A&P Chapter 17- Blood

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Marieb and Hoehn, 9th Edition

Blood components

Cellular and liquid components, consisting of formed elements and plasma.

Formed elements

Consists of buffy coat (WBCs and platelets) and erythrocytes (RBCs).

Leukocytes

White blood cells (WBCs) that make up < 1% of whole blood). The only components of blood that are complete cells (contains a nucleus).

Erythrocytes

Red blood cells that constitute 45% of the total volume of blood, a percentage known as hematocrit; have no nucleus; bound by a plasma membrane; lack a nucleus and essential organelles.

Blood

The only liquid fluid in the human body; consists of a sticky, opaque fluid with a characteristic metallic taste; denser than water; slightly alkaline with a pH between 7.35 and 7.45; accounts for approximately 8% of body weight.

Buffy Coat

A thin, whitish layer that is present at the erythrocyte-plasma junction.

Distribution function of blood

Delivers oxygen, transports metabolic waste products, and transports hormones.

Regulatory function of blood

Maintains body temperature; maintains normal pH levels; maintains adequate fluid volume in circulatory system.

Protective function of blood

Prevents blood loss (initiates clot formation); prevents infection via antibodies, complement proteins, and white blood cells.

Plasma

A sticky fluid consisting mainly of water (90%) with over 100 different dissolved solutes; includes nutrients, gases, hormones, wastes and products of cell activity.

Plasma components

Water (90%), electrolytes, plasma proteins (8%),non-protein nitrogenous substances, organic nutrients, respiratory gases, and hormones.

Plasma proteins

Consists of albumin (60%), globulins (36%), fibrinogens (4%), and gamma (antibodies released by plasma cells).

Albumin

Accounts for 60% of plasma protein, acts as a carrier for certain molecules through circulation, is an important blood buffer, and is the major blood protein that contributes to plasma osmotic pressure.

Hemoglobin

RBC protein that makes red blood cells red, binds easily and reversibly with oxygen, and functions in the transport of oxygen; makes blood more viscious. About 65% of the body's iron supply is in hemoglobin.

Spectrin

RBC protein that maintains the biconcave shape of an erythrocyte, allowing erythrocytes to twist, turn, and become cup-shaped as they travel through capillaries smaller than themselves.

Oxyhemoglobin

When oxygen binds to iron, it assumes a three-dimensional shape and becomes ruby red.

Directional transport of blood oxygen

Moves from lungs to tissue cells.

Deoxyhemoglobin

In body tissues, oxygen detaches from iron, hemoglobin resumes its former shape, and the released oxygen diffuses from the blood into the tissue fluid and tissue cells.

Carbaminohemoglobin

The combining of carbon dioxide (20%) in the blood with hemoglobin, binding to amino acids rather than to the heme (red pigment) group.

Directional transport of carbon dioxide

Moves from tissues cells to the lungs.

Hematopoiesis

Blood cell formation.

Red Bone Marrow

Composed primarily of a soft network of reticular connective tissue bordering on wide blood capillaries called blood sinusoids.

Hematopoietic Stem Cell

Undifferentiated precursor cells (prior to commitment to a specific blood pathway). Also known as hemocytoblast.

Stages of Erythropoiesis

Hematopoietic stem cell, pro erythroblast, basophilic erythroblast, polychromatic erythroblast, orthochromatic erythroblast, reticulocyte, erythrocyte. (7 sequences).

Erythropoiesis

Erythrocyte production process that takes about 15 days to complete the cycle.

Myeloid Stem Cell

Hematopoietic stem cell descendant

Proerythroblast

Committed (stem) cell.

Basophilic Erythroblast

Phase I of red blood cell formation that produces ribosome synthesis.

Polychromatic Erythroblast

First half of Phase II of red blood cell formation where hemoglobin is synthesized an iron accumulates.

Orthochromatic Erythroblast

Second half of Phase II of red blood cell formation when cell cytoplasm changes from blue to pink, and the nucleus degenerates and is pinched off, causing the cell to collapse inward (biconcave shape).

Reticulocyte

Newly-formed erythrocyte that contains a reticulum (network) of clumped ribosomes.

Reticulocyte Counts

Provides an approximate index of the rate of RBC formation.

Erythropoietin (EPO)

A glycoprotein hormone that stimulates the formation of erythrocytes. Kidneys and liver produce EPO production.

Triggers of EPO

Hypoxia-inducible factor (HIF) occurs when oxygen deficient enzymes are unable to carry out their normal functions, causing a drop normal blood oxygen.

Results of EPO

Reduced numbers of red blood cells due to hemorrhage or excessive RBC destruction; insufficient hemoglobin per RBC (iron deficiency); reduced availability of oxygen (as might occur in high altitudes or during pneumonia).

Dietary Requirements of Erythropoiesis

Amino acids, lipids, carbohydrates, and iron.

Iron Storage

Iron is stored in the hemoglobin (65%), liver, spleen, and bone marrow.

Protein-Iron Complexes

Ferritin, hemosiderin, and transferrin.

Bilirubin

A yellow pigment that is released to the blood and binds to albumin for transport. Liver cells secrete it (via bile) into the intestines where it is metabolized into urobilinogen, and exits the body as sterobilin (via feces).

Erythrocyte Disorders

Anemia and Polycythemia

Anemia

A condition in which the blood's oxygen-carrying capacity is too low to support normal metabolism. Conditions include fatigue, pale coloration, shortness of breath, and chilled body temperature.

Causes of Anemia

Blood loss (hemorrhagic anemia), insufficient RBC production (iron-deficiency anemia, pernicious anemia, renal anemia, aplastic anemia), too many RBC destroyed (thalassemias, sickle-cell anemia).

Hemostasis

A plug-the-hole defensive reaction of the body to stop bleeding from cuts or tears. Steps of hemostasis nclude vascular spasm, platelet plug formation, and coagulation.

Vascular Spasm

Step 1 of hemostasis causes vasoconstriction, chemicals release endothelial cells and platelets, and reflexes initiated by local pain receptors. Most effective in smaller blood vessels.

Platelet Plug Formation

Step 2 of hemostasis, platelets aggregate to form a plug to temporarily seal a break in the blood vessel wall.

Prostacyclin

A prostaglandin chemical released by the endothelial cells that restricts aggregation to the injury site. Also called PGI2.

Adensosine 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

Step 3 of hemostasis, also known as blood clotting, reinforces the platelet plug with fibrin threads that act as a :molecular glue" for the aggregated platelets. Blood is transformed from a liquid to a gel in a multi-step process that involves a series of substances called clotting factors or procoagulants.

Prothrombin Activator

Chemical agent, once present, that helps blood clot to form within 10 to 15 seconds. Catalyzes the conversion of prothrombin into thrombin.

Fibrinogen

Also called fibrin, it is long, hair-like strands that glue platelets together to form a web that make the structural basis of a clot.

Anticoagulant

Factor that inhibits clotting.

Clot Retraction

Further stabilizes the clot.

Platelet-derived growth factor (PDGF)

Released by platelets to stimulate smooth muscle cells and fibroblasts to divide and rebuild vessel walls.

Fibrinolysis

The removal of unneeded clots when healing has occurred.

Antithrombin III

A protein present in plasma, it quickly inactivates any thrombin not bound to the fibrin, and inhibits the activity of other intrinsic pathway clotting factors.

Heparin

A natural anticoagulant contained in basophil, mast cell granules, and found on the surface of endothelial cells. It inhibits thrombin.

Disorders of Hemostasis

Thromboembolic disorders, bleeding disorders, and disseminated intravascular coagulation (DIC).

Thromboembolic Disorder

Undesirable clot formation: Thrombus, a clot that develops and persists in an unbroken blood vessel; Embolus, a free-floating thrombus that has come detached.

Bleeding Disorder

Thrombocytopenia, causes spontaneous bleeding from small vessels all over the body; Hemophilia, a hereditary genetic condition with a deficiency of factor VIII (anti-hemophilic factor) that causes bleeding into the tissues from any tissue trauma.

Disseminated Intravascular Coagulation (DIC)

Widespread clotting occurs in intact blood vessels and the residual blood becomes unable to clot.

Whole Blood Transfusion

Routine medical procedure when blood loss is rapid and substantial.

ABO Blood Groups

Based on the absence or presence of type A or type B agglutinogens, the group includes A, B, AB, and O blood types.

Type A Blood

Contains only type A agglutinogen.

Type B Blood

Contains only type B agglutinogen.

Type AB Blood

Contains both type A and type B agglutinogens.

Type O Blood

The most common blood type in North America; contains neither type A or type B agglutinogens.

Rh Blood Groups

There are 52 Rh agglutinogens, each of which is called a Rh Factor; only C, D, and E antigens are fairly common.

Transfusion Reaction

Occurs when mismatched blood is infused, and the recipient's plasma agglutinogens attacks the donor's red blood cells.

Universal Donor

Theoretically refers to type O donors because their blood contains neither type A or type B agglutinogens.

Universal Recipient

Theorectically refers to type AB recipients because they can recieve blood transfusions from any of the ABO blood groups.

Autologous Transfusion

Patient predonates his blood in case it is needed in the future.

Differential White Blood Cell Count

Determines the relative proportions of individual leukocyte types.

Prothrombin Time

Assess the amount of time it takes blood to clot.

Complete Blood Count (CBC)

Counts the different types of formed elements, the hematocrit, measurements of hemoglobin content, and the size of RBCs.

Hemoglobin F

A unique hemoglobin found in fetuses that has a higher affinity for oxygen than adult hemoglobin. After birth, the liver rapidly destroys the fetal erythrocytes carrying hemoglobin F.

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