Module 3: Respiration Flashcards

1
Q

What is gas exchange driven by?

A

Pressure gradients at both PULMONARY capillaries and SYSTEMIC capillaries

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2
Q

Alveoli PO2 = ____ mmHg

A

103

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3
Q

Describe the PO2 levels of pulmonary capillaries as they return from the tissues and when they leave to go to the rest of the body

A

PO2 of blood returning from tissues = 40 mmHg

PO2 of blood leaving pulmonary capillaries is saturated with O2 so it goes up to 100 mmHg

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4
Q

Alveoli PCO2 = _____ mmHg

A

40

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5
Q

Describe the PCO2 levels of pulmonary capillaries as they return from the tissues and when they leave to go to the rest of the body

A

PCO2 of blood returning from tissues = 45 mmHg

PCO2 of blood leaving pulmonary capillaries has REDUCED it’s CO2 so that it it is 40 mmHg

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6
Q

The tissue PO2 can be as low as ___ mmHg (depending on _____)

A

20 mmHg

metabolism demand

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7
Q

Tissue capillary PO2 of blood entering tissues is:

A

90-100 mmHg

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8
Q

Blood leaving the tissue capillaries that has already delivered its O2 is approx: ____ mmHg

A

40

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9
Q

Tissue PCO2 = ____ mmHg (depending on ____)

A

46 mmHg

metabolism demand

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10
Q

Tissue capillary PCO2 is ____ mmHg

A

40 mmHg

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11
Q

Blood leaving the tissue capillaries that has increased it’s CO2 now is approx. ____ mmHg

A

45 mmHg

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12
Q

Percentage of Oxygen in atmospheric air:

Calculate it’s partial pressure

A

21%

PO2 = 760 x 21% = 159 mmHg

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13
Q

Percentage of CO2 in atmospheric air

Calculate it’s partial pressure

A

.03%

PCO2 = 760 x .03% = .22 mmHg

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14
Q

What is the percentage of O2 and CO2 in alveolar pressures?

A
O2 = 14.5% (760-47)(14.5%)
CO2 = 5.5%
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15
Q

What is an average resting Cardiac Output (CO)

A

5 L/min

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16
Q

What is the average exercise cardiac output (CO)?

A

up to 25 L/min

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17
Q

Which is more compliant with alveoli ventilation: the base or the apex of the lungs?

Why?

A

The base because the alveoli are smaller and have a reduced surface tension and therefore easier to inflate

The apex inflates during extremes of ventilation (WOB/accessory muscles, etc)

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18
Q

Pulmonary circulation and function are ____ dependent.

A

Gravity

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19
Q

What happens if alveolar gas pressure exceeds capillary pressure?

A

Perfusion slows or stops

The capillary “collapses” or “is compressed” thus blood flow stops

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20
Q

Where are the three zones of ventilation and perfusion located in the lung?

A

Zone I: At apex (small area)

Zone II: Area above left atria

Zone III: Base of the lung

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21
Q

Zone I: describe relationship between pressures and what happens to perfusion

A

Alveolar pressure > arterial capillary pressure > venous capillary pressure

Perfusion: is STOPPED by the alveolar pressure

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22
Q

Zone II: relationship between pressures and what happens to perfusion

A

Arterial capillary pressure > alveolar pressure > venous capillary pressure

Perfusion: is SLOWED DOWN by alveolar pressure

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23
Q

Zone III: relationship between pressures and what happens to perfusion:

A

Arterial capillary pressure > venous capillary pressure > alveolar pressure

Perfusion: is NOT EFFECTED by the alveolar pressure

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24
Q

V/Q ratio

A

Compares the amount of air that enters the alveoli each minute with the amount of blood that travels through pulmonary capillaries each minute (Cardiac Output)

AKA: Alveolar Ventilation / Cardiac Output

25
Q

V/Q ratio between base and apex of lung:

A

Apex: Ventilation exceeds perfusion so a very small portion of lung

Base: Perfusion exceeds ventilation

26
Q

Clinical V/Q

A

The sum of V/Q from all zones

Normal = 4.2L / 5.0L = 0.8 (ventilation slightly less than perfusion)

27
Q

How do you calculate alveolar ventilation?

A

(Tidal Volume - Dead Space) x RR

(500ml - 150 ml) x 12 = 4.2 L

28
Q

What happens to V/Q during moderate exercise?

A

V/Q remains at 0.8

Both ventilation and respiration increase proportionately

29
Q

What happens to V/Q during intense exercise?

A

V/Q increase 5/1

This means ventilation increases much more than perfusion

30
Q

Are lungs a limiting factor in exercise?

A

NO!!

31
Q

If blood flow is obstructed then what happens to V/Q?

Name a clinical example

A

V/Q INCREASES infinitely

ex: Pulmonary Embolism

32
Q

If ventilation is obstructed then what happens to V/Q?

Name a clinical example

A

V/Q DECREASES

ex: COPD

33
Q

What drives oxygen transport across alveolar capillary membranes?

A

The pressure gradient

34
Q

How long (in seconds) does it take RBC to travel through pulmonary capillaries

A

0.75 seconds

35
Q

How long (in seconds) does it take to bind O2 to hemoglobin?

A

0.25 seconds

36
Q

SaO2 =

A

saturation of oxygen in arterial blood

37
Q

100% saturation of oxygen in the blood =

A

transport a max of 20 ml of O2 per 100 ml of blood

38
Q

______ partial pressure of arterial O2 (paO2) will ______ Hb affinity for O2

A

INCREASED partial pressure of arterial O2 (paO2) will INCREASE Hb affinity for O2

39
Q

______ partial pressure of arterial O2 (paO2) will ______ Hb affinity for O2

A

DECREASED partial pressure of arterial O2 (paO2) will DECREASE Hb affinity for O2

40
Q

What does the “Oxyhemoglobin dissociation curve” demonstrate?

A

Saturation amounts at different pressures

41
Q

Describe the “flat” top portion of the oxyhemoglobin dissociation curve:

A

Represents a “buffer” zone
60-100 mmHg

Increased O2 binding to Hb is maintained at these pressures

42
Q

Describe the “steep” portion of the oxyhemoglobin dissociation curve:

A

This portion progressively favors O2 to be released into systemic tissue

O2 dissociation from Hb is increasing as these pressures decrease

43
Q

What are the 4 factors that alter the oxyhemoglobin dissociation curve?

A
  1. Body temperature
  2. 2,3 DPG levels
  3. pH (H+) levels
  4. CO2 levels
44
Q

What does 2,3 DPG do?

A

DPG alters the hemoglobin to decrease O2 affinity

45
Q

“Right Shift” of oxyhemoglobin dissociation curve:

A

Occurs when:
Inc. CO2, Inc. H+, DEC pH levels, Inc. temp, Inc. BPG

Results in a decreased affinity for Hb and O2

46
Q

“Left Shift” of oxyhemoglobin dissociation curve:

A

Occurs when:
H+ dec, CO2 dec, Temp dec, pH INC., dec. DPG

Results in increased affinity for Hb and O2

47
Q

Acidosis

A

Elevated H+ levels

48
Q

Hypercapnia

A

Elevated CO2 levels

49
Q

Alkalosis

A

Decreased H+ levels

50
Q

Hypocapnia

A

Decreased CO2 levels

51
Q

Bohr Effect

A

Presence of CO2 will decrease O2 and Hb affinity

i.e., Increased CO2 levels will alter affinity

Typically occurs in tissue

52
Q

Haldane Effect

A

Presense of O2 will decrease CO2 and Hb affinity

i.e., increased O2 levels will alter affinity

Typically occurs in lungs

53
Q

If PaO2 is 100 mmHg then the blood is _____ saturated.

Is this in a healthy or unhealthy individual?

A

98%

healthy

54
Q

If PaO2 is 60mmHg then the blood is _____ saturated.

Is this in healthy or unhealthy individual?

A

90%

Beginning of “flat” portion of curve…starting to be unhealthy

55
Q

If PaO2 is 40 mmHg then the blood is ____ saturated

Is this in healthy or unhealthy individual?

A

75%

Typical of blood leaving exercising muscle

56
Q

Is CO2 more soluble or less soluble than O2?

A

CO2 is 20 times more soluble than O2 and diffuses much quicker than O2 and thus doesn’t require a large pressure gradient

57
Q

What are the 3 “forms” of carbon dioxide transport?

A
  1. CO2 dissolves into plasma
  2. CO2 binds to hemoglobin
  3. CO2 forms bicarbonate (HCO3-)
58
Q

What are the percentages associated with each form of CO2 transport?

A
  1. CO2 dissolving into plasma: 5-10%
  2. CO2 binding to hemoglobin: 5-30%
  3. CO2 forms bicarbonate: 60-90%