A&P 17: Blood Flashcards
Hematocrit
Percentage of erythrocytes in the total volume of a blood sample
Buffy coat
Thin, whitish layer present at the erythrocyte-plasma junction when blood is centrifuged; made of leukocytes & platelets
Plasma
Straw-colored, sticky fluid; mostly water (90%) but has > 100 different dissolved solutes (nutrients, gases, hormones, wastes & products of cell activities, proteins, & inorganic ions/electrolytes)
Albumin
Accounts for 60% of plasma protein; acts as a carrier to shuttle certain molecules through the circulation; important blood buffer; major blood protein contributing to plasma osmotic pressure (pressure that helps keep water in the bloodstream)
Formed elements
Erythrocytes, leukocytes, & platelets
Erythrocytes (red blood cells)
Small cells shaped like biconcave discs
Hemoglobin
Protein that makes red blood cells
Heme
Red pigment that binds to the protein globin
Globulin
Protein consisting of 4 polypeptide chains (2 alpha, 2 beta), each binding a ring-like heme group
Oxyhemoglobin
What hemoglobin is called when oxygen binds to iron; assumes 3D shape & becomes ruby red
Deoxyhemoglobin
Reduced hemoglobin; oxygen detaches from hemoglobin, hemoglobin resumes its former shape, & becomes dark red
Carbaminohemoglobin
20% of carbon dioxide transported in the blood combines with hemoglobin but binds to globin’s amino acids rather than to the heme group; formation of this occurs more readily when hemoglobin is in the reduced state (dissociated from oxygen)
Hematopoiesis
Blood cell formation
Red bone marrow
Where hematopoiesis occurs; composed largely of a soft network of reticular connective tissue bordering on wide blood capillaries (blood sinusoids)
Hematopoietic stem cell
Hematocytoblast; all formed elements arise from this undifferentiated precursor cells residing in red blood marrow
Erythropoiesis
Erythrocyte production
Myeloid stem cell
Erythropoiesis begins when this cell transforms into a proerythroblast
Proerythroblast
A myeloid stem cell transforms into this committed cell that gives rise to basophilic erythroblasts
Basophilic erythroblasts
Cell that produces huge number of ribosomes & transforms into a polychromatic erythroblast & then an orthochromatic erythroblast
Polychromatic erythroblast
Develops from a basophilic erythroblast; develops into an orthochromatic erythroblast
Orthochromatic erythroblast
Develops from a polychromatic erythroblast; when it has accumulated most of its hemoglobin, it ejects most of its organelles, its nucleus disintegrates & pinches off, which allows the cell to collapse inward & eventually assume the biconcave shape
Reticulocyte
Young erythrocyte; named because it still contains a scant reticulum of clumped ribosomes
Reticulocyte counts
Provide a rough index of the rate of RBC formation
Erythropoietin (EPO)
Glycoprotein hormone, stimulates the formation of erythrocytes
Ferritin & hemosiderin
Since free iron ions (Fe2+, Fe3+) are toxic, iron is stored inside cells as these protein-iron complexes
Transferrin
In blood, iron is transported loosely bound to this transport protein
Bilirubin
When heme splits from globin, the balance of the heme group is degraded to this yellow pigment that is released to the blood & binds to albumin for transport
Anemia
Condition in which the blood’s oxygen-carrying capacity is too low to support normal metabolism; = a sign of some disorder rather than a disease in itself
Microcytes
Erythrocytes produced in a person with iron-deficient anemia are small and pale & called this because they can’t synthesize their normal complement of hemoglobin
Intrinsic factor
Cells in a person with pernicious anemia produce this substance that must be present for vitamin B12 to be absorbed by intestinal cells
Macrocytes
Without B12, developing erythrocytes grow but can’t divide & these large, pale cells result
Thalassemias
Typically occur in people of Mediterranean ancestry; one of the globin chains is absent or faulty & the erythrocytes are thin, delicate, & deficient in hemoglobin
Sickle-cell anemia
Havoc caused by abnormal hemoglobin (hemoglobin S) results from a change in 1 of the 146 amino acids in a beta chain of the globin molecule; this alteration causes the beta chains to link together under low oxygen conditions, forming stiff rods so that hemoglobin S becomes spiky & sharp & red blood cells become crescent-shaped when they unload oxygen
Polycythemia
Abnormal excess of erythrocytes that increases blood viscosity, causing it to sludge
Blood doping
Practiced by some athletes competing in aerobic events; artificially induced polycythemia
Leukocytes (WBCs)
Only formed elements that are complete cells (with nuclei & the usual organelles)
Diapedis
Process by which WBCs are able to slip out of the capillary blood vessels
Amoeboid motion
Leukocytes move through tissue spaces by forming flowing cytoplasmic extensions that move them along
Positive chemotaxis
Phenomenon in which leukocytes follow the chemical trail of molecules released by damaged cells or other leukocytes
Leukocytosis
WBC count of over 11000 cells/microliter; normal homeostatic response to an infection within the body
Granulocytes
Spherical cells including neutrophils, eosinophils, & basophils; larger & much shorter lived than erythrocytes; lobed nuclei (rounded nuclear masses connected by thinner strands of nuclear material); membrane-bound cytoplasmic granules stain specifically with Wright’s stain; all are phagocytes to some degree
Neutrophils
Most numerous WBCs (50-70%); 2x as large as erythrocytes; 2 types of granules that take up basic/blue & acidic (red) dyes so cytoplasm is lilac colored
Defensins
Smaller granules in neutrophils containing this potent brew of anti microbial proteins
Polymorphonuclear leukocytes (polys)
Because neutrophil nuclei consist of 3-6 lobes, they are often called this
Respiratory burst
Process in which cells metabolize oxygen to produce potent germ-killer oxidizing substances (ex. Bleach, hydrogen peroxide)
Eosinophils
Account for 2-4% of all leukocytes; approximately the size of neutrophils; nucleus is bilobed (looks like old-fashioned telephone receiver); has large, coarse granules that stain from brick red to crimson; lead counter-attack against parasitic worms; complex role in allergies & asthma
Basophils
Rarest of WBCs (0.5-1%); cytoplasm has large, coarse histamine-containing granules that have an affinity for basic dyes, stain purplish black; deep purple nucleus is generally U or S-shaped with 1 or 2 conspicuous constrictions
Agranulocytes
Lymphocytes & monocytes (WBCs that lack visible cytoplasmic granules); nuclei are spherical or kidney shaped
Lymphocytes
Accounts for 25%+ of the WBC population (2nd most numerous leukocyte); large, dark purple nucleus that occupies most of the cell volume; closely associated with lymphoid tissues
T lymphocytes (T cells)
Function in the immune response by acting directly against virus-infected cells & tumor cells
B lymphocytes (B cells)
Give rise to plasma cells, which produce antibodies
Antibodies
Immunoglobulins; produced by plasma cells; released to the blood
Monocytes
Account for 3-8% of WBCs; largest leukocytes; pale blue cytoplasm & a darkly staining purple nucleus (distinctly U or kidney-shaped); differentiate into macrophages
Macrophages
Highly mobile cells with prodigious appetites; actively phagocytic; crucial in body’s defense against viruses, certain intracellular bacterial parasites, & chronic infections (tuberculosis); important in activating lymphocytes to mount their immune response
Leukopoiesis
Production of WBCs, stimulated by chemical messengers
Interleukins
1 of 2 families of hematopoietic factors, numbered IL-3, IL-5 etc
Colony-stimulating factors (CSFs)
1of 2 families of hematopoietic factors; named for the leukocyte population they stimulate
Lymphoid stem cells
Early branching of the pathway of leukocyte differentiation divides these cells, which produce lymphocytes, from the myeloid stem cells
Myeloid stem cells
Cells that give rise to formed elements
Myeloblasts
Committed cells that accumulate lysosomes
Promyelocytes
Myeloblasts accumulate lysosomes becoming these cells
Myelocyte
The distinctive granules of each granulocyte type appear next in this stage and then cell division starts
Band cell
After the myelocyte stage, the nuclei arc, producing this stage
Monoblast & promonocyte stages
Cells following the monocyte line pass through these 2 stages before leaving the bone marrow & becoming monocytes
T & B lymphocyte precursors
T & B lymphocytes are derived from these cells, which arise from the lymphoid stem cell
Leukopenia
Abnormally low WBC count, commonly induced by drugs, particularly glucocorticoids and anticancer agents
Platelets
Not cells in the strict sense; 1/4 the diameter of a lymphocyte; = cytoplasmic fragments of extraordinarily large cells (megakaryocytes)
Megakaryocytes
Extraordinarily large cells that fragment becoming platelets
Thrombopoietin
Hormone that regulates the formation of platelets
Megakaryoblast
Repeated mitoses of this cell occur in the platelet line, but cytokinesis does not
Hemostasis
If a blood vessel wall breaks, a whole series of reactions is set in motion to accomplish this process, which stops the bleeding
Vascular spasm
Damaged blood vessels respond to injury by constricting
Prostacyclin
A prostaglandin that prevents platelet aggregation in undamaged tissue & restrict aggregation to the site of the injury (as does nitric oxide)
Adenosine diphosphate (ADP)
Potent aggregating agent that causes more platelets to stick to the area & release their contents
Serotonin & thrombocytes A2
Messengers that enhance vascular spasm & platelet aggregation
Coagulation (blood clotting)
Process that reinforces the platelet plug with fibrin threads that act as a molecular glue for the aggregated platelets
Clotting factors
Procoagulants; blood is transformed from a liquid to a gel in a multistory process that involves a series of these substances
Intrinsic/extrinsic pathway
Coagulation may be initiated by either of these pathways
Platelet factor 3 (PF3)
Phosphatidylserine
Prothrombin activator
Once factor X has been activated, it complexes with calcium ions, PF3 & factor V combine to form this
Tissue factor (TF) or factor III
Factor triggered by exposing blood to a factor found in tissues underneath the damaged endothelium
Prothrombin
Plasma protein that is converted into the active enzyme thrombin
Thrombin
Active enzyme that arises from prothrombin
Fibrinogen
Soluble clotting factor that is transformed into fibrin by thrombin
Fibrin
Insoluble fiber strands formed from fibrinogen
Factor XIII (fibrin stabilizing factor)
In the presence of calcium ions, thrombin also activates this cross-linking enzyme that binds the fibrin strands tightly together, forming a fibrin mesh
Anticoagulants
Factors that inhibit clotting
Clot retraction
Within 30-60 minutes, this platelet-induced process further stabilizes a clot
Serum
As platelets contract, they pull on the surrounding fibrin strands, squeezing this fluid (plasma minus the clotting proteins) from the mass , compacting the clot & drawing the ruptured edges of the blood vessel more closely together
Platelet-derived growth factor (PDGF)
Released by platelets, this factor stimulates smooth muscle cells & fibroblasts to divide & rebuild the vessel wall
Fibrinolysis
Process that removes unneeded clots when healing has occurred
Plasmin
Critical natural clot-buster; fibrin-digesting enzyme that is produced when the plasma protein plasminogen is activated
Plasminogen
Plasma protein that produces plasmin when activated
Tissue plasminogen activator (tPA)
The presence of a clot in and around the blood vessel causes the endothelial cells to secrete this
Antithrombin III
A protein present in plasma that quickly inactivates any thrombin not bound to fibrin
Protein C
A protein produced in the liver that inhibits the activity of other intrinsic pathway clotting factors
Heparin
Natural anticoagulant contained in basophilic & mast cell granules & on the surface of endothelial cells
Thromboembolic disorders
Disorders resulting from conditions that cause undesirable clot formation
Bleeding disorders
Disorders that arise from abnormalities that prevent normal clot formation
Disseminated intravascular coagulation (DIC)
Disorder with characteristics of both thromboembolic disorders & bleeding disorders
Thrombus
A clot develops & persists in an unbroken vessel
Embolus
If a thrombus breaks away from a vessel & floats freely in the bloodstream, it becomes this “wedge”
Embolism
When an embolus encounters a blood vessel too narrow for it to pass through, it becomes this & this obstructs the vessel
Aspirin
Antiprostaglandin drug that inhibits thromboxane A2 formation (blocking platelet aggregation & platelet plug formation)
Warfarin
Mainstay of outpatient treatment to reduce the risk of stroke in those prone to atrial fibrillation (condition where blood pools in the heart)
Thrombocytopenia
A condition in which the number of circulating platelets is deficient, causing spontaneous bleeding from small blood vessels all over the body
Hemophilia
Refers to several hereditary bleeding disorders that have similar signs & symptoms
Factor VIII (antihemophilic factor)
Hemophilia A results from a deficiency of this factor
Whole blood transfusions
Procedure that is routine when blood loss is rapid and substantial
Packed red cells
In cases where blood loss is not rapid or substantial, transfusions of these are preferred for restoring oxygen-carrying capacity (whole blood in which most of the plasma & leukocytes have been removed)
Agglutinogens
RBC antigens, so named because they promote agglutination (clumping)
ABO blood groups
Blood groups based on the presence or absence of 2 agglutinogens (type A & type B)
Agglutinins
Unique to the ABO blood groups is the presence in the plasma of these preformed antibodies
Rh factor
1 of 52 Rh agglutinogens
Hemolytic disease of the newborn
AKA erythroblastosis fetalis; pregnant mother’s antibodies cross the placenta and destroy the baby’s RBC’s when an Rh factor incompatibility exists; baby becomes anemic and hypoxic; brain damage and death may result unless transfusions are done before birth to provide the fetus with more erythrocytes for oxygen transport
Tranfusion reaction
when mismatched blood is infused, this occurs, in which the recipient’s plasma agglutinins attach the donor’s RBCs
Universal donor
group O blood because O red blood cells bear neither the A nor the B antigen
Universal recipients
group AB blood because AB plasma is devoid of antibodies to both A and B antigens; can receive transfusions from any of the ABO groups
Autologous transfusions
the patient predonates his own blood, and it is stored and immediately available if needed during an operation
Plasma expanders
purified human serum, albumin, hetastarch, and dextran; provide no benefits over much cheaper electrolyte solutions and are associated with significant complications of their own
Differential white blood cell count
determines the relative proportions of individual leukocyte types; valuable diagnostic tool
Prothrombin time
test used to assess the ability of blood to clot
Platelet count
test done when thrombocytopenia is suspected
Complete blood count (CBC)
test that includes counts of the different types of formed elements, the hematocrit, measurements of hemoglobin content, and size of RBC’s
Hemoglobin F
unique hemoglobin formed by a fetus that has a higher affinity for oxygen than does adult hemoglobin (hemoglobin A)
