Hematology Flashcards
What is the main function of RBCs?
To carry oxygen via hemoglobin molecules
Blood is a body fluid with 4 main functional components…
- Plasma
- Red blood cells (erythrocytes)
- White blood cells (leukocytes)
- Platelets (thrombocytes)
Describe RBC shape
biconcave disk
Describe RBC nucleus
Anucleate (no nucleus) - not alive
What blood component contributes to blood viscosity?
RBCs
Which is more numerous in the blood? RBCs or WBCs?
RBCs
Briefly describe erythropoiesis
Process of RBC production
- Multipotent stem cell differentiates into myeloid stem cell
- Myeloid stem cell differentiates into an erythrocyte (stimulated by erythropoietin produced by the kidneys)
- Erythrocyte differentiates into a reticulocyte (newborn RBC)
Reticulocyte
Immature RBCs, still contain some ribosomal RNA (producing hemoglobin)
Erythropoiesis begins in the…
bone marrow
Reticulocytes do not normally circulate in the peripheral blood except in states of…
anemia
Erythropoietin
Hormone produced by renal tubule cells in response to blood O2 levels - stimulates erythropoiesis
When the need for oxygen is significant and acute (eg. in a state of anemia), the bone marrow might push out …
immature RBC precursors or reticulocytes into the bloodstream
RBC oxygenation happens in …
lungs
RBCs pick up oxygen molecules via … from the lung alveoli
diffusion
Hemoglobin is comprised of …
4 globulin subunits (2 alpha, 2 beta)
Hemoglobin
Oxygen carrying molecule in the blood. Heme (iron-containing molecule) bound to globin proteins.
Alterations in hemoglobin sructure will alter its ability to…
carry oxygen
Describe carbon monoxide poisoning
Carbon monoxide poisoning causes hemoglobin to bind more tightly to oxygen, causing oxygenated blood to flow through the body but without dropping oxygen off to the tissues.
Why does carbon monoxide not cause cyanosis?
Cyanosis (bluish color in skin due to oxygen shortage) does not occur because the blood circulating is rich in oxygen (however, it is not distributing that oxygen to tissues).
When O2 binds hemoglobin, it induces…
a conformational change in the structure that makes it more receptive to more oxygen binding
One molecule of hemoglobin can carry…
4 oxygen molecules
Name the 5 different types of WBC
- Neutrophil
- Eosinophil
- Basophil
- Monocyte
- Lymphocyte
During WBC development, hematopoietic stem cells differentiate into two major progenitor cells…
- Myeloid stem cells
- Lymphoid stem cells
Platelets arise from…
multinucleated megakaryocytes in bone marrow
Describe the nucleus of platelets
Platelets are small, anuclear cells
What is the role of platelets?
Platelets interact with proteins from the coagulation cascade and lead to blood clotting
What is plasma?
Liquid component of blood, mostly water and proteins, electrolytes
Plasmapheresis
Separation of plasma from the cellular blood components
What is a CBC test?
A complete blood count test (CBC) is a common blood test that measures the levels of the different components of blood to evaluate overall health and detect conditions like anemia.
MCV
Mean corpuscular volume: measure of the average size or volume of RBCs, key component of the CBC
Hematocrit
Measures proportion of RBCs in the blood (key component of CBC)
[RBC volume]/[Total blood volume] *100
RDW
Red cell distribution width: measure of the variation in size of RBCs in a blood sample (component of the CBC)
MCH
Mean corpuscular hemoglobin: measure of the average amount of hemoglobin contained in each red blood cell
MCHC
Mean corpuscular hemoglobin concentration: measure of the average concentration of hemoglobin within a given volume of RBCs
MPV
Mean platelet volume
Would having large RBCs affect your hematocrit?
Yes, if you have large RBCs your hematocrit would be higher despite having the same number of RBCs as another person with smaller RBCs.
Microcytosis
RBCs are smaller than average (less than 80fl)
Macrocytosis
RBCs are larger than average (more than 95fl)
The RDW increases when…
a population of abnormal RBCs (microcytic or macrocytic) suddenly starts circulating in the blood
The MCHC decreases when…
there are issues in hemoglobin synthesis
What is the purpose of a peripheral blood smear?
It is used to examine the appearance, size and shape of RBCs under the microscope. It can provide more info about the reason for any abnormal values observed in the CBC.
What are some examples of abnormal RBC morphologies that can be detected in a peripheral blood smear? (5)
- Spherocyte (spherical rather than biconcave disk)
- Sickle cell (crescent rather than biconcave disk)
- Red cell fragment
- Acanthocyte (spiky or irregular projections)
- Elliptocyte (oval or elongated shape)
Define anemia
Decreased ability of blood to carry oxygen to the cells due to decreased overall hemoglobin
What are the potential causes for decreased overall hemoglobin?
- Decreased RBC number
- Decrease in the body’s ability to make hemoglobin
- Decreased hemoglobin function
Symptoms of anemia
Fatigue, pallor, weakness
Why is cyanosis not a symptom of anemia?
Cyanosis happens when hemoglobin cannot be saturated properly. It is usually due to a lack of oxygen rather than a lack of hemoglobin.
