Erythrocytes
Describe what hemoglobin (Hb) is.
- Hb makes up most of what is found in erythrocytes
- it's a protein that binds gases (predominantly oxygen) and transports it in the body
- within the hemoglobin are four heme groups
- in one heme group there is one iron molecule which binds with the oxygen to form a covalent bond (hence each Hb can carry four oxygen molecules)
- this weak covalent bond allows for quick and efficient exchanging of gases
Define the following terms:
- amoeboid movement
- chemotaxis
- phagocytosis
Amoeboid movement: leukocytes send out cytoplasm to move itself
Chemotaxis: ability of a cell to respond to chemicals
Phagocytosis: process of ingesting other cells
Describe the first step of hemostasis and how it is regulated.
Vascular spasm is the first step. This is where vasoconstriction occurs as soon as the damage is noticed. Vasoconstriction reduces the blood flow here and slows down blood loss.
It is regulated using nitric oxide which causes vasodilation to occur at all times unless damage occurs, in which then it is no longer being released.
What is the stimulus for the extrinsic pathway?
The tissue factor from subendothelial cells start to be displayed, causing the extrinsic pathway to occur.
If a patient has the blood B+, what antigens and antibodies would they have?
A patient with B+ blood would have:
- B and Rh antigens
- A antibodies
When erythrocytes die, what happens to each of the following components of the cell:
- amino acids
- iron
- bilirubin
Amino Acids: recycled and used to create new hemoglobin in red bone marrow
Iron: recycled and used to create new hemoglobin in red bone marrow (not all Fe3+ are recycled again)
Bilirubin: sent to the liver to be excreted from the body such as in feces, urine or sweat
Name the cell lines that each of the following formed blood components come from:
- erythrocytes
- platelets
- T lymphocyte
- neutrophil
- monocyte
- basophil
- eosinophil
- B lymphocyte
Rule of thumb: If it doesn't have "lymph" in it, it comes from the myeloid cell line. If it does, it comes from the lymphoid cell line.
Myeloid Cell Line:
- erythrocytes (red blood cells)
- platelets
- neutrophil (granulocyte)
- basophil (granulocyte)
- eosinophil (granulocyte)
- monocyte (agranulocyte)
Lymphoid Cell Line:
- T lymphocyte (agranulocyte)
- B lymphocyte (agranulocyte)
Why isn't the platelet plug formation a long term solution to fixing blood vessel damage?
The platelet is a temporary, delicate plug made from the increase amounts of platelets being drawn to the damage site via aggregation. While helpful in slowing down the blood loss, it is not a long term goal because the platelets won't stick to each other without some sort of molecular "glue", which is developed in the coagulation step of hemostasis.
What is the enzyme complex of the intrinsic pathway made of?
Enzyme complex for intrinsic pathway consists of factors IXa, VIIIa and Ca2+. This helps activate factor X into Xa.
Which blood types have:
1) no antigens
2) no antibodies
1) O- has no antigens making the patient a universal donor.
2) AB+ has no antibodies making the patient a universal recipient.
How is the structure of RBCs helpful to their function? What is the structure of these cells?
Biconcave disc cell structure:
- gives high surface area to volume ratio which allows for faster and more efficient exchange (of oxygen) to occur
- maximizes the ability to transport, such as how stacks are created to allow blood to flow smoothly
- allows cells to bend & flex through tiny spaces which can minimize peripheral resistance
Erythrocytes also lose their nucleus and organelles as to allow for more hemoglobin molecules - "bags of hemoglobins"
What are granules? What types of formed elements have them?
Granules - small particles in granulocytes (leukocytes) that contain enzymes, toxins and other accessories to assist with certain functions of each specific granulocytes.
The formed elements that have granules are leukocytes, specifically granulocytes, and platelets!
How do the reasons for bleeding disorders differ from the reasons for hypercoagulable disorders?
For bleeding disorders (where blood isn't able to clot):
- often result from not having the correct clotting factors or proteins
- not having enough platelets
- having impaired liver functions
For hypercoagulable disorders (where blood has too many clots):
- occurs from either creating too many clots or not breaking down clots fast enough
- thrombosis (the abnormal clot formation) occurring can lead to emboli that could cause ischemia and/or infarction
- slow blood flow could also cause more clots to form
What is the prothrombin activator enzyme complex?
Seen in the common pathway, the prothrombin activator enzyme complex consists of Xa, Va and Ca2+. This is the enzyme complex that converts prothrombin into its active form, thrombin. This is also where factor Xa is used after being formed in the two pathways prior to this one.
What is agglutination? Is this a repairing or a destructive process?
When an antibody binds with an antigen of a matching type, it causes the destruction of erythrocytes (hemolysis).
This is an extremely destructive process.
What is anemia? What are 3 possible reasons for anemia to occur?
Anemia - the decreased carrying of oxygen in blood
1. Decreased Hb - one could have lots of erythrocytes but no Hb.
(i.e. iron deficiency anemia in which heme groups nor Hb can't be made due to the lack of iron)
2. Decreased hematocrit - one could not have as much erythrocytes as needed.
(i.e. hemolytic anemia in which erythrocytes are broken down extremely fast)
3. Abnormal Hb - irregular hemoglobin makes it harder for oxygen to be transported.
(i.e. sickle cell anemia in which the cells are sickle-shaped and can't transport as much oxygen)
How do B lymphocytes and T lymphocytes compare and contrast?
B Lymphocytes: interact with foreign bodies indirectly by producing antibodies that recognize foreign antigens and destroy cells.
Both: are derived from the lymphoid cell line, are agranulocyte white blood cells, and identify and destroy foreign bodies.
T Lymphocytes: interact with foreign bodies directly by binding to foreign antigens and destroying the cell.
Why is thrombolysis so important? What is used to destroy the clot?
The blood clot is no longer needed once a wound is healed. Having the clot stay in the body would increase one's chances of having an embolus which could lead to severe consequences. Fibrin is degraded by plasmin, causing the whole clot to unravel.
What is the overall goal of coagulation?
What are the three goals for the coagulation cascade?
Overall goal: strengthen platelet plug & make it long lasting.
1) Activate factor X -> Xa
2) Activate prothrombin -> thrombin
3) Activate fibrinogen -> fibrin
Goal 1 is achieved in the intrinsic and extrinsic pathways.
Goals 2 and 3 are achieved in the common pathway.
An injured individual requires an immediate blood transfusion. It is found that when testing for the patient's blood type, the patient's blood agglutinates with both blood type B and AB. However, the blood seems healthy when the patient's blood interacts with both blood types A and O. What antibodies does this patient have? What ABO blood types would be the safest to give to this patient?
Based off of the agglutination occurring, it can be assumed that the patient has anti-B antibodies in their blood. This means that they cannot receive blood from anyone who has any B antigens.
Possible donors:
Type A (A antigens)
Type O (no antigens)
Describe what erythropoiesis is and the steps for the formation of it.
Bonus question! What's the difference between reticulocytes and erythrocytes?
The making of erythrocytes! Red bone marrow is the origin for this.
1) Committing to becoming an erythrocyte
2) Erythropoietin is used in order to stimulate the cell
3) Lots of hemoglobin are synthesized
4) Organelles and nucleus leave the cell
5) The cell joins the blood!
Bonus:
Reticulocytes - immature erythrocyte without a nucleus
Erythrocytes - mature red blood cell
How are platelets made? What is this process called?
Thrombopoesis
1) HSC (where all blood components start from)
2) Myeloid cell line
3) Megakaryoblast created
4) Undergoes repeated mitosis without cytokinesis creating huge cell with huge nucleus (megakaryocyte created)
5) The megakaryocyte then lies by the bone marrow sinusoids where it sticks out cytoplasmic "arms" that get cut off by blood flow
What is happening in the fourth step of hemostasis?
Clot Retraction: similar to how actin and myosin would act in skeletal muscles, actin and myosin fibers in platelets help retract the clot from the wound so as to allow for repairing of the damage to occur. This action will suture together the edges of the damaged vessel, similar to how stitches are used.
How do factors V and VIII become activated (Va and VIIIa)?
By thrombin despite thrombin being produced after these are already activated. This is because the factors already have some activity and as thrombin is getting more and more produced, the factors are getting more activated. This is a positive feedback loop. Once activated clotting factors have left the local area of vasoconstriction, they get broken down by other enzymes in the blood.
For the following three situations, are the blood transfusions occurring helpful or harmful?
1) Donor: AB- ; Recipient: O+
2) Donor: A- ; Recipient: AB+
3) Donor: O+ ; Recipient: B-
Remember - look at donor antigens and compare with recipient antibodies.
1) Harmful! Donor has A and B antigens, but recipient has anti-A and anti-B antibodies. This would cause agglutination.
2) Helpful! Donor has A antigens, and recipient has no antibodies. *AB+ blood type is also a universal recipient*
3) Harmful! Donor has Rh antigens, but recipient has anti-A and anti-Rh antibodies! This would cause agglutination.