Hemoglobin Flashcards
1
Q
hemoglobin
A
- solid compound = heme + globin
- gives color to the RBCs
- aids in oxygen transport by adult RBCs
- occupies 1/3 of the cell
- remaining 2/3 = water
2
Q
site of hemoglobin formation
A
Bone marrow
- in developing red cells
- formed after 1 week
3
Q
components of hemoglobin
A
a. protoporphyrin IX
b. Fe2+
c. polypeptide chains
d. 2,3 diphosphoglyceric acid
4
Q
precursor of heme
A
Protoporphyrin IX
- initiates heme synthesis
- 4 molecules required
- first produced before joining with globin
- needed for new RBC & Hgb production only; present in the circulation where it monitors the number of RBCs
*N.V. (blood) = 16-60ug/dL
5
Q
combines with protoporphyrin IX to form the heme
A
Fe2+
- 4 atoms required
6
Q
polypeptide chains
A
- globin chains linked with each other forming a polypeptide
- protein part of the hemoglobin
- 2 sets required
7
Q
changes the hemoglobin’s affinity for oxygen
A
2,3 Diphosphoglyceric acid (2,3 DPG)
- by-product of the Embden-Meyerhof (glycolytic) pathway
- temporarily located @ the center of hemoglobin
8
Q
tissue oxygenation
A
- tissues are given oxygen
- 2,3 DPG regulates oxygen distribution of adult RBCs onto tissues needing it the most
9
Q
T/F:
↑ plasma 2,3 DPG = ↓ O2 affinity
A
TRUE
- 2,3 DPG GIVES O2 to tissues needing it most
10
Q
heme synthesis is ______________
A
Enzymatically directed
- enzymes are initially combined to produce products that give orders to protoporphyrin IX to make heme
- has a sequence of steps
- occurs mainly in erythroid precursors
11
Q
heme
A
protoporphyrin IX + Fe2+
12
Q
globin chain production
A
- “globin” = “globe” form
- designation is based on the differences of color & structure
13
Q
globin chains
A
- alpha (α)
- beta (β)
- gamma (γ)
- epsilon (ε)
- delta (δ)
- zeta (ζ)
14
Q
phases of protein synthesis
A
a. transcription
b. processing
c. translation
d. transfer
15
Q
production of mRNA in one of the amino acids
A
Transcription
- DNA sends a command to mRNA to find 1 amino acid to form the globin after complete preparation of heme
- DNA makes sure that the new Hgb of new RBCs will have the same Hgb structure as the dead RBCs
16
Q
T/F:
having different kinds of hemoglobin in RBCs is normal
A
FALSE
- having different kinds of hemoglobin will cause an adverse effect on the body –> functional ability of the RBCs are affected
- there should only be 1 kind of hemoglobin for all RBCs
17
Q
processing
A
formation of the final mRNA processed by (pre)mRNA
18
Q
mRNA translates the message onto different amino acids
A
Translation
- mRNA leaves the nucleus for a ribosome in the cytoplasm (tRNA)
19
Q
tRNA collects a specific amino acid from the cytoplasm & carry them to the appropriate site in the ribosome
A
Transfer
- mRNA tells the tRNA the specific amino acid needed from the DNA’s instruction
20
Q
hemoglobin variants
A
- different stages during the development of life
- identified by electrophoresis
- variants include:
- embryonic variant
- fetal Hgb
- adult Hgb
21
Q
present in the first 3 months after conception/copulation
A
Embryonic Hgb
- production: yolk sac
- existing Hgb in the embryo:
- Portland (ζ2γ2)
- Gower I (ζ2ε2)
- Gower II (α2ε2)
22
Q
meaning of “2” in α2ε2
A
indicates where one globin chain links to the other
23
Q
copulation
A
when sperm & egg cells meet
24
Q
fetal hemoglobin
A
- present from 4th month of embryonic development to birth
- production at birth: liver
- globins: α2γ2
25
adult hemoglobin
- from 1 year old above
- types:
- - HbA1 (α2β2)
- - HbA2 (α2δ2)
*types differ in structure only
26
the most common type of adult hemoglobin
HbA1
- aka "HBA"
- 97% of adult Hgb
HbA2
- 2%(-3%) of adult Hgb
27
location/s of functional hemoglobin
a. yolk sac
- embryonic variant
b. liver
- fetal stage
c. bone marrow
- adult stage
28
in the _____________ stage once hemoglobin is incorporated into the cell, it changes color
basophilic erythroblast stage (RBC)
| - color changes from blue to red
29
T/F:
| after RBCs dies, hemoglobin is captured by the macrophages
TRUE
| - to be transported to the spleen & liver, as well as the bone marrow
30
when hemoglobin is degraded, ___________ & _________ are recycled, while ______________ is excreted
IRON & GLOBIN CHAINS are recycled (heme synthesis); BILIVERDIN is excreted
- macrophage ingests Hgb --> digestion occurs --> Hgb broken down to Fe & biliverdin --> biliverdin converted to bilirubin & Fe used for heme synthesis
- globin waits for an available heme for combination
31
heme degradation
breaking apart of Fe & porphyrin
32
biliverdin
by-product of protoporphyrin breakdown
33
after completion of heme synthesis, excess porphyrin is found in the __________
mitochondrion
- porphyrin will be complexed to zinc
- porphyrin-zinc complex commands bone marrow to stop producing RBCs when a significant amount is obtained
34
excess protoporphyrin not used for heme production
Free erythrocyte porphyrin (FEP)
| - normal: FEP = remaining Fe
35
↑ FEP, ↓ Fe
indicative of IDA & lead (Pb) poisoning
- there is not enough Fe remaining for heme synthesis
*Pb poisoning: Pb affects the enzymatic sequence of heme production; one enzyme is destroyed by Pb --> heme synthesis inhibited
36
heme production remnants normally present
ferritin aggregates
| - seen after heme synthesis
37
hemoglobin derivatives that are beneficial to the body
Physiologic Hgb
a. oxyhemoglobin
- carries O2 around the body
b. reduced hemoglobin
- collects CO2 to be excreted
- reduced from being oxidized by O2
38
hemoglobin readily converted into a series of compounds by acids/alkali, RedOx agents, & heat
Non-beneficial Hgb
a. methemoglobin
b. sulfhemoglobin
c. carboxyhemoglobin
d. carboxysulfhemoglobin
39
hemiglobin (Hi)
Methemoglobin
- normal: 1.5% of the total hemoglobin
- Fe in heme group is Fe3+ --> unable to carry O2 to tissues
40
T/F:
| Fe3+ is an absorbing state
FALSE
- Ferric is NOT AN ABSORBING STATE
- presence of Fe3+ in Hi is due to the bone marrow's error of placing the wrong state onto the nRBCs
41
effects of increased Hi
a. cyanosis
- low oxygen supply in the body
b. functional anemia
- due to low oxygenation
42
T/F:
| Hi can be reversible
TRUE
| - Hi can be reduced back to Hgb by enzymes
43
oxidation of Fe to Fe3+ state by drugs & chemicals containing sulfur
Sulfhemoglobin (SHb)
| - sulfur penetrates into RBC, resulting in the oxidation of Fe2+ --> Fe3+
44
produced in a person with increased SHb
Green hemochrome
| - (yellow) sulfur powder + (bluish) color of patient (due to deoxygenation)
45
inclusions observed when sulfur keeps oxidizing the whole cell
Heinz bodies
| - denatured precipitated hemoglobin
46
hemoglobin which has an affinity for CO2
Carboxysulfhemoglobin
- cannot transport O2 since it prefers to collect CO2
- CO2 is not excreted --> more dangerous
- NOT REVERSIBLE; wait for the cells with it to die
47
this hemoglobin derivative binds with CO more than O2
Carboxyhemoglobin (HbCO)
- binds with CO 210x more than O2
- builds up until typical symptoms appear (CO poisoning)
48
CO
Carbon Monoxide
- the most dangerous gas
- sources: gasoline, tobacco smoking
- product of heme degradation to bilirubin
- "fart" (by-product) of macrophage ingestion
49
T/F:
| the presence of 40% HbCO in blood can lead to death
FALSE
| - MORE THAN 40% HbCO in blood causes death due to ACUTE CO poisoning
50
other effects of (Hb)CO
a. chronic CO poisoning
| b. hemolytic anemia
51
chronic CO poisoning
Prolonged exposure to small amounts of CO
- normal
- body is not exposed to CO 24/7 --> body can still replenish new RBCs
52
CO in hemolytic anemia
High/increased
- RBCs do not reach the normal lifespan (120 days)
- too much Hgb is released --> macrophage ingest free Hgb --> more CO produced by digestion
53
T/F:
| Free Hgb can combine with gases if not encased in the RBCs
TRUE
- since they are exposed to different gases, free Hgb can eat whatever gases it wants
*when encased in RBCs, Hgb is only limited to O2 & CO2 because of 2,3 DPG
