Gas Transport and Exchange

What are the 3 mechanisms for Carbon transportation

1. CO2 dissolved in the plasma and RBC water (about 7-10%) 2. Carbaminohemoglobin (23-30%) 3. bicarbonate (60-70%)

Explain autoregulation as determined by the effects on carbon dioxide airway resistance: Small air flow with large blood flow

1. Increased local PCO2 2. Dilates airway of smooth muscle 3. decreases airway resistance 4. increase ventilation 5. Large air flow and large blood flow

What are the effects of PO2 on Hb saturation?

1. When PO2 is 10-60mmHg Oxygen will bind rapidly to hemoglobin. 2. As PO2 increases to 60mmHg -> 90% of the hemoglobin becomes saturated. 3. At normal PO2 (100mmHg) Hemoglobin is 97% saturated --> IDEAL

Explain the mechanism of poisoning with carbon monoxide and the treatment.

1. carbon monoxide binds to the same site on Hb as oxygen with 250 times the affinity 2. at PalvCO = 0.4 mm Hg, Hb is half-saturated with carbon monoxide 3. at PalvCO = 0.6 mm Hg, carbon monoxide concentrations are lethal 4. treated with 100% oxygen

Explain autoregulation as determined by the effects on carbon dioxide airway resistance: Large airflow with small blood flow.

1. decreased local CO2 pressure 2. Constricts airway smooth muscle 3. increases airway resistance 4. decreases ventilation 5. small air flow and small blood flow

Explain Autoregulation as determined by the effects of oxygen on pulmonary vascular resistance: Small air flow with large blood flow

1. decreased local PO2 2. Vasoconstriction of pulmonary blood vessels 3. increases vascular resistance 4. decreases perfusion 5. Small air flow and small blood flow

Explain Autoregulation as determined by the effects of oxygen on pulmonary vascular resistance: Large air flow with small blood flow:

1. increases local Po2 2. Vasodilation of pulmonary blood vessels 3. decreases vascular resistance 4. increases perfusion 5. Large air flow and large blood flow

Effect of PCO2 on oxygen and hemoglobin affinity

1. increasing PCO2 shifts the curve to the right 2. actively metabolizing tissues produce more CO2 resulting in increased oxygen-Hb dissociation 3. exercise ; increased tissue PCO2 ; shifts curve to the right

What are the components of the respiratory membrane?

1. surfactant fluid layer lining the inner alveolar surface 2. alveolar epithelium 3. epithelial basement membrane 4. interstitial space between alveolar and capillary membranes 5. capillary basement membrane 6. capillary endothelium

due to the pressure gradients, net oxygen diffusion occurs into _____________ and carbon dioxide diffusion occurs into ____________.

1. tissues 2.blood

about ______mL oxygen is transported to and absorbed by the tissues per 100 mL of blood

5ML

at bottom of lung the V/Q ratio is about __________of normal

60%

Explain Physiological dead space

Anatomical dead space PLUS wasted space in the alveoli which are ventilated but not perfused V/Q = infinity note: The top of the lung ventilation exceeds perfusion, during exercise there is a noted increase of blood flow to the top of the lungs --> decrease dead space

Explain autoregulation in of pulmonary blood flow.

If Oxygen partial pressure is low in some alveoli (< 70mmHg), the adjacent blood vessels constrict over 3-10 to increase vascular resistance. This is done to redistribute blood flow to alveolar regions of higher oxygen content so that perfusion matches ventilation

Compare the partial pressure of oxygen and CO2 in inspired air.

In inspired are Oxygen has a high Partial pressure of 152mmHg. However, CO2 is only 0.3 mmHg

How does acidity effect hemoglobin saturation?

Increased acidity (decreased pH) shifts the curve to the right. Decreases affinity for oxygen due to the pronation of hemoglobin causing a structural change. As blood flow through an acidic environment it will dump off oxygen Decrease in acidity ( increase pH) shifts curve to the left.

What are the values for partial pressure of oxygen and CO2 in alveolar air, pulmonary Veins, and systemic capillaries

Oxygen's partial pressure is 100mmHg for alveolar air, pulmonary Veins, and systemic capillaries. Carbon dioxide's partial pressure is 40mmHG in alveolar air, pulmonary veins, and systemic capillaries

Explain the countertransport of bicarbonate with chloride anion and the chloride shift.

The bicarbonate anions that are formed undergo countertransport with chloride anions at the RBC membrane: bicarbonate is transported out of the RBC into the plasma and chloride is transported into the RBC. The resulting venous blood has a higher chloride concentration in the RBC's than the arterial blood (chloride shift).

What are the values of partial pressure of oxygen and carbon dioxide in systemic veins and pulmonary Capillaries?

The partial pressure of oxygen is 40mmHg in both systemic veins and pulmonary capillaries. The partial pressure of CO2 is 46 mmHg in both systemic and pulmonary capillaries.

What is the buffering effect of hemoglobin?

The proton formed from the enzyme carbonic anhydrase reaction reaction reacts with the negative charges of the hemoglobin this helps prevent excess acidity

Increased DPG increases...

The unloading of oxygen to tissues. **if absent, the high affinity of hemoglobin for oxygen would impair oxygen delivery

Perfusion must always match...

Ventilation

What are the factors that affect the binding of oxygen to Hb?

a. PO2 in blood b. pH c. temperature d. PCO2 e. 2,3-diphosphoglycerate (DPG)

Effect of temperature on oxygen and hemoglobin affinity.

actively metabolizing tissues have higher temperatures resulting in increased oxygen-Hb dissociation. increase of temp shifts curve to the right

If V/Q = 0, what alveolar partial pressures are produced for O2 and CO2 and why?

alveolar air equilibrates with gases in the pulmonary capillaries which is venous blood i. PvO2 = 40 mm Hg NORMALLY (100mmHg) ii. PvCO2 = 46 mm Hg NORMALLY ( 40)

Explain the movements of oxygen and carbon dioxide at the alveoli/capillary interface and the systemic capillary/tissue interface based on the partial pressures.

c. net diffusion of oxygen from the alveolar space into the capillary will cease when the pressures have equalized; net diffusion of carbon dioxide from the pulmonary capillary blood into the alveolar space will cease when the pressures have equalized d. blood leaving the pulmonary capillaries, and entering the pulmonary veins, will have the same partial pressures as the alveolar air e. blood leaving the heart, and entering the systemic capillaries, will also have these same values of partial pressures

DPG (2,3-diphosphoglycerate) is formed during glycolysis is ___________ affinity of hemoglobin for oxygen by binding reversibly to hemoglobin.

decreases

Explain physiological shunt

fraction of blood flowing through pulmonary capillaries that is not oxygenated due to insufficient ventilation V/Q = 0

type of hemoglobin normally present in the fetus that is different from adult hemoglobin (HbA); fetal Hb has _______________________ than maternal Hb, promoting oxygen transport across the placenta for release to fetal tissues.

higher affinity for oxygen

What is the net effect of the proton released from the carbonic anhydrase reaction?

increase acidity of the venous blood compared to arterial blood.

Exercise increases ___________ and ____________.

increases oxygen transport and increases oxygen delivered to tissue

Define venous admixture

pulmonary capillary blood combines with the shunted blood in the pulmonary veins. the result of mixing of shunted non-reoxygenated blood with reoxygenated blood distal to the alveoli. The shunted blood is a result of 1) Anatomic shunts and 2) shunt-like effects. actually lowers the PaO2 from 100 mm Hg to about 95 mm Hg

What is carbonic anhydrase reaction?

the enzyme carbonic anhydrase (CA) catalyzes the reaction of CO2 with water to form carbonic acid (H2CO3); the carbonic acid spontaneously breaks down to form bicarbonate anion and a proton

If V/Q = infinity, what alveolar partial pressures are produced for O2 and CO2 and why?

ventilation is normal but no perfusion: V/Q = V/0 = infinity a. without blood flow, there are no gases in the venous blood to establish equilibrium with the alveolar gases b. alveolar gases equilibrate with inspired air; no oxygen is lost from inspired air and no carbon dioxide is received c. nl humidified inspired air: PalvO2 = 152 mm Hg, PalvCO2 = 0.3 mm Hg