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Exercise Physiology (KPE 264) > Mod 4: Respiratory Function and Regulation During Exercise > Flashcards

Mod 4: Respiratory Function and Regulation During Exercise Flashcards

1
Q

what’s the difference between internal and external respiration?

A

External respiration, also known as breathing, involves both bringing air into the lungs (inhalation) and releasing air to the atmosphere (exhalation). During internal respiration, oxygen and carbon dioxide are exchanged between the cells and blood vessels.

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2
Q

describe the different lung volume measurements and how they are influenced by exercise

A

Spirometry

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3
Q

explain how respiratory rate(AKA ventilation rate) changes during exercise(going from rest to exercise)

A

increases

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4
Q

air movement into and out of lungs

A

pulmonary ventilation (external resp)

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5
Q

gas exchange between lungs and the blood

A

pulmonary diffusion(external resp)

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6
Q

movement of O2 and CO2 via the blood

A

Gas Transport(internal resp)

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7
Q

gas exchange between capillary blood and the tissues

A

Capillary diffusion (internal resp)

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8
Q

air moved with each breath
-amount of air entering and leaving the lungs with each normal breath

A

Tidal volume (VT)
500ml

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9
Q

fresh air which actually reaches alveoli
VT-“dead space volume” (VD
-not all tidal volume reaches alveoli

A

Alveolar Volume (VA)

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10
Q

the greatest amount of air that can be expired after a maximal inspiration

A

vital capacity (VC)

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11
Q

the sum of the vital capacity and the residual volume

A

total lung capacity (TLC)

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12
Q

the volume of air remaining in the lungs after normal expiration

A

functional residual capacity

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13
Q

the amount of air remaining in the lungs after maximal expiration

A

residual volume(RV)

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14
Q

normal individual expiration (total lung capacity)

A

6-8 L

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15
Q

ventilation rate

A

(per unit of time) depends on tidal volume and respiratory rate(breathing frequency)

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16
Q

what are ventilation rates at rest

A

minute ventilation (VI or VE) -VT x RR
=500 ml x 12 breaths/min
=6000ml/min (total air flow each min)

BUT NOT ALL OF THAT AIR IS USED
need to subtract dead space volume(can be influenced by smoking)

Alveolar Ventilation VA
= VA x f
=(VT-VD) x RR
(500-150(dead space)) x 12 breaths/min
= 4200 ml/min –> fresh air flow each min
if u have lots of dead space and want to keep alveolar ventilation the same u need to: increase tidal volume or increase breathing frequency

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17
Q

ventilation rate at maximal exercise for avg untrained male

minute and alveolar ventilation

A

minute ventilation
VI = VT x RR
=3000ml x 40 breaths/min
=120L/min (20x HIGHER THAN REST)

alveolar ventilation
VA=VA x RR
=(VT-VD) x f(RR)
=(3000-175ml) x 40b/min
=113L/min is alveolar ventilation–>27 X higher than rest–> acc getting to alveoli after accounting for dead space

-dead space increases during max exercise but is offset by big tidal volume so not a big issue

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18
Q

what are the factors that determine gas exchange

A
  1. Partial pressure gradient across the barrier(alveoli has capillaries surrounding it, in between there’s a barrier)
    high–> low pressure, pressure gradient across barrier
  2. diffusion capacity (solubility of a gas)
    low solubility=high partial pressure across barrier to get across
    high solubility=dont need big pressure gradient to get across
  3. characteristics of the barrier
    -thin, 1 cell thick
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19
Q

how is partial pressure of a gas calculated? why is it important?

A
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20
Q

what are the changed that happen in PO2 and PCO2 in the body-what are the normative(avg) values?

A
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21
Q

gas exchange pathway between alveoli and capillaries

A

inspired air path: bronchial tree–> alveoli
blood path: right ventricle–> pulmonary arteries–> pulmonary capillaries

-alveoli surrounded by capillaries

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22
Q

what are the 2 main functions of gas exchange

A
  1. replenish blood oxygen supply
  2. removes co2 from blood
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23
Q

portion of total pressure due to presence of a single gas

Pa (2 atm) + Pb (1atm) = Ptotal(3 atm)

A

partial pressure

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24
Q

what is the P O2 in dry atmospheric air at sea level?

given: fraction of O2 :0.2093
pressure of atmospheric air: 760 mmHg

A

=fraction x total pressure
=0.2093 x 760 mm Hg
=159 mmHg

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25
Q

what happens to air pressure as altitude increases

A

lower pressure
-closer to earth , PP of gases is higher

26
Q

what’s the effect of water vapor(humidity) on gas pressure?

where does it happen in the body?

A

water molecules disperse gas molecules

=increase total volume of air (water + gas)
=decrease gas pressure for given volume of air

INVERSE RELATIONSHIP: water enters air, gas molecules spread out, volume of air increases, pressure decreases

-happens in trachea

27
Q

what is the Pressure of Oxygen (PO2) in dry atmospheric air vs in tracheal air? WHY

A

Dry atmospheric air: 159 atm
tracheal air: 149 atm

pressure decreased in trachea bc water molecules got into gas, increasing volume, decreasing pressure

28
Q

what happens to PO2 as oxygen travels throughout the body?

from atmosphere–> trachea–> alveoli–> tissue cell—> venous blood

A
  1. atomsphere : starting PO2
  2. Trachea: small dec Pressure due to water vapour and inc volume
  3. Alveoli: LARGE DECEASE in pre
    ssure due to mixing with venous blood (deox blood returning to lungs)
  4. Arterial blood: small decrease in pressure, similar to alveoli–> DETERMINES O2 bound to hemoglobin
    pp of o2 in arterial blood determines ho much blood is bound to hemoglobin, which determines amount/content of oxygen actually in the blood stream to get to working muscles
  5. Tissue Cell: LARGEST DEC in pressure, relative to O2 used in muscle, during exercise use more O2 than at rest, so LARGER drop during exercise than at rest
  6. Venous Blood: Depends on muscle tissue O2 use (O2 leftover), larger drop in PP(as low as 5) during exercise than at rest

** In this system rest, start with PO2=105, PCO2=40, end with PO2=40, PCO2=46**
** Heavy exercise: end with PO2=25, PCO2=60**

CO2 is more soluble, so it can diffuse finw w gradient 40 and 46

29
Q

what determines the amount of O2 bound to hemoglobin, and ultimately the amount of O2 in the bloodstream?

A

the partial pressure of O2 in arterial blood

-arterial blood O2 pressure drops, O2 delivery to tissues is compromised bc less O2 is bound to hemoglobin

30
Q

at higher altitudes, pressure is low, so the overall diffusion gradient at skm is decreased from 60 mmHg to 15 mmHg which compromised athletic ability. What would be the body’s first way to buffer the reduced PaO2(the partial pressure of oxygen in the arterial blood) be?

A

struggling for O2, so increase pulmonary ventilation
-immediate increase in pulmonary ventilation, breathing deeper, tidal volume INC, resp rate INC
-try to buffer arterial drop in pp of O2

31
Q

Calculate blood oxygen content if given PO2

A
32
Q

What’s the importance of loading and unloading phases of the oxyhemoglobin dissociation curve and how the curve “shifts” during exercise?

A

100-80 % oxyhemoglobin saturation | oxygen content 20-15 ml O2/100 ml blood: O2 delivered to tissues

  1. Loading Portion of Curve
    -saturation stays high even with large changes in PO2
    100->40 % oxyhemoglobin saturation | oxygen content 20->7 ml O2/100 ml blood
  2. UnLoading Portion of Curve
    -saturation changes quickly with even small changes in PO2, allowing oxygen unloading to tissues

40->0 % oxyhemoglobin saturation | oxygen content 7->0 ml O2/100 ml blood

33
Q

describe the a-VO2 difference at rest and during exercise.

-whats the difference

A

Muscle at rest
artery: 20 mlO2/100 ml blood
capillary: 4-5 ml O2/100 ml blood TAKEN UP so subtract
Vein: 15-16 ml O2/100 ml blood

20-15-16=4-5ml O2/100 ml blood taken up at capillaries

Muscle during intense aerobic exercise
artery: 20 mlO2/100 ml blood
capillary: 15 ml O2/100 ml blood TAKEN UP so subtract
Vein: 5ml ml O2/100 ml blood

20-5=15ml O2/100 ml blood taken up at capillaries

Difference:
more O2 is uptaken by capillaries during intenxe exercise which leaves a much more deox blood afterward

34
Q

describe the transport of O2 in the blood and in the muscle

A

Myoglobin: takes O2 into muscle
- ONLY found in muscle, not in bloodstream
-binds O2 tighter than O2(left shift in curve, increases affinity)
-shuttles O2 to mitos

oxHgb comes by in the capillary and offloads the O2(PaO2=100), turns into Hgb leaves. the O2 binds to Mb in muscle (PO2=40)turning into oxmgb, o is delivered to mitos (PO2 is less than 5). big conc gradient between capillary and mito which allows for offloading

-during exercise PaO2 stays same at 100 but PvO2 and Po2 get as low as 15, and Po2 of mito can be as low as 1

35
Q

Pa O2

A

arterial oxygen pressure

36
Q

PA O2

A

Alveolar oxygen pressure

37
Q

Sa O2

A

arterial O2 saturation

38
Q

Ca O2

A

arterial O2 content

39
Q

PAO2 –> Oa O2 –> SaO2 –> CaO2

A

pressure determines saturation which determines content

40
Q

what determines how much oxygen binds to hemoglobin

A

high pressure= O2 binds well and tightly to hemoglobin molecules so it can be effectively delivered

41
Q

oxyhemoglobin

A

oxygenated heomglobin

42
Q

what determines blood oxygen content?
-what are the normative

A

[Hgb] = g/10 ml of g%
Normal =15 g% (range: 13-18 g%), women are lower. lower hemoglobin =hard to deliver O2

1g Hgb binds 1.34 ml O2 when 100% saturated
Blood O2 content=[Hgb] x 1.34 x % sat
eg. arterial blood:
CaO2=15g/100ml x 1.34 ml O2/g x 0.98 (can get thru finger tool to know O2 %)
= 19.7 ml O2/100 ml blood =197 ml/L
+ SMALL amount of O2 dissolved in plasma (3ml/L)

43
Q

what determines blood oxygen content

A
44
Q

how much O2 binds to 1 hgb when its fully saturated?

A

1.34 ml

45
Q

what type of blood? arterial or venous?

higher PO2=more O2 bound to Hgb

po2=100 mm Hg
Hemoglobin =98.5% saturated

A

Arterial blood

46
Q

what type of blood? arterial or venous?

lower PO2=less O2 bound to Hgb
Po2 =40 mm Hg
hgb=75% saturates

A

venous blood

GOOD FOR UNLOADING?

47
Q

“shifting” of oxyhgb dissociation curve:
- leftward shift towards lower PO2 means increased affinity for O2 (more tightly bound
-rightward shifttowards higher PO2 means DEcreased affinity for O2(less tightly bound)

WHICH WOULD WE WANT DURING EXERCISE?

A

righward shift(decreased affinity)
-protected by buffer(straight line at top of graph)
-we want O2 to be easily stripped off (Offloaded) at muscle cells so it can be used

48
Q

how to temp and Ph effect the shift of the oxyhgb dissociation cure to the right? (which is what we want during exercise)

A

Temp
-warmer temp decreases affinity(inc pressure) (43 degrees)
-20 deg increases affinity, 37 deg is body temp

pH
lower pH decreases affinity (more acidic)(inc pressure)(7.2)
-7.6 inc affinity, 7 .4 is body pH

decreased affinity allows for more O2 to be offloaded at the tissues bc its not as tightly bound to hemoglobin

-right shift promotes oxygen offloading, BUT it doesnt influence the top so we can still get oxygen binding tighly in the arterials, and it comes off easier as the curve dips

49
Q

calculate CaO2 (content) in arterial blood given:

PaO2=15g/100 ml
Each gram of hemoglobin is capable of carrying 1.34 mL of oxygen
oxygen sat # = 98

A

CaO2= PaO2 x 1.34 x o sat
=15g/100 ml x 1.34 ml/g x 0.98
=20 ml O2/100 ml
=200 ml/L

50
Q

calculate CvO2 (content) in venous blood(@ rest) given:

PvO2= see 40 mmHg so (O2 sat=75%)
PaO2=15g/100 ml
Each gram of hemoglobin is capable of carrying 1.34 mL of oxygen
oxygen sat # = 98

A

CvO2= PaO2 x 1.34 x o sat
= 15 x 1.34 x 75
=15 ml O2/100 ml blood
= 150 ml/L

RESTING a-v O2 diff= 50 ml O2/L of blood

51
Q

calculate CvO2 (content) in venous blood(@ EXERCISE) given:

PvO2= see 15 mmHg so (O2 sat=25%)
PaO2=15g/100 ml
Each gram of hemoglobin is capable of carrying 1.34 mL of oxygen
oxygen sat # = 98

A

CVO2= PaO2 x 1.34 x osat
=15 g/100 ml x 1.34 x 0.25
= 50 ml O2/100 ml =50 ml/L

** EXERCISE a-v O2 diff= 150 ml O2/L blood**

52
Q

summary

A

pressure –> saturation –> content

CaO2 doesnt change, CVO2 dec during exercise
- S shape ox oxhgb curve so buffer
-mgb transfers O2 in muscle

53
Q

describe how CO2 is transported from the muscle to the lungs

A
54
Q

what signals control ventilation during exercise

A
55
Q

what is the ventilatory threshold?

A
56
Q

what are the major and minor roles of ways that bicarbonate ions (HCO3) in blood co2 transport

A

Minor
-freely dissolved in plasma
-carbaminohemoglobin

Major
CO2 + H2O <–> H2CO3(carbonic acid) <–> H + HCO3 *bicarbonate ion)
-key enzyme in rbcs: CARBONIC ANHYDRASE
- H is buffered by Hgb (blood ph drops a tiny bit but its ok)

57
Q

what do RBCs do for co2 transport? what role does it play
describe how CO2 is transported from the muscle to the lungs

A

Co2 from tissues (now in plasma) enters RBC and combines w water to make carbonic acid : CO2 + H2O <–> H2CO3 through enzyme carbonic anhydrase which immediately dissociates into a H ion and HCO3 (bicarbonate), H is buffered by Hgb so i doesnt cause a major change in blood pH.

HCO3 leaves RBC and circulates within plasma ultimately going towards lungs to exhale co2

in the tissues rxn goes forward: inc co2 formed = inc HCO3
in lungs rnx is in reverse: dec in HCO3 as CO2 is released

58
Q

how does the respiratory center in the brain control the ventilation rate?
-inspiratory and expiratory

A
  • in brainstem(medulla oblangata, pons)
    -signals go to these centers to tell us to breathe heavier and more etc
    -establish rate and depth of breathing via signals to respiratory muscles (involuntary)
    -cortex overrides signals if necessary (voluntary)
59
Q

what are the inputs that go to the respiratory centers?

A

1. central command from the brain
2. signals from active muscle (cause an input to inc inspiration)
3. central chemoreceptors
- stimulated by inc CO2 (H) in CSF
-inc rate and depth of breathing and removes excess CO2 from body
4. Peripheral Chemoreceptors(aortic and carotid bodies
- sensitive to arterial blood PO2, PCO2, H ion
5. Mechanoreceptors/stretch receptors(lungs)
-in pleurae, bronchioles, alveoli
-“sense” movement
6. Voluntary control(motor cortex)
-can adjust your breathing rate by choice

1 and 2 are neural factors
3 and 4 are chemical factors (respond to changes in bloodstream)

60
Q

neurohumoral control of ventilation during exercise

A

humoral=chemical
-matches o2 delivery w demand
-levels off

61
Q

how is ventilation during exercise linked to energy metabolism

A

VE matches VO2 during most low-moderate exercise intensities
-in vo2 max test, ventilation goes up in proportion to VO2 to a certain point (VENTILATORY THRESHOLD)
- above 60% VO2 max, VE increases DISproportionately (ventilatory threshold (VT))
-due to a disproportionate increase in PCO2 at higher exercise intensities
-above VT the increase in VE to remove CO2 is disproportionate to the bodies actual need for O2

-ventilation inc to maintain PaCO2 and PaO2
-primary stimulus at onset of exercise in inc in neural drive
-chemical changes fine tunes response

Exercise Physiology (KPE 264) (7 decks)

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