or females have a higher level of 2,3- DPG?
females
58
What is myoglobin?
an oxygen-binding protein found in skeletal and cardiac muscle
59
where is there more myoglobin?
in the "red" muscles
60
does training enhance the cell store of myoglobin?
it is not clear
61
When does myoglobin release the O2 that it is storing?
At very low O2 tensions Ex: at very start of exercise and during intense exercise Thought to help shutting O2 to mitochondria

Exercise Physiology (17 decks)

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