Gas transport Flashcards
What does most of the dissolved co2 in the tissue undergo?
Hydrolysis
What is dissolved at the tissues and then enters the RBC’s?
Co2
Excess _______ diffuses out of RBCs
HCO3-
Name the steps of chloride shift
As HCO3- moves out of RBCs,
Cl- moves into RBC,
Cl- liberated from NaCl
HCO3- combines with Na to form NaHCO3
at the lungs, CO2 dissolved in plasma diffuses into what?
Alveoli
Diffusion
Movement of molecules from an area of higher pressure to an area of lower pressure.
What is the distance of the alveolar capillary membrane?
approx 4 microns
List the layers of the alveolar capillary membrane.
Surfactant, Alveolar epithelium, Interstitium, Capillary endothelium, Plasma and RBC’s
Oxygen Time of Diffusion
0.25-0.4 seconds
Carbon Dioxide Time of Diffusion
0.015 seconds
Formula for Estimating Diffusion via A-aDO2
A-aDO2= PAO2-PaO2 = P(A-a)O2
What is the Alveolar Air Equation?
PAO2 = PIO2-(PACO2 x 1.25)
How is oxygen transported in the body?
- Dissolved in plasma (1% of Oxygen)
2. In combination with Hb (Just under 99% of Oxygen)
Normal Hb levels in Males:
14-18g/dL
Normal Hb levels in Women:
12-16g/dL
How many mL of Oxygen can ONE gram of Hb carry?
1.34mL
Bicarb converts to _____?
Dissolved CO2
Additional dissolved CO2 diffuses into ____.
Alveoli
Reverse chloride shift
HCO2- in plasma moves back into RBC,
Cl- in RBC moves back to plasma
Haldane Effect
Deoxygenated blood has a greater affinity for CO2 than oxygenated blood
Better able to pick up CO2 at tissues
Bohr Effect
Increased PCO2 shifts the O2/Hb dissociation curve to the right
Hb has less affinity for for O2; better to release O2 at tissues
Histotoxic hypoxia
Tissues are unable to use O2
Cause of histotoxic hypoxia
Cyanide poisoning
What is the initial response to response to hypoxia
Hyperventilation
Tachycardia
What is the chronic response to hypoxia
Polycythemia
Mechanisms of transport
1% bound to plasma proteins
8% dissolved in plasma and RBCs
12% bound to Hb
80% transported as bicarbonate
What is the difference between Adult and Fetal Hb?
HbF (Fetal Hemoglobin) has a higher affinity for Oxygen until they reach the age of 1
What is Sickle cell Anemia?
Crescent shaped RBC that is fragile and tends to agglutinate. Caused by HbS (Sickle Hemoglobin)
What is Met Hb?
Iron in the Hemoglobin becomes oxidated (Rusty) and can’t carry Oxygen.
What is the formula for the O2 Content of Blood (CaO2)?
CaO2 = (1.34 x Hb x saturation)+(PaO2 x 0.003)
What does a right shift in the Hb affinity curve mean?
A less affinity for O2. (Not much O2 picked up in lungs, Oxygen more easily released at tissues)
What does a left shift in the Hb affinity curve mean?
A greater affinity for O2. (Picks up more O2 in the Lungs, Oxygen not as easily released at tissues)
What Factors shift the curve to the right?
RIGHT
Rise, In, 2,3 dp G, [H+] (low pH, high Pco2), Temperature
What Factors shit the curve to the left?
Drop in Temperature, PCO2, and 2,3 DPG. As well as rise in pH
What Increases Oxygen consumption?
exercise, fever, shivering, seizures. (increase in metabolic rate)
What decreases Oxygen consumption?
paralysis, hypothermia, poison (when a persons metabolic rate is lower)
