[TRANSES] MODULE 3 UNIT 2 Flashcards
The main function of hemoglobin is (?).
to transport oxygen
Since oxygen is (?), it has to depend on
hemoglobin found in red blood cells for its transport to the
different organs and tissues of the human body.
non-water soluble
Hemoglobin increases (?) solubility in blood by about a
hundredfold.
O2
This means that without hemoglobin, in order to
provide sufficient (?), blood
would have to make a complete circuit through
the body in less than a second, instead of the
minute that it actually takes.
oxygen to the tissues
That would take a mighty powerful heart, which
in normal circumstances cannot be maintained
by the human heart leading to increased cardiac
output that may result to (?).
heart failure
During (?), each of the four heme iron atoms in a
hemoglobin molecule can reversibly bind one oxygen molecule.
oxygenation
Approximately (?) of oxygen is bound by each gram of
hemoglobin.
1.34 mL
Let’s follow the path of oxygen from the lungs to the peripheral
tissues.
Oxygen diffuses from the (1) of the lungs, little sacs at the end of the finely divided air passageways in the lung into the (2) of
the bloodstream and then into the (3), where it binds to hemoglobin.
- alveoli
- capillaries
- red blood cells
The concentration of oxygen is relatively high in the alveoli, about
(?) mmHg which means that Hb is virtually 100% saturated in the
lungs and all four heme molecules have an O2 molecule bound to
them.
100 mmHg
The concentration of oxygen is relatively high in the alveoli, about
100 mmHg which means that Hb is virtually (?) in the
lungs and all four heme molecules have an O2 molecule bound to
them.
100% saturated
The concentration of oxygen is relatively high in the alveoli, about
100 mmHg which means that Hb is virtually 100% saturated in the
lungs and all (?) have an O2 molecule bound to
them.
four heme molecules
The reference interval for arterial oxygen saturation is (?).
96% to 100%
The affinity of hemoglobin for oxygen relates to the partial
pressure of oxygen (PO2), often defined in terms of the amount of
oxygen needed to saturate 50% of hemoglobin, called the (?).
P50 value
The relationship is described by the (?) of hemoglobin, which plots the percent oxygen saturation of hemoglobin versus the PO2
oxygen dissociation curve
The curve is (?), which indicates low hemoglobin affinity for
oxygen at low oxygen tension and high affinity for oxygen at high
oxygen tension.
sigmoidal
Cooperation among hemoglobin subunits contributes to the (?).
shape of the curve
Hemoglobin that is completely (?) has little affinity for
oxygen.
deoxygenated
The secret to hemoglobin’s success as an oxygen delivery
molecule is the fact that it has (?) that communicate to
each other.
four subunits
In order to achieve [?] (an average of 1 O2 molecule per hemoglobin), the amount of O2 needs to be about 18 mm Hg.
25% saturation
In order to achieve 25% saturation (an average
of 1 O2 molecule per hemoglobin), the amount
of O2 needs to be about (?).
18 mm Hg
In order to achieve [?] (an average of 2 O2 molecules per hemoglobin), the amount of O2 needs to be about 27 mm Hg.
50% saturation
In order to achieve 50% saturation (an average
of 2 O2 molecules per hemoglobin), the amount
of O2 needs to be about (?).
27 mm Hg
Therefore, it is easier to bind the second molecule of O2 than the
first. This was illustrated by (?), Nobel Prize winners for Chemistry for their studies of the structures of hemoglobin and myoglobin.
Max Perutz and John Kendrew
Using (?), hemoglobin was found to have two
different forms or shapes.
X-ray diffraction
The (?) is dependent on the presence or
absence of oxygen.
conformation or shape
The experiments revealed that (?) has a relatively low attraction for oxygen, but when one molecule of oxygen binds to a heme group, the structure changes to the oxygenated form, which has a greater attraction for oxygen.
deoxyhemoglobin
Therefore, the (?) binds more easily, and the
third, and fourth even more easily.
second molecule of O2
The oxygen affinity of (?) is many times greater than
that of deoxy-hemoglobin.
oxy-hemoglobin
The oxygen dissociation curve illustrates the relationship between
(?).
yung graph is asa top second column HAHAHAHA
oxygen saturation of hemoglobin and the partial pressure of
oxygen
(?) is the partial pressure of oxygen (O2) needed for 50% O2 saturation of hemoglobin.
P50
↓ 2,3-bisphosphoglycerate (2,3-BPG) (e.g., multiple transfusion of stored blood)
In the Left-shifted (L): ↓ P50
↓ H+ ions (↑pH)
In the Left-shifted (L): ↓ P50
↓ (PCO2)
In the Left-shifted (L): ↓ P50
Hemoglobin F and hemoglobin variants
In the Left-shifted (L
o Hemoglobin F and hemoglobin variants
↑ oxygen affinity
In the Left-shifted (L)
o Hemoglobin F and hemoglobin variants
Alkalosis
In the Left-shifted (L)
↑ 2,3-BPG (e.g., in response to
hypoxic conditions such as in
high altitudes)
In the Right-shifted (R): ↑ P50
↑ H+ ions (↓ pH)
In the Right-shifted (R): ↑ P50
↑ PCO2, and/or temperature
In the Right-shifted (R): ↑ P50
o Pulmonary insufficiency
In the Right-shifted (R)
o Hemoglobin variants
↓ oxygen affinity
In the Right-shifted (R)
o Congestive heart failure
In the Right-shifted (R)
o Severe anemia
In the Right-shifted (R)
Factors that affect Hemoglobin affinity for Oxygen:
A patient with arterial and venous PO2 levels in the
reference intervals (80 to 100 mm Hg arterial and 30 to 50
mm Hg venous)
SHIFT TO THE LEFT
Factors that affect Hemoglobin affinity for Oxygen:
A patient with arterial and venous PO2 levels in the
reference intervals (80 to 100 mm Hg arterial and 30 to 50
mm Hg venous)
Partial pressure of oxygen
Factors that affect Hemoglobin affinity for Oxygen:
A patient with arterial and venous PO2 levels in the
reference intervals (80 to 100 mm Hg arterial and 30 to 50
mm Hg venous)
↑ percent oxygen saturation
Factors that affect Hemoglobin affinity for Oxygen:
A patient with arterial and venous PO2 levels in the
reference intervals (80 to 100 mm Hg arterial and 30 to 50
mm Hg venous)
↑ affinity for oxygen
↓ affinity for oxygen
↑ pCO2
↓ pH
↑ H+
SHIFT TO THE RIGHT
↓ affinity for oxygen
↑ pCO2
↓ pH
↑ H+
pH of blood
↓ affinity for oxygen
↑ pCO2
↓ pH
↑ H+
Bohr effect
↑ cellular respiration
↑ metabolic activity
↑ CO2
↓ O2
Strenuous physical activities
↑ cellular respiration
↑ metabolic activity
↑ CO2
↓ O2
SHIFT TO THE RIGHT
↑ cellular respiration
↑ metabolic activity
↑ CO2
↓ O2
pH of blood
To transport CO2 through the venous blood, it diffuses into
the red blood cells combining with water to form carbonic
acid (H2CO3).
Bohr effect
This reaction is facilitated by the enzyme, (?).
carbonic anhydrase
The carbonic acid will then dissociate to release (?).
H+ and bicarbonate (HCO3 -)
In addition to hydrogen ions and carbon dioxide, a key allosteric effector of hemoglobin is (?)
2,3-BPG
(?) a small molecule made in red blood cells.
2,3-BPG
2,3-BPG affects (?) by binding in a small central cavity of deoxygenated hemoglobin. This shifts the equilibrium
towards deoxy-hemoglobin.
oxygen-binding affinity
2,3-BPG affects oxygen-binding affinity by binding in a small central cavity of deoxygenated hemoglobin. This shifts the equilibrium
towards (?).
deoxy-hemoglobin
The presence of acids leads to:
↑ H+
↓ pH
↑ O2
This promotes formation of the (?) of hemoglobin, shifting the oxygen dissociation curve to the right, promoting oxygen release to actively respiring tissues.
deoxy form
This promotes formation of the deoxy form of hemoglobin, shifting the oxygen dissociation curve to the right, promoting (?) release to actively respiring tissues.
oxygen
At high altitude, when oxygen in the atmosphere is scarce
because the air is “(?),”
thinner
At high altitude, when oxygen in the atmosphere is scarce
because the air is “thinner,”:
↑ 2,3- BPG (helping hemoglobin to release more of its bound oxygen = ↑ aerobic capacity)
↑ CO2
↓ O2
t takes about (?) hours for 2,3-BPG levels to rise, and over
longer periods of time, the levels continue to increase as
part of the acclimation effect.
24 hours
Giving the developing fetus better access to oxygen from the
mother’s bloodstream:
Interestingly, (1) does not bind to fetal hemoglobin.
This results in tighter binding of oxygen relative to (?).
- 2,3-BPG
- maternal hemoglobin
Through (?), the thermal energy diffuses to the blood in nearby capillaries.
heat transfer
Through heat transfer, the thermal energy diffuses to the
blood in nearby capillaries.
↑ metabolic rates
↑ thermal energy
↑ average kinetic energy
↑ temperature
↓ affinity for oxygen
Higher temperature in the blood is interpreted by the body that cells are working harder thus requiring (?) to keep them going.
more oxygen
In response to higher temperature, the (?) decrease its affinity for oxygen to facilitate delivery to the tissues
Hb
Thus, (?) the oxygen dissociation curve to the right such as when tissues are actively engaged in physical activity, these tissues would require and eventually receive more O2.
increased temperature in the blood shifts
↑ cellular respiration
↑ metabolic activity
↑ CO2
↓ O2
↑ H+ ions
↑ 2,3-BPG
Carbon dioxide
(?) diffuses from the tissues to red cells to form H2CO3 which dissociates to H+ and HCO3 -resulting to a shift of the curve to the right.
CO2
CO2 diffuses from the tissues to red cells to form (?) which dissociates to H+ and HCO3 -resulting to a shift of the curve to the right.
H2CO3
CO2 diffuses from the tissues to red cells to form H2CO3 which dissociates to (?) resulting to a shift of the curve to the right.
H+ and HCO3 -
CO2 diffuses from the tissues to red cells to form H2CO3 which dissociates to H+ and HCO3 -resulting to a (?).
shift of the curve to the right
Once the (?) reach the lungs, O2 will diffuse into the deoxygenated Hb resulting to release of H+ that will combine with HCO3 -to form H2CO3 which in turn will dissociate to water and
CO2 where the latter will diffuse out of the cells and eventually expelled by the lungs.
red cells
Once the red cells reach the lungs, (?) will diffuse into the deoxygenated Hb resulting to release of H+ that will combine with HCO3 -to form H2CO3 which in turn will dissociate to water and
CO2 where the latter will diffuse out of the cells and eventually expelled by the lungs.
O2
Once the red cells reach the lungs, O2 will diffuse into the (?) resulting to release of H+ that will combine with HCO3 -to form H2CO3 which in turn will dissociate to water and
CO2 where the latter will diffuse out of the cells and eventually expelled by the lungs.
deoxygenated Hb
Once the red cells reach the lungs, O2 will diffuse into the deoxygenated Hb resulting to release of (?) that will combine with HCO3 -to form H2CO3 which in turn will dissociate to water and
CO2 where the latter will diffuse out of the cells and eventually expelled by the lungs.
H+
Once the red cells reach the lungs, O2 will diffuse into the deoxygenated Hb resulting to release of H+ that will combine with (?) to form H2CO3 which in turn will dissociate to water and
CO2 where the latter will diffuse out of the cells and eventually expelled by the lungs.
HCO3 -
Once the red cells reach the lungs, O2 will diffuse into the deoxygenated Hb resulting to release of H+ that will combine with HCO3 -to form H2CO3 which in turn will dissociate to water and
CO2 where the latter will diffuse out of the cells and eventually expelled by the (?).
lungs
This phenomenon is explained by the (?) which describes the binding of oxygen to Hb which promotes the release of CO2.
Haldane effect
(?) are hemoglobins that were previously produced in a normal red blood cell precursor but have been exposed to certain drugs, toxic agents, environmental chemicals or gases.
Dyshemoglobins
These (?) are dysfunctional hemoglobins that cannot properly dispense its function of transporting oxygen because the offending agent has modified the structure of the Hb molecule.
dyshemoglobins
3 Dyshemoglobins
- Carboxyhemoglobin (COHb)
- Methemoglobin (MetHb or Hemiglobin)
- Sulfhemoglobin
– produced when Hb is exposed to carbon monoxide which as an
affinity of 240 times that of oxygen.
Carboxyhemoglobin (COHb)
Binding of carbon monoxide to Hb shifts the oxygen dissociation
curve to the left increasing its affinity and impairing release of
oxygen to the tissues.
Carboxyhemoglobin (COHb)
Sources of (?) include house fires, car exhaust, indoor
heaters, and stoves.
CO poisoning
(?) occurs during the degradation of heme and contributes to the baseline COHb concentration found in healthy people.
Endogenous production
In patients afflicted with (?), COHb can reach concentrations of 8%.
hemolytic anemias
In patients afflicted with hemolytic anemias, COHb can reach
concentrations of (?)%.
8%
Values also may be elevated in (?).
severe sepsis
In (?), COHb levels may be as high as 15%.
smokers
In smokers, COHb levels may be as high as (?)%.
15%
As a result, smokers may have a higher (?) to compensate for the hypoxia.
hematocrit and polycythemia
As a result, smokers may have a higher hematocrit and polycythemia to compensate for the (?).
hypoxia
Treatment involves removal of the patient from the carbon
monoxide source and administration of (?) oxygen.
100%
The use of (?) is controversial.
hyperbaric oxygen therapy
It is primarily used to prevent neurologic and cognitive impairment
after acute carbon monoxide exposure in patients whose COHb
level exceeds 25%.
hyperbaric oxygen therapy
Hyperbaric oxygen therapy is primarily used to prevent neurologic and cognitive impairment after acute carbon monoxide exposure in patients whose COHb level exceeds (?)%.
25%
(?) may be detected by spectral absorption instruments at 540 nm.
Carboxyhemoglobin
It gives blood a cherry red color, which is sometimes imparted to the skin of victims.
Carboxyhemoglobin
A diagnosis of (?) is made if the COHb level is greater than 3% in nonsmokers and greater than 10% in smokers.
carbon monoxide poisoning
– formed when the iron (Fe+2) in Hb is reversibly oxidized to the
ferric (Fe3+) state.
Methemoglobin (MetHb or Hemiglobin)
Normally, a small amount of (?) is continuously formed by oxidation of iron during the normal oxygenation and deoxygenation of hemoglobin.
methemoglobin
However, methemoglobin reduction systems, predominantly the
(?), normally limit its accumulation to only 1% of total hemoglobin.
NADH-cytochrome b5 reductase 3 (NADH-methemoglobin
reductase) pathway
However, methemoglobin reduction systems, predominantly the
NADH-cytochrome b5 reductase 3 (NADH-methemoglobin
reductase) pathway, normally limit its accumulation to only (?)% of
total hemoglobin.
1%
While MetHb levels up to (?)% are generally asymptomatic,
increased levels of more that 30% of the total Hb may result to
cyanosis, and symptoms of hypoxia (e.g., headache, dyspnea,
vertigo, changes in mental status).
25%
While MetHb levels up to 25% are generally asymptomatic,
increased levels of more that (?)% of the total Hb may result to
cyanosis, and symptoms of hypoxia (e.g., headache, dyspnea,
vertigo, changes in mental status).
30%
Levels greater than 50% have resulted to coma and death.
Methemoglobin
Levels greater than (?)% have resulted to coma and death.
50%
Types of Methemoglobinemia
Acquired
Hereditary
also known as toxic methemoglobinemia is due to exposure of affected individuals to exogenous oxidants such as nitrites (e.g., ingestion of nitrite-containing well water, gastroenteritis resulting in nitrite production), primaquine, dapsone or benzocaine.
Acquired
If the level of MetHb is less than 30%, (?) may be sufficient for recovery.
removal of the offending agent
If the level is more than 30%, (?), which reduces ferric iron to the ferrous state, is given to patients intravenously.
methylene blue
due to mutations in the gene that codes for NADHcytochrome b5 reductase 3 (CYB5R3), resulting in a diminished capacity to reduce methemoglobin.
Hereditary
It may also arise from mutations in the a-, β- , or γ-globin gene,
resulting in a structurally abnormal polypeptide chain that favors the oxidized ferric form of iron and prevents its reduction, this phenomenon is called the (?).
M hemoglobin or Hb M
– a spectral absorption analysis instrument that measures concentrations of oxygenated hemoglobin (oxyHb), deoxygenated hemoglobin (deoxyHb or reduced Hb), carboxyhemoglobin (COHb), and methemoglobin (MetHb) as a percentage of the total hemoglobin concentration in the blood sample.
CO-oximeter
(?) shows an absorption peak at 630 nm.
MetHb
Blood samples with high levels of MetHb have (?).
chocolate brown color
Since Hb M has different absorption peaks, it may be detected using (?), high performance liquid chromatography (HPLC) and DNA mutation testing.
Hb electrophoresis
- is a rare condition that may result from exposure to sulfonamides, acetanilide, phenazopyridine, nitrates, trinitrotoluene, and phenacetin.
Sulfhemoglobin
(?) is unique because its presence is not detected by co-oximetry.
Sulfhemoglobin
Unlike the other dyshemoglobins, (?) shifts the oxygen dissociation curve to the right, resulting in oxygen being more readily available to tissues.
sulfhemoglobin
(?) should be suspected when a patient who has cyanosis has a normal PO2 and elevated methemoglobin concentration by co-oximetry but does not respond to methylene blue therapy.
Sulfhemoglobinemia
Treatment involves administering oxygen and discontinuing the
offending agent.
Sulfhemoglobin
