respiratory - topic 6 Flashcards
how is O2 transported?
mostly by hemoglobin, because very little dissolves
what is fetal hemoglobin?
alpha2gamma2, which has a higher affinity to pull O2 from mom
does O2 contribute to the pressure gradient when bound to Hb?
no, O2 bound to Hb doesn’t contribute to the pressure gradient
what is sickle cell anemia caused by?
Hbs that form sickled rods when deoxygenated, causing lower O2 affinity
what happens when O2 binds to Hb?
It is fully reversible, binding creates a conformational change that makes further binding easier
what is the shape of the O2-Hb disassociation curve?
sigmoidal, sharp increases from 0-40%, levels off at 60 mmHg
what is P50 in the O2-Hb curve?
when Hb is 50% saturated, indicates affinity (higher = lower)
when does affinity increase?
at lower temps, lower PCO2, lower 2,3-DPG, increased pH (basic)
when does affinity decrease?
higher temps, higher PCO2, higher 2,3-DPG, lower pH (acidic)
what happens to O2 affinity in HB during excercise?
higher PCO2 -> lower affinity (we want more O2 for the cells and tissues)
what is the Bohr effect?
CO2 production increase will decrease pH, which shifts the curve to the right to promote O2 release to tissues
what is 2,3-DPG?
a product of glycolysis
what happens during CO poisoning?
CO binds to Hb’s irreversibly, and causes a left shift in disassociation curve, which prevents O2 release
what is hypoxia?
insufficient O2 for cells to maintain aerobic metabolism (localized)
what is cyanosis?
blue/grey extremities that can be caused by hypoxia
what is hypoxemia?
low O2 in arterial blood, usually leads to hypoxia
what is hypoxic hypoxia?
low PaO2, so less O2 to tissues, caused by pulmonary diseases like COPD and fibrosis
what is circulatory hypoxia?
hypoxia caused by reduced blood flow, usually from vascular diseases
what is anemic hypoxia?
hypoxia due to inability of blood to carry enough O2 (caused by low Hb (anemia) or bad Hb (HbCO)
what is histotoxic hypoxia?
hypoxia caused by a blockage of the ETC, caused by poisons like cyanide
what is the process of CO2 transport?
CO2 diffuses into RBCs and is hydrated into H2CO3 by carbonic anhydrase
H2CO3 dissasociates into H+ and HCO3-
HCO3- is transported into plasma in exchange for Cl-
H+ stays in RBC to be buffered by deoxyhumoglobin
process is reversed in lungs
what keeps the pH balance?
ratio of [HCO3-] (balanced by renal) and PCO2 (balanced by lungs)
what is respiratory acidosis?
hypoventilation causes increased PCO2 and [H+]
what is respiratory alkalosis?
hyperventilation causes decreased PCO2 and [H+]
