chapter 12 - blood and lymph

Hemoglobinemia

excess free hemoglobin buildup in circulation

serum

plasma without clotting factors

thrombocytes

platelets

peripheral blood

-Blood obtained from the circulation away from the heart, such as from the fingertip, heel pad and earlobe or from an antecubital vein -whole blood circulating in blood vessels carrying oxygen, nutrients, and waste materials (when you obtain an animal's blood sample from a vein or artery you are taking peripheral blood)

neutrophils

-account for 40% to 75% of circulating leukocytes and are the most abundant white blood cell type in the blood of dogs, cats, and horses. -are larger than red blood cells and smaller than monocytes. -Mature neutrophils are also known as polymorphonuclear leukocytes (PMNs) because, when mature, their nuclei become lobulated or segmented and take on many different shapes. -A mature neutrophil can have from two to five nuclear segments -involved in the early stages of the inflammatory response

leukopoiesis

-the general term for the formation of white blood cells. It starts out with the same pluripotential stem cell population that produced proerythroblasts and megakaryocytes. Each specific type of white blood cell has its own stimulus for production.

there are 3 types of polycythemia

-Relative polycythemia is seen when there is a loss of fluid from blood (hemoconcentration), such as when an animal is dehydrated because of vomiting, diarrhea, profuse sweating, or not drinking enough water. -Compensatory polycythemia is a result of hypoxia. The bone marrow is stimulated to make more red blood cells because the tissues aren't getting enough oxygen. Animals living at high altitudes develop compensatory polycythemia. A patient with congestive heart failure may become polycythemic because the heart isn't pumping enough blood to the tissues. This causes the kidney to produce more erythropoietin that will stimulate red bone marrow pluripotential stem cells to mature to red blood cells. This is another form of compensatory polycythemia. -Polycythemia rubra vera is a rare bone marrow disorder characterized by increased production of red blood cells for an unknown reason.

Lymphocytes

-The four types of white blood cells that are part of the body's immune system: T cells, B cells (which transform into plasma cells), and natural killer (NK) cells. They have individual functions that regulate an animal's immune system.

white blood cells

-WBCs or leukocytes. -Mature white blood cells are generally larger than mature red blood cells. There are five types of white blood cell that are normally present in circulating blood. -They are classified into granulocytes and agranulocytes, based on the presence of cytoplasmic granules when they are stained. Mature granulocytes contain prominent cytoplasmic granules, whereas mature agranulocytes lack obvious granules. -The granulocytes are neutrophils, eosinophils, and basophils. The agranulocytes are lymphocytes and monocytes

anticoagulant

-a chemical that when added to blood prevents the blood from clotting after it is removed from the body. -One of the most common anticoagulants is ethlyenediaminetetraacetic acid or EDTA

packed cell velume (PCV) test

-a test done to diagnose polycythaemia, dehydration or anemia in certain patients. It is generally a part of the full blood count test that is used to estimate the need for certain blood transfusions and monitor the response to treatment.

differential cell count

-a test that analyzes and quantifies the types of WBCs found in blood -Many polychromatophilic hematology stains are a combination of blue and red dyes dissolved in methyl alcohol. One commonly used stain is a Wright's stain, which contains blue and red-orange dyes. The methylene blue dye component will stain acidic structures such as RNA or DNA a blue or purple color. This means nuclei will stain blue or purple. Basic structures such as hemoglobin and some cytoplasmic granules are stained orange or red by the eosin dye component. There are two other commonly used stains. The "Diff-Quik" stain is a modified Wright's stain that is commonly used in clinical practice to stain a blood smear quickly. -New methylene blue stain is a monochromatic stain that will stain only acidic structures. When exposed to new methylene blue stain, ribosomes in the cytoplasm of immature RBCs that are still making hemoglobin are precipitated into the cytoplasm and can be seen as small blue dots or a blue meshlike structure in the cytoplasm. There is no hemoglobin production in mature RBCs so there are no ribosomes present to precipitate. There are normally a few reticulocytes in circulating blood, but the number will increase if the bone marrow is releasing the RBCs before they are mature.

platelets

-also known as thrombocytes. They are not complete cells, but are pieces of cytoplasm that bud off from giant, multinucleated bone marrow cells called megakaryocytes and are sent into the circulation. -Platelets have many functions in the body, but they are most important for normal hemostasis. Hemostasis is the process by which blood is prevented from leaking out of damaged blood vessels. Platelets have specific roles in the clotting process, along with endothelial cells in the blood vessel wall and coagulation factors. The two specific functions of platelets in hemostasis are the formation of a platelet plug and stabilization of the plug, making it irreversible.

Opsonin

-an antibody or other substance that binds to foreign microorganisms or cells, making them more susceptible to phagocytosis. -The coating process is called opsonization and allows the neutrophil to begin phagocytosis.

thrombin

-an enzyme in blood plasma which causes the clotting of blood by converting fibrinogen to fibrin. -In the presence of thrombin, platelets change shape and develop pseudopods that allow them to intertwine with each other

eosinophils

-are named for the red granules in the cytoplasm of mature cells when the cells are viewed on a stained blood smear. They make up 1% to 6% of the total circulating white blood cells. -are slightly larger than neutrophils. After eosinophils have been produced in the bone marrow, they stay there for several days before they go out into circulation. -most often indicates a parasitic infection, an allergic reaction or cancer.

marginal pool of neutrophils

-composed of neutrophils that line the walls of small blood vessels, mainly in the spleen, lungs and abdominal organs -not circulating -not contained in blood samples obtained for lab analysis

circulating pool of neutrophils

-contained in blood as it flows thru the blood vessels -located in lumen of the vessel -blood samples are obtained from this pool -Normal range of neutrophils in peripheral blood is based on this pool.

Ninety percent of the destruction of senescent red blood cells occurs by

-extravascular hemolysis, or destruction of red blood cells outside the cardiovascular system. -The red blood cells are removed from circulation by macrophages located primarily in the spleen. The membranes of the phagocytized cells are ruptured and hemoglobin is released and degraded into amino acids, iron, and heme. The amino acids are returned to the liver where they are used to build more proteins. The iron is transported to the bone marrow where it will be recycled during erythropoiesis to make new red blood cells. The heme will be further broken down into free or unconjugated bilirubin. It will attach to the plasma protein albumin, and be transported to the liver. Here it will be conjugated or bound to a compound called glucuronic acid. Conjugated bilirubin will be excreted into the intestines from the liver as a bile pigment, where it will eventually be converted into urobilinogen by intestinal bacteria. Some of this urobilinogen will be reabsorbed and eliminated in the urine as urobilin. Some of the urobilinogen will be converted to stercobilinogen and excreted in the feces as stercobilin. Urobilin and stercobilin are two pigments normally present in urine and feces and are what help give each their normal color.

10% of normal red blood cell destruction takes place by

-intravascular hemolysis, or destruction that takes place within blood vessels. -While in circulation, a red blood cell is exposed to many oxidative stresses, which can result in red blood cell fragmentation and/or destruction. When the red blood cell membrane ruptures within a vessel, hemoglobin is released directly into the bloodstream. The unconjugated hemoglobin is quickly picked up by haptoglobin, a transport protein in plasma, to form a haptoglobin-hemoglobin complex. This complex travels to the macrophages in the liver for further breakdown, similar to what happens with extravascular hemolysis. When haptoglobin is filled with unconjugated hemoglobin, as in cases of severe hemolysis, excess unconjugated hemoglobin appears in the plasma, making it a pink, red, or brown color. This is referred to as hemoglobinemia. This excess of unconjugated hemoglobin has no way to get to the liver, so it is carried to the kidney, where it is eliminated in the urine, making it red in color. This is referred to as hemoglobinuria.

Monocytes

-make up 5% to 6% of the circulating white blood cells in all common domestic species. Monocytes are the largest white blood cells in circulation. Their nuclei can be many shapes, from round to pseudolobulated. This means that monocyte nuclei can have similar shapes to those of neutrophils. Monocytes have abundant cytoplasm that stains gray and may contain vacuoles of varying sizes -Monocytosis and monocytopenia refer to an increase and decrease in the number of circulating monocytes, respectively.

granulocytes

-neutrophils, eosinophils, and basophils. -They are included in this category because of the prominent appearance of granules in their cytoplasm when viewed on a stained blood smear. Eosinophil granules pick up the acidic stain and appear red, basophil granules pick up the basic stain and appear blue, and neutrophils don't pick up either stain very well, so they appear colorless or faintly violet on a stained blood smear.

fibrinogen

-plasma protein that is converted to fibrin in the clotting process -the formation of thrombin also converts fibrinogen, a soluble plasma protein, to insoluble strands of fibrin, which will attach to the platelet surface and ultimately help cement the platelets in place.

platelet aggregation

-property of platelets to adhere to an injured surface and then attract other platelets, which clump together or aggregate at the area, plugging up an injury to the vascular system -The platelets squeeze together to form a primary hemostatic plug

what's the function of white blood cells?

-provide defense for the body against foreign invaders. Each type of white blood cell has its own unique role in this defense. If all the white blood cells are functioning properly, an animal has a good chance of remaining healthy. Individual white blood cell functions will be discussed with each cell type. -white blood cells use peripheral blood to travel from their site of production in the bone marrow to their site of activity in the tissues. There is a constant flow of white blood cells out of marrow and into tissues in an attempt to control the millions of foreign invaders that attack an animal's body every day.

whole blood

-refers to the mixture of both plasma and formed elements -the blood contained in the cardiovascular system

basophils

-the least common leukocyte and constitute less than 1% of circulating white blood cells. It is therefore difficult to quantitate a basophilia or a basopenia. Basophils are recognized by of their large intensely staining basophilic or blue cytoplasmic granules. The basophil granules are water soluble and are frequently washed out during the staining procedure, so they are not always readily visible on a stained smear. -Not much is known about the function of basophils. They are the least phagocytic of the granulocytes. Their granules contain histamine and heparin. Histamine helps initiate inflammation and acute allergic reactions. Eosinophils are attracted to the site of an allergic reaction by 310eosinophilic chemotactic factor released from the basophil or mast cell granules. Heparin acts as a localized anticoagulant to keep blood flowing to an injured or damaged area.

Erythropoiesis

-the process by which red blood cells are created -The proerythroblasts further divide multiple times through several stages where each stage produces a more mature cell type. At a certain stage the cells will lose their nuclei and stop multiplying. They also start producing hemoglobin. From this stage they have to mature through three more stages to become mature red blood cells 298(RBCs). The entire process takes about 1 week in the dog, 4 to 5 days in the cow, and 36 hours in birds. The rate of erythropoiesis is controlled by hormones, mainly erythropoietin (EPO) and the availability of the materials needed to make red blood cells: iron, folic acid, vitamin B12, and protein. -produced primarily by the peritubular interstitial cells of the kidney

Hematopoiesis

-the production of all blood cells that occurs as a continuous process throughout an animal's life. -In the fetus, hematopoiesis takes place in the liver and spleen. In a newborn animal, this process takes place primarily in the red bone marrow located in most of the bones of the body. Many bones are involved because of the high demand for blood cells during growth and development. As the animal matures, the rate of production slows because the animal isn't growing as fast. Some of the red bone marrow becomes less active, is dominated by fat cells, and becomes known as yellow bone marrow. However, yellow marrow can be reactivated by increased demands from the body. The type of bone marrow is named on the basis of its gross appearance.

primary lymphoid organs

-thymus: located in the cranial thorax. It is largest in size when an animal is young, but shrinks and is replaced by fat as the animal matures, making it difficult to locate in adult animals. The thymus is made up of many lobules contained in a connective tissue capsule. The outer portion of the lobules contains a large number of lymphocytes. The thymus is responsible for most of the production of mature T cells (thymus-derived lymphocytes) from precursors sent from the bone marrow. Once in the thymus they are called thymocytes. Here they divide rapidly and leave the thymus and travel to the secondary lymphoid organs. T cells are important in stimulating a cell-mediated immune response. Young animals do not have a fully developed immune system, which means that they rely heavily on the thymus to fight infections and ultimately survive. -bursa of fabricius: found only in birds and is similar in structure and function to the thymus. It is a round sac that sits right above the cloaca. Peyer's Patches -peyer's patches: located in the wall of the small intestine. They have various structures and functions depending on 314the species. However, their common function is the activation of B cells to produce antibodies against antigens in the small intestines. Peyer's patches are just one type of gut-associated lymphoid tissue (GALT) located throughout various areas of intestinal mucosa and submucosa. -secondary lymphoid organs: The secondary lymphoid organs are developed later in fetal development and persist in adult animals. They include the spleen, lymph nodes, and tonsils. Their main function is to trap and process antigens and mature lymphocytes that mediate immune responses. Unlike the primary lymphoid organs these organs will enlarge in response to antigenic stimulation.

Fibrinolysis

Breakdown and removal of a clot

lymphatic system

Composed of a network of vessels, ducts, nodes, and organs. Provides defense against infection.

hemoglobin analysis

Hemoglobin (Hgb) analysis measures the concentration of hemoglobin contained in the red blood cells in a specific volume of blood.

Oxyhemoglobin

Hemoglobin combined with oxygen

Neutrophilia

If there is an increased demand for neutrophils in tissue, bone marrow will release its reserve stores of mature—and, if necessary, immature—neutrophils into blood, so they can be transported to the site where neutrophils are needed. If a blood sample is drawn while these neutrophils are in transit, there will be a higher than normal number of neutrophils in the sample. (based on a differential cell count)

B lymphocytes (B cells)

Inactive B cells travel through lymph nodes, the spleen, and other lymphoid structures, but rarely circulate in peripheral blood. B cells are ultimately responsible for humoral immunity (antibody production is involved). Each B cell is preprogrammed to produce only one specific antibody type against one 311specific antigen. On its cell surface, a B cell has thousands of receptors shaped to fit only one antigen shape. Every antigen has a unique shape made up of amino acids on its cell surface. This area is called the epitope. The sequence of amino acids determines the shape of the epitope. There is a B cell that has a complementary combining site or receptor that fits the shape of the epitope. When the B cell and antigen are joined, an antigen-antibody complex is formed. All the other B cells will be unaffected. The amazing thing is that the B cells are preprogrammed to produce antibodies against antigens to which they have never been exposed. When B cells recognize an antigen, they transform into plasma cells that release antibodies. This is called humoral immunity.

Eosinophilia

Increase in numbers of eosinophils in the bloodstream.

Hypoxia

Low oxygen saturation of the body, not enough oxygen in the blood

Mean Corpuscular Hemoglobin Concentration (MCHC)

Mean corpuscular hemoglobin concentration (MCHC) is another parameter that is clinically helpful to evaluate the erythrocytes in the presence of anemia. It measures the ratio of the weight of hemoglobin to the volume of red blood cells.

platelet adhesion

Platelets sticking to exposed collagen underlying damaged endothelial cells in vessel wall

How are RBC's able to transport oxygen where it is needed?

RBCs are able to perform this function using hemoglobin, a protein that is formed during RBC development. It is made up of four heme units associated with one globin chain. The heme unit is the pigmented portion of hemoglobin. Each heme unit contains an iron atom (Fe2+) to which one oxygen molecule can attach. Therefore, one hemoglobin molecule can carry four molecules of oxygen.

T lymphocytes (T cells)

T cells are processed in the thymus before going to peripheral lymphoid tissue. T cells are responsible for cell-mediated immunity (no antibody production involved) and for activating B cells. Most of the lymphocytes in peripheral blood are T cells.

how do RBC's maintain cell shape and deformability?

The biconcave disc shape provides more membrane surface area for the diffusion of oxygen and carbon dioxide. Also, it allows for a shorter diffusion distance in and out of the cell. Membrane deformability refers to the flexibility of the cell membrane, allowing it to change shape to travel through the various blood vessels in the body.

red blood cell count

The red blood cell count (RBC count) measures the number of red blood cells in a specific volume of blood. It is reported as the RBC count.

Total leukocyte count

The total leukocyte count (WBC count) expresses the total number of white blood cells in a specific volume of blood. The number of each type of white blood cell is also counted either by an automated blood analyzer or by evaluating a stained blood smear.

thrombopoiesis

Thrombopoiesis, the production of platelets, begins when a specific stimulant acts on the unipotential stem cell in the red bone marrow, causing it to differentiate into a megakaryocyte. The megakaryocyte is a large multinucleated cell that never leaves the bone marrow. Pieces of cytoplasm from the megakaryocyte are released into peripheral blood as platelets. Platelets are also known as thrombocytes. Thrombopoiesis can take up to 7 days to reach completion.

total plasma protein

Total plasma protein (TP) measures the amount of protein in the plasma portion of a specific volume of blood. It can be measured by an automated blood analyzer or by using a hand-held refractometer.

how do RBC's transport carbon dioxide to the lungs?

When the RBCs reach the tissue cells, there is an exchange of oxygen and carbon dioxide. Oxygen is taken from the hemoglobin in the RBCs by the cells in the tissues. At the same time, carbon dioxide, along with other metabolic waste, is released into the blood where it breaks down into ions that are transported to the lungs. Some of the carbon dioxide is taken up by the RBCs but not bound to the iron in the heme molecules.

how does clotting work?

When the outer endothelial lining of a blood vessel is damaged, the exposed subendothelium contains proteins, such as collagen, fibronectin, and von Willebrand factor, that attract platelets to adhere to it. This is known as platelet adhesion. At the same time, the endothelium produces tissue factors that activate the coagulation cascade to form thrombin. In the presence of thrombin, platelets change shape and develop pseudopods that allow them to intertwine with each other. This is known as platelet aggregation. The platelets squeeze together to form a primary hemostatic plug. Meanwhile, the formation of thrombin also converts fibrinogen, a soluble plasma protein, to insoluble strands of fibrin, which will attach to the platelet surface and ultimately help cement the platelets in place.

polycythemia

a condition that results in the animal's PCV being higher than normal, or an increase above normal in the number of red blood cells

Reticulocyte count

a count of the number of immature forms of the red blood cells per a specific total number of red blood cells. This count is used to characterize the type of anemia in an animal.

blood

a fluid connective tissue that flows throughout the entire body

Red Cell Distribution Width (RDW)

a numerical expression of variation in red blood cell size. The variation in size from cell to cell in a blood sample is called anisocytosis. Marked anisocytosis can be seen in cases of severe anemia where the bone marrow is pumping RBCs out at such a high rate they don't have time to mature fully. These immature RBCs are larger than a fully mature RBC already in circulation.

Chemotaxis

a process by which neutrophils and other cells are attracted by inflammatory chemicals produced by the interaction between microorganisms and the tissues they are invading. This allows the neutrophil to recognize what to ingest.

Thrombopoiesis, the production of platelets, begins when

a specific stimulant acts on the unipotential stem cell in the red bone marrow, causing it to differentiate into a megakaryocyte. The megakaryocyte is a large multinucleated cell that never leaves the bone marrow. Pieces of cytoplasm from the megakaryocyte are released into peripheral blood as platelets. Platelets are also known as thrombocytes. Thrombopoiesis can take up to 7 days to reach completion.

Spleen

a tongue-shaped organ located on the left side of the abdomen. It is near the stomach in simple-stomached animals and near the rumen in ruminants. Not only does the spleen store red blood cells and produce red blood cells during fetal development, but it also filters the blood and lymph. The spleen is covered with a capsule made up of fibrous connective tissue and smooth muscle. The capsule sends branches called trabeculae into the soft tissue of the spleen. These trabeculae contain blood vessels, nerves, lymph vessels, and smooth muscle cells. In carnivores, the trabeculae are very muscular, whereas ruminants have trabeculae that are less muscular. When the smooth muscle cells contract, they squeeze stored blood cells out of the spleen and back into circulation. Because carnivores have more muscular branches, they are able to squeeze more blood out of the spleen. The soft tissue interior of the spleen is divided into two areas, white pulp and red pulp, each with a distinct function. The white pulp is formed of localized areas of lymphoid tissue containing lymphocytes that can clone themselves during an immune response. The red pulp consists of blood vessels, tissue macrophages, and blood cell storage spaces called sinuses. The tissue macrophages filter out antigens and other foreign material from lymph and remove dead, dying, and abnormal red blood cells.

plasma cells

are derived from B cells in response to an antigenic stimulus. The B cells that are activated by their unique antigen multiply by mitosis in a process called blastic transformation to become plasma cells. Plasma cells produce, store, and release antibodies that are also known as immunoglobulins. Plasma cells can be found in any tissue in the body, but are most numerous in tissues engaged in antibody formation (e.g., lymph nodes, spleen). Plasma cells are rarely found in peripheral blood.

natural killer cells (NK cells)

are found in the blood and lymph. These granular lymphocytes are able to identify and kill virus-infected cells, stressed cells, and tumor cells. They differ from phagocytes in that they do not ingest the target cell. Instead, they bind to the cell and induce cellular changes that lead to apoptosis (programmed cell death) or lysis of the cell. It is important to note that NK cells do not cause lysis of virus-infected cells, because this would release virions (virus particles) instead of controlling infection. Instead, apoptosis is triggered in virus-infected cells, to ensure death of the virus, which lysis does not. NK cells have two types of receptor to help determine which cells to kill: the killer-activating receptor (KAR) and the killer inhibitory receptor (KIR). The KIR binds with specific molecules on a cell's surface. This binding demonstrates that the cell is healthy and inhibits the NK cell from killing it. If the KIR does not bind to the cell, the NK cell will kill the cell. When there is decreased expression of the specific molecules on the cell's surface, the KAR is triggered, causing apoptosis of the cells. Cells with decreased numbers of molecules or damaged/altered molecules are destroyed because they are likely to be unhealthy. NK cells kill by binding to suspected cells. Once the KIR verifies a harmful cell, the NK cell with the KAR releases perforins (proteins that form pores in cell membranes) and proteolytic enzymes such as granzymes. Granzymes move into the target cell via the newly formed pores and cause apoptosis by breaking down the cell structure and its contents. NK cells are stimulated by cytokines, including interleukins and interferons. Tumor cells, damaged cells, and infected cells release cytokines as stress signals. This stimulates NK cell action and ultimate destruction of harmful cells. Both T cells and B cells can become memory cells. These cells are clones of an original lymphocyte. They don't participate in an initial immune response to a specific antigen but survive in lymphoid tissue waiting for a second exposure to that same antigen. When the animal is exposed to the antigen for a second time, the memory cells are ready to respond. This response is much quicker and of greater magnitude than the initial immune response.

agraulocytes

are mature white blood cells that do not contain specific staining granules in their cytoplasm. They include lymphocytes and monocytes.

lymph nodes

are small, kidney bean-shaped filters located at various points along lymphatic vessels. They trap antigens and other foreign material carried in lymph. A lymph node is divided into a cortex and a medulla, which have lymphatic sinuses running through them (Figure 12-25). Lymph flows from the tissues into the node in afferent vessels that empty just beneath the capsule, which lies outside the cortex. It leaves the lymph node in efferent vessels that exit the lymph node through the indented hilus area. The nodules located in the cortex are made up of predominantly B cells, although T cells and macrophages are also found in smaller numbers in lymph nodes.

Subendothelium

connective tissue between the endothelium and inner elastic membrane in the intima of arteries

Eosinopenia

deficiency in the number of eosinophils in the blood

Neutrophils leave the blood vessel by squeezing between the cells of the endothelium in a process called

diapedesis

deoxyhemoglobin

hemoglobin without oxygen

Anemia

lack of a normal number of red blood cells

Mean Corpuscular Volume (MCV)

measures the average volume or size of the individual red blood cells. It is a helpful way to evaluate the erythrocytes in the sample, especially when anemia is present.

platelet count

measures the total number of platelets (thrombocytes) in a specific volume of blood sample. Thrombocytosis and thrombocytopenia are used to describe a higher than normal or lower than normal platelet count, respectively. In cats, there may be a false thrombocytopenia due to platelet clumping in the blood sample and/or platelets overlapping with red blood cells, making the two indistinguishable by an automated blood analyzer.

If an infection is out of control, all the reserves of neutrophils can be used up faster than the bone marrow can replace them. If this happens, the number of neutrophils in circulation decreases, because the neutrophils are leaving the bloodstream and entering tissue, and there are no cells in the bone marrow to replace them. This condition is called:

neutropenia

the five types of white blood cells

neutrophils, eosinophils, basophils, lymphocytes, and monocytes

the three main functions of red blood cells are:

oxygen transport, transporting carbon dioxide to the lungs, and maintaining cell shape and deformability

function of monocytes

participate in inflammatory responses. They do not spend much time in bone marrow or the circulation before they enter into tissues where they can live for up to 100 days. When monocytes enter tissues, they become macrophages. Collectively, the tissue macrophages and monocytes are known as the mononuclear phagocyte system (MPS).

the two types of defense functions

phagocytosis and immunity

Neutrophils can phagocytize, or engulf, microorganisms such as bacteria and other microscopic debris in tissues (Figure 12-18). Their granules contain digestive enzymes that are capable of destroying bacteria and viruses that have been engulfed. During ingestion, the cell membrane of the neutrophil will enclose the bacteria to create a pouch called a

phagosome

All blood cell types are derived from a single primitive stem cell type called a

pluripotential or multipotential stem cell

Hemoglobinuria

presence of hemoglobin in the urine

thrombopoietin

produced by the liver to stimulate platelet formation

venipuncture

puncture of a vein to remove blood, instill a medication, or start an intravenous infusion

erythrocytes

red blood cells

the process of aging

senescence -As a red blood cell becomes senescent, its enzyme activity decreases and the cell membrane loses its deformability by becoming rounder, 300enclosing a smaller volume. Approximately 1% of aging, dead, or abnormal red blood cells are removed from circulation and destroyed every day. This may occur intravascularly or extravascularly. Oxidative stresses known as free radicals contribute to the rapid aging and destruction of red blood cells. These stresses are exacerbated by certain diseases and toxins present in an animal's body.

In most species the red marrow sites are the

skull, ribs, sternum, vertebral column, pelvis, and the proximal ends of the femurs.

Plasma

the clear liquid part of the blood

Monopoiesis

the formation and maturation of monocytes.

complete blood count

the hemogram or CBC. It is used to evaluate plasma proteins, red blood cells, white blood cells, and platelets. The CBC is one of the most useful clinical evaluations performed on a patient. The health status of an animal and clues as to what may be causing a pathologic condition are commonly reflected in the results of a CBC. The following parameters are normally included in a CBC.

Granulopoiesis

the process by which a pluripotential stem cell differentiates into one of three types of granulocyte: neutrophils, eosinophils, or basophils. Early granulocytes are difficult to distinguish from one another because they all appear as large cells with lots of cytoplasm, large round nuclei, and a first set of nonspecific granules. The nonspecific granules are later replaced by specific granules that are unique to each granulocyte type.

Lymphopoiesis

the process that produces lymphocytes, some of which develop outside the bone marrow.

endothelium

the tissue which forms a single layer of cells lining various organs and cavities of the body, especially the blood vessels, heart, and lymphatic vessels. It is formed from the embryonic mesoderm.

The packed cell volume (PCV), or hematocrit (HCT) is

the volume of packed erythrocytes measured and expressed as a percentage of a total volume of blood. The two methods for determining the PCV are automated analyzers (blood analyzers) and gross examination of a centrifuged 301microhematocrit tube. When using microhematocrit tubes, an unclotted blood sample from a lavender-top vacuum tube is used to fill two tubes. The ends of the tubes are plugged with clay and the tubes are spun in a microhematocrit centrifuge, causing separation of the blood sample into three components or layers: plasma, buffy coat, and red blood cells. To measure the PCV, the microhematocrit tube is placed on a special card so the top of the clay lines up with the 0% line. The tube is rolled along the card until the top of the plasma intersects the 100% line. The line that intersects the top of the red blood cell layer is the PCV value and is reported as a percentage.

Haptoglobin

transport protein in plasma

blood has three main functions

transportation, regulation and defense.

leukocytes

white blood cells

jaundice (icterus)

yellow-orange coloration of the skin and whites of the eyes caused by high levels of bilirubin in the blood (hyperbilirubinemia)

blood regulation

• Blood aids in the regulation of body temperature. Body temperature regulators are located in the brain and are partially influenced by the temperature of the blood that passes through or over them. • Blood plays a part in tissue fluid content. The composition of body tissue fluid is kept as constant as possible. If an animal is low in tissue fluid or dehydrated because of vomiting, diarrhea, profuse sweating, or some pathologic condition that causes it to lose fluid, some of the plasma will leave the bloodstream and enter the body tissues in an effort to compensate for the fluid loss. This leaves less plasma in the bloodstream, and the cells become more concentrated (hemoconcentration). If an animal has too much body fluid, for example after subcutaneous fluids are administered, the excess fluid will enter the bloodstream. This extra fluid in the plasma dilutes the number of cells (hemodilution). • Blood aids in the regulation of blood pH (acid-base balance). Normal blood pH falls in a range of 7.35 to 7.45, with the ideal being 7.4 (slightly alkaline). Blood must be maintained within this narrow range for the animal to remain healthy. The pH must remain slightly alkaline to buffer the acidic waste products of cellular metabolism that it carries. The pH of arterial blood is slightly more alkaline than that of venous blood because most of the acidic waste products are carried in venous blood, resulting in lower pH.

blood defense

• Blood carries white blood cells to tissues exposed to foreign invaders. These cells contribute to an animal's immune system to help keep the animal healthy. • Blood carries platelets to sites of vessel damage to aid in hemostasis so that the animal does not bleed excessively.

blood transportation

• Erythrocytes, or red blood cells, contain hemoglobin, which carries oxygen to every cell in the body. 296 • Nutrients and other essential elements are dissolved in the blood plasma, and are also transported to tissues via arteries and capillaries. • Blood carries waste products from cellular metabolism via veins to the lungs and kidneys where the waste products are eliminated from the body. • Blood transports hormones from endocrine glands to target organs; it also transports white blood cells to various sites of activity where they participate in defending the body from infection. • Blood transports platelets to sites of damage in blood vessel walls to form a plug that will control bleeding; this is a mechanism known as hemostasis. Platelets are also involved in activation of the blood-clotting cascade.

function of eosinophils

• Inflammatory response. Eosinophils are attracted to and inhibit local allergic and anaphylactic reactions. Their granules contain anti-inflammatory substances that are released at the site of an allergic reaction. • Immunity. Eosinophils can ingest substances associated with the humoral immune response (e.g., antigen-antibody complexes). • Phagocytosis. Eosinophils have minimal phagocytic and bactericidal functions. The contents of eosinophil granules are especially toxic to large pathogenic organisms, such as protozoa and some parasitic worms.

function of lymphatic system

• Removal of excess tissue fluid. Cells receive some of the nutrients carried by plasma through diffusion. The fluid that enters the interstitial (tissue) spaces will eventually be put back into the circulation. Part of the fluid will be picked up directly by the capillaries in the tissues and enter the venous part of the systemic circulation. Some of the fluid will enter lymphatic capillaries. If there is inadequate lymph drainage to an area, the interstitial fluid can build up, causing edema (excess fluid accumulation) of the tissues of the area. There are other causes of edema, but they all relate to inadequate fluid drainage from tissue. • Waste material transport. The interstitial fluid that enters lymphatic capillaries will contain some of the waste materials from the tissue cell metabolism and will be carried to the systemic circulation by lymph and eventually eliminated. • Filtration of lymph. Interstitial fluid that enters the lymphatic capillaries will also contain microorganisms, cellular debris, and other foreign matter that must be removed from lymph before it enters the bloodstream. This will occur as the lymph passes through the lymph nodes. • Protein transport. Some large proteins, especially enzymes, are transported in lymph to the systemic circulation from their cells of origin. These proteins are too large to enter the venous circulation directly. Lymph has the ability to pick up larger protein molecules than the capillaries and deposit them into the systemic circulation.