Flashcards in HIS 4-8 Blood Deck (70):
pH of blood
7.4 (slightly alkaline)
% composition of formed blood cells. RBC vs WBC and platelets.
99% RBC, 1% WBC and Platelets
Haem: Essential part of hemoglobin. Contains Fe2+ bound by 4 N's. Haem is also found in other biologically important hemoproteins such as myoglobin and cytochrome. It is mainly synthesized in the mitochondria of liver and bone marrow, while degraded in the spleen.
Myoglobin has very high affinity for O2 and slow dissociation. This allows myglobin to hold its breath for longer. Found in muscle tissue.
It harbors only one heme group, whereas hemoglobin has four. Although its heme group is identical to those in Hb, Mb has a higher affinity for oxygen than does hemoglobin. This difference is related to its different role: whereas hemoglobin transports oxygen, myoglobin's function is to store oxygen.
Myoglobin O2 bonding
Bonds only one O2 and does not have co-operative binding, therefore high k50, higher affinity, and lower disassociation.
Hyperbolic dissociation curve as opposed to sigmoidal.
Hemoglobin and O2 bonding, affinity and disassociation.
Hemoglobin has cooperative binding. Bonding with heme causes slight conformational shift, owing to increased affinity. This is allosteric regulation and co-opterativity. Upon the bonding of an O2, some salt bridges are broken and the Hemoglobin enters a more relaxed state.
So it has a lower affinity than myoglobin. The affinity increases as O2 binds. Therefore, affinity increases where O2 is high (lungs) and decreases where O2 is low (tissues). It also means that O2 dissociates at a higher partial pressure of O2, therefore responding to small changes in O2 concentration. The fourth O2 bind has an affinity 300x greater than the 1st.
quaternary structure, composed of 4 globular polypeptide chains (composed of two α and two β subunits) held together by noncovalent interactions. Each chain has a haem bound to an Fe+ by N bonds. Each Hgb molecule can bind 4 O2.
Fetal hemoglobin structure
Fetal hemoglobin has gamma chains in place of beta.
BOHR Effect: Oxygen is released more easily at lower pH (or increased CO2). This is in addition to the allosteric effect and so the sigmoidal curve shifts to the right in low pH.
How, and in what 2 ways is CO2 carried away from tissue?
70% of CO2 is carried as carbonic acid. CO2+H20 = H2CO3, reaction catalyzed by carbon anhydrase. In blood, H2CO3 releases H+. This H+ is acidic but it is mopped up by side chains of amino acid residues.
The other 30% bond to the nitrogen of an amino group.
2,3-biphosphoglycerate. Where does it come from and how does it effect hemoglobin?
Byproduct of glycolysis. It binds to deoxy hb and decreases the affinity for O2, therefore increasing the disassociation tendency. This moves the sigmoidal curve to the right and encourages hb to release its O2 in the tissues. In anemia or anaerobic metabolism, 2,3-biphosphoglycerate is produced in abundance and has the secondary effect of enhancing O2 disassociation.
How many RBS are formed per second?
Hematocrit, aka packed cell volume, is the lab measurement of RBS in blood. Should be 45%.
Name the 4 granulocytes
Name the 2 agranulocytes
lymphocytes (B/T and natural killer cells), and monocytes (which differentiate into macrophages and dendritic cells).
Neutrophils: 95% of granulocytes. First line of defense. Phagocytes. Elevated count indicates infection.
Synthesize and store histamine and heparin.
Eosinophils: Combat viral and parasitic infections. Play a role in allergic response. Secrete histamine.
Cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells.
Name the 2 lymphocytes
T and B cells
Monocytes: Enter tissues and engulf bacteria (macrophages) as well as process and remove old RBCs.
monocytes-a type of phagocyte.
CAD: Cell adhesion molecules
Cell adhesion molecules allow cells to secure themselves at sites of infection.
Erythopoiesis begins with proerythroblast and goes undergoes 7 stages of mitosis, each time replicating and becoming more developed.
Nutrients needed for erythropoiesis
B12, amino acids, Folate, Iron.
Anemia: Occurs from too little hemoglobin.
-decreased hemoglobin in RBCs
-Increased blood loss
(B12 or folate deficiency, leukemia, marrow failure-aplastic anemia), over destruction of RBC's (genetic), or morphological.
Caused by marrow failure
Anemia sign; loss of skin or mucous membrane color in eyes.
Anemia sign; upward curving of nails.
Anemia sign; cracking at sides of mouth.
Anemia sign; inflammation or infection of the tongue.
Polycythemia (2 types)
Excess of RBC's in blood:
Primary Polycythaemia: Tumor like condition leding to thick, viscous blood.
Secondary Polycythaemia: adaptive to altitude athletes.
Relative Polycythemia: Blood looses fluid but not RBCs. (Dehydration)
1,3 biphosphoglycerate is a side product of glycolysis. Converted to 2,3 BPG, it plays an important role in reducing Hb's affinity of O2, theirby helping Hb release its O2 in anemic conditions. It is produced more in anaerobic and anemic states. Moves the saturation curve left.
How do RBCs store DNA?
RBCs do not have DNA, as they have no nucleus.
How do RBCs import glucose into their cytosol? And how does it relate to diabetes?
Glucose receptor cells transport glucose across the membrane through facilitated diffusion, moving down concentration gradient without ATP. The transport is NOT mediated by insulin, so diabetics with poor glucose control have RBCs with high glucose content.
What effect does H2O2 have on RBCs?
H2O2 is a reactive oxygen species that converts oxidizes Fe^2+ making Fe^3+ in Hb, which bonds to H2O instead of O2.
Hemoglobin with oxidized Fe^2+, which binds to water instead of O2.
Lacking O2, eg high altitude.
What is the role of NADPH in RBCs?
NADPH fights reactive oxygen species (ROS) that oxidize heme, thereby helping to increase the lifespan of RBCs.
Reactive oxygen species (ROS)
Reactive oxygen species attack DNA, lipids, and proteins, causing cell death.
In RBC's they oxidize Fe2+, shorten cell life, and can cause anemia.
3 enzymes, with the help of NADPH, convert ROS's to H2O and O2:
SOD, catalase, and glutathione peroxidase.
G6P is necessary in the creation of NADPH in RBCs (catalyzed by G6P dehydrogenase), which fights the reactive oxygen species that would otherwise oxidize Fe^2+ in heme. A deficiency would cause less O2 caring capacity and reduced RBC life, resulting in anemia.
G6P dehydrogenase deficiency is a common form of haemolytic anemia.
Pentose phosphate pathway
Occurs in the cytoplasm of RBCs. Glucose-6-phosphate (G6P) is metabolized to produce 2 NADPH, which is a key reducing agent that protects Hb from oxidation by reactive oxygen species (eg H2O2).
Sickle Cell Anemia
HbS. Point mutation changes a glutamate to a valine. HbS unit have hydrophobic interactions that attract each other forming long hemoglobin chains that distort the cell shape.
A treatment given to people with Sickle cell anemia. It increases production of fetal hemoglobin which has a greater affinity to O2.
All blood cells are derived from a single pluripotent stem cell. They then go on to form RBC's WBC's and platelets.
What percentage of hemopoiesis is leucopoiesis and erythropoiesis?
Leucopoiesis accounts for 2/3 of production do to the short life of WBCs, despite only 1% of blood cells being white.
The other 1/3 of production is erythropoiesis because of their 120 day lifespan.
Mean Cell volume test
Tells the average volume of an RBC. Helps to distinguish types of anemia.
Mean Cell hemoglobin test
Tells the concentration of Hb in and average RBC.
Anemia due to blood loss
Trauma, internal bleed, excessive menstruation. Iron is lost, so cells are microcytic.
Anemia due to lack of erythropoiesis.
Iron, folate, B12 deficiency.
Marrow failure: aplastic anemia
Marrow invasion: leukemia
Most common cause. Hb deficiency or chronic blood loss.
Caused by chronic disease; marrow failure or marrow invasion.
Excessive hemolysis (eg G6P dehydrogenase deficiency).
Pernicious anemia: B12/intrinsic factor deficiency. Can be caused by gastrectomy, celiac disease, etc.
Cells grow too large with odd shape.
Megaloblastic anemia; folate deficiency.
How does glucose enter RBCs?
Glucose enters through a non-insulin dependent transporter.
RBCs can hold onto the excess glucose. Thus, RBC glucose is a good clinical indicator of how well a diabetic manages their condition.
Normocytic anemia, caused by excessive breakdown of RBCs. Most commonly due to increased oxidative stress.
Oxidative stress can be caused by antibiotics, antipyretics, inflammation and lava beans. And G6P dehydrogenase deficiency.
Blood types explained:
A and B blood types have corresponding antigens present on their cell surface. And the immense system has corresponding antibodies that fight off the other cells.
A blood has an A antigen and anti-B antibodies.
AB has A and B antigens and no antibodies.
O has no notions but anti-A and anti-B antibodies.
Therefore, AB can is the universal acceptor and O is the universal donor.
O and A are the most common in Europe.
Rhesus blood group
A group of blood type antigens, Cc, Dd, Ee. Dd is by far the most common
Rh+ means the blood is positive for Dd antigens. Does not have an antibody. The vast majority of people.
Rh- means the blood does not have the Dd antigen. Has and antibody against Dd.
Rh+ antigen will agglutinate amongst anti-Rh antibodies.
Blood is tested for blood type and transmittable disease. It is centrifuged and the RBCs are separated from plasma and RBCs. Preservatives and energy sources are added to prolong shelf-life.
The clumping of cells in the presence of an antibody.
Agglutination and hemolysis occurs when incompatible blood types are mixed.
Prior to blood transfusion:
Blood types are established. And cross matching is carried out to ensure that no agglutination and hemolysis occurs due to error.
O-. This means the the RBCs have no antigens present.
While O- may not have the antigens, it will have some antibody-A and antibody-B…And even though the Plasma is separated, it cannot all be taken out. This can cause problems when much blood is needed.
AB+. This means that the blood has all of the antigens and will not recognize the new blood as foreign.
Fetus Rhesus incompatibility. What are the parents?
Mother Rh-, Father Rh+, baby Rh+.
During first child, the mother will establish anti-Rh antibodies (primarily against D antigen). Subsequent children will be at risk of hemolysis from the mother's antibodies, causing anemia, jaundice, and death.
Rh- mothers with Rh+ child is given anti-D antibodies postpartum, which greatly reduces the issues of future incompatibility.
Blood enzyme: CK
Creatine Kinase catalyses the reaction of creatine phosphatase to creatine. It is released into the plasma from excessive turnover of muscle cells.
It is likely to be high after extreme exercise, surgery, MI, or Muscular Dystrophy.
Why measure enzymes in assays?
And why not?
Enzymes act as important markers and are easy to measure. However, they are not specific because they are normally present in more than one tissue.
Multiple forms of an enzyme that possess the ability to catalyze different reactions. They can be composed of slightly different subunits, or have tissue dependent activities depending on conditions.
Eg. creatine kinase is a dimer and lactate dehydrogenase is a tetramer of the same subunits.
Eg. Alkaline phosphatase is encoded on different chromosomes depending on what tissues it is in.
Liver function tests:
AST, ALT, ALP (alanine phosphatase), conjugated bilirubin, albumin, coagulation,
Amylase: hyperamylasaemia indicates pancreatitis.
Component of thin filament of muscle fiber. Useful for identifying MI.