Lecture 18: Gas Exchange: CO2 Flashcards
2 ways O2 is transported
dissolved in plasma (1.5%)
bound to hemoglobin protein (98.5%)
extent to which O2 binds to hemo depends on
PO2 in plasma
def of oxy-hemoglobin dissociation curve
relationship between extent of oxygen binding to hemo and PO2
lung PO2 is _____ than PO2 in blood
greater
so O2 goes into blood
factors that affect oxyhemoglobin dissociation curve
temperature
Blood pH
PCO2
Bohr shift definition
curve shifts right
hemoglobin molec will RELEASE MORE oxygen at any PO2
Bohr shift caused by
reduction in blood pH
increase in blood CO2
inc in temp
when blood pH reduced
tissue more acidic
release more O2
Higher temperature
fluid is warmer
less CO2
Bohr shift is most important at
tissue capillaries
hemoglobin here will release O2 more readily
High blood pH value
7.6
Low blood pH value
7.2
normal blood pH value
7.4
X axis of graph
PO2
Y axis
% sat of hemoglobin
when blood pH high
hold onto more oxygen
when pH low
Bohr shift
release more O2
When low blood PCO2
hold onto more O2
When high blood PCO2
release more O2
110 degrees
too hot
death
low temperature
hold onto more O2
high temp
release more O2
Fully saturated hemoglobin can bind
1.34 mL oxygen
adults have this much hemoglobin
men: 160 g/L blood
women: 140-150 g/L blood
arterial blood in healthy person is _____% saturated
100
O2 conc= (equation)
g hemoglboin X 1.34 mL O2
O2 conc for men (Number)
213.3 mL O2/L blood
160g Hb/L X 1.34 mL O2/g HB
anemia
low blood hemoglobin conc
hypoxia
low blood O2 low hemoglobin sat is a STATE don't have to be anemic to be hypoxic can result from holding breath
Carbon Monoxide Poisoning
binds to Hb 250X better than O2
treatment: pure O2
BUT: must wait for CO bound Hb to be replaced by body
takes time
CO2 from tissue moves…
from active tissue cells
to plasma
to RBCs
2 things formed in RBCs for CO2 transport
H2CO3 (carbonic acid) and carbaminohemoglobin
70% CO2 transported in plasma is
bicarbonate ions
23% CO2 transported in plasma is
carbaminohemoglobin
7% CO2 transported in plasma is
disolved in plasma
Oxygen loading at pulm cap
is time dependent
oxygen loading at pulm caps depends on
rate of gas difussion and rate of blood flow through pulm caps
transit time
complete diffusion of O2 in most alveolar-cap units takes
0.25 secs (healthy)
transit time at rest is
0.8 secs
chloride shift across RBC
systemic caps
internal resp
reverse chloride shift across RBC
pulmonary caps
external resp
external respiration across RBCs
pulmonary caps
reverse chloride shift
internal respiration across RBCs
systemic caps
chloride shift
point of cholride shift
to load up plasma with bicarbonate
