Class Notes (1,100,000)
CA (620,000)
U of S (3,000)
PHSI (100)
PHSI 208 (100)
Lecture 6

PHSI 208 Lecture Notes - Lecture 6: Fetal Hemoglobin, Red Blood Cell, Respiratory Acidosis


Department
Physiology
Course Code
PHSI 208
Professor
Baillie Landon
Lecture
6

This preview shows half of the first page. to view the full 3 pages of the document.
!PHSI!208.6!–!University!of!Saskatchewan!
Prof:&Landon&Baillie&
!
January'22,'2016'–'Respiratory'6'
!
Oxygen!binding!is!expressed!as!a!percentage.!The!amount!of!O2!bound!to!hemoglobin!at!any!
given!PO2!is!expressed!as!the!percent!saturation!of!hemoglobin.!Active!muscles!may!have!a!
PO2!as!low!as!20!mmHg!resulting!in!a!larger!release!of!O2.!
!
The!oxyhemoglobin!saturation!curve!is!determined!in&vitro!in!the!laboratory.!A!PO2!of!600!
mmHg!is!needed!to!get!Hb!to!completely!bind!to!O2.!Maternal!and!fetal!hemoglobin!have!
different!oxygen-binding!properties.!Fetal!hemoglobin!are!better!at!taking!O2!and!have!gamma!
instead!of!globular!protein.!
!
Physical&factors&altering&hemoglobin’s&affinity&for&O2:&
&
Effect!of!pH:!Maximal!exertion!pushes!a!cell!into!anaerobic!metabolism.!This!can!cause!a!
decreasing!shift!in!pH!by!causing!an!increased!amount!of!H+!being!taken!up!into!the!cytoplasm!
and!extracellular!space.!A!shift!in!hemoglobin!saturation!will!occur!as!a!result!of!the!pH!change.!
This!is!called!the!Bohr!effect.!
Hemoglobin!will!more!readily!bind!to!O2!when!pH!is!higher.!
Acid!binds!to!Hb!and!decreases!its!affinity!for!O2.!
!
Effect!of!PCO2:!Increased!aerobic!metabolism!results!in!increased!CO2!production.!This!
increases!the!PCO2!in!the!blood!and!does!2!things:!
Readily!binds!with!Hb,!decreasing!binding!spots!for!O2.!
CO2!is!readily!converted!to!carbonic!acid.!(Readily!dissociates!into!H+!and!HCO3-).!
!
Effect!of!temperature:!Active!muscles!produce!heat,!and!increased!heat!causes!a!conformation!
change!in!Hb,!leading!to!decreased!affinity!and!more!O2!to!be!dropped!at!the!very!active!
muscles.!
!
Effect!of!the!metabolic!compound!2,3-DPG!(diphosphoglycerate):!This!is!a!by-product!of!
glycolysis!in!red!blood!cells.!Chronic!hypoxia!increases!2,3-DPG!production!while!RBCs!release!
ATP!during!hypoxia.!Ascent!to!higher!altitude!with!low!atmospheric!PO2!and!anemia!can!
increase!2,3-DPG!production.!
!
CO2&Transport:&
&
It!is!very!important!to!remove!CO2!from!the!body.!Elevated!PCO2!causes!acidosis!(low!pH)!
which!leads!to!interruptions!in!hydrogen!bonds!and!denaturing!of!proteins.!Abnormally!high!
PCO2!depresses!the!central!nervous!system,!causing!confusion,!coma,!or!even!death.!
!
Although!CO2!is!very!soluble,!cells!produce!far!more!CO2!than!plasma!is!capable!of!carrying,!
therefore!the!body!has!a!mechanism!to!carry!CO2!to!the!lungs.!!
!
You're Reading a Preview

Unlock to view full version