Respiratory Physiology Part 3 Flashcards Preview

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What is the difference between external and internal respiration ?

External respiration (lungs)
Internal respiration (body tissues)


Basic Properties of Gases: What is Dalton’s Law of Partial Pressures?


Total pressure exerted by a mixture of gases is the sum of the pressures exerted by each gas

The partial pressure of each gas is directly proportional to its percentage in the mixture

Total Pressure = P1 + P2


What happens to gravity when you increase the altitude?

For example at 10,000ft the atmospheric pressure wound not be 760mmHg let’s suppose it is 523mmHg. If we change that here then how does that change affect the partial pressure of oxygen? Work out the math:

It decreases.

0.209 x 523 = 109 mmHg at sea level.

Ex: (0.786 x 760 = 597)
Ex: (0.209 x 760 = 159)


What is Henry's law?

The amount of gas that will dissolve in a liquid also depends on what? 2

Gas will dissolve in a liquid in proportion to its partial pressure

it’s solubility and temp of the liquid


The direction and the movement of a gas are determined by it’s?

What happens when the partial pressure of CO2 is higher in the pulmonary capillaries than in the lungs?

Clinical application example?

partial pressure

will move into the lungs

Hyperbaric chamber- increase environmental pressure graident of oxygen so oxygen will be driven into the tissues and help facilitate wound healing.


Alveoli contain more CO2 and water vapor than atmospheric air.
This is due to?

1. Gas exchange in the lungs
2. Humidification of air
3. Mixing of alveolar gas that occurs with each breath


Partial pressure gradient for O2 in the lungs is described as?

Venous blood Po2 = ___ mm Hg
Alveolar Po2 = ____ mm Hg

O2 partial pressures reach equilibrium of ___ mm Hg in ~___ seconds, about ___ the time a red blood cell is in a pulmonary capillary





Describe the CO2 partial pressure gradient in the lungs compared to that of O2?

Venous blood Pco2 = __ mm Hg
Alveolar Pco2 = __ mm Hg

CO2 is __ times more soluble in plasma than oxygen
CO2 diffuses in _____ amounts with oxygen

less steep




What is ventilation?
What is perfusion?

How must they relate for efficeint gas exchage?

Ventilation: amount of gas reaching the alveoli
Perfusion: blood flow reaching the alveoli

Ventilation and perfusion must be matched (coupled, i.e. working together) for efficient gas exchange


Influence of local PO2 on perfusion:
1. Changes in PO2 in the alveoli cause changes in what?

2. Where alveolar O2 is low, arterioles what? In an attempt to what?

3. Where alveolar O2 is high, arterioles what? In an attempt to what?

4. What is another name for this phenomenon?

1. the diameters of the arterioles

2. Where alveolar O2 is low, arterioles constrict
In an attempt to redirect blood to areas where PO2 is higher

3. Where alveolar O2 is high, arterioles dilate
Increase blood flow into the area to pick up the O2

4. shunting


Influence of local PCO2 on ventilation:
1. Changes in Pco2 in the alveoli cause changes in what?

2. Where alveolar CO2 is high, bronchioles what? Allowing what?

3. Where alveolar CO2 is low, bronchioles what?

1. the diameters of the bronchioles

2. Where alveolar CO2 is high, bronchioles dilate

3. Allowing CO2 to be eliminated
Where alveolar CO2 is low, bronchioles constrict


Describe the thickness and area of the respiratory membrane?

0.5 to 1 μm thick
Large total surface area (40 times that of one’s skin)


What would make the respiratory membrane thicker?

What would reduce the surface area and whats happening during this time?

Thickens if lungs become
1. waterlogged and
2. edematous, and
3. gas exchange becomes inadequate

Reduction in surface area with emphysema, when walls of adjacent alveoli break down


Partial pressures and diffusion gradients are _____ compared to external respiration

Po2 in tissue is always _____ than in systemic arterial blood

Po2 of venous blood is ___ mm Hg and Pco2 is __ mm Hg





O2 is transported 2 ways in the blood. What are they?
(also in what percentage is it found in each)

1.5% dissolved in plasma

98.5% loosely bound to each Fe of hemoglobin (Hb) in RBCs
4 O2 per Hb


Hemoglobin-O2 combination
is what?

Hemoglobin that has released O2 is called what?

Describe the chemical reaction these two structures participate in?

Oxyhemoglobin (HbO2)

Reduced hemoglobin (HHb)

HHb + O2 {Lungs and Tiisues} HbO2 + H+


As O2 binds, Hb affinity for O2____?

As O2 is released, Hb affinity for O2 ___?

Hemoglobin is Fully (100%) saturated if what?

Hemoglobin is partially saturated if what?



Fully (100%) saturated if all four heme groups carry O2

Partially saturated when one to three hemes carry O2


Loading and unloading of O2 is facilitated by what?

change in shape of Hb


Rate of loading and unloading of O2 is regulated by

1. (partial pressure of O2) Po2
2. Temperature
3. Blood pH
4. PCO2
5. Concentration of BPG


Concentration of BPG rises when what happens?

O2 uptake in the lungs is compromised (altitude and obstructive lung disease)


The binding and release of O2 is influenced by it’s what?

Describe the Oxygen-hemoglobin dissociation curve?

partial pressure

Hemoglobin saturation plotted against Po2 is not linear
S-shaped curve


What kind of blood has the highest rate of saturated hemoglobin?

Whats the PO2?
Hb is how saturdated?

arterial blood

Po2 = 100 mm Hg
Hb is 98% saturated


Hb saturation is lower in the venous blood due to what?

In venous blood
Po2 is?
Hb is?

oxygen uptake by the tissues.

In venous blood
Po2 = 40 mm Hg
Hb is 75% saturated


Hemoglobin is almost completely saturated at a Po2 of ___?

Further increases in Po2 produce ______ in O2 binding?

O2 loading and delivery to tissues is adequate when PO2 levels are what?

70 mmHg

Only small increases

below normal levels (get in and out of the taxi even faster)


Only ____% of bound O2 is unloaded during one systemic circulation

If O2 levels in tissues drop what will happen? 2


1. More oxygen dissociates from hemoglobin and is used by cells
2. Respiratory rate or cardiac output need not increase


Other Factors Influencing Hemoglobin Saturation? 4

Decreases in these factors shift the curve to the what?

Increases in
1. temperature,
2. H+(decreased pH),
3. Pco2, and
4. BPG



What will Increases in temperature, H+(decreased pH), Pco2, and BPG do? 3

Where will this occur?

1. Modify the structure of hemoglobin and decrease its affinity for O2
2. . Enhance O2 unloading
3. Shift the O2-hemoglobin dissociation curve to the right

Occur in systemic capillaries


What are BPG levels produced by?

How does it bind to Hb?

When does BPG increase?

red blood cells as they break down glucose through glycolysis


When oxygen levels are chronically low


How does BPG affect the affinity of O2 for Hb?

What does this allow?

Decreases affinity of O2 for Hb allowing the O2 to be released (unbound)

so that it can go to tissues where needed


As cells metabolize glucose the affinity for oxygen to hemoglobin changes.

Cellular respiration: cells metabolize glucose, use __ and release ___?

Therefore the ___ and ___ increase in concentration in capillary blood = ____?

Declining pH ______ the hemoglobin-O2 bond (Bohr effect) so that O2 is _______here (in the tissues where it is most needed)

O2 and release CO2

PCO2 and H+