Oxygen and CO2 Transport

Question 0

O2 Content

Answer 0

Dissolved O2 + 1.34(Hb)(Hb-O2)

Expressed as a volume percent

Question 1

Henry’s Law

Answer 1

Amount of gas in a fluid depends on partial pressures

• Means that gases move thru fluids by following their pressure gradient
• Once combined w/ a molecule, like Hb, they no longer exhibit a partial pressure

Question 2

Arterial Blood Saturation

Answer 2

97.4%

Question 3

Venous blood O2 saturation

Answer 3

75%

Question 4

Oxygen diffusion constant

Answer 4

.003/PatmO2

Question 5

Affects of HbCO

Answer 5

1. Reduces # of sites available for O2
2. Increases the affinity for already bound O2
   - less release of O2 at tissues

Question 6

CO-poisoning

Answer 6

Decreased levels of tissue O2 leading to anemia

Symptoms include: Cherry-red appearance
Dizziness
Confusion

• Lethal amount=0.6mmHg
• Treatment=95%O2/5%CO2

Question 7

O2 Capacity

Answer 7

Maximal amount of O2 Hb is capable of carrying; DOES NOT include dissolved O2

Question 8

Hb Saturation

Answer 8

(HbO2/O2 capable of binding) X 100

or

(O2 content- O2 dissolved/ O2 capacity) X 100

Question 9

Pulse oximeter

Answer 9

Compares photon reflectance of 2 different wavelengths of light to determine Hb/HbO2 ratio

650nm (red)- HbO2 reflects; Hb absorbs

900nm(infrared)- HbO2 absorbs; Hb reflects

*Not affected by concentrations or skin color because a ratio is measured

Question 10

Pulse oximeter issues

Answer 10

Cannot tell you [Hb] and what Hb is saturated with (could be CO)

Question 11

Hypercapnia

Answer 11

Increased CO2 leads to respiratory acidosis

-Shortness of breath, confusion, fatigue

Question 12

Hyperventilation

Answer 12

Can lead to respiratory alkalosis

-Dizziness, light-headedness, numbness of hands/feet

Question 13

Normal P50

Answer 13

About 26 mmHg

*Increased P50 => Hb-saturation curve shifts to right

Question 14

DPG in stored blood

Answer 14

Can degrade; leads to increased O2 affinity of Hb

Question 15

Polycythemia

Answer 15

A result of chronic hypoxia; results in an increased Hcrt but also increased viscosity and work load on the heart

Question 16

Transportation mechanisms of CO2

Answer 16

1. Dissolved in blood
   - diffuses 20x more rapidly than O2
2. Bicarbonate buffer system
   - CO2 moves into RBCs and is converted to H2CO3 by carbonic anhydrase; H+ is added to Hb and HCO3- exits into the plasma and Cl- enters
   * Opposite @ the lung capillaries
3. Carbamino compounds
   • Binds to Hb; high affinity to deoxyhemoglobin found primarily in the tissues

Question 17

Mixing blood samples w/ 2 different PCO2s

Answer 17

Average the PCO2s of the samples

-Can do this due to the fact that the curve is linear and shows no saturation

Question 18

Mixing Blood Samples w/ 2 different PO2s

Answer 18

Must average the O2 content of the samples and then find the corresponding PO2; occurs due to non-linear relationship of curve

*Lungs are continually doing this since different regions have different PO2s

Question 19

Non-Respiratory Functions of the Lung

Answer 19

Defense Mechanism: Macrophages phagocytize foreign particles and secrete activator substances for other WBCs

Air Condition: Nasal concha warm and humidify inspired air

Olfactory: Shmolfactory

Filtration: Performed by mucous lined, ciliated pseudostratified columnar epithelia; smoking decreases function of mucociliatory escalator

Blood Filter: can filter out harmful objects, like emboli, and store them in the pulmonary capillaries

Blood Reservoir: contains reserves of blood for left ventricle in times of increased stress

Metabolism of circulating substances: performed by the endothelial cells

Question 20

Bronchiectasis

Answer 20

Scarring of the airways due to recurrent infection/inflammation; can be caused by a damaged muscociliatory escalator

*Could also happen to incubated pts. since they have decreased coughing capabilities; foreign substance must be removed by suction

Question 21

Thiazide diuretics

Answer 21

Contribute to H+ loss and Ca2+ reabsorption