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MLS Heme Lec 11

QuestionAnswer
Where does globin chain synthesis occur and what what cell stages are involved RBC ribosome pronormoblast to reticulocyte
Globin chain synthesis is directed by 8 genetic loci per haploid genome
How many types of globin chains are produced by genes and what are the names 7, Zeta, Epsilon, Gamma-A, Gamma-G, Delta, Beta, and Alpha
What processes are involved for DNA replication transcription, translation, and codons
Location of genes Chromosome 16= Zeta (embryonnic), Alpha Chromosome 11= Epsilon (embryonic), Gamma, Delta, Beta
Activation of globin genes progress from Zeta to Alpha on chromosome 16 Epsilon to gamma, delta, beta on chromosome 11
Which chains only appear during embryonic development epsilon and zeta chains, produced up to 3 month following conception
Once produced, which chain is always present alpha
Embryonic hemoglobin hemoglobin gower 1 (zeta2, epsilon2) hemoglobin gower 2 (alpha2, epsilon2) hemoglobin portland (zeta2, gamma 2)
Production of gamma chains is active from what point and which hemoglobin is it third fetal month until 1 yr postnatally fetal hemoglobin (alpha2, gamma2)
By age 2 how much fetal hemoglobin is left <2%
What occurs postnatally between 3 and 6 months beta chain rises gradually and reaches adult percentages
What is the shape of normal adult hemoglobin tetramer consisting of 2 alpha chains 2 non-alpha chains- beta, delta, or gamma hydrogen bonds and salt bridges
Alpha2, Beta2 -hemoglobin A- is found in what percentage in both adults and newborns 95-97% Adult 30% Newborn
Alpha2, Delta2 -hemoglobinA2- percentage in both adults and newborns 2-3% Adult 1% Newborn
Alpha2, Gamma2 -hemoglobinF- percetage for both adults and newborns 1-2% Adult 70% Newborn
Hemoglobin production 1. heme is inserted into globin chains 2. amino acids become twisted in a helical shape and coil like a pretsel 3. comprises 33% of cell (2.8 million hemoglobin molecules/RBC)
If amino acid sequence changes what can happen the hemoglobin will not coil and the red cell is no longer pliable
Hemoglobin function delivery and release of oxygen to tissue facilitation of carbon dioxide excretion
One of the most important controls of hemoglobin affinity for oxygen is RBC organic phosphate 2,3-diphosphoglycerate (2,3-DPG) Produced in the Leubering-Rapaport Shunt
Deoxyhemoglobin hemoglobin when 2,3-BPG is present
Describe hemoglobin when 2,3-BPG is present it widens the space between the beta chains, forming an anionic salt bridge
Oxyhemoglobin occurs in the lung, hemoglobin when 2,3-BPG is absent
Describe hemoglobin when 2,3-BPG is absent the salt bridge is broken and the hemoglobin will carry more oxygen
Salt bridge in doxyhemoglobin causes a lower affinity for oxygen
Absent salt bridge in oxyhemoglobin causes beta chains to be pulled together which expels 2,3-BPG
Hemoglobin affinity for oxygen determines the proportion of oxygen that is released to the tissues or loaded onto the cell at a given oxygen pressure (PO2)
Increased oxygen affinity hemoglobin has a high affinity for oxygen, does not readily give up oxygen (in lungs)
Decreased oxygen affinity hemoglobin has a low affinity for oxygen, releases oxygen more readily
Oxygen affinity for hemoglobin is usually expressed as PO2 at which 50% of the hemoglobin is saturated with oxygen (P50)
P50 is normally 26 mm Hg
Hemoglobin-Oxygen Dissociation Curve sigmoid curve that results from hemoglobin-oxygen saturation is plotted vs partial pressure of oxygen (PO2)
PO2 partial pressure of oxygen
Hemoglobin-Oxygen Dissociation Curve description a physiological curve shape of a curve permits a considerable amount of oxygen to be delivered to the tissues with a small drop of oxygen tension
What is the oxygen tension in the lungs near 100 mm Hg 100% saturated
As RBCs circulate, oxygen is released when PO2 drops to 40 mm Hg 25% of oxygen is released at this point
P50 occurs around 22 mm Hg
Right shift in curve Hypoxia- reduction of oxygen supply to tissues Increased 2,3-BPG Anemia Acidosis Fever
Oxygen affinity is decreased more oxygen is released to the tissues
Decreased oxygen delivered to the tissues causes a oxygen tension drop 12% is released at 40mm Hg
Left shift in a curve Decreased 2,3-BPG Alkalosis Increased quantity of abnormal Hgb Multiple transfusions Fetal hemoglobin- red cells have high affinity for oxygen
During a Left Shift pH increases Temperature decreases 2,3-BPG decreases
During a Right Shift pH decreases Temperature increases 2,3-BPG increases
Acquired Nonfunctional Hemoglobins hemoglobin molecules have been altered
Altered hemoglobin causes compromised oxygen transport and consequences
Hypoxia inadequate amount of oxygen at tissue level
Cyanosis bluish color of skin due to presence of high amounts of deoxyhemoglobin in blood
3 nonfunctional hemoglobins Carboxyhemoglobin Methemoglobin Sulhemoglobin
Carboxyhemoglobin occurs when hemoglobin is exposed to carbon monoxide, can be fatal
Hemoglobins affinity for carbon monoxide vs oxygen is >200 times greater than affinity of oxygen
Smokers can have a carbon monoxide level up to 12%
Methemoglobin hemoglobin with iron in the ferric (+3) state
Methemoglobin is incapable of binding to oxygen
Increased levels of methemoglobin are formed when exposed to certain oxidizing drugs or chemicals
What age group is more susceptible to methemoglobin production Infants, HbF more readily converts
Sulfhemoglobin Irreversible change in hemoglobin molecule
Sulfhemoglobin structure Sulfur atom combines with each of the four heme groups and binds to the oxygen
Sulfhemoglobin affinity for oxygen vs hemoglobin 1/100
Senescence cell aging
Aging is characterized by Decline in glycolytic enzyme which decreases ATP production
During aging the cell loses the ability to Maintain shape Deformability Membrane integrity
Senescence results in what type of cells Spherocyte Rigid Burr
What removes senescent cells macrophages of the RE system
Transferrin returns iron to the BM or liver where it is stored as ferritin
Globin is broken down into amino acids and recycled
Protoporphyrin ring breaks down into toxic bilirubin which is carried to the liver by albumin
Where and why is bilirubin conjugated In the liver to make is more soluble and excretable
What is conjugated bilirubin converted into and why Urobilinogen by bacteria which is then excreted in the stool and a small amount in the kidney
90% of extravascular erythrocyte destruction takes place in the Spleen Liver Bone Marrow or Histocytes
10% of erythrocyte destruction is intravascular and results from RBC hemolysis
RBC hemolysis RBC ruptures in the blood vessels and hemoglobin is released directly into the bloodstream
RBC lifespan 120 days
Function of haptoglobin Picks up the alpha & beta dimers from ruptured RBC and takes them to the liver
How does haptoglobin prevent kidney damage Becomes a larger molecule that cannot be excreted by the kidney
The dimers are converted to bilirubin
Percent of RBCs removed daily 1%
The 1% is replaced by Reticulocytes from the bone marrow pool
What analysis is performed on a blood smear 100 cell differential of WBC RBC morphology examined Platelet estimation performed
Created by: mlrlemons