As the blast cells differentiate, the resultant cells can be assigned to a particular cell line. Erythropoiesis is the development of red blood cells. There are several recognizable steps in this lineage:. Granulopoiesis is the process by which white blood cells develop. The myeloid series has the most characteristic cell lineage:.
Eosinophils and basophils undergo sequential stages of differentiation in a very similar manner to those of neutrophils. Their specific granules are also produced during the myelocyte stage. The platelet lineage is similar. Large, multilobed promegakaryocytes develop into megakaryocytes, which are the largest cells of the bone marrow 30 to 40 microns.
Platelets form through the segmentation of these cells. Monocytes develop from promonocytes and lymphocytes develop from prolymphocytes. These elements are difficult to distinguish in normal bone marrow smears. Pre-Lab Quiz What is the difference between blood, plasma, and serum? Answer: Blood is the combination of blood cells with acellular plasma. Plasma is the blood minus the cells. Serum is plasma without clotting factors or fibrin.
Answer: This drawing should show the biconcave disc shape from above and the dumbbell shape in the cross section. The reticulocyte would look the same as the RBC but would also contain organelles. All cells are 7. Answer: You would expect to see an increase in the number of eosinophils, which typically respond to helminthic parasites by degranulating, since these parasites are large and cannot be phagocytosed.
Answer: This patient most likely has a bacterial infection. Neutrophil counts are raised in the acute inflammatory response to bacteria. Slides Please select whether to view the slides in study mode or quiz mode. In study mode, the images will contain labels and a description.
In quiz mode, labels and description will be hidden. Study Mode. Virtual Microscope Slides Blood Smear Identify each of the following cell types in the blood smear: erythrocyte neutrophil platelet eosinophil lymphocyte.
Identify cells in the different stages of erythropoiesis and granulopoiesis. Pathology Please select whether to view the slides in study mode or quiz mode. Quiz Name the cell type. Answer: Allergy or Parasitic infection Eosinophil.
Answer: Bacterial Infection Neutrophil. Answer: Histamine and Heparin Basophil. Answer: Platelet - Blood Clotting. Answer: Band Cell. Become segmented. Answer: Reduction in ribosomes blue and increase in hemoglobin orange. Answer: Large cell is a promyeloblast. B cells and T cells, also called B lymphocytes and T lymphocytes , play prominent roles in defending the body against specific pathogens disease-causing microorganisms and are involved in specific immunity.
One form of B cells plasma cells produces the antibodies or immunoglobulins that bind to specific foreign or abnormal components of plasma membranes. This is also referred to as humoral body fluid immunity. T cells provide cellular-level immunity by physically attacking foreign or diseased cells. A memory cell is a variety of both B and T cells that forms after exposure to a pathogen and mounts rapid responses upon subsequent exposures.
Unlike other leukocytes, memory cells live for many years. B cells undergo a maturation process in the bone marrow, whereas T cells undergo maturation in the thymus. This site of the maturation process gives rise to the name B and T cells. The functions of lymphocytes are complex and will be covered in detail in the chapter covering the lymphatic system and immunity. Smaller lymphocytes are either B or T cells, although they cannot be differentiated in a normal blood smear.
Abnormally high lymphocyte counts are characteristic of viral infections as well as some types of cancer. Abnormally low lymphocyte counts are characteristic of prolonged chronic illness or immunosuppression, including that caused by HIV infection and drug therapies that often involve steroids.
Monocytes originate from myeloid stem cells. They normally represent 2—8 percent of the total leukocyte count. Macrophages are monocytes that have left the circulation and phagocytize debris, foreign pathogens, worn-out erythrocytes, and many other dead, worn out, or damaged cells.
Macrophages also release antimicrobial defensins and chemotactic chemicals that attract other leukocytes to the site of an infection. Some macrophages occupy fixed locations, whereas others wander through the tissue fluid. Abnormally high counts of monocytes are associated with viral or fungal infections, tuberculosis, and some forms of leukemia and other chronic diseases. Abnormally low counts are typically caused by suppression of the bone marrow. Most leukocytes have a relatively short lifespan, typically measured in hours or days.
Production of all leukocytes begins in the bone marrow under the influence of CSFs and interleukins. Secondary production and maturation of lymphocytes occurs in specific regions of lymphatic tissue known as germinal centers. Lymphocytes are fully capable of mitosis and may produce clones of cells with identical properties.
This capacity enables an individual to maintain immunity throughout life to many threats that have been encountered in the past. Leukopenia is a condition in which too few leukocytes are produced. If this condition is pronounced, the individual may be unable to ward off disease. Excessive leukocyte proliferation is known as leukocytosis. Although leukocyte counts are high, the cells themselves are often nonfunctional, leaving the individual at increased risk for disease.
Leukemia is a cancer involving an abundance of leukocytes. It may involve only one specific type of leukocyte from either the myeloid line myelocytic leukemia or the lymphoid line lymphocytic leukemia. In chronic leukemia, mature leukocytes accumulate and fail to die. In acute leukemia, there is an overproduction of young, immature leukocytes. In both conditions the cells do not function properly. As in leukemia, the malignant leukocytes do not function properly, and the patient is vulnerable to infection.
Some forms of lymphoma tend to progress slowly and respond well to treatment. Others tend to progress quickly and require aggressive treatment, without which they are rapidly fatal. You may occasionally see platelets referred to as thrombocytes , but because this name suggests they are a type of cell, it is not accurate.
A platelet is not a cell but rather a fragment of the cytoplasm of a cell called a megakaryocyte that is surrounded by a plasma membrane. As noted earlier, thrombopoietin, a glycoprotein secreted by the kidneys and liver, stimulates the proliferation of megakaryoblasts, which mature into megakaryocytes. These remain within bone marrow tissue Figure 3 and ultimately form platelet-precursor extensions that extend through the walls of bone marrow capillaries to release into the circulation thousands of cytoplasmic fragments, each enclosed by a bit of plasma membrane.
These enclosed fragments are platelets. Each megakarocyte releases — platelets during its lifespan. Following platelet release, megakaryocyte remnants, which are little more than a cell nucleus, are consumed by macrophages. After entering the circulation, approximately one-third migrate to the spleen for storage for later release in response to any rupture in a blood vessel. They then become activated to perform their primary function, which is to limit blood loss.
Platelets remain only about 10 days, then are phagocytized by macrophages. Platelets are critical to hemostasis, the stoppage of blood flow following damage to a vessel. They also secrete a variety of growth factors essential for growth and repair of tissue, particularly connective tissue. Infusions of concentrated platelets are now being used in some therapies to stimulate healing.
Thrombocytosis is a condition in which there are too many platelets. This may trigger formation of unwanted blood clots thrombosis , a potentially fatal disorder. If there is an insufficient number of platelets, called thrombocytopenia , blood may not clot properly, and excessive bleeding may result.
Figure 4. View University of Michigan Webscopes and explore the blood slides in greater detail. The Webscope feature allows you to move the slides as you would with a mechanical stage. You can increase and decrease the magnification. There is a chance to review each of the leukocytes individually after you have attempted to identify them from the first two blood smears.
In addition, there are a few multiple choice questions. Are you able to recognize and identify the various formed elements? You will need to do this is a systematic manner, scanning along the image. The standard method is to use a grid, but this is not possible with this resource. Try constructing a simple table with each leukocyte type and then making a mark for each cell type you identify.
Attempt to classify at least 50 and perhaps as many as different cells. Based on the percentage of cells that you count, do the numbers represent a normal blood smear or does something appear to be abnormal?
Leukocytes function in body defenses. They squeeze out of the walls of blood vessels through emigration or diapedesis, then may move through tissue fluid or become attached to various organs where they fight against pathogenic organisms, diseased cells, or other threats to health. Granular leukocytes, which include neutrophils, eosinophils, and basophils, originate with myeloid stem cells, as do the agranular monocytes.
The other agranular leukocytes, NK cells, B cells, and T cells, arise from the lymphoid stem cell line. The most abundant leukocytes are the neutrophils, which are first responders to infections, especially with bacteria.
Leukemia and lymphoma are malignancies involving leukocytes. Platelets are fragments of cells known as megakaryocytes that dwell within the bone marrow. While many platelets are stored in the spleen, others enter the circulation and are essential for hemostasis; they also produce several growth factors important for repair and healing.
Answer the question s below to see how well you understand the topics covered in the previous section. Show Answers.
B lymphocytes: also, B cells lymphocytes that defend the body against specific pathogens and thereby provide specific immunity. T lymphocytes: also, T cells lymphocytes that provide cellular-level immunity by physically attacking foreign or diseased cells.
Skip to main content. Module 2: The Cardiovascular System: Blood.
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