Blood

Functions of Blood (12.1) Substance DITRIBUTION/TRANSPORTATION REGULATION of substances Body PROTECTION

Blood Functions: Distribution (12.1) Blood transports: Oxygen from the lungs and nutrients from the digestive tract Metabolic wastes from cells to the lungs and kidneys for elimination Hormones from endocrine glands to target organs

Blood Functions: Regulation (12.1) Blood maintains: Appropriate body temperature by absorbing and distributing heat to other parts of the body Normal pH in body tissues using buffer systems Adequate fluid volume in the circulatory system

Blood Functions: Protection (12.1) Blood prevents blood loss by: Initiating clot formation when a vessel is broken Blood prevents infection by: Synthesizing and utilizing antibodies Activating WBCs to defend the body against foreign invaders

Physical Characteristics of Blood (12.1) Average volume of blood: 5–6 L for males; 4–5 L for females Viscosity (thickness) - 4 - 5 (where water = 1) Average pH of blood is 7.4 Salinity = 0.85% Reflects the concentration of NaCl in the blood Temperature is 100F slightly higher than “normal” body temperature Blood accounts for approximately 8% of body weight

Composition of Blood (12.2) Blood is the body’s only fluid connective tissue Liquid = plasma (55%) Formed elements (45%) Erythrocytes, or red blood cells (RBCs) Leukocytes, or white blood cells (WBCs) Platelets - fragments of cells

Blood Plasma (12.6) Blood plasma components: Water = 90-92% Inorganic/Organic substances = 6-8% Important for maintain osmotic pressure of the blood, transport of lipids works as a clotting protein. transportation of nutrients such as glucose and urea Regulation of blood pH (electrolytes)

Components of Whole Blood (12.2/12.3) Plasma (55% of whole blood) Buffy coat: leukocyctes and platelets (<1% of whole blood) Formed elements Erythrocytes (45% of whole blood) 1 Withdraw blood and place in tube Centrifuge 2 Hematocrit – the volume percentage of RBC in a sample of whole blood. Males: 47% ± 5% Females: 42% ± 5%

Erythrocytes (RBCs) 12.3 Biconcave disc No nucleus, no centrioles, no organelles Filled with hemoglobin (Hb) - 97% of cell contents Essential for carrying oxygen Most numerous of the formed elements Dedicated to respiratory transport.

Blood Cell Production (12.4) Hemopoiesis – blood cell production Occurs in the red bone marrow Axial skeleton and girdles Epiphyses (end) of the humerus and femur Marrow contains immature erythrocytes Erythropoiesis – production of RBC’s.

Erythropoiesis (12.4) Hemocytoblasts – produce myeloid stem cells which develop into proerythroblasts Erythroblasts – has nucleus and is synthesizing hemoglobin molecules (4 days) Reticulocyte – the nucleus is shed, but other organelles are still present making more proteins. After 2-3 days, the organelles are shed and the reticulocyte enters the blood stream. Erythrocyte – Once the reticulocyte has been in the blood stream for 24 hours, it is considered a mature RBC.

Fate and Destruction of Erythrocytes (12.4) The life span of an erythrocyte is 100–120 days Travels about 750 miles in that time (Chicago to NYC) Old erythrocytes become rigid and fragile, and their hemoglobin begins to degenerate Dying erythrocytes are engulfed by macrophages Heme and globin are separated Iron is removed from the heme and salvaged for reuse

Hormonal Control of Erythropoiesis Erythropoietin (EPO) release by the kidneys is triggered by: Hypoxia due to decreased RBCs Decreased oxygen availability Increased tissue demand for oxygen Enhanced erythropoiesis increases the: RBC count in circulating blood Oxygen carrying ability of the blood RBC/Oxygen levels EPO release RBC production

Erythropoietin Mechanism Imbalance Start Normal blood oxygen levels Stimulus: Hypoxia due to decreased RBC count, decreased availability of O2 to blood, or increased tissue demands for O2 Imbalance Increases O2-carrying ability of blood Reduces O2 levels in blood . Erythropoietin stimulates red bone marrow Kidney (and liver to a smaller extent) releases erythropoietin Enhanced erythropoiesis increases RBC count Figure 17.6

Erythrocyte Disorders Polycythemia Abnormal excess of erythrocytes Increases viscosity, decreases flow rate of blood Anemia – blood has abnormally low oxygen- carrying capacity Blood oxygen levels cannot support normal metabolism Signs/symptoms include fatigue, paleness, shortness of breath, and chills

Erythrocyte Disorders Sickle-cell anemia – results from a defective gene Codes for an abnormal hemoglobin called hemoglobin S (HbS) This defect causes RBCs to become sickle-shaped in low oxygen situations

Leukocytes (WBCs) 12.5 Leukocytes – complete cells with nucleus and organelles 4-8,000/mm3 Number increases in response to bacterial/viral invasion (over 11,000/mm3) Protect the body from infectious microorganisms

Two major types of WBCs 12.5 Granulocytes include Neutrophils, Eosinophils, Basophils (ben) Are 2x larger than RBC and only live for 12 hours Have lobed nuclei Are all phagocytic cells Agranulocytes include Monocytes, Lymphyocytes Live for months to years Normal shaped nuclei Lack granules

Granulocytes (12.5) Neutrophils account for 65-75% of WBC Our body’s bacteria slayers Eosinophils account for 1–4% of WBC Lead the body’s attack against parasitic infections Lessen the severity of allergies by phagocytizing immune complexes (ending allergic reactions) Basophils account for 0.5-1% of all WBC Releases histamine – inflammatory chemical that acts as a vasodilator and attracts other WBCs

Agranulocytes (12.5) Lymphocytes Account for 20-25% of WBC The most important cells of the immune system T cells - attack foreign cells directly B cells - give rise to cells that produce antibodies Monocytes account for 3–7% of WBC They are the largest leukocytes They leave the circulation, enter tissue, and differentiate into macrophages

Leukocyte disorders Leukocytosis Leukopenia Leukemia WBC count is abnormally high at 11,000 cells per millimeter cubed. This is common during sickness Leukopenia decrease in WBC count - below 4,800 mm3 Leukemia cancer of WBC Bone marrow begins to make abnormal WBC’s that grow faster, and larger than normal cells.

Platelets “Thrombocyte” Platelets are small cell fragments Platelets function in the clotting mechanism by forming a temporary plug that helps seal breaks in blood vessels

BLOOD TYPING KEY TERMS ANTIGEN: Proteins on the surface of red blood cells that determine blood type and stimulate B cells to produce antibodies. ANTIBODY: Proteins that B cells of the immune system produced in response to non-self antigens (antibodies react with antigens) AGGLUTINATION: Clumping of blood cells in response to a reaction between an antibody and antigen.

Human Blood Groups (12.9) RBC membranes have antigens on their external surfaces These antigens are: Unique to the individual Recognized as foreign if transfused into another individual Promoters of agglutination Presence or absence of these antigens is used to classify blood groups

Blood Groups (12.9) Humans have 30 varieties of naturally occurring RBC antigens The antigens of the ABO and Rh blood groups cause vigorous transfusion reactions when they are improperly transfused

ABO Blood Groups (12.9) The ABO blood groups consists of: Two antigens (A and B) on the surface of the RBCs Two antibodies in the plasma (anti-A and anti-B)

ABO Blood Groups

Rh Blood Groups (12.9) 85% of the population have the presence of the Rh antigen on RBCs = Rh+ 15% - Lack of antigen indicated as Rh– Anti-Rh are not spontaneously formed only in Rh– individuals Only after the Rh– individual receives Rh+ blood will the anti-Rh antibodies form. A second exposure to Rh+ blood will result in a negative transfusion reaction with agglutination.

Transfusion Reactions (12.9) Transfusion reactions occur when mismatched blood is infused Donor’s cells are attacked by the recipient’s plasma antibodies causing: Diminished oxygen-carrying capacity Clumped cells (agglutination) that impede blood flow Ruptured RBCs that release free hemoglobin into the bloodstream Circulating hemoglobin precipitates in the kidneys and causes renal failure

Fetal and maternal blood types (12.10)

Fetal and maternal blood types (12.10) Rh- mom pregnant with an Rh+ fetus Rh– mother becomes sensitized when Rh+ blood (from Rh+ baby or a Rh+ transfusion) causes her body to synthesis Rh+ antibodies In a second pregnancy, Rh+ antibodies of a sensitized Rh– mother cross the placenta and attack and destroy the RBCs of an Rh+ baby

Determine the blood type.. Has A antigens Universal donor A antibodies Universal recipient AB antigens Both Antibodies Rh factor is present NO antibodies Type A Type O Type B Type AB Type AB Type O + Type AB

Blood Type testing (12.9) When serum containing anti-A or anti-B antibodies is added to blood, agglutination (clumping) will occur. Positive reactions indicate (clumping) Signifying the correct blood type BLOOD TYPE: AB- *antibodies serum

Blood type being tested Blood Typing (12.9) Blood type being tested RBC antigen Serum Reaction Anti-A Anti-B AB A and B + B – A O None