A thin, whitish layer called the _______________ is present at the erythrocyte-plasma junction.
Erythrocytes normally constitute about 45% of the total volume of a blood sample, a percentage known as the ____________.
A straw-colored, sticky fluid. Makes up 55% of whole blood. Least dense component.
Accounts for some 60% of plasma protein. It acts as a carrier to shuttle certain molecules through the circulation, is an important blood buffer, and is the major blood protein contributing to the plasma osmotic pressure.
Erythrocytes, leukocytes, and platelets. 2 are not even true cells.
Erythrocytes or Red Blood Cells (RBCs)
Small cells, about 7.5 micrometers in diameter. Shaped like biconcave discs-flattened discs with depressed centers.
Protein that makes red blood cells red, binds easily and reversibly with oxygen, and most oxygen carried in blood is bound to it.
Hemoglobin is made up of the red __________ pigment bound to the protein globin.
Consists of four polypeptide chains-two alpha and two beta - each binding a ringlike heme group.
When oxygen binds to iron, assumes a new 3D shape and becomes ruby red.
Oxygen detaches from iron, hemoglobin resumes its former shape, and the result is dark red.
About 20% of the carbon dioxide transported in the blood combines with hemoglobin, but it binds to globin's amino acids rather than to the heme group. This formation of __________________ occurs more readily when hemoglobin is in the reduced state (dissociated from oxygen).
Blood cell formation.
Red Bone Marrow
Hematopoiesis occurs in the ____________, which is composed largely of a soft network of reticular connective tissue bordering on white blood capillaries called blood sinusoids.
Hematopoietic stem cell or hemocytoblast
All formed elements arise from this.
Myeloid Stem Cell
Erythropoiesis begins when a hematopoietic stem cell descendant called a _______________ transforms into a proerythroblast.
Gives rise to basophilic erythroblasts that produce huge numbers of ribosomes.
produce huge numbers of ribosomes.
(Phase 1 of Ribosome synthesis)
Hemoglobin is synthesized and iron accumulates as the basophilic erythroblast transforms into a _____________ and then an _____________.
(Phase 2 of Hemoglobin accumulation)
When an orthochromatic erythroblast has accumulated almost all of its hemoglobin, it ejects most of its organelles. Additionally, its nucleus degenerates and is pinched off, allowing the cell to collapse inward and eventually assume the biconcave shape. The result is the ______________ (essentially a young erythrocyte), so named because it still contains a scant reticulum of clumped ribosomes.
(Phase 3 of Ejection of nucleus)
Provide a rough index of the rate of RBC formation. Below or above the 1-2% reticulocytes range indicates abnormal rates of erythrocyte formation.
A glycoprotein hormone, stimulates the formation of erythrocytes.
Ferritin & Hemosiderin
Transport protein that transports iron in blood.
A yellow pigment that is released to the blood and binds to albumin for transport.
A condition in which the blood's oxygen-carrying capacity is too low to support normal metabolism.
Erythrocytes produced in response to anemia. They are small and pale because they cannot synthesize their normal complement of hemoglobin.
A substance that must be present for Vitamin B12 to be absorbed by intestinal cells.
Without vitamin B12, developing erythrocytes grow but cannot divide, and so these large, pale cells result.
Typically occur in people of Mediterranean ancestry, such as Greek and Italians. One of the globin chains is absent or faulty, and the erythrocytes are thin, delicate, and deficient in hemoglobin.
The havoc caused by the abnormal hemoglobin, hemoglobin S (HbS), results from a change in just one of the 146 amino acids in a beta chain of the globin molecule.
"Many blood cells" - is an abnormal excess of erythrocytes that increases blood viscosity, causing it to sludge, or flow sluggishly.
Practiced by some athletes competing in aerobic events, is artificially induced polycythemia. Some of the athlete's RBCs are drawn off and stored. The body quickly replaces these erythrocytes because removing blood triggers the erythropoietin mechanism. Then, when the stored blood is reinfused a few days before the athletic event, a temporary polycythemia results. The additional infusion should translate into increased oxygen-carrying capacity.
Leukocytes or White Blood Cells (WBCs)
the only formed elements that are complete cells, with nuclei and the usual organelles. Accounting for less that 1% of total blood volume. Critical for our defense against disease.
White blood cells are able to slip out of the capillary blood vessels.
Once out of the bloodstream, leukocytes move through the tissue spaces by ______________ (the form flowing cytoplasmic extensions that move them along).
By following the chemical trail of molecules released by damaged cells or other leukocytes, a phenomenon called _______________, they pinpoint areas of tissue damage and infection and gather there in large numbers to destroy foreign substances and dead cells.
A white blood cell count of over 11,000 cells/micrometer. This condition is a normal homeostatic response to an infection in the body.
Neutrophils, eosinophils, and basophils, are all roughly spherical in shape. They are larger and much shorter lived (in most cases) than erythrocytes. They characteristically have lobed nuclei and their membrane-bound cytoplasmic granules stain quite specifically with Wright's stain. Functionally all are phagocytes to some degree.
The most numerous white blood cells, account for 50-70% of the WBC population. They are about twice as large as erythrocytes. The cytoplasm contains very fine granules that are difficult to see. Because their granules take up both basic (blue) and acidic (red) dyes. Together, the two types of granules give the cytoplasm a lilac color.
A potent "brew" of antimicrobial proteins.
Polymorphonu-clear Leukocytes (PMNs)
Neutrophil nuclei consist of three to six lobes. Because of this nuclear variablility, they are often called _______________.
When a cell metabolize oxygen to produce potent germ-killer oxidizing substances such s bleach and hydrogen peroxide
Account for 2-4% of all leukocytes and are approximately the size of neutrophils. Their nucleus usually resembles an old-fashioned telephone receiver-it has two lobes connected by a broad band of nuclear material. They lack an enzyme that specifically digests bacteria. They lead the counter-attack against parasitic worms, such as flatworms and roundworms that are too large to be phagocytized.
The rarest WBCs, accounting for only .5-1% of leukocyte population. Their cytoplasm contains large, coarse, histamine-ontaining granules that have an affinit for the basic dyes and stain purplish-black.
Lymphocytes and monocytes, WBCs that lack visible cytoplasmic granules. Although similar to each other structurally, they are functionally distinct and unrelated cell types. Their nuclei are typically spherical or kidney shaped.
Account for 25% or more of the WBC population, are the second most numerous leukocytes in the blood. When stained, a typical lymphocyte has a large, dark-purple nucleus that occupies most of the cell volume. Large numbers of lymphocytes exist in the body, but relatively few (mostly the small lymphocytes) are found in the bloodstream.
T Lymphocytes (T cells)
function in the immune response by acting directly against virus-infected cells and tumor cells.
B Lymphocytes (B cells)
give rise to plasma cells, which produce antibodies (immunoglobulins) that are released to the blood.
Account for 3-8% of WBCs. With an average diameter of 18 micrometers, they are the largest leukocytes. They have abundant pale-blue cytoplasm and a darkly staining purple nucleus, which is distinctively U or kidney shaped.
When circulating monocytes leave the bloodstream and enter the tissues, they differentiate into highly mobile _________ with prodigious appetites. Macrophages are actively phagocytic, and they are crucial in the body's defense against viruses, certain intracellular bacterial parasites, and chronic infections such as tuberculosis.
Like erythropoiesis, _____________, or the productio of WBCs, is stimulated by chemical messengers. The
Chemical messengers that stimulate the production of WBCs. They can act either as paracrines or hormones, are glycoproteins that fall into two families of hematopoietic factors, ___________ and ____________, or ____. ________ are numbered, but but most _________ are named for the leukocyte population they stimulate.
Lymphoid Stem Cells
Myeloid Stem Cells
Give rise to all other formed elements.
Accumulate lysosomes, becoming promyelocytes.
Granulocyte precursor, developing from the myeloblast and developing into the myelocyte.
The distinctive granules of each granulocyte type appear next in the ___________ stage and then cell division stops.
A cell undergoing granulopoiesis, derived from a metamyelocyte, and leading to a mature granulocyte
Monoblast and Promonocyte
Cells following the monocyte line pass through the __________________ stages before leaving the bone marrow.
T and B Lymphocyte Precursors
T and B lymphocytes are derived from __________________, which arise from the lymphoid stem cell.
An abnormally low WBC count, commonly induced by drugs, particularly glucocorticoids and anticancer agents.
Not cells in the strict sense. Small, disc shaped cell fragments. Essential for the clotting process.
Platelets are cytoplasmic fragments of extraordinarily large cells called ____________.
A hormone that regulates the formation of platelets.
Precursor cell to a promegakaryocyte, which in turn becomes a megakaryocyte during haematopoiesis
If a blood vessel wall breaks, a whole series of reactions is set in motion to accomplish ___________, which stops the bleeding. Its response is fast, localized, and carefully controlled.
First step in hemostasis. Smooth muscle contracts causing vasoconstriction.
Intact endothelial cells release nitric oxide and a prostaglandin call ________.
Adenosine Diphosphate (ADP)
A potent aggregating agent that causes more platelets to stick to the area and release their contents.
Serotonin and Thromboxane A2
Messengers that enhance vascular spasm and platelet aggregation
Coagulation or Blood Clotting
Reinforces the platelet plug with fibrin threads that act as a "molecular glue" for the aggregated platelets.
Clotting factors or procoagulants
Blood is transformed from a liquid to a gel in a multistep process that involves a series of substances called _________________.
Factors needed for clotting are present within the blood.
Tissue factor it requires is outside of the blood.
(PF3) Platelet Factor 3
Once factor X has been activated, it complexes with calcium ions, PF3, and factor V to form _______________. This is usually the slowest step of the blood clotting process, but once ______________ is present, the clot forms in 10-15 seconds.
Tissue Factor (TF) or Factor III
Triggered by exposing blood to a factor found in tissues underneath the damaged endothelium. This factor is called _______________________.
Phase 2 of of coagulation: Prothrombin activator catalyzes the conversion of a plasma protein called ________ into the active enzyme thrombin.
An active enzyme. It catalyzes the transformation of the soluble clotting factor fibrinogen into fibrin.
A soluble clotting factor that is transformed into fibrin.
The _________ molecules then polymerize (join together) to form long, hair like, insoluble ________ strands. The ______ strands glue the platelets together and make a web that form the structural basis of the clot.
Factor XIII (Fibrin Stabilizing Factor)
A cross-linking enzyme that binds the fibrin strands tightly together, forming a fibrin mesh.
Factors that inhibit clotting. Whether or not blood clots depends on a delicate balance between clotting factors and ________________.
Within 30-60 minutes, a platelet-induced process called ____________ further stabilizes the blot. Platelets contain contractile proteins (actin and myosin), and they contract in much the same manner as smooth muscle cells.
As the platels contract, they pull on the surrounding fibrin strands, squeezing __________ (plasma minus the clotting proteins) from the mass, compacting the clot and drawing the ruptured edges of the blood vessel more closely together.
Platelet-derived growth factor (PDGF)
_______________ released by platelets stimulates smooth muscle cells and fibroblasts to divide and rebuild the vessel wall.
Removes unneeded clots when healing has occurred. This cleanup detail is crucial because small clots form continually in vessels throughout the body. Without ____________, blood vessels would gradually become completely blocked.
The critical natural "clot buster" is a fibrin-digesting enzyme called ________.
Plasmin is produced when the plasma protein ____________ is activated.
Tissue Plasminogen Activator (tPA)
The presence of a clot in and around the blood vessel causes the endothelial cells to secrete ____________.
A protein present in plama, quickly inactivates any thrombin not bound to fibrin.
Antithrombin III and _____________, another protein produced in the liver, also inhibit the activity of other intrinsic pathway clotting factors.
The natural anticoagulant contained in basophil and mast cell granules is also found on the surface of endothelial cells. It inhibits thrombin by enhancing the activity of antithrombin III. It also inhibits the intrinsic pathway.
Result from conditions that cause undesirable clot formation.
Arise from abnormalities that prevent normal clot formation.
Disseminated Intravascular Coagulation (DIC)
Has characteristics of both thromboembolic and bleeding disorders, involves both widespread clotting and severe bleeding.
A clot that develops and persists in an unbroken blood vessel.
When thrombus breaks away from the vessel wall and floats freely in the bloodstream. This is usually not a problem until it encounters a blood vessel too narrow for it to pass through.
When an embolus encounters a blood vessel too narrow for it to pass through it become an _____________, obstructing the vessel.
Used to prevent undesirable clotting. Antiprostaglandin drug that inhibits thrombaxane A2 formation (blocking platelet aggregation and platelet plug formation). May help with reduction in incidence of heart attack.
Reduce the risk of stroke in those prone to atrial fibrillation, a condition in which blood pools in the heart. _____________ interferes with the action of vitamin K in the production of some clotting factors.
A condition in which the number of circulating platelets is deficient. It causes spontaneous bleeding from small blood vessels all over the body. Even normal movement leads to widespread hemorrhage, evidenced by many small purplish spots, called petechiae, on the skin.
Several hereditary bleeding disorders that have similar signs and symptoms.
Factor VIII (Antihemophilic Factor)
Hemophilia A results from a deficiency of _______________. It accounts for 77% of the cases of hemophilia.
Whole Blood Transfusions
Routine when blood loss is rapid and substantial.
Packed Red Cells
IN all other cases of blood transfusion, infusions of _______________ (whole blood from which most of the plasma and leukocytes have been recoved) are preferred for restoring oxygen-carrying capacity.
RBC antigens that promote agglutinatin.
ABO Blood Groups
Based on the presence or absence of two agglutinogens, type A and type B.
Unique to the ABO blood groups is the presence in the plasma of preformed antibodies called __________. They act against RBCs carrying ABO antigens that are not present on a persons own blood cells.
There are 52 named Rh agglutinogens, each of which is called an _________. Only three of these, the C, D, and E antigens are fairly common.
Hemolytic Disease of the Newborn or Erythroblastosis Fetalis
Rh- women who carry Rh+ babies first pregnancy usually results in a healthy baby. If bleeding occurs as the placenta detaches from the uterus, the mother may be sensitized by her baby's Rh+ antigens that pass into her blood stream. If so, she will form anti-Rh antibodies unless treated with RhoGAM before or shortly after she has given birth. If the mother is not treated and becomes pregnant again with an Rh+ baby, her antibodies will cross through the placenta and destroy the baby's RBCs, producing a condition know as _____________.
When mismatched blood is infused, a _____________ occurs in which the recipient's plasma agglutinins attack the donor's red blood cells. (Note that the donor's plasma antibodies may also agglutinate the recipient's RBCs, but these antibodies are so diluted in the recipient's circulation that this does not usually present a problem.)
Group 0 RBCs bear neither the A nor the B antigen, so theoretically group O is the _______________.
Since group AB plasma is devoid of antibodies to both A and B antigens, group AB people are theoretically _________ and can receive blood transfusions from any of the ABO groups.
The patient predonates his or her own blood, and it is stored and immediately available if needed during an operation.
Purified human serum albumin, hetastarch, and dextran provide no benefits over much cheaper electrolyte solutions and are actually associated with significant complications of their own.
Differential White Blood Cell Count
Determines the relative proportions of individual leukocyte types and is a valuable diagnostic tool. For example, a high eosinophil count may indicate a parasitic infection or an allergic response somewhere in the body.
Clinicians determine the _________________ to assess the ability of blood to clot when thrombocytopenia is suspected.
Clinicians may do a ____________ when thrombocytopenia is suspected.
Complete Blood Count (CBC
Routine during a physical exam and before hospital admissions. Includes counts of the different types of formed elements, the hematocrit, measurements of hemoglobin content, and size of RBCs.
The fetus forms a unique hemoglobin, _____________, that has a higher affinity for oxygen than does adult hemoglobin (hemoglobin A).