HEMOGLOBIN METABOLISM Flashcards
_____________is a highly studied protein found in red blood cells
(RBCs) and makes up around ______ of the content within RBCs.
● Hemoglobin within RBCs is stable, protecting it from denaturation and
kidney excretion, whereas free hemoglobin outside of RBCs has a
short lifespan
HEMOGLOBIN
95%
Its main role is to transport oxygen from the lungs to body tissues and
carry carbon dioxide from tissues to the lungs for exhalation.
Hemoglobin
Hemoglobin contributes to____________ by binding and
releasing hydrogen ions
acid-base balance
It also participates in the regulation of vascular tone by transporting __________
Hemoglobin
nitric oxide
____________is made up of a ring of carbon,
hydrogen, and nitrogen atoms called
_______________with a central atom of
divalent ferrous iron (Fe²⁺).
heme - protoporphyrin IX
Each of the four heme groups is positioned in
a pocket of the ____________ near the
surface of the hemoglobin molecule.
polypeptide chain
__________ in heme binds reversibly with
one oxygen molecule. When it’s oxidized to
the __________ it can no longer bind
oxygen, leading to the formation of
___________
Ferrous iron - ferric state (Fe³⁺), - methemoglobin.
_______________ consists of four globin chains that are categorized
into two identical pairs of unlike polypeptide chains.
Hemoglobin
In globin structures These chains are designated using ___________
Greek letters
Each globin chain contains __________ separated by seven
nonhelical segments, connecting the helices.
eight helices
Hemoglobin can be described by its primary _________________
secondary _________________, tertiary ________________ quaternary____________________
primary (amino acid
sequence), secondary (arrangement of helices and nonhelices),
tertiary (pretzel-like configuration), and quaternary (complete
hemoglobin molecule) protein structures
The quaternary describes the ___________, which is _____________
attached to four polypeptide chains. It can carry up to four
molecules of oxygen.
complete hemoglobin molecule
spherical and contains four heme groups
The kidneys detect hypoxia and respond by producing
______________, a hormone.
erythropoietin (EPO),
EPO signals the ____________ to produce more ____________ and ____________
bone marrow
red blood cells
accelerates hemoglobin synthesis.
This process increases the oxygen-carrying capacity of the
blood, alleviating the hypoxia
EPO
Hemoglobin reference values can vary, but typical levels are
_____________ for men, ____________ and higher
for _____________
13.5-18.0 g/dL - men
12.0-15.0 g/dL for women
higher - newborns.
3 HEMOGLOBIN FUNCTION
● OXYGEN TRANSPORT
● CARBON DIOXIDE TRANSPORT
● NITRIC OXIDE TRANSPORT
(OCN)
Hemoglobin’s primary function is to ___________, ___________, ___________
bind oxygen in the lungs (high
oxygen affinity), transport oxygen, and efficiently release oxygen to
body tissues (low oxygen affinity)
Each of the four heme iron atoms in hemoglobin can reversibly bind
one oxygen molecule, with approximately __________of oxygen bound
per gram of hemoglobin.
1.34 mL
Hemoglobin’s affinity for oxygen
depends on _____________
the partial pressure of
oxygen (PO2)
__________ is sigmoidal, indicating that
hemoglobin has low oxygen affinity
at low oxygen tension (tissues)
and high affinity at high oxygen
tension (lungs)
curve
OXYGEN TRANSPORT
A PO2 of around _________ results in 50% oxygen saturation
of hemoglobin. A ________in the curve occurs when ______ saturation
happens at a lower PO2, while a
right shift indicates _________saturation
at a higher PO2.
27 mmhg - left shift and right - 50%
Myoglobin, found in __________ and ________, is a
monomeric, high-affinity oxygen-binding heme protein with a
hyperbolic oxygen dissociation curve
cardiac and skeletal muscle
___________ releases oxygen only at very low partial
pressures, making it less effective than hemoglobin at
delivering oxygen to tissues at physiologic oxygen tensions.
Myoglobin
Elevated serum myoglobin levels can indicate ______________, __________, __________, ____________
muscle damage in myocardial infarction, trauma, or rhabdomyolysis,
and in renal failure,
myoglobin may be present in ____________
urine.
_____________ the main hemoglobin in newborns, has a left-shifted
oxygen dissociation curve (higher oxygen affinity) compared
to Hb A.
Hgb F
This difference is due to a specific amino acid variation in
the 2,3-BPG binding site between the _____ and ________
γ and β chains - Hgb F
______________aids in extracting oxygen from
the maternal circulation but may hinder oxygen delivery to
tissues.
Hb F’s high oxygen affinity
__________ have a higher RBC count, hemoglobin
concentration, and hematocrit compared to adults, gradually
decreasing to adult levels by ___________ as Hb F is replaced
by Hb A
Newborn
6 months
_______________is produced by vascular endothelial cells and
causes relaxation of smooth muscle in the vascular walls,
leading to vasodilation
Nitric oxide
_______________ has a very short half-life, but some enters
red blood cells (RBCs) and can bind to _______ in the beta
chain of hemoglobin. This binding forms _____________
Free nitric oxide
cysteine
S nitrosohemoglobin
● Hypoxic Vasodilation Theory:
This process stimulates vasodilation and increases blood flow, a
phenomenon known as ____________
hypoxic vasodilation.
Some researchers propose that hemoglobin acts to _______________
preserve and
transport nitric oxide to hypoxic microvascular areas
Hemoglobin may work in conjunction with other systems to
regulate _________________
local blood flow to microvascular areas.
● Hypoxic Vasodilation Theory:
It can bind and inactivate nitric oxide, causing ____________
and decreased blood flow when oxygen levels are high.
vasoconstriction
Conversely, it can release nitric oxide, causing _____________ and
increased blood flow when oxygen levels are low.
vasodilation
WHAT ARE THE THREE DYSHEMOGLOBINS
● METHEMOGLOBIN
● SULFHEMOGLOBIN
● CARBOXYHEMOGLOBIN
______________ is formed through the reversible oxidation of
heme iron to the ferric state (Fe³⁺)
Methemoglobin
limit methemoglobin accumulation
NADH-cytochrome b5 reductase pathway
______________ cannot transport oxygen
Methemoglobin
● METHEMOGLOBIN
At levels exceeding __________ of total hemoglobin, _______
(bluish skin and mucous membrane discoloration) and
__________ symptoms may occur
Levels above _______ can lead to_____________
30% - cyanosis and hypoxia
50% - coma and death.
Methemoglobinemia (elevated methemoglobin levels) can be
__________ or __________
acquired or hereditary
Acquired: ____________, __________, ____________, ________, ____________
○ Hereditary: ______________, ____________
○ Acquired: exposure to external oxidants, such as nitrites,
primaquine, dapsone, or benzocaine
○ Hereditary: Cytochrome b5 reductase deficiency and Hb M
(M hemoglobin)
● METHEMOGLOBIN
Blood with high levels of methemoglobin takes on a
_________________ and does not revert to the typical ______________after oxygen exposure.
chocolate brown color - red
color
The formation of sulfhemoglobin involves adding a sulfur atom to the
pyrrole ring of heme, resulting in a ___________
greenish pigment.
individuals with elevated levels exhibit___________ (a bluish discoloration of
the skin).
cyanosis
○________________ cannot be converted back to normal Hb A
sulfhemoglobin
irreversible oxidation of hemoglobin by certain drugs (such as
__________, ______________, ______________, __________) or exposure to
sulfur-based chemicals in industrial or environmental settings
● SULFHEMOGLOBIN
sulfanilamides, phenacetin, nitrites, and phenylhydrazine
___________ is formed when carbon monoxide (CO) binds to heme iron
COHb - carboxyhemoglobin
_____________ has a much higher affinity for hemoglobin (240 times) compared to
oxygen. This affinity shift impairs the release of oxygen to body tissues
Carbon monoxide
Carbon monoxide is often referred to as the ____________ because it’s ____________ and _________ making its presence hard to detect. Victims may quickly become __________
(oxygen-deprived).
“silent killer”
odorless and colorless
hypoxic
Toxic effects start to appear at COHb levels of ___________, including symptoms like
_____________, _________, _____________
20-30% - headache, dizziness, and disorientation - Carboxyhemoglobin
COHb levels exceeding __________ of total hemoglobin can result in __________, ____________, ___________, _________, ____________, __________
40% - coma, seizures, low - carboxyhemogloin
blood pressure, cardiac arrhythmias, pulmonary edema, and may lead to death.
● Treatment involves removing the source of carbon monoxide exposure and
administering _____________ to facilitate the displacement of CO from hemoglobin
100% oxygen - CARBOXYHEMOGLOBIN
Red blood cells A. K. A.
aka Erythrocytes
Size of erythrocytes
7-8um
RBC average
7.2um
RBC Shape:
Biconcave Disc
RBC Lifespan:
90-120 days
RBC Function:
Efficient transport of oxygen from the lungs to the tissues,
and carbon dioxide from the tissues to the lungs
Hemoglobin
@Oxyhemoglobin
@Deoxyhemoglobin
Most hemoglobin found on the ___________
periphery
RBC
__________ volume
__________ surface area
- 90fL volume
- 140um2 surface area
Very thin cell membrane
* Large surface area compared to
volume
RBC
RBC is composed of ___________ proteins, ______lipids, ________ carbohydrates
52%, 40%, 8%
To separate the intracellular fluid
environment from the extracellular fluid
environment
RBC Membrane
Allow nutrient and ion passage selectively
in and out of the cell
RBC Membrane
➤Allow the cell to deform when required
RBC Membrane
