Respiratory 4 Flashcards
Oxygen is carried both physically _____ in the blood and chemically combined to _____
dissolved; hemoglobin1
If cells utilize more oxygen than normal, the gradient _____ which _____ flow of oxygen from the blood to the tissues.
increases; increases
Tissue ____ is a function of:
1) The rate of O2 transport to the tissues in blood (blood flow
(2) The rate at which the tissues use O2.
PO2
Increased blood flow and/or increased metabolism will result in ____ O2 delivery to the tissues.
more
Without Hemoglobin, ____ would need to be 83.3 L/min to transport sufficient oxygen to meet the needs of the tissues at rest.
CO
______ of total oxygen content is dissolved in plasma (PaO2 = 100 mmHg)
2%
____ of O2 reversibly binds to hemoglobin inside of the RBC -does not contribute to partial pressure
98%
2,3- BPG binds to which subunit of hemoglobin
Beta
Which form of iron is the normal state used in hemoglobin used for O2 binding?
Ferrous (Fe 2+)
Which form of iron is the methemoglobin state causing less O2 release to tissues?
Ferric (Fe 3+)
4 subunits each of which each binds 1 O2molecule.
Hemoglobin A (α22):
The amount of oxygen bound to Hb depends on what 2 things?
- Plasma PO2
- Number of binding sites in RBCs – depends on the Hb amount per RBC. (normally each RBC contains ~1 million Hb molecules)
Reduction in the amount of hemoglobin in the blood significantly ____ the blood oxygen content.
reduces
____ is the % saturation of hemoglobin in the arteries
SaO2
What is the average % saturation of hemoglobin in the arteries(SaO2)
97%
What is the average Hb (g of hemoglobin/ 100mL of blood?
15 g Hb/100 mL
_____ is the partial pressure of oxygen in arterial blood
PaO2
what is the average partial pressure of oxygen in arterial blood (PaO2)
95 mmHg
_____ binds to Beta subunits of deoxy HB and decreases its O2affinity. It causes more oxygen unloading.
2,3-BPG
What is the average saturation of hemoglobin in the veins SvO2?
75%
At what PO2 do the peripheral chemoreceptors increase alveolar ventilation?
60 mmHg
Increased dissolved O2 leads to _____ hemoglobin bound to oxygen
Increased
______ Indicates DECREASED affinity between hemoglobin and oxygen
Bohr effect / right shift in oxyhemoglobin dissociation curve
In a ____ shift of the oxyhemoglobin dissociation curve, oxygen is MORE likely to dissociate from Hemoglobin.
Right shift
What are the 4 things causing the right shift of the oxyhemoglobin dissociation curve?
Increased H+ ions
Increased CO2
Increased temp
Increased BPG
A ____ shift of the oxyhemoglobin dissociation curve Indicates an INCREASED affinity between oxygen and hemoglobin; In this instance, oxygen is LESS likely to dissociate from hemoglobin.
Left shift
A left shift of the oxyhemoglobin dissociation curve is caused by:
–Decreased PCO2
–Increased pH (ex. 7.6)
–Decreased temperature
–Decreased 2,3-BPG
Does CO or O2 have a higher affinity for hemoglobin?
CO
Heme with Fe3+ does not bind O2 as readily (reduced affinity) & also causes any heme groups in the same Hb molecule with heme in the Fe2+ state to have have higher affinity for bound O2; net effect is reduced O2 delivery to the tissues
–Can occur due to G6PDH deficiency or upon exposure to some local anesthetics (prilocaine and benzocaine).
Methemoglobin
–α2g2 (no β chains)
–Higher affinity for oxygen than HbA because it doesn’t contain the Beta chain that binds to 2, 3-BPG.
Hemoglobin F (Fetal hemoglobin)
–Normal α units, abnormal beta units (due to one amino acid change)
–When deoxygenated, RBCs form sickle shapes, obstructing small vessels
–O2 has lower affinity for HbS than Hb A
Hemoglobin S (sickle cell
Does methemoglobin cause a left or a right shift?
Left shift
Does methemoglobin reduce or increase O2 release to tissues?
Reduce
_____ is low dissolved O2 (PaO2)
Hypoxemia
Does hemoglobin bind CO2?
Yes
What is the main way CO2 is transported?
Bicarbonate
What are the 3 ways CO2 can be transported?
- Dissolved CO2
- Carbamino-hemoglobin (CO2Hgb)
- Bicarbonate (HCO3-)
What is the protein that exchanges HCO3 into plasma for Cl?
Band 3 protein
CO2 forms a ____, _____ bond with hemoglobin (on terminal amine groups)
loose, reversible
CO2 forms a loose, reversible bond with hemoglobin on _____ groups
terminal amine
In RBCs, ______ rapidly forms carbonic acid from H2O and CO2, which in turn dissociates to H+ and HCO3-
carbonic anhydrase
Deoxygenated Hb promotes _____ binding of CO2 to Hb
increased
Oxygenated Hb promotes _____ of CO2 from Hb.
dissociation
