Flashcards in TBL12 - Blood Deck (22):
Define the fractions of blood composed of RBCs (hematocrit), leukocytes and platelets (buffy coat), and plasma. What percentage of plasma volume do proteins compose? What is blood serum?
1) Hematocrit - 45%; Buffy coat - <1%; Plasma - 55%
2) Proteins compose 7% of plasma volume
3) Blood serum is plasma minus the clotting proteins
What is characteristic of RBCs in normal blood smears? Define the functional relevance of the biconcavity.
1) Mature RBCs are biconcave, which accounts for their characteristic central pallor in normal blood smears
2) A biconcave shape provides a large surface area for
primary functions: transporting O2 from lungs to tissues and returning CO2 from tissues to lungs for elimination
What occupies most of the RBC cytoplasm? Relate their biconcavity to the cytoskeleton and orange-red to pink color to the hemoglobin (check if this is right)
1) Cytoskeleton and hemoglobin occupy most of the RBC cytoplasm
2) During final stages of erythropoietic development in
bone marrow, RBCs lose the nucleus and almost all organelles except the cytoskeleton and then enter the circulation
3) Hemoglobin is a conjugated protein containing the pigment heme and the protein globin. Heme is a porphyrin combined with iron
What are neutrophils characterized by? What are other names for neutrophils and what is this based off of?
1) Neutrophils are characterized by multilobulated nuclei and fine cytoplasmic granules
2) Based on their multilobulated nuclei, neutrophils are also called polymorphonuclear leukocytes, PMNs, polys, and polymorphs
How are cytoplasmic lysosomes of neutrophils visualized? How do smaller fine granules appear in a blood smear? Relate content of the fine granules to the main function of PMNs.
1) Cytoplasmic lysosomes of neutrophils are typically visualized by electron microscopy
2) The smaller fine granules are the faintly stained granules visible in blood smears
3) The fine granules are sacs of enzymes produced from lysosomes that act in digested foreign bacteria
What is the lifespan of leukocytes and where do they travel to?
Unlike erythrocytes that remain in the circulation during their 120-day life span, all leukocytes circulate only a few days before traversing the capillary endothelium into the interstitial fluid of the surrounding connective tissue
What is anemia and why can a loss of central pallor indicate sickle cell anemia?
1) A deficiency of RBCs and/or hemoglobin is anemia
2) Loss of central pallor indicates a loss of the biconcave shape of RBCs, meaning that there is a deformity in the shape of the RBCs such as sickle cell anemia
What conditions cause neutrophilia and neutropenia?
1) Bacterial infection causes neutrophilia (elevated levels of neutrophils)
2) Neutropenia is an abnormal decrease in neutrophil numbers in peripheral blood so that too few cells are available to defend against bacterial infections. Neutropenia may be caused by genetic, drug-induced, or other factors, but it is often associated with autoimmune diseases and is a common feature of AIDS
What is a “shift to the left” that can occur with bacterial infections?
1) A small percentage (1%-3%) of band cells may normally enter the bloodstream, but a significantly increased number indicates a rise in cell production
2) Increase in band cells means an infection is imminent because the band cells can then differentiate into neutrophils to fight the infection
3) Known clinically as a shift to the left, this condition may indicate leukemia
Define the phagocytic function of eosinophils. Interpret how their granular contents affect the functions of mast cells and basophils
1) Nuclear shapes and recall granular colors of the eosinophils and basophils (Their specific granules are distinctive, uniform in size, highly refractile, and have an affinity for acid dyes and thus stain dark pink to crimson)
2) The cells phagocytose antigen-antibody complexes and parasites, and elevated cell numbers occur in parasitic infections and allergic responses such as hay fever and asthma
3) These granules contain various hydrolytic enzymes and secrete histaminase, which inactivates histamine produced by basophils and mast cells
Why are basophils difficult to identify in normal blood smears?
Basophils account for ≤ 1% of circulating leukocytes; thus, they are very difficult to identify in normal blood smears
Which primary conditions induce eosinophilia?
Eosinophilia—an increased absolute number of circulating eosinophils above normal—occurs in parasitic infestations, allergic reactions, and some malignancies
How is mild and severe basophilia distinguished?
1) Mild basophilia may be part of a general inflammatory response to some infections, for example, smallpox, chickenpox, or influenza. It also occurs in allergic disorders or autoimmune inflammation such as rheumatoid arthritis or ulcerative colitis
2) More often, and for unclear reasons, basophilia is noted in malignant hematologic conditions called myeloproliferative disorders. The most common such condition is chronic myeloid leukemia, in which basophils are often markedly increased, as are eosinophils, neutrophils, and immature neutrophilic forms such as band cells, metamyelocytes, myelocytes, and promyelocytes. In patients with chronic myeloid leukemia, an increasing basophil count can suggest worsening of disease
Compare nuclear shapes and amounts of cytoplasm in lymphocytes and monocytes.
Each monocyte has a nucleus that varies in form and may have an oval, kidney, or horseshoe shape. In contrast to the coarse, dark-staining nuclear chromatin of lymphocytes, monocyte nuclear chromatin is finely granular and pale stained, and indented. Monocyte cytoplasm has a blue-gray tinge and contains a moderate number of small, scattered azurophilic granules but no specific granules
What are the main types of lymphocytes?
T cells and B cells, which are indistinguishable in blood smears, are the main types of lymphocytes
What do monocytes become and when?
Monocytes are precursor cells that enter the interstitial fluid to become macrophages during acute inflammatory responses
When does lymphocytosis occur in infants and adolescents, and what is infectious mononucleosis?
Lymphocytosis is an abnormal increase in absolute number of lymphocytes in peripheral blood. It often occurs in infants and adolescents during infections that would likely produce a neutrophil response in adults. Of the many causes, the most common is primary infection with Epstein-Barr virus (EBV). The condition, also known as infectious mononucleosis, causes a rise in circulating T lymphocyte numbers in response to EBV infection of B cells. Lymphocytes are larger than normal and look atypical. Specific antibodies to EBV nuclear antigen appear in the blood and last for life
Why does monocytosis occur with chronic infections such as bacterial endocarditis?
Although monocytosis is rare, many conditions may cause it: chronic bacterial infections, bacterial endocarditis (inflammation of the inner lining of the heart wall), typhoid, malaria, syphilis, and protozoan infections.
What do platelets look like? Relate platelets to blood clot formation.
1) Platelets (aka thrombocytes) are tiny cytoplasmic fragments, visible in blood smears only when they cluster into larger clumps
2) Platelets play a major role in blood coagulation
What is the largest hemopoietic cell in the bone marrow? What happens after their stimulation by thrombopoietin?
1) Megakaryocytes are the largest hemopoietic cell in the bone marrow
2) After their stimulation by thrombopoietin, organized cytoplasmic fragmentation forms the platelets
What causes thrombocytopenia?
Thrombocytopenia is a condition involving abnormal depletion of platelets in blood. It may be caused by failure of bone marrow to produce adequate numbers of platelets or by a greater rate of removal of platelets from blood. Platelets are critical for blood clotting, so an
untreated disorder leads to bruising and severe bleeding