Human Anatomy and Physiology Blood Human Anatomy and Physiology

Introduction Blood, a type of connective tissue, is a complex mixture of cells, chemicals, and fluid. Blood transports substances throughout the body, and helps to maintain a stable internal environment. The blood includes red blood cells, white blood cells, platelets, and plasma. There are about one billion red blood cells in two to three drops of blood. For every 600 red blood cells, there are about 40 platelets and one white cell.

Blood Volume and Composition An average-sized adult has a blood volume of about 5.3 quarts (5 liters). A blood hematocrit is normally 45% cells and 55% plasma. Plasma is a mixture of water, amino acids, proteins, carbohydrates, lipids, vitamins, hormones, electrolytes, and cellular wastes.

Blood Cells – Red Blood Cells Red blood cells (erythrocytes) are biconcave disks that contain one-third oxygen-carrying hemoglobin by volume. When oxygen combines with hemoglobin bright red oxyhemoglobin results. Deoxygenated blood (deoxyhemoglobin) is darker. Red blood cells discard their nuclei during development and so cannot reproduce or produce proteins.

Red Blood Cell Production and Its Control In the embryo and fetus, red blood cell production occurs in the yolk sac, liver, and spleen; after birth, it occurs in the red bone marrow. Red marrow can be found in the flat bones and in the spongy bone located in the epiphysis of the long bones. The average life span of a red blood cell is 120 days. The total number of red blood cells remains relatively constant due to a negative feedback mechanism utilizing the hormone erythropoietin.

Erythropoietin Hormone released from the kidneys and liver in response to the detection of low oxygen levels.

Dietary Factors Affecting Red Blood Cell Production Vitamins B12 and folic acid are needed for DNA synthesis, so they are necessary for the reproduction of all body cells, especially in hematopoietic (blood cell producing) tissue. Iron is needed for hemoglobin synthesis. A deficiency in red blood cells or quantity of hemoglobin results in anemia.

Anemia Anemia is a condition in which the body does not have enough healthy red blood cell The body needs certain vitamins, minerals, and nutrients to make enough red blood cells. Iron, Vitamin B12, and folic acid are three of the most important ones. Symptoms of Anemia: You may have no symptoms if the anemia is mild. Some of the first symptoms include feeling grumpy, tired, headaches, or problems thinking. As symptoms progress, symptoms may include brittle nails, light headedness, pale skin, sore tongue, shortness of breath.

Destruction of Red Blood Cells With age, red blood cells become increasingly fragile and are damaged by passing through narrow capillaries. Macrophages in the liver and spleen phagocytize damaged red blood cells. Hemoglobin from the decomposed red blood cells is converted into heme and globin. Heme is decomposed into iron which is stored or recycled and biliverdin and bilirubin which are excreted in bile.

Types of White Blood Cells White blood cells (leukocytes) help defend the body against disease. Five types of white blood cells are in circulating blood and are distinguished by size, granular appearance of the cytoplasm, shape of the nucleus, and staining characteristics. They are formed from hemocytoblasts (hematopoietic stem cells).

Types of White Blood Cells Granulocytes Neutrophils have red-staining fine granules and a multi-lobed nucleus; they comprise 54-62% of leukocytes. Eosinophils have coarse granules that stain deep red, a bilobed nucleus, and make up only 1-3% of circulating leukocytes. .Basophils have fewer granules that stain blue; they account for fewer than 1% of leukocytes. Agranulocytes Monocytes are the largest blood cells, have variably- shaped nuclei, and make up 3-9% of circulating leukocytes. Lymphocytes are long-lived, have a large, round nucleus, and account for 25-33% of circulating leukocytes

Neutrophil Eosinophil Lymphocyte Monocyte Basophil

Functions of White Blood Cells Leukocytes (WBCs) can squeeze between cells lining walls of blood vessels and attack bacteria and debris.

Neutrophils and Monocytes Both are phagocytic, with monocytes engulfing the larger particles.

Eosinophils moderate allergic reactions defend against parasitic infections

Includes mast cells that migrate to damaged tissues and release histamine to promote inflammation and heparin to inhibit blood clotting. Basophils

Lymphocytes The major players in specific immune reactions Some produce antibodies Originate from stem cells and differentiate into either B cells or T cells in lymphoid tissue (thymus or bone marrow) Found in lymph and blood

White Blood Cell Counts Leukocytosis occurs after an infection when excess numbers of leukocytes are present. Leukopenia occurs from a variety of conditions, including AIDS, in which low numbers of leukocytes are present. A differential white blood cell count can help pinpoint the nature of an illness, indicating whether it is caused by bacteria or viruses. It lists the percentages of the types of leukocytes in a blood sample.

Blood Platelets Blood platelets are fragments of megakaryocytes. Platelets help repair damaged blood vessels by adhering to their broken edges.

Blood Plasma Plasma is the clear, straw-colored fluid portion of the blood. Mostly water but contains a variety of substances. Transports nutrients and gases, regulates fluid and electrolyte balance, and maintains a favorable pH.

Plasma Proteins The plasma proteins remain in the blood and interstitial fluids and are not normally used as energy sources. Three major types: albumins, globulins, and fibrinogen

Nutrients and Gases The most important blood gases are oxygen and carbon dioxide. The plasma nutrients include amino acids, monosaccharides, nucleotides, and lipids. Since lipids are not soluble in the water of the plasma, they are surrounded by protein molecules for transport through the bloodstream as lipoproteins. Lipoproteins are classified on the basis of their densities, which reflects their composition. Types of lipoproteins include HDL, LDL, VLDL, and chylomicrons.

Nonprotein Nitrogenous Substances CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Generally include amino acids, urea, and uric acid. Urea and uric acid are the by-products of protein and nucleic acid catabolism.

Plasma Electrolytes Plasma electrolytes are absorbed by the intestine or are by-products of cellular metabolism. They include sodium, potassium, calcium, magnesium, chloride, bicarbonate, phosphate, and sulfate ions. Some of these ions are important in maintaining osmotic pressure and pH of the plasma.

Hemostasis Hemostasis refers to the stoppage of bleeding. Following injury to a vessel, three steps occur in hemostasis: blood vessel spasm platelet plug formation blood coagulation.

Blood Vessel Spasm Cutting a blood vessel causes the muscle in its walls to contract in a reflex, or engage in vasospasm. This reflex lasts only a few minutes, but it lasts long enough to initiate the second and third steps of hemostasis.

Platelet Plug Formation Platelets stick to the exposed edges of damaged blood vessels, forming a net with spiny processes protruding from their membranes. A platelet plug is most effective on a small vessel.

Blood Coagulation Blood coagulation is the most effective means of hemostasis. Blood coagulation is very complex and uses clotting factors. Once a blood clot forms, it promotes still more clotting through a positive feedback system. After a clot forms, fibroblasts invade the area and produce fibers throughout the clots. A clot that forms abnormally in a vessel is a thrombus; if it dislodges, it is an embolus.

Blood Groups and Transfusions Antigens and Antibodies Clumping of red blood cells following transfusion is called agglutination. Agglutination is due to the interaction of proteins on the surfaces of red blood cells (antigens) with certain antibodies carried in the plasma. Only a few of the antigens on red blood cells produce transfusion reactions. These include the ABO group and Rh group.

ABO Blood Group Type A blood has A antigens on red blood cells and anti-B antibodies in the plasma. Type B blood has B antigens on red blood cells and anti-A antibodies in the plasma. Type AB blood has both A and B antigens, but no antibodies in the plasma. Type O blood has neither antigen, but both types of antibodies in the plasma

ABO Blood Group Adverse transfusion reactions are avoided by preventing the mixing of blood that contains matching antigens and antibodies. Adverse reactions are due to the agglutination of red blood cells

Blood Types & Transfusion Possibilities Antigens Antibodies Can Receive Can Donate To A anti-B O, A A, AB B anti-A O, B B, AB AB A,B none all O both anti-A and anti-B only O

Rh Blood Group The Rh factor was named after the rhesus monkey. If the Rh factor surface protein is present on red blood cells, the blood is Rh positive; otherwise it is Rh negative. There are no corresponding antibodies in the plasma unless a person with Rh-negative blood is transfused with Rh-positive blood; the person will then develop antibodies for the Rh factor. Erythroblastosis fetalis develops in Rh-positive fetuses of Rh-negative mothers but can now be prevented.

Blood Types in the U.S. Blood Type & Rh How Many Have It Frequency O Rh Positive 1 person in 3 37.4% O Rh Negative 1 person in 15 6.6% A Rh Positive 1 person in 3 35.7% A Rh Negative 1 person in 16 6.3% B Rh Positive 1 person in 12 8.5% B Rh Negative 1 person in 67 1.5% AB Rh Positive 1 person in 29 3.4% AB Rh Negative 1 person in 167 0.6%

Blood TYpes Most common blood type is type O + Least common blood type is AB -

14. Use the results shown to determine the blood type for each sample. Blood Typing 14. Use the results shown to determine the blood type for each sample. - = No Clumps + = Clump A B Rh Blood Type: ___ To determine a person’s blood type, we add three different serums to blood samples and see if clumps form. Clumps = Positive (+) No Clumps = Negative (-) What would the blood type be for this sample? #13

- = absent + = present Blood Typing Rh Blood Type: ___ A B Rh Blood Type: ___ Blood Typing Use the results shown to determine the blood type for each sample. A B Rh Blood Type: ___ A B Rh Blood Type: ___ A B Rh Blood Type: ___ - = absent + = present

Universal Recipient has blood type AB+ Universal Donor has blood type O-