Oxygen and CO2 Transport Flashcards
O2 Content
Dissolved O2 + 1.34(Hb)(Hb-O2)
Expressed as a volume percent
Henry’s Law
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
Arterial Blood Saturation
97.4%
Venous blood O2 saturation
75%
Oxygen diffusion constant
.003/PatmO2
Affects of HbCO
- Reduces # of sites available for O2
- Increases the affinity for already bound O2
- less release of O2 at tissues
CO-poisoning
Decreased levels of tissue O2 leading to anemia
Symptoms include: Cherry-red appearance
Dizziness
Confusion
- Lethal amount=0.6mmHg
- Treatment=95%O2/5%CO2
O2 Capacity
Maximal amount of O2 Hb is capable of carrying; DOES NOT include dissolved O2
Hb Saturation
(HbO2/O2 capable of binding) X 100
or
(O2 content- O2 dissolved/ O2 capacity) X 100
Pulse oximeter
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
Pulse oximeter issues
Cannot tell you [Hb] and what Hb is saturated with (could be CO)
Hypercapnia
Increased CO2 leads to respiratory acidosis
-Shortness of breath, confusion, fatigue
Hyperventilation
Can lead to respiratory alkalosis
-Dizziness, light-headedness, numbness of hands/feet
Normal P50
About 26 mmHg
*Increased P50 => Hb-saturation curve shifts to right
DPG in stored blood
Can degrade; leads to increased O2 affinity of Hb
Polycythemia
A result of chronic hypoxia; results in an increased Hcrt but also increased viscosity and work load on the heart
Transportation mechanisms of CO2
- Dissolved in blood
- diffuses 20x more rapidly than O2 - 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 - Carbamino compounds
- Binds to Hb; high affinity to deoxyhemoglobin found primarily in the tissues
Mixing blood samples w/ 2 different PCO2s
Average the PCO2s of the samples
-Can do this due to the fact that the curve is linear and shows no saturation
Mixing Blood Samples w/ 2 different PO2s
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
Non-Respiratory Functions of the Lung
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
Bronchiectasis
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
Thiazide diuretics
Contribute to H+ loss and Ca2+ reabsorption