Blood Functions Blood maintains: – Appropriate body temperature by absorbing and distributing heat to other parts of the body – Normal pH in body tissues – Adequate fluid volume in the circulatory system

Blood Functions: Protection Blood prevents blood loss by: – Activating plasma proteins and platelets – Initiating clot formation when a vessel is broken Blood prevents infection by: – Synthesizing and utilizing antibodies – Activating complement proteins & WBCs to defend the body against foreign invaders

Physical Characteristics of Blood Average volume: – 5–6 L for males; 4–5 L for females The pH is 7.35–7.45 Accounts for approximately 8% of body weight

Composition of Blood Blood is the body’s only fluid tissue (a connective tissue) 2 major components – Liquid = plasma (55%) – Formed elements (45%) Erythrocytes, or red blood cells (RBCs) Leukocytes, or white blood cells (WBCs) Platelets – cell fragments

Components of Whole Blood Withdraw blood and place in tube 1 2 Centrifuge Plasma (55% of whole blood) Formed elements Buffy coat: leukocyctes and platelets (<1% of whole blood) Erythrocytes (45% of whole blood)

Blood Plasma Blood plasma components: – Water = 90-92% – Proteins = 6-8% Albumins-maintain osmotic pressure of the blood Globulins- used for transport purposes Fibrinogen-a clotting protein – Organic nutrients – glucose, carbohydrates, amino acids – Electrolytes – sodium, potassium, calcium, chloride, bicarbonate – Non-protein nitrogenous substances – lactic acid, urea, creatine – Respiratory gases – oxygen and carbon dioxide

Formed Elements – Only WBCs are complete cells – RBCs have no nuclei or organelles, and platelets are just cell fragments Most F.E. survive in the bloodstream for only a few days Most do not divide but are renewed by cells in bone marrow

Erythrocytes (RBCs) Biconcave disc – Folding increases surface area (30% more surface area) Anucleate, no centrioles, no organelles – No cell division – No mitochondria means they generate ATP anaerobically This prevents consumption of O 2 being transported Filled with hemoglobin (Hb) - 97% of cell contents – Hb functions in gas transport Most numerous of the formed elements

Erythrocyte Function Erythrocytes are dedicated to respiratory gas transport Hb reversibly binds with oxygen and most oxygen in the blood is bound to Hb Composition of Hb – A protein called globin – A heme molecule (a metal complex with iron as the central metal atom, that can bind or release molecular oxygen.) Heme groups are embedded in the hemoglobin protein,

Production of Erythrocytes Hematopoiesis – blood cell formation – Occurs in the red bone marrow Axial skeleton and girdles Epiphyses of the humerus and femur

Anemia – blood has abnormally low oxygen-carrying capacity There are many forms of anemia, each with its own cause. Anemia can be temporary or long term, and it can range from mild to severe. – Blood oxygen levels cannot support normal metabolism – Signs/symptoms include fatigue, paleness, shortness of breath, and chills Erythrocyte Disorders

Leukocytes (WBCs) – Protect the body from infectious microorganisms – Can leave capillaries – Move through tissue spaces – Many are phagocytic- that engulfs and absorbs waste material, harmful microorganisms, or other foreign bodies in the bloodstream and tissues. Two major types of leukocytes – Granulocytes: Neutrophils, Eosinophils, Basophils – Agranulocytes: Monocytes, Lymphyocytes Leukemia - a cancer of WBC

Granulocytes – Contain cytoplasmic granules that stain specifically with Wright’s stain – Are larger and usually shorter-lived than RBCs – Have lobed nuclei – Are all phagocytic cells

Account for 65-75% of total WBC’s Neutrophils have two types of granules that: – Contain peroxidases, hydrolytic enzymes, and defensins (antibiotic-like proteins) Neutrophils are our body’s bacteria slayers Granulocytes: Neutrophils

Eosinophils account for 1–4% of WBCs – Function: Lead the body’s counterattack against parasitic infections Lessen the severity of allergies by phagocytizing immune complexes (ending allergic reactions) Granulocytes: Eosinophils

Account for 0.5-1% of all WBCs – Have large, purplish-black granules that contain histamine Histamine – inflammatory chemical that acts as a vasodilator and attracts other WBCs (antihistamines counter this effect) Granulocytes: Basophils

Account for 20-25% or more of WBCs and: – Found mostly in lymphoid tissue (some circulate in the blood) Most important cells of the immune system Involved in graph rejection, fighting tumors and viruses There are two types of lymphocytes: T cells and B cells – T cells - attack foreign cells directly – B cells give rise to plasma cells, which produce antibodies Agranulocytes: Lymphocytes

Account for 3–7% of leukocytes – They are the largest leukocytes – They have purple-staining, U- or kidney-shaped nuclei – They leave the circulation, enter tissue, and differentiate into macrophages – Increase in # during chronic infections. Monocytes

Platelets are fragments of megakaryocytes Platelets function in the clotting mechanism by forming a temporary plug that helps seal breaks in blood vessels. Platelets Platelet

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

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) Agglutinogens (antigens) and their corresponding antibodies cannot be mixed without serious reactions ABO Blood Groups

The universal donor has Type O negative blood type. The universal plasma donor has Type AB positive blood type. Group A – has only the A antigen on red blood cells (and B antibody in the plasma) Group B – has only the B antigen on red blood cells (and A antibody in the plasma) Group AB – has both A and B antigens on red blood cells (but neither A nor B antibody in the plasma) Group O – has neither A nor B antigens on red blood cells (but both A and B antibody are in the plasma)

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

Rhesus (Rh) factor Is an inherited trait that refers to a specific protein found on the surface of RBCs. If your blood has the protein, you're Rh positive — the most common Rh factor. If your blood lacks the protein, you're Rh negative. Rh factor doesn't affect your health, it can affect pregnancy. your body might produce Rh antibodies after exposure to the baby's red blood cells. Typically, the antibodies aren't a problem during the first pregnancy. with a subsequent pregnancy with an Rh positive baby. In this case, your existing Rh antibodies might cross the placenta and fight the baby's red blood cells. This could lead to life-threatening anemia