Blood • Blood is not an epithelial tissue, and it’s not loose or dense connective tissue; it’s classified as a “special connective tissue”. • You have about 5 liters of blood (30 pints), but that is only half of the body fluid. • The other half includes fluid around each cell, and joint fluids, etc.
Blood plasma circulates outside of the blood vessels too! PLASMA EXTRACELLULAR FLUID ↑↓ ↓↑ ↓↑ SYNOVIAL FLUIDS JOINTS CSF
Blood consists of the following: • Plasma • Red blood cells • White blood cells • Platelets
FUN FACTS • In one day, your blood travels nearly 12,000 miles. • Your heart beats around 35 million times per year. Your heart pumps a million barrels of blood during the average lifetime -- enough to fill three supertankers. If an artery is cut, blood will shoot out 30 feet.
Plasma • Plasma is what the blood cells float around in. If you spin a blood sample in a test tube, the red blood cells sink to the bottom, and you’ll see the yellow plasma on top. • Some people who need blood just need the packed RBCs, some need the platelets, others need the plasma, and some need whole blood, which is both plasma and RBCs.
Overview: Composition of Blood Figure 17.1
PLASMA CONTENTS • Water (90%) • Dissolved substances (10%) • Proteins • Albumin (egg white). Most common protein in blood (homeostasis) • Antibodies • Clotting factors called fibrinogen and fibrin. • Lipoproteins (move fats through blood: HDL, LDL) • Nutrients • Glucose (main energy source) • Amino Acids (builds proteins) • Wastes (urea) • Gases (O2, CO2, Nitrogen) • Electrolytes = ions (Na+, K+, Cl-, Ca++)
ERYTHROCYTES (Red blood cells) • 5 million • Like a doughnut with the hole not fully cut out. • These are among the smallest cells in the body • They have no nucleus • Biconcave to increase surface area • Filled with hemoglobin (Hgb), which carries O2 throughout the body. Oxygenated Hgb is bright red, deoxyHgb is deeper red, almost a bluish-purple.
ERYTHROCYTES: • Average life span is 120 days. Old ones are destroyed in the spleen and liver, and Hgb and iron are recycled. • There are 30 trillion RBCs in the body. • About 25% of the body’s cells are RBCs. • 2.4 million RBCs are destroyed per second so that’s how many are made per second. • 8.6 billion RBCs are made each hour. • 200 billion are made each day. • They are made in the red bone marrow (spongy bone).
Disorders of RBCs • Polycythemia • Anemia • Too few RBC’s • Iron deficiency • Hemorrhagic anemia (person lost blood) • Hemolytic anemia (immune disorder, infection, blood transfusion) • G6PD deficiency • Hemoglobin abnormalities • Pernicious (Megaloblastic) anemia (lack of vitamin B12 or intrinsic factor) • Thalassemia • Sickle cell disease • Hereditary spherocytosis
PolycythemiaToo many RBC’s; can cause clots. Need to donate blood frequently
ANEMIA • Any condition of RED BLOOD CELLS in which the blood’s capacity for carrying oxygen is diminished. • HYPOXIA is lack of oxygen to tissues. • It can be caused from: • Ischemia (reduced blood flow to a tissue) • Malfunctioning hemoglobin • Increasing altitude
Anemia • Characteristic sign of anemia: see reticulocytes in the blood (immature red blood cells). • Remnants of the nucleus are still in the cell.
Anemia can be caused by many things. One type of anemia is from too few RBC’s.
IRON DEFICIENCY ANEMIA that was treated with blood transfusion These are the healthy RBCs from blood transfusion
Hemolytic Anemia • Hemolysis means rupture of RBC’s. • Hereditary (born with the genes that cause the disease) • Immune disorders and G6PD deficiency. • Acquired • Infections (malaria), and receiving the wrong blood type in a transfusion.
G6PD Deficiency • Hereditary, X-linked; almost all are males • G6PDH is an enzyme which is important for RBC metabolism. • G6PD is the most common human enzyme defect. • A person with this would have a hard time maintaining iron in a reduced state, and they develop hereditary (NOT acquired) hemolytic anemia in response to a number of causes, most commonly infection or exposure to certain medications, chemicals, or ingestion of fava beans.
HEMOGLOBINOPATHIES • Pernicious anemia (megaloblastic anemia) • Thalassemia • Sickle Cell Disease • Hereditary Spherocytosis
Pernicious anemia (megaloblastic anemia) • Caused by lack of vitamin B12 or intrinsic factor • When a person has gastric bypass surgery, the stomach is no longer able to produce intrinsic factor, which is needed to absorb vitamin B12, which is needed to make hemoglobin in RBC’s. • Without this vitamin, the blood cells are fewer and much larger than normal (megaloblastic). • The surgery patient must take vitamin B12 shots or sublingual supplements for the rest of their life.
Megaloblastic Anemia (Large RBCs: Note that the lymphocyte is the same size as the huge RBCs)
ThalassemiaA hereditary form of anemia where the RBCs have abnormal hemoglobin that deforms the cells TEAR DROP TARGET CELLS SPHEROCYTE
Sickle Cell Disease • A hereditary mutation resulting in one valine amino acid substituted for glutamic acid. • Present in African Americans more than in other groups, and is always characterized by sickled erythrocytes. • The sickle shape helps prevent malaria infections, but it also causes blood clots.
Sickle Cell Anemia SICKLE CELL
Hereditary spherocytosis • The red blood cells shrink over time due to problems with the red blood cell membrane. Many of the RBC’s look small and round.
RBC, Hgb, Hct • Red blood cell (RBC) count is a count of the actual number of red blood cells per volume of blood. Both increases and decreases can point to abnormal conditions. • Hemoglobin (Hgb) measures the amount of oxygen-carrying protein in the blood. • Hematocrit (Hct) measures the percentage of red blood cells in a given volume of whole blood.
Hematocrit • A quick screening test for anemia is the hematocrit. • A drop of blood is drawn up a small glass capillary tube and the tube is centrifuged to pack the red blood cells at the bottom with the plasma on top. • Hematocrit measures the percentage of blood volume that consists of erythrocytes. • The hematocrit is the ratio of packed red blood cells to total blood volume. • Normal is about 45% (46% for men and 38% for women.)
Mean Corpuscular Volume • Mean corpuscular volume (MCV) is a measurement of the average size of your RBCs. • The MCV is elevated when your RBCs are larger than normal (macrocytic), for example in anemia caused by vitamin B12 deficiency. • When the MCV is decreased, your RBCs are smaller than normal (microcytic) as is seen in iron deficiency anemia or thalassemias.
Mean Corpuscular Hemoglobin • Mean corpuscular hemoglobin (MCH) is a calculation of the average amount of oxygen-carrying hemoglobin inside a red blood cell. • Macrocytic RBCs are large so tend to have a higher MCH, while microcytic red cells would have a lower value.
Mean Corpuscular Hemoglobin Concentration • Mean corpuscular hemoglobin concentration (MCHC) is a calculation of the average concentration of hemoglobin inside a red cell. • Decreased MCHC values (hypochromia) are seen in conditions where the hemoglobin is abnormally diluted inside the red cells, such as in iron deficiency anemia and in thalassemia. • Increased MCHC values (hyperchromia) are seen in conditions where the hemoglobin is abnormally concentrated inside the red cells, such as in burn patients and hereditary spherocytosis, a relatively rare congenital disorder.
Red Cell Distribution Width • Red cell distribution width (RDW) is a calculation of the variation in the size of your RBCs. • Having a few RBC’s with various shapes is called aniscocytosis. • Having many RBC’s with various shapes is called poikilocytosis. • In some anemias, such as pernicious anemia, anisocytosisand poikilocytosis causes an increase in the RDW.
BLOOD TYPING: The ABO SYSTEM • Blood typing is the technique for determining which specific protein type is present on the RBC membranes. • Only certain types of blood transfusions are safe because the cell membranes of the red blood cells carry certain types of proteins that another person’s body will think is a foreign body and reject it.
BLOOD TYPING • These proteins are called antigens (something that causes an allergic reaction). There are two types of blood antigens: Type A and Type B. • A person with Type A antigens on their blood cells have Type A blood. • A person with Type B antigens have Type B blood. • A person with both types has type AB blood. • A person with neither antigen has type O blood.
BLOOD TYPING • If a person with type A blood gets a transfusion of type B antigens (from Type B or Type AB, the donated blood will clump in masses (coagulation), and the person will die. • The same is true for a type B person getting type A or AB blood. • Type O- blood is called the universal donor, because there are no antigens, so that blood can be donated to anyone. • Type AB+ blood is considered the universal acceptor, because they can use any other type of blood. This blood type is fairly rare. • The rarest blood type is AB negative.
RH FACTOR • There is another term that follows the blood type. The term is “positive” or “negative”. This refers to the presence of another type of protein, called the Rh factor. A person with type B blood and has the Rh factor is called B positive. • A person with type B blood and no Rh factor is called B negative.
RH FACTOR • The reason this is so important is that if an Rh- mother has an Rh+ fetus in her womb (from an Rh+ father), her antibodies will attack the red blood cells of the fetus because her body detects the Rh protein on the baby’s red blood cells and thinks they are foreign objects. This is called Hemolytic Disease of the Newborn (HDN).