Physiology Test 2

What is the equation for partial pressure?

Partial pressure = % of total gas x barometric pressure

What is the percent of oxygen in the air

21% (0.21)

How does oxygen move into the alveoli?

By bulk flow

How does oxygen diffuse into the arterials?

By diffusion

What is the equation for inspired PO2?

Inspired PO2=(total pressure -47) x % of gas

How does oxygen and carbon dioxide move through the circulatory system?

By bulk flow, which is movement of air due to a total pressure gradient

How does oxygen and carbon dioxide move in the pulmonary and systemic capillaries?

By random molecular motion

What does water do to the partial pressure of oxygen?

Decreases it

What determines the arterial PO2 and PCO2 in a perfect gas-exchanging lung?

The alveolus

Why does alveolar gases remain relatively constant during a breath?

The volume of the alveoli are larger compared to the arterials

What are the determinants of alveolar PO2 and CO2?

Alveolar ventilation, amount of pulmonary blood and level of metabolism

Doubling alveolar ventilation will do what to PCO2?

Decrease it by half

True or false: Doubling alveolar ventilation will double PO2.

False

What does hyperventilation cause?

Decrease in PaCO2

What does hypoventilation cause?

increased PaCO2

What is the calculation for alveolar PO2?

% of inspired oxygen x ( barometric pressure - partial pressure of water) - arterial CO2/ R

What is Frick's Law of Diffusion?

Factors affecting the volume of gas diffusing across a barrier per unit time.

What decreases lung diffusing capacity?

Emphysema and pulmonary edema

Does CO2 or PO2 has higher diffusivity?

CO2

True or False: emphysema and pulmonary fibrosis decreases the diffusivisty

False

What do emphysema and pulmonary fibrosis do to the arterial PO2?

Decreases it

What do emphysema and pulmonary fibrosis do to the arterial PCO2?

Increases it

What do emphysema and pulmonary fibrosis do to the alveolar PO2?

It does not affect alveolar ventilation

What does an increase in metabolism without an increase in ventilation do to PO2?

Decrease arterial PO2

How much oxygen is normally carried physically dissolved in blood?

0.003 Per mL of blood or 1.5%

Where is deoxyhemoglobin found?

In mixed venous blood,

What is the percent saturation of mixed venous blood?

75%

Where is arterial blood usually found?

At the end of the pulmonary capillaries

What is the percent saturation of arterial blood?

Around 97%

When do we want hemoglobin to bind to oxygen?

In the pulmonary capillaries

When do we want hemoglobin to release Oxygen?

In the systemic capillaries

What is the calculation for the oxygen-carrying capacity?

Hemoglobin concentration x 1.34

What is the calculation for percent calculation?

Oxygen bound to Hb/ oxygen - carrying capacity

What is the calculation of oxygen bound to Hb?

Percent saturation x oxygen-carrying capacity

What is the primary determinant of oxygen percent saturation?

Arterial PO2

Does oxygen bound to hemoglobin contribute to arterial PO2?

No

As PO2 increases, hemoglobin saturation _______.

increases

What happens when hemoglobin is present in the blood?

Much more oxygen can be loaded into the blood

What is the PO2 at the beginning of the pulmonary capillaries?

40

What is the PO2 at the end of the pulmonary capillaries?

100

What is the calculation for oxygen bound to hemoglobin content?

Oxygen carrying capacity x percent saturation

What is the calculation for physically dissolved oxygen

0.003 x arterial PO2

What is the calculation of total blood oxygen content

Oxygen bound to heme + physically dissolved oxygen

What is the PO2 and % saturation at the beginning of the systemic capillaries

PO2 =100

% sat = about 97%

What is the PO2 and % saturation at the end of the capillaries

PO2=40

% sat= 75%

What diffuses first during diffusion in the systemic capillaries?

Oxygen

Does an increase of PO2 increase oxygen content in a perfect lung that has a PO2 of 100?

No

What is the significance of the flat portion of the oxyhemoglobin dissociation curve?

It constitutes a safety factor because the PO2 can decrease to 60 and the percent saturation is still 90%

When does heme start to release oxygen?

At a PO2 less than 60

What reduces the affinity of hemoglobin for oxygen?

CO2, hydrogen ions, 2,3-BPG, and temperature

A decrease in pH will cause the dissociation curve to shift to.....

The right

An increase in pH will cause the dissociation curve to shift to.....

The left

A decrease in H ions will cause the dissociation curve to shift to.....

The left

An increase in H ions will cause the dissociation curve to shift to.....

The right

A decrease in CO2 will cause the dissociation curve to shift to.....

The Left

An increase in CO2 will cause the dissociation curve to shift to.....

The right

A decrease in temperature will cause the dissociation curve to shift to.....

The left

An increase in temperature will cause the dissociation curve to shift to.....

The right

What does a shift to the right mean for the dissociation curve?

A decrease in percent saturation

What does a shift to the left mean for the dissociation curve

An increase in percent saturation

Mixed venous blood will cause the dissociation curve to shift to.....

Right aiding to the release of oxygen to the tissues

How does metabolism affect hydrogen ions?

Increases them which will decrease pH and decrease percent saturation

How does metabolism affect temperature?

It increases temperature which decreases percent saturation

How does metabolism affect PCO2?

It increases CO2 which decreases percent saturation

Does arterial or mixed venous blood release oxygen more quickly?

Mixed venous blood

What does P50 mean?

Decrease in oxygen affinity which means more oxygen is being released in the blood.

True or False: Affinity of oxygen decreases as the dissociation curve shifts to the right?

True

An increase in 2,3- BPG will cause the dissociation curve to shift to.....

Right

A decrease in 2,3- BPG will cause the dissociation curve to shift to.....

Left

Why is 2,3-BPG produced ?

Due to low oxygen at high altitude

Does the production of 2,3-BPG happen quickly or slowly?

Slowly

A decrease in barometric pressure will do what to O2?

Decrease it

What does carbon monoxide do to the oxygen content?

Decreases it

What does carbon monoxide do to the oxygen percent saturation?

Decreases it

What does carbon monoxide do to the affinity for oxygen?

Increases it

What does anemia do to the oxygen content?

Decreases it

Why isn't the percent saturation decreased in anemia?

The arterial PO2 is normal

What does anemia do to the carrying capacity of oxygen

It decreases it

What does 50% carboxyhemoglobin mean?

50% of hemoglobin are bound to hemoglobin

True or False: the O2 bound to hemoglobin vs PO2 curve is shifted to the right for carbon monoxide and anemia due to a decrease in percent saturation

False, it's shifted to the right due to a decrease in oxygen content. The percent saturation in anemia is normal

Why is there a higher O2 content for 50% CO Hb at a lower PO2 compared to normal and anemia blood?

There is a higher affinity in blood with carbon monoxide causing the oxygen to hold on to hemoglobin more tightly

How is blood transported in blood and at what percents?

5-10%- physically dissolved

5-10% - carbamino compound

80-90% - bicarbonate

Where is bicarbonate formed?

In the red blood cells in the systemic capillaries

Where does the anhydrase reaction shift to the left?

In the pulmonary capillaries due to CO2 being formed and diffuse into the alveoli to be exhaled

Where does the anhydrase reaction shift to the right ?

In the systemic capillaries due to CO2 forming bicarbonate in the red blood cells

What happens when CO2 binds with H2O?

Increase in hydrogen ions helping oxygen to be released from hemoglobin and diffuse into the tissues

What happens to hydrogen ions when CO2 is diffusing into the alveoli and O2 is diffused into the arterials?

The decrease as they bind to bicarbonate and oxygen will bind to hemoglobin

True or False: Carbon monoxide decreases oxygen carrying capacity

True

Carbon is transported in the blood mostly as ...

Bicarbonate

What makes up an alveolar-capillary unit?

An alveolus and all of its blood supply

Define shunt

perfusion without ventilation

How does shunt affect alveoli and arterial PO2 and PCO2?

It decreases the PO2

It increases the PCO2

What is the determinant of alveolar gases during shunt?

The mixed venous blood

What is the determinant of alveolar gases during alveolar dead space ?

The inspired air

What is alveolar dead space?

Alveoli that are ventilated but not perfused

How does high V/Q ratio affect alveolar PO2 and PCO2?

It increases the PO2 and decreases the PCO2

Does gas exchange suddenly stop during shunt?

No, gas exchange will continue until equilibrium is met

Does gas exchange suddenly stop during alveolar dead space?

Yes, there isn't any blood flow for gasses to defuse

True or False: Low V/Q means there is low ventilation or issues with the airways

True

True or False: High V/Q means there is low blood flow

True