As the infection continues, lymphocytes increase. Worm infections can trigger an increase in eosinophils, whereas allergic conditions, such as hay fever, trigger an increase in basophils.
Normally, one cubic millimeter of blood contains between , and , platelets. If the number drops below this range, uncontrolled bleeding becomes a risk, whereas a rise above the upper limit of this range indicates a risk of uncontrolled blood clotting. Hemoglobin is the oxygen-carrying protein that is found within all RBCs. It picks up oxygen where it is abundant the lungs and drops off oxygen where it is needed around the body.
Hemoglobin is also the pigment that gives RBCs their red color. As its name suggests, hemoglobin is composed of "heme" groups iron-containing rings and "globins" proteins. In fact, hemoglobin is composed of four globin proteins—two alpha chains and two beta chains—each with a heme group. The heme group contains one iron atom, and this can bind one molecule of oxygen. Because each molecule of hemoglobin contains four globins, it can carry up to four molecules of oxygen.
See hemoglobin structure in Albert's Molecular Biology of the Cell. In the lungs, a hemoglobin molecule is surrounded by a high concentration of oxygen, therefore, it binds oxygen. In active tissues, the oxygen concentration is lower, so hemoglobin releases its oxygen. This behavior is much more effective because the hemoglobin——oxygen binding is "co-operative". This means that the binding of one molecule of oxygen makes it easier for the binding of subsequent oxygen molecules. Likewise, the unbinding of oxygen makes it easier for other oxygen molecules to be released.
This means that the response of hemoglobin to the oxygen needs of active tissues is much quicker. Aside from the oxygen saturation of hemoglobin, other factors that influence how readily hemoglobin binds oxygen include plasma pH, plasma bicarbonate levels, and the pressure of oxygen in the air high altitudes in particular.
The molecule 2,3-disphosphoglycerate 2,3-DPG binds to hemoglobin and lowers its affinity for oxygen, thus promoting oxygen release. In individuals who have become acclimatized to living at high altitudes, the level of 2,3-DPG in the blood increases, allowing the delivery of more oxygen to tissues under low oxygen tension. Fetal hemoglobin differs from adult hemoglobin in that it contains two gamma chains instead of two beta chains.
Fetal hemoglobin binds oxygen with a much greater affinity than adult hemoglobin; this is an advantage in the womb because it allows fetal blood to extract oxygen from maternal blood, despite its low concentration of oxygen. Old or damaged RBCs are removed from the circulation by macrophages in the spleen and liver, and the hemoglobin they contain is broken down into heme and globin. The globin protein may be recycled, or broken down further to its constituent amino acids, which may be recycled or metabolized.
The heme contains precious iron that is conserved and reused in the synthesis of new hemoglobin molecules. During its metabolism, heme is converted to bilirubin, a yellow pigment that can discolor the skin and sclera of the eye if it accumulates in the blood, a condition known as jaundice. Instead, the plasma protein albumin binds to bilirubin and carries it to the liver, where it is secreted in bile and also contributes to the color of feces.
Jaundice is one of the complications of an incompatible blood transfusion. This occurs when the recipient's immune system attacks the donor RBCs as being foreign. The rate of RBC destruction and subsequent bilirubin production can exceed the capacity of the liver to metabolize the bilirubin produced. Hemoglobinopathies form a group of inherited diseases that are caused by mutations in the globin chains of hemoglobin.
Sickle cell anemia is the most common of these and is attributable to a mutation that changes one of the amino acids in the hemoglobin beta chain, producing hemoglobin that is "fragile". When the oxygen concentration is low, RBCs tend to become distorted and "sickle" shaped.
These deformed cells can block small blood vessels and damage the organs they are supplying. This can be very painful, and if not treated, a sickle cell crisis can be fatal. Another inherited anemia that particularly affects individuals of Mediterranean descent is thalassemia. A fault in the production of either alpha or beta globin chains causes a range of symptoms, depending on how many copies of the alpha and beta genes are affected. Some individuals may be carriers of the disease and have no symptoms, whereas if all copies of the genes are lost, the disease is fatal.
The porphyrias are a group of inherited disorders in which the synthesis of heme is disrupted. Depending upon the stage at which the disruption occurs, there are a range of neurological and gastrointestinal side effects.
Karl Landsteiner, Nobel Laureate from Nobelprize. Turn recording back on. National Center for Biotechnology Information , U. Show details Dean L. Search term. Chapter 1 Blood and the cells it contains. This chapter introduces the components of blood. Blood contains cells, proteins, and sugars. Box Meet the blood cells. Red blood cells transport oxygen.
White blood cells are part of the immune response WBCs come in many different shapes and sizes. Neutrophils digest bacteria. Monocytes become macrophages. Lymphocytes consist of B cells and T cells. Platelets help blood to clot. Your complete blood count A complete blood count CBC is a simple blood test that is commonly ordered as part of a routine medical assessment. Table 1 Complete blood count.
As we showed recently [ 4 ], all papers regarding the number of bacteria in the human gastrointestinal tract that gave reference to the value stated could be traced to a single back-of-the-envelope estimate [ 3 ]. That order of magnitude estimate was made by assuming 10 11 bacteria per gram of gut content and multiplying it by 1 liter or about 1 kg of alimentary tract capacity. To get a revised estimate for the overall number of bacteria in the human body, we first discuss the quantitative distribution of bacteria in the human body.
After showing the dominance of gut bacteria, we revisit estimates of the total number of bacteria in the human body. Table 1 shows typical order of magnitude estimates for the number of bacteria that reside in different organs in the human body. The estimates are based on multiplying measured concentrations of bacteria by the volume of each organ [ 9 , 10 ]. Values are rounded up to give an order of magnitude upper bound. For the skin, we used bacterial areal density and total skin surface to reach an upper bound.
Table 1 reveals that the bacterial content of the colon exceeds all other organs by at least two orders of magnitude. Importantly, within the alimentary tract, the colon is the only substantial contributor to the total bacterial population, while the stomach and small intestine make negligible contributions.
Such estimates are often very illuminating, yet it is useful to revisit them as more empirical data accumulates.
Yet, the parts of the alimentary tract proximal to the colon contain a negligible number of bacteria in comparison to the colon content, as can be appreciated from Table 1. As discussed in Box 1 , we integrated data sources on the volume of the colon to arrive at 0. This is a critical parameter in our calculation. We used a value of 0. The volume of the colon content of the reference adult man was previously estimated as mL g at density of 1.
A recent study [ 15 ] gives more detailed data about the volume of undisturbed colon that was gathered by MRI scans. Taking a height of 1. This volume includes an unreported volume of gas and did not include the rectum.
Most recently, studies analyzing MRI images of the colon provided the most detailed and complete data. The inner colon volume in that cohort was mL in total [ 16 , 17 ]. This cohort was, however, significantly taller than the reference man. Normalizing for height, we arrive at mL total volume for a standard man. Therefore, this most reliable analysis together with earlier studies support an average value of about 0.
We can sanity-check this volume estimate by looking at the volume of stool that flows through the colon. An adult human is reported to produce on average — grams of wet stool per day [ 18 ]. The colonic transit time is negatively correlated with the daily fecal output, and its normal values are about 25—40 hours [ 18 , 19 ].
By multiplying the daily output and the colon transit time, we thus get a volume estimate of — mL, which is somewhat lower than but consistent with the values above, given the uncertainties and very crude estimate that did not account for water in the colon that is absorbed before defecation.
To summarize, the volume of colon content as evaluated by recent analyses of MRI images is in keeping with previous estimates and fecal transit dynamics. Values for a reference adult man averaged 0. We are now able to repeat the original calculation for the number of bacteria in the colon [ 3 ]. Given 0. Considering that the contribution to the total number of bacteria from other organs is at most 10 12 , we use 3.
The most widely used approach for measuring the bacterial cell density in the colon is by examining bacteria content in stool samples. This assumes that stool samples give adequate representation of colon content.
We return to this assumption in the discussion. The first such experiments date back to the s and s [ 20 , 21 ]. In those early studies, counting was based on direct microscopic clump counts from diluted stool samples. Values are usually reported as bacteria per gram of dry stool.
For our calculation, we are interested in the bacteria content for the wet rather than dry content of the colon. Table 2 reports the values we extracted from 14 studies in the literature and translated them to a common basis enabling comparison. Full references are provided in Table A in S1 Appendix. Mean bacteria number is calculated using the geometric mean to give robustness towards outlier values. Values quoted directly from the articles are written in bold, values derived by us are written in italic.
Values reported with more than two significant digits are rounded to two significant digits as the uncertainty makes such overspecification nonsensible.
From the measurements collected in Table 2 , we calculated the representative bacteria concentration in the colon by two methods, yielding very close values: the geometric mean is 0. We note that the uncertainty estimate value takes into account known variation in the colon volume, bacteria density, etc. One prominent such bias is the knowledge gap on differences between the actual bacteria density in the colon, with all its spatial heterogeneity, and the measurements of concentration in feces, which serve as the proxy for estimating bacteria number.
What is the total mass of bacteria in the body? From the total colon content of about 0. Given the dominance of bacteria in the colon over all other microbiota populations in the body, we conclude that there is about 0.
Given the water content of bacteria, the total dry weight of bacteria in the body is about 50—g. This value is consistent with a parallel alternative estimate for the total mass of bacteria that multiplies the average mass of a gut bacterium of about 5 pg wet weight, corresponding to a dry weight of 1—2 pg, see S1 Appendix with the updated total number of bacteria. The total bacteria mass we find represents about 0. Many literature sources make general statements on the number of cells in the human body ranging between 10 12 to 10 14 cells [ 26 , 27 ].
An order of magnitude back-of-the-envelope argument behind such values is shown in Box 3. We thus arrive at 10 13 —10 14 human cells in total in the body, as shown in Fig 1. For these kind of estimates, where cell mass is estimated to within an order of magnitude, factors contributing to less than 2-fold difference are neglected.
Thus, we use kg as the mass of a reference man instead of 70 kg and similarly ignore the contribution of extracellular mass to the total mass. These simplifications are useful in making the estimate concise and transparent. An alternative method that does not require considering a representative "average" cell systematically counts cells by type.
Such an approach was taken in a recent detailed analysis [ 1 ]. The number of human cells in the body of each different category by either cell type or organ system was estimated. For each category, the cell count was obtained from a literature reference or by a calculation based on direct counts in histological cross sections.
Summing over a total of 56 cell categories [ 1 ] resulted in an overall estimate of 3. In our effort to revisit the measurements cited, we employed an approach that tries to combine the detailed, census approach with the benefits of a heuristic calculation used as a sanity check. In four cases red blood cells, glial cells, endothelial cells, and dermal fibroblasts , we arrived at revised calculations as detailed in Box 4.
The largest contributor to the overall number of human cells are red blood cells. Calculation of the number of red blood cells was made by taking an average blood volume of 4.
The latter could be verified by looking at your routine complete blood count, normal values range from 4. This led to a total of 2. This is similar to the earlier report of 2. See Table B in S1 Appendix for full references.
This estimate is based on a ratio between glial cells and neurons in the brain. This ratio of glia:neurons was held as a broadly accepted convention across the literature. However, a recent analysis [ 28 ] revisits this value and, after analyzing the variation across brain regions, concludes that the ratio is close to The study concludes that there are 8.
The number of endothelial cells in the body was earlier estimated at 2. We could not find a primary source for the total length of the capillary bed and thus decided to revisit this estimate.
We used data regarding the percentage of the blood volume in each type of blood vessels [ 29 ]. Using mean diameters for different blood vessels [ 30 ], we were able to derive S1 Data the total length of each type of vessel arteries, veins, capillaries, etc. The number of dermal fibroblasts was previously estimated to be 1.
We wished to incorporate the dermal thickness d into the calculation. Dermal thickness was directly measured at 17 locations throughout the body [ 34 ], with the mean of these measurements yielding 0. Combining these we find: N der. Our revised calculations of the number of glial cells, endothelial cells, and dermal fibroblast yield only 0. This leaves us with 3. We note that the uncertainty and CV estimates might be too optimistically low, as they are dominated by the reported high confidence of studies dealing with red blood cells but may underestimate systematic errors, omissions of some cell types, and similar factors that are hard to quantify.
In Fig 2 , we summarize the revised results for the contribution of the different cell types to the total number of human cells. This is the subject of the following analysis. Representation as a Voronoi tree map where polygon area is proportional to the number of cells. It is prudent in making such estimates to approach the analysis from different angles.
In that spirit, we now ask does the cumulative mass of the cells counted fall within the expected range for a reference adult? To properly tackle that question, we first need to state what the anticipated result is, i. A comprehensive systematic source for the composition of total cell mass rather than total cell count is the Report of the Task Group on Reference Man [ 6 ], which gives values for the mass of the main tissues of the human body.
This mass per tissue analysis includes both intra- and extracellular components. To distinguish between intra- and extracellular portions of each tissue, we can leverage total body potassium measurements [ 38 ] as detailed in S1 Appendix. Fig 3 compares the main tissues that contribute to the human body, in terms of cell number and masses.
For comparison, the contribution of bacteria is shown on the right, amounting to only 0. A striking outcome of this juxtaposition is the evident discordance between contributors to total cell mass and to cell number. Splenomegaly is common. As the disease progresses, anemia and thrombocytopenia will appear. Hypogammaglobulinemia develops in almost all patients, increasing the risk of infections, predominantly with encapsulated gram-positive organisms. Autoimmune hemolytic anemia and hypersplenism are common.
The natural history of the disease is measured in years. T cell CLL is a more aggressive disease. The skin is commonly involved and splenomegaly is seen early in the course of the disease. Multiple myeloma results from the monoclonal proliferation of a plasma cell. The malignant population retains its ability to secrete immunoglobulins.
As this production continues unchecked, it results in hyperglobulinemia that produces a single "M" spike on protein electrophoresis. Most myelomas secrete IgG or IgA. IgE and IgM myelomas are extremely rare. The clinical presentation includes bone pain and anemia. Symptoms of hypercalcemia, renal failure, and hyperviscosity may be present. On the peripheral smear a normochromic, normocytic anemia is encountered. Rouleaux formation is common.
Plasma cells can be found in circulation, and when predominant, a diagnosis of plasma cell leukemia is made. The protein electrophoresis reveals the M spike with greater than 3 g of the immunoglobulin. Immunoelectrophoresis identifies and quantifies the increased immunoglobulin.
The hyperglobulinemia is exclusively related to the abnormal antibody; all other immunoglobulins are decreased. Consequently, susceptibility to infection is increased. In the urine, Bence Jones proteins are found. Myeloma cells secrete osteoclast activating factor, which produces hypercalcemia and lytic bone lesions, especially in flat bones. As there is little or no osteoblastic activity, bone scans and alkaline phosphatase often remain negative.
Turn recording back on. National Center for Biotechnology Information , U. Boston: Butterworths ; Search term. Definition White blood cells WBC are a heterogeneous group of nucleated cells that can be found in circulation for at least a period of their life.
Technique Leukocytes can be evaluated through several techniques of varying complexity and sophistication. Among those most commonly used are: Leukocyte peroxidase, which is present in myeloid cells and ANLL acute nonlymphoblastic leukemia blasts.
It plays a role in the killing of bacteria. It is not found in ALL acute lymphoblastic leukemia cells. Leukocyte alkaline phosphatase is found in the more mature cells of the myeloid series, bands and neutrophils. It is useful for the differential diagnosis between CML chronic myelocytic leukemia where it is low, from leukemoid reactions, where it is normal. Sudan Black B is a lipid stain positive in the neutrophilic granules of precursors and mature granulocytes.
Periodic acid—Schiff PAS demonstrates the presence of polysaccharides. Neutrophilic granules stain with this technique. Lymphocytes may have PAS-positive granules. Acid phosphatase. Macrophages and osteoclasts possess this enzyme.
T cell ALL blasts and hairy cells are also positive. Acid phosphatase is tartrate resistant in hairy cell leukemia. Leukocyte esterases are found in monocytes and neutrophils in varying concentrations.
Alpha naphtyl esterase is strongly positive in monocytes and weakly positive in neutrophils. The reverse is true for AS-D chloroacetate esterase. These enzymes are useful to differentiate the monocytic from granulocytic precursors in ANLL.
Terminal deoxynucleotidyl transferase TdT is present in thymocytes and lymphocyte precursors. It is absent in ANLL. Ia is an antigen present in mouse B lymphocyte precursors. It is also found on myeloid cells. An Ia-like antigen is present in human cells. Surface immunoglobulins sIg are synthesized and carried attached to the membrane of B lymphocytes. Most commonly they belong to the IgM class. Receptors for the Fc fragment of immunoglobulins are also found on the membrane of B and T lymphocytes and monocytes.
Basic Science WBC are classified into granulocytes, lymphocytes, and monocytes. Neutrophils Quantitative abnormalities Granulocytes can be increased in circulation by four different mechanisms: increased production, decreased egress from the circulation, demargination, and release from storage compartments.
The Leukemias Acute leukemia results from the malignant proliferation of cells of the myeloid acute nonlymphoblastic leukemia or ANLL or lymphoid acute lymphoblastic leukemia or ALL progeny. Hematology and oncology. In: Stein JH, ed. Internal medicine. Boston: Little, Brown, Surface markers on leukemia and lymphoma cells: recent advances. Renewal and commitment to differentiation of hemopoietic cells an interpretative review. Quesenberry P, Levitt L. Hemopoietic stem cells. N Engl J Med.
Neoplastic diseases of the blood. New York: Churchill Livingstone, Wintrobe MM. Clinical hematology. Cecil textbook of medicine. Philadelphia: W. Saunders, Chapter In this Page. Related information. PubMed Links to PubMed. Similar articles in PubMed. Complete blood count reference values of cord blood in Taiwan and the influence of gender and delivery route on them. Pediatr Neonatol. Epub May 6. Association of ABO incompatibility with elevation of nucleated red blood cell counts in term neonates.
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