16. CP Gas Transport Flashcards
What is the solubility of O2 in plasma?
0.3 ml O2 / dl blood / 100 mmHg
What is the average O2 content of arterial blood?
What is the oxygen content of blood at 100& saturation?
Average = 20 mlO2 / dl blood (200ml O2 / L)
At 100% = 20.1 mlO2 / dl blood
What results in a right shift (lower affinity) of oxygen binding?
High CO2
High Temperature
2,3 BPG
(Eg. Being in the tissues)
What is the O2 saturation in venous blood?
What is the O2 content in venous blood?
Saturation in venous blood = 75%
O2 content in venous blood = 15.2 ml O2
What is the arterial - venous O2 difference?
Include definition and value.
Definition: The difference between the content of O2 in the arterial blood vs venous blood. (How much O2 was used.)
Value: 4.6 mlO2 / dl blood difference
What is the CO2 production vs O2 consumption for:
Carbohydrates
Fatty Acids
Carbohydrates 1/1
Fatty Acids: 7 CO2 : 10 O2
What is the average CO2 produced / O2 consumed for all fuels combined? (Experimental average)
8 CO2 : 10 O2
(.8)
What is the equation for respiratory quotient (RQ)?
CO2 produced / O2 consumed
What three forms can CO2 take when transported in the blood?
Dissolved
Carbamino compounds (bound to amines)
As bicarbonate
What is the solubility of CO2 in blood plasma?
6ml CO2 / dl blood / 100 mmHg
(20x higher than O2)
What is the CO2 content in blood?
2.7 ml CO2 / dl
What is the Haldane Shift?
The phenominon by which O2 changes the conformation of Hb to reduce the affinity of Hb for CO2
How much CO2 is carried as cabamindo compounds?
3ml CO2 / dl of blood
Functions of Erythrocytes
Deliver nutrients and O2
removes waste products
maintain homeostasis
circulation
What is the key regulator of erythropoeisis?
What happens with a defect in Hypoxia inducible factor?
erythropoietin (regulated by HIF)
made by kidneys due to anemia, low Hb, decreased RBF, or central hypoxia
genetic deletion results in anemia, polycythemia while impaired regulation of HIF leads to erythrocytosis
What is the life cycle of red blood cells?
last for 120 days and then rupture in the red pulp of the spleen
released Hb is ingested by monocyte/macrophages immediately
blood travels from the lungs to the vessels to the tissues where the O2 is deposited
oxygen can travel in the blood two ways. Why is the level of dissolved oxygen in the blood so low?
Dissolved O2 has a really low solubility, with PaO2 being only 95-100mmHg. This would mean that during heavy exercise when CO increases, tissue demands would be 2-3000 ml O2/min
There just isn’t enough dissolved O2 in the blood to go around (b/c of low solub.)
How does O2 bind to Hgb?
Hgb has four different chains with iron binding affinity and each molecule of Hgb can carry 4 O2 molecules
note that Hgb A is adult form
Hgb F is fetal form
What is the normal oxygen concentration on a dissociation curve?
15 Hb/100ml Blood
1g hb can combine with 1.34 ml O2
in total there is about 20.1ml O2/100ml blood
What are the normal PaO2 and O2 saturation values (arterial blood)
what are the normal values for PvO2 and O2 saturation (venous blood)
This is in resting tissues
arterial: PaO2=95-100mmHg
O2 sat=97.5%
Venous: PvO2=40mmHg
O2 sat=75%
What is the O2 saturation when PaO2 is > 60mmHg?
O2 sat is at least 85%
(17ml O2/dl blood)
What is the Hb saturation percentage when PaO2 is 27mmHg?
50%
What happens to oxygen when Hb concentration decreases?
Oxygen carrying capacity will decrease regardless of O2 saturation
What happens when Hb concentration increases?
Oxygen carrying capacity will increase regardless of O2 saturation
What is the “left shift” of the ODC?
what dz are assx?
represents increased affinity of Hb for O2 (Hb doesn’t want to share O2 with the tissues)
assx with polycythemia and methemoglobinemia
What is the “right shift” of the ODC?
represents decreased affinity of Hb for O2 (doesn’t want to hold on to O2)
assx with anemia, good for unloading O2
What causes a right shift? (Bohr Effect)
increased CADET
CO2 (hypercarbic)
Acid (high H, low pH)
2,3 BPG (DPG) (more chronic)
Exercise
Temp
What is oxygen capacity?
What is oxygen content?
What is Oxygen Saturation?
OC: max amount of O2 that can be carried by hgb in blood (20.1mlO2/dl blood)
Ocontent: how much O2 is actually being carried by the blood (19.5ml O2/dl blood)
OS: spots occupied by O2 as a percentage of total available spots
what are the four things that blood needs to form/function properly
what are two disorders assx with inadequate levels of these components?
- adequate nutrition
- vitamin B12 (cyancobalamin)
- folate (B9)
- iron availability
not enough B12 or folate leads to megaloblastic macrocytic anemia
poor b12 absorption leads to pernicious anemia
What dz is assx with a deficiency in iron?
microcytic anemia (most common type)
-be hgb needs iron in order to bind to O2
What dz is assx with deficient transport of transferrin to developing erythroblasts?
hypochromic anemia
How does iron and ATP work together
ATP is required to maintain Fe in the 2+ form within the heme
(Fe3 is bad for oxygen binding/dissociation)
What is hemachromatosis?
iron overloading leading to cirrhosis, hyperpigmentation and DM
there is primary/genetic and secondary as well as neonatal forms
secondary: can be caused by multiple blood transfusions, bad erythropoiesis, and increased iron intake
neonatal: develops in uteru from an unknown cause
Anemia decreases O2 carrying capacity. Why?
Hgb concentration is proportional to blood O2 content
1/2 hgb concentration is approx. equal to 1/2 blood O2 content (??) but the saturation doesn’t change
describe primary polycythemia
genetics (low EPO)
extra RBCs leading to increased blood volume (2x)
increased viscosity (10x water)
Normal CO (ish)
Describe secondary polycythemia
hypoxia (high EPO)
extra RBCs
CO may be abnormal
Describe physiologic polycythemia
high altitude adaptation
extra RBCs
normal CO
What is methemoglobinemia?
increased met-hemoglobin
iron is in Fe3 (ferric) form
decreased O2 available to tissues
LEFT shift in OHDC
blood is chocolate colored (okay, brown?)
blue skin

What is the a-v O2 difference?
difference between arterial blood O2 content vs. venous blood O2 content
helps determine oxygen consumption
what is the respiratory qoutient?
RQ=volume of CO2 produced/volume of O2 consumed or
Vdot CO2/Vdot O2
The relationship between O2 used and CO2 produced is determined by the fuel being burned in the body
Carbs
Fats
Proteins
Carbs: 1:1 ratio (1 CO2 per 1 O2) (1.0 RQ)
Fats: 7:10 ratio (7 CO2 per 10 O2) (0.7 RQ)
Proteins: 9:10 ratio (9 CO2 per 10 O2) (0.9 RQ)
How is CO2 transported in the blood?
arterial blood: 90% HCO3-
5% dissolved
5% carbamino
Venous blood: 60% HCO3-
10% dissolved
30% carbamino
Carbamino compounds carry CO2 in the blood because
CO2 binds to plasma proteins or Hb but does not bind to heme groups
instead, binds to amine group
this causes a Haldane (left) shift
in the presence of O2, there is a reduced affinitty of the amine chain for CO2
How does CO2 and bicarbonate work?
- CO2 is produced and exits tissues
- carbonic anhydrase (high levels in RBCs) hydrates CO2 to form H2CO3
- H2CO3 dissociates into H and HCO3
- H is buffered in RBCs by deoxyhemoglobin and carried in venous blood here
- HCO3- produced is exchanged for Cl- across RBCs and carried to lungs
- in the lungs: dissolved CO2 moves into alveoli, CO2 dissciates from proteins, HCO3 is converted back to CO2
Volume of O2 in blood
Volume of CO2 in blood
O2: 20ml/100ml blood
CO2: 50ml CO2/100ml blood
Major form of O2 transport
Major form of CO2 transport
O2: bound to heme
CO2: HCO3
Volume dissolved in blood:
O2:
CO2:
O2: 0.3ml/100ml blood
CO2: 3ml/100ml blood
Other forms of O2 in blood
other forms of CO2 in blood
O2-none
CO2: carbamino