transport of O2 and CO2 Flashcards
what are the properties of haemoglobin
-quaternary protein with 4 subunits
-each subunit has a polypeptide chain and a haem group
-the haem group contains a single iron ion. this holds onto oxygen
-haem group has a high affinity for oxygen
what to haemoglobin happens at low oxygen tension
does not readily associate with O2 therefore low saturation level
what to haemoglobin happens as oxygen tension rises
-one O2 molecule enters haemoglobin and associates causing a conformational change in Hb to allow more O2 molecules to bind
-accounts for the steepness of the curve
what happens when haemoglobin reaches 100% saturation
no more oxygen can bind so the curve levels off
what is the three ways CO2 is transported
-5% is dissolved in plasma
-10% combines directly with Hb to form carbaminohaemoglobin
-85% transported to form hydrogencarbonate ions
what is the Bohr effect
Describes the effect that an increasing concentration of CO2 has on the haemoglobin
when the curve shifts to the right
what is the process of CO2 effect on red blood cell and bohr effect
-CO2 enters red blood cells forming carbonic acid which dissociates to release H+ ions
-H+ affects pH of cytoplasm to acidic
-change in pH affects tertiary structure of Hb so reduces affinity of Hb for oxygen
-so in high CO2 concentrations oxygen dissociates from red blood cell
what’s the effect on water potential of the blood of the conc of glucose increases
water potential decreases
how does partial pressure of oxygen affect oxygen-haemoglobin binding
as partial pressure of oxygen increases, the affinity of haemoglobin for oxygen also increases. when partial pressure is low, oxygen is released from haemoglobin
explain the role of carbonic anhydride in the bohr effect
-carbonic anhydrase is present in red blood cells
-converts carbon dioxide to carbonic acid which dissociates to produce H+
-these combine with the haemoglobin to form haemoglobinic acid
-encourages oxygen to dissociate from haemoglobin
explain the role of bicarbonate ions in gas exchange
-produced alongside carbonic acid
-70% of carbon dioxide is carried in this form
-in lungs bicarbonate ions are converted back into co2 which we breathe out
what is the chloride shift
-the intake of chloride ions across a red blood cell membrane
-this depolarises the cell after bicarbonate ions have diffused out
how does foetal haemoglobin differ from adult haemoglobin
-partial pressure of oxygen is low by the time it reaches the foetus therefore foetal haemoglobin has a higher affinity for oxygen than adult
this allows both mothers and child’s oxygen needs to be met
