University:
Stanford University
Course:
MED 101 | Human Anatomy
Academic year:

2024
Views:

254

Pages:

1
Author:

larbi43100

‭Hemoglobin binding capacity.‬ ‭ e‬‭have‬‭a‬‭concentration‬‭of‬‭hemoglobin‬‭in‬‭the‬‭blood‬‭which‬‭is‬‭equivalent‬‭to‬ W ‭approximately‬‭15g‬‭per‬‭100ml‬‭of‬‭blood‬‭(approximately‬‭13g‬‭in‬‭women)‬‭and‬ ‭one‬ ‭molecule‬‭of‬‭hemoglobin‬‭is‬‭capable‬‭of‬‭fixing‬‭the‬‭equivalent‬‭of‬‭1.34‬‭ml‬ ‭of O2.‬ ‭ he‬ ‭maximum‬ ‭O2‬ ‭fixation‬ ‭capacity‬ ‭for‬ ‭hemoglobin‬ ‭is‬ ‭then‬ ‭20.1ml‬ ‭per‬ T ‭100ml‬ ‭of‬ ‭blood.‬ ‭This‬ ‭capacity‬ ‭of‬ ‭100‬ ‭ml‬ ‭corresponds‬ ‭to‬ ‭what‬ ‭we‬‭call‬‭the‬ ‭oxyphoric power of the blood.‬ ‭ e‬ ‭then‬ ‭define‬ ‭the‬ ‭O2‬ ‭saturation.‬ ‭This‬ ‭saturation‬ ‭corresponds‬ ‭to‬ ‭a‬ W ‭percentage.‬‭When‬‭we‬‭have‬‭98%‬‭of‬‭the‬‭O2‬‭which‬‭is‬‭transported‬‭by‬‭Hb‬‭we‬ ‭have‬ ‭an‬ ‭O2‬ ‭saturation‬ ‭which‬ ‭is‬ ‭maximum.‬ ‭This‬ ‭O2‬ ‭saturation‬ ‭therefore‬ ‭corresponds to the ratio:‬ ‭ his O2 saturation is maximum (98%) at the outlet of the capillary but‬ T ‭is only 75% in venous blood.‬ ‭This curve represents O2 saturation (SaO2) versus O2 pressures.‬ ‭Two important pressures to remember:‬ ‭⮚‬ ‭There‬ ‭pressure‬ ‭has‬‭there‬ ‭exit‬ ‭of‬ ‭capillary‬ ‭ ulmonary‬ ‭(Or‬‭blood pressure): PaO2 maximum therefore‬ p ‭SaO2 max. (98%)‬ ‭⮚‬ ‭The pressure at the exit of the tissue (or venous pressure): the‬ ‭ ressure‬ p ‭being lower, there is only 75% of the O2 which binds to the Hb‬ ‭ he‬ ‭first‬ ‭factor‬ ‭which‬ ‭modifies‬ ‭the‬ ‭fixation‬ ‭of‬ ‭oxygen‬ ‭on‬ ‭hemoglobin‬ ‭is‬ T ‭therefore‬ ‭the‬ ‭partial‬ ‭pressure‬ ‭of‬‭oxygen.‬‭So‬‭at‬‭the‬‭tissue‬‭level‬‭where‬‭the‬ ‭pressure‬ ‭is‬ ‭lower,‬ ‭a‬ ‭desaturation‬ ‭of‬ ‭oxyhemoglobin‬ ‭occurs.‬ ‭The‬ ‭O2‬ ‭is‬ ‭therefore‬ ‭released‬ ‭to‬ ‭the‬ ‭muscle‬ ‭tissues‬ ‭and‬ ‭the‬ ‭hemoglobin‬ ‭will‬ ‭then‬ ‭associate‬ ‭with‬ ‭the‬ ‭CO2‬ ‭since,‬ ‭at‬ ‭the‬ ‭tissue‬ ‭level,‬ ‭there‬ ‭is‬ ‭production‬ ‭of‬ ‭CO2 and therefore an increase in PCO2.‬