Blood

Characteristics of Blood Connective tissue Plasma and cells Transports substances between body cells and the external environment

Blood Volumes Varies with body size (type), fluid and electrolyte concentrations, and amount of adipose (fat) Average adult volume – 5 liters (4-5 L for women, 5-6 L for men) Hematocrit – usually 45%

Blood Cell Types Erythrocytes – Red blood cells Leukocytes – White blood cells Thrombocytes - platelets

Red Blood Cells (RBCs) Biconcave disks that thin near the centers increased surface area for transporting gases Have nuclei early in development, but extrude them No nucleus – more room for hemoglobin, but cannot reproduce or make proteins

Hemoglobin Oxygen-carrying protein 1/3 of each RBC Gives blood its color Oxyhemoglobin Deoxyhemoglobin Hypoxia Cyanosis

Red Blood Cell Counts RBCC – the number of RBCs in 1 mm3 of blood Adult male average – 4.6 – 6.2 million Adult female average – 4.2 – 5.4 million Determines blood’s oxygen carrying capacity Important diagnostic tool

Blood Cell Production RBCs are normally flexible, elastic, and able to pass through small blood vessels More fragile as they age Macrophages phagocytize and destroy damaged RBCs in the liver and spleen in about 120 days

White Blood Cells (WBCs) Function to protect against disease Phagocytize bacterial cells Produce antibodies Move by diapedesis 2 main types: Granulocytes – neutrophils, eosinophils, and basophils Agranulocytes – monocytes and lymphocytes

Granulocytes - Neutrophils Lobed nucleus with 2-5 sections Dark staining nucleus and pale granules 54-62% of WBCs Contain many lysosomes – actively phagocytizes bacteria

Granulocytes - Eosinophil Contains coarse, uniformly sized granules 2 lobes on nucleus Stains red 1-3% of WBCs Kills parasites Helps control inflammation and allergic reactions

Granulocyte - Basophils Fewer, more irregular granules than eosinophils Granules stain deep blue Less than 1% of WBCs Contain heparin (inhibits blood clotting) and histamine (increases blood flow to injured tissues)

Agranulocytes - Monocytes Largest blood cells May live weeks to months 3-9% of WBCs Change to macrophages in tissue

Agranulocyte - Lymphocytes Form in red bone marrow and lymphatic system Slightly larger than RBCs Large, round nucleus with rim of cytoplasm May live for years 25-33% of WBCs Important for immune response

White Blood Cell Count (WBCC) Number of WBCs in 1 mm3 of blood Adult average – 5000 – 10,000 cells Leukocytosis – high count Leukopenia – low count Differential WBCC (DIFF) More neutrophils – bacterial infection More eosinophils – parasitic infection, allergic reaction Leukemia

Platelets-- Thrombocytes Not complete cells Form from megakaryocytes that fragment Lack nuclei Half size of RBCs Live 10 days Average count – 300,000/mm3 Help close breaks in damaged blood vessels Initiate formation of blood clots

Plasma 92% water Functions include: Transporting nutrients, gases, and vitamins Regulating fluid and electrolyte balance Maintaining pH

Hemostasis Step 1: Vascular spasms Step 2: Platelet plug formation Step 3: Coagulation Step 4: Fibroblasts invade clot Process takes 3-6 minutes

Hemostasis

Blood Disorders Normally clots are good, but an embolism is a clot that dislodges and travels elsewhere in the body. This can result in a coronary (heart) or a stroke (brain). A brain (cerebral) aneurysm is a bulging, weak area in the wall of an artery that supplies blood to the brain. In most cases, a brain aneurysm causes no symptoms and goes unnoticed. In rare cases, the brain aneurysm ruptures, releasing blood into the skull and causing a stroke.

Blood Groups ABO blood group is based on the presence or absence of 2 major antigens (RBC surface molecules) 4 possible combinations: A B AB O Blood typing game

video

Rh Blood Group 85% people are Rh+ Rhesus (Rh) factor is an inherited protein found on the surface of red blood cells. If your blood has the protein, you're Rh positive. If your blood lacks the protein, you're Rh negative.