Gas Transport 4

Question 1

Oxygen is transported in what 2 forms in the body?

Answer 1

Question 2

How to calculate total oxygen content in the boddy

Answer 2

Question 3

PO2 (partial pressure) in the bloodstream determines

Answer 3

How much oxygen will dissolve in plasma and physically combine with hemoglobin

Question 4

Dissolved oxygen is determined by

Answer 4

O2 solubility (coefficient) in plasma

Question 5

O2 solubility is proportional to

Answer 5

partial pressure of O2 (called Henry’s LAw)

Question 6

Answer 6

Question 7

Answer 7

Question 8

Hemoglobin

Answer 8

Question 9

What is globin and what can bind to it

Answer 9

Question 10

What state does O2 bind to hemoglobin

Answer 10

Question 11

Is oxygenation of hemoglobin a reversible process?

Answer 11

Yes, because oxygen can also be given to tissue

Question 12

How many oxygens can bind to a hemoglobin?

Answer 12

4

Question 13

What kind of an event is the process of oxygenation of hemoglobin?

Answer 13

Cascade event, as more oxygen bind it becomes easier and easier for the other oxygen molecules to bind until 4 have been bound to 1 hemoglobin

Question 14

What is full saturation of hemoglobin

Answer 14

When all 4 sites are bound

Question 15

What is our oxygenation capacity

Answer 15

Question 16

How to calculate oxygen saturation

Answer 16

Question 17

Are partial pressure of oxygen and oxygen saturation different?

Answer 17

Yes, the amount of O2 combined with hemoglobin varies with oxygen partial pressure. Oxygen that is bound with hemoglobin does not exert partial pressure ONLY dissolved oxygen in the plasma. (partial pressure is about gas molecules vs saturation is how much oxygen is bound to hemoglobin and available in the blood)

Question 18

Describe the oxyhemoglobin dissociation curve

Answer 18

Sigmoid shape
-In the alveoli (far right) we need a significant drop in PO2 before oxygen loading will be affected (need high affinity/attraction in lungs so oxygen binds to hemoglobin in lungs)
-As we drop down in partial pressure (tissues) we want lower affinity/attraction of oxygen to hemoglobin, so oxygen will offload and be delivered to the tissues (not much change in partial pressure to drop to deliver more and more oxygen)

Question 19

Describe the difference between an adult and fetal oxyhemoglobin dissociation curve

Answer 19

In the fetal curve, the slope is steep and plateau happens sooner, therefore a much lower partial pressure is needed for hemoglobin to be fully saturated with oxygen because its receiving oxygen from a placenta and not the lungs

Question 20

Name the effects of RBC count have on the oxyhemoglobin dissociation curve

Answer 20

Only changed the content of oxygen and number of RBC available to carry it. Doesn’t impact shape of curve, but does effect carrying capacity

Question 21

What are the effects of carbon monoxide on the oxyhemoglobin dissociation curve

Answer 21

Question 22

Name 8 symptoms of carbon monoxide poisoning (as it worsens)

Answer 22

Really low levels can cause us to faint (doesnt take much)

Question 23

How to treat carbon monoxide poisoning

Answer 23

Hyperbaric chamber to deliver 100% oxygen at pressures above atmospheric pressure (promotes dissociation of carbon monoxide from hemoglobin to allow oxygen to bind)

Question 24

What is the P50 value

Answer 24

Question 25

What are factors that can shift the oxyhemoglobin dissociation curve left or right

Answer 25

Left shift: LESS carbon dioxide and increased pH (basic) = loading of oxygen becomes easier in the lungs (but offloading becomes more difficult = want to stay bound) -> can look at p50 (normative value = 28, in this graph = 20) so we need partial pressure to drop more to have greater offloading of oxygen Right shift: More Co2, acidic, increased temperature decreases oxygens affinity to cause mor oxygen offloading in the tissue. It takes more pressure to load the oxygen now (but less pressure to offload) -> p50 is closer to 30

Question 26

How much oxygen do we have in our blood at arterial blood and resting venous blood

Answer 26

Question 27

What 3 forms is carbon dioxide transported into in the body?

Answer 27

**CO2 has much higher solubility so there should be more CO2 in plasma than oxygen

Question 28

Describe the Haldane effect

Answer 28

Higher CO2 in blood when O2 is lower

Question 29

Describe the carbon dioxide dissociation curve

Answer 29

**Body can carry infinite amount of CO2 compared to oxygen is a finite value

Question 30

Do we need oxygen and carbon dioxide to work together

Answer 30

Yes

Question 31

Describe the difference in normal vs abnormal gas exchange

Answer 31

**PA vs Pa and Ca

Question 32

Describe the ideal lung (single compartment model of pulmonary gas exchange)

Answer 32

All inspired air and pulmonary vessels participates in gas exchange

Question 33

Describe the real lung (three compartment model of pulmonary gas exchange)

Answer 33

1st compartment (wasted ventilation): Some inspired air participates in gas exchange while others go into dead space (eg. blocked or collapsed alveoli) or in conducting zones (eg. trachea or bronchi) 2nd compartment (gas exchange): Alveolar gas is matched with the capillary blood not the venous blood (where gas exchange is actually occurring 3rd compartment (wasted perfusion): Not all our blood participates in gas exchange resulting in wasted perfusion

Question 34

What are 4 mechanisms of hypoxemia

Answer 34

A-a: alveolar arterial gradient

Question 35

Describe normal ventilation

Answer 35

We breathe because we want to blow off CO2 from body not because we need more oxygen Hyperventilation: Too little CO2 Hypoventilation: Too much CO2

Question 36

Describe alveolar hypoventilation

Answer 36

Question 37

Mechanisms of hypoventilation -> therefore hypoxemia

Answer 37

1) Alcohol poisoning/drug overdoses 2) Spinal cord injury 3) Chest wall/respiratory muscle weakness 4) Stiff lungs 5) Loss of neuromuscular junction

Question 38

What is FiO2

Answer 38

Fracture of inspired oxygen

Question 39

Describe ranges of P(A-a) O2 for FiO2 changes

Answer 39

As we increase FiO2 we increase the amount of oxygen tremendously in the alveolar-arterial gradient

Question 40

Do people with nasal prongs have an increased or decrease FiO2

Answer 40

Increased because of oxygen delivery

Question 41

What causes diffusion impairment of gases

Answer 41

1) Thickened blood gas barrier -> rate of diffusion is slow (may only be evident during exercise not at rest because of increased blood flow rate decreasing time for gas exchange)

Question 42

Describe V/Q (ventilation/perfusion) mismatching and shunts -> atelectasis (alveolar collapse) vs normal vs dead space

Answer 42

High V/Q = q is smaller Low V/Q = v is smaller -> severe hypoxemia (no air entry due to poor ventilation)

Question 43

What value is considered a V/Q mismatch

Answer 43

Any number that is not 0.8

Question 44

Atelectasis

Answer 44

Causes alveolar collapse which could lead to lung colapsing

Question 45

Do you think giving supplemental oxygen would help someone who has a shunt

Answer 45

No, because they have no ventilation

Question 46

How might PT's help someone who is hypoventilating

Answer 46

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