Cardiovascular System Part 2: Blood PDF

Cardiovascular System Part 2: Blood Prepared by: Medical –Surgical Nursing Staff  Learning Outcomes After the end of this chapter, the students will be able to: List the functions of blood. Describe the composition and physical characteristics of whole blood. Explain...

Cardiovascular System Part 2: Blood Prepared by: Medical –Surgical Nursing Staff  Learning Outcomes After the end of this chapter, the students will be able to: List the functions of blood. Describe the composition and physical characteristics of whole blood. Explain why it is classified as a connective tissue. Discuss the composition and functions of plasma. Describe the structure, function, and production of Blood cells. Describe the ABO and Rh blood groups. Explain the basis of transfusion reactions.  Blood is the river of life that surges within us, transporting nearly everything that must be carried from one place to another. Long before modern medicine, blood was viewed as magical an elixir that held the mystical force of life because when it drained from the body, life departed as well. Today, blood still has enormous importance in the practice of medicine. Clinicians examine it more often than any other tissue when trying to determine the cause of disease in their patients The functions of the blood: 1. Transportation of: ▪ Oxygen and nutrients to the tissues for use and storage. ▪ Metabolic wastes to the kidney, liver and skin. ▪ Hormones from the glands to the target tissues. ▪ Enzymes. ▪ Processed molecules: (e.g. Vitamin D & Lactate). 2. Regulation: ▪ Osmosis: (proper concentrations of ions). ▪ pH (Acid base balance). ▪ Body temperature. 3. Protection: ▪ Against excessive loss (Hemostasis). ▪ Against disease: WBCs, phagocytosis, antibodies,…etc. The Composition of the Blood The Composition of the Blood Composition of the blood: 1- Plasma: ▪ Plasma is separated from blood by a coagulant and centrifugation. > 90% of plasma is water. ▪ Fresh plasma is a straw-colored fluid decanted from the top of the centrifuge tube. (Plasma contains clotting proteins) ▪ Serum: a cell-free fluid decanted from clotted blood. (Serum lacks the clotting protein). The Composition of Plasma Water (about 90%). Plasma contains over 100 different dissolved solutes, including: nutrients, gases, hormones, wastes and products of cell activity, proteins, and inorganic ions (electrolytes). Electrolytes. (Na+, Cl−, etc.) vastly outnumber the other solutes.  Plasma proteins Function Albumin: Main contributor to osmotic 60% of plasma proteins pressure. Globulins Alpha & Beta Produced by liver; 36% of plasma proteins most are transport proteins that bind to lipids, metal ions, and fat- soluble vitamins. Gamma Antibodies released by plasma cells during immune response.Fibrinogen: Produced by liver; forms fibrin 4% of plasma proteins threads of blood clot. The Formed Elements of Blood The formed elements of blood include: Erythrocytes. Leukocytes. Platelets  Red Blood Cells (Erythrocytes) Erythropoiesis: The production of RBCs. In response to low blood O2 levels, the kidneys produce erythropoietin, which stimulates RBCs production in red bone marrow. Lifespan ~ 120 days. The average RBC count is 5.500.000 cells/mm3 of blood. Function of RBCs: The primary functions of red blood cells are to transport O2 from the lungs to the various tissues of the body and to help transport CO2 from the tissues to the lungs. Hematocrit: The proportion of blood occupied by RBCs (40-45%). Hemoglobin: (Iron protein) found in the RBC consists of 4 polypeptide chains. Normal hemoglobin level are: 16 g/dl for men and 14 g/dl for women. Function of hemoglobin: Carries oxygen and carbon dioxide between the lungs and the body cells The major breakdown product of hemoglobin is bilirubin.  Anemia Anemia is defined as a low number of red blood cells (low hemoglobin or hematocrit). Anemia classification according to cause: 1. Dietary deficiencies of iron (iron-deficiency anemia), vitamin B12, or folic acid. 2. Bone marrow failure due to toxic drugs or cancer 3. Blood loss from the body (hemorrhage). 4. Inadequate secretion of erythropoietin in kidney disease 5. Excessive destruction of erythrocytes (for example, sickle- cell disease)  Polycythemia Polycythemia is an abnormal excess of erythrocytes that increases blood viscosity. Types of Polycythemia: A- Physiologic polycythemia: ▪ A common type of polycythemia, occurs in natives who live at altitudes of 14,000 to 17,000 feet, where the atmospheric oxygen is very low. ▪ The blood count is generally 6-7 million/mm3. B- Secondary (Polycythemia vera): ▪ A pathologic condition in a bone marrow cancer, is characterized by dizziness and an exceptionally high RBC count (8–11 million cells/μl)  White Blood Cells (Leucocytes) ▪ Largest-sized blood cells ▪ Lowest numbers in the blood (4,500 – 11,000 per microliter) ▪ Formed in the bone marrow and some in lymph glands ▪ Primary cells of the immune system ▪ Fights disease and foreign invaders ▪ Life span is from 24 hours to several years There are five different types of WBCs A. Granular leucocytes: ✓ Neutrophils ✓ Eosinophils ✓ Basophils A. A granular leucocytes: ✓ Lymphocytes (T & B & natural killers) ✓ Monocytes Platelets (Thrombocytes): Formed in the bone marrow Smallest of the blood cells Counted: 150,000 – 400,000/ mm3. Functions: ▫ Involved in the clotting process ▫ Seal wounds and prevent blood loss ▫ Help repair damaged vessels Half-life: 8-12 days. 30% stored in the spleen. So, Splenectomy leads to an increase in platelet count (Thrombocytosis).  Hemostasis prevents blood loss When a blood vessel is damaged, loss of blood is minimized by three processes: ▪ Vascular spasm ▪ Platelet plug formation. ▪ Blood clotting. Blood Grouping People have different blood types, and transfusion of incompatible blood can be fatal. RBC plasma membranes, like those of all body cells. The ABO blood groups are based on the presence or absence of two agglutinogens: Type A and type B. Depending on which of these a person inherits, his or her ABO blood group will be one of the following: A, B, AB, or O. Agglutinins (Antibodies) Unique to the ABO blood groups is the presence in the plasma of preformed antibodies called agglutinins. The agglutinins act against RBCs carrying ABO antigens that are not present on a person’s own red blood cells. Normally, antibodies do not develop against an antigen unless the body is exposed to that antigen. A newborn lacks these antibodies, but they begin to appear in the plasma within two months and reach adult levels between 8 and 10 years of age. Blood Groups Blood group A: Has type A antigen & anti-B antibodies. Blood group B: Has type B antigen & anti-A antibodies. AB blood group: Has both antigens, with neither A or B antibodies. people with blood group AB are called “Universal receivers." The O blood group: Has neither antigens, while possesses both anti-A and anti-B antibodies. People with blood group 0 are called “Universal donors " A Rh+ B Rh+ AB Rh+ 0Rh+ A Rh- B Rh- AB Rh- 0 Rh- Blood Antigens antibodies Can give Receive group blood to blood from none AB AB, A, B, O AB A and B A A B A and AB A and O B B A B and AB B and O O none A and B AB, A, B, O O Rh Blood Group Another important blood group is the Rh blood group, named as it was first studied in the rhesus monkey. People are Rh-positive if they have certain Rh antigens on the surface of their red blood cells, and they are Rh-negative if they do not have these Rh antigens. The ABO blood type and the Rh blood type are usually designated together. For example, a person designated as type A in the ABO blood group and Rh-positive is said to be A-positive. Rh Blood Group Antibodies against the Rh antigens do not develop unless an Rh-negative person is exposed to Rh-positive red blood cells. This can occur through a transfusion or by the transfer of blood across the placenta to a mother from her fetus. A person with Rh+ blood can receive blood from a person with Rh- blood without any problems. Hemolytic Disease of the Newborn (HDN) Rh incompatibility can pose a major problem in a pregnancy when the mother is Rh negative and the fetus is Rh-positive. Any anti-Rh antibodies produced by the mother may cross the placenta and destroy fetal red blood cells. Mechanism of developing HDN 1. If the mother is Rh-negative and is pregnant with an Rh-positive fetus, fetal blood leaks through the placenta and mixes with the mother's blood. 2. The mother becomes sensitized to the fetal Rh antigens and produces anti-Rh antibodies, which can cross the placenta into the fetal blood (in late pregnancy or during delivery). 3. In later pregnancies, if the fetus is Rh-positive, the fetal blood leaks into the mother’s blood, she rapidly produces large amounts of anti-Rh antibodies, which can cross the placenta to the fetus, resulting in HDN References 1. Marieb E. & Hoehn K. ( 2023). Human Anatomy & Physiology, 12th Global Edition-Pearson Education Limited. 2. VanPutte C., Regan J., & Russo A. (2021). Seeley’s Essentials of Anatomy & Physiology, 11th Edition- McGraw Hill Education.