Blood and Cardio

• Blood


  Sticky, opaque fluid that is heavier and thicker than water
• Blood


  • Color range: Oxygen-rich blood is scarlet red, Oxygen-poor blood is dull red or purple
  • Metallic, salty taste
  • pH is slightly alkaline between 7.35 and 7.45
  • Temperature is slightly higher than body temperature at 38°C or 100.4°F
• Blood Volume


  • About 5–6 liters, or about 6 quarts, of blood are found in a healthy adult
  • Blood makes up 8 percent of body weight
• Plasma


  • 90 percent water
  • Straw-colored fluid
• Dissolved Substances in Plasma


  • Waste products
  • Nutrients
  • Salts (electrolytes)
  • Respiratory gases
  • Hormones
• Plasma Proteins

  • Albumin is an important blood buffer and contributes to osmotic pressure
  • Clotting proteins help to stem blood loss when a blood vessel is injured
  • Antibodies help protect the body from pathogens
• Erythrocytes (Red Blood Cells or RBCs)


  Carries Oxygen

  
• Characteristics of Red Blood Cells


  • Normal count is 5 million RBCs per cubic millimeter (mm3) of blood
  • Anucleate (no nucleus)
  • Contain few organelles; lack mitochondria
  • Essentially bags of hemoglobin (Hb)
  • Shaped like biconcave discs
• Hemoglobin


  • An iron-bearing protein
  • Binds oxygen
  • Each hemoglobin molecule can bind 4 oxygen molecules
  • Each erythrocyte has 250 million hemoglobin molecules
  • Normal blood contains 12–18 g of hemoglobin per 100 milliliters (ml) of blood

  
• Leukocytes (White Blood Cells or WBCs)


  Crucial in body's defense against disease
• Characteristics of White Blood Cells


  • 4,800 to 10,800 WBCs per mm3 of blood
  • Complete cells, with nucleus and organelles
  • Able to move into and out of blood vessels (diapedesis)
  • Respond to chemicals released by damaged tissues (known as positive chemotaxis)
  • Move by amoeboid motion

  
• Types of Leukocytes

  • Granulocytes
  • Agranulocytes
• Granulocytes


  • Granules in their cytoplasm can be stained
  • Possess lobed nuclei
  • Include neutrophils, eosinophils, and basophils
• Agranulocytes


  • Lack visible cytoplasmic granules
  • Nuclei are spherical, oval, or kidney-shaped
  • Include lymphocytes and monocytes
• Neutrophils


  • Most numerous WBC
  • Multilobed nucleus
  • Cytoplasm stains pink and contains fine granules
  • Function as phagocytes at active sites of infection
  • Numbers increase during infection
  • 3,000–7,000 neutrophils per mm3 of blood (40–70% of WBCs)
• Eosinophils


  • Nucleus stains blue-red
  • Brick-red cytoplasmic granules
  • Function is to kill parasitic worms and play a role in allergy attacks
  • 100–400 eosinophils per mm3 of blood (1–4 percent of WBCs)
• Basophils


  • Rarest of the WBCs
  • Large histamine-containing granules that stain dark blue
  • Contain heparin (anticoagulant)
  • 20–50 basophils per mm3 of blood (0–1 percent of WBCs)
• Lymphocytes


  • Large, dark purple nucleus
  • Slightly larger than RBCs
  • Reside in lymphatic tissues
  • Play a role in immune response
  • 1,500–3,000 lymphocytes per mm3 of blood (20–45% of WBCs)

  
• Monocytes


  • Largest of the white blood cells
  • Distinctive U- or kidney-shaped nucleus
  • Function as macrophages when they migrate into tissues
  • Important in fighting chronic infection
  • 100–700 monocytes per mm3 of blood (4–8 percent of WBCs)
• Platelets


  • Fragments of megakaryocytes (multinucleate cells)
  • Needed for the clotting process
  • Normal platelet count is 300,000 platelets per mm3 of blood
• Hematopoiesis (Blood Cell Formation)


  • The process of blood cell formation
  • Occurs in red bone marrow (myeloid tissue)
  • All blood cells are derived from a common stem cell (hemocytoblast)
  • Hemocytoblasts form two types of descendants: Lymphoid stem cell, which produces lymphocytes, and Myeloid stem cell, which can produce all other formed elements
• Formation of Red Blood Cells

  1. RBCs are anucleate, so they are unable to divide, grow, or synthesize proteins

  2. RBCs wear out in 100 to 120 days

  3. When worn out, RBCs are eliminated by phagocytes in the spleen or liver

  4. Lost cells are replaced by division of hemocytoblasts in the red bone marrow
• Formation of Red Blood Cells

  1. Rate of RBC production is controlled by a hormone called erythropoietin

  2. Kidneys produce most erythropoietin as a response to reduced oxygen levels in the blood

  3. Homeostasis is maintained by negative feedback from blood oxygen levels

  
• Formation of White Blood Cells and Platelets

  1. WBC and platelet production is controlled by hormones

  2. Colony stimulating factors (CSFs) and interleukins prompt bone marrow to generate leukocytes

  3. Thrombopoietin stimulates production of platelets from megakaryocytes
• Hemostasis


  • The process of stopping the bleeding that results from a break in a blood vessel
  • Blood usually clots within 3 to 6 minutes
  • The clot remains as endothelium regenerates
  • The clot is broken down after tissue repair
• Vascular Spasms


  • Immediate response to blood vessel injury
  • Vasoconstriction causes blood vessel to spasm
  • Spasms narrow the blood vessel, decreasing blood loss
• Antigens


  • Blood contains genetically determined proteins known as antigens
  • Antigens are substances that the body recognizes as foreign and that the immune system may attack
  • Most antigens are foreign proteins
  • We tolerate our own "self" antigens
• Antibodies


  • Antibodies are the "recognizers" that bind foreign antigens
  • Blood is "typed" by using antibodies that will cause blood with certain proteins to clump (agglutination) and lyse
• Rhesus factor / Rh factor


  • A certain type of protein found on the outside of blood cells
  • People are either Rh-positive (they have the protein) or Rh-negative (they do not have the protein)
  • The majority of people, about 85%, are Rh-positive
• RH Incompatibility


  • A person with the Rh positive factor will not make anti-Rh antibodies
  • Those with Rh negative factor will produce the antibodies
  • Therefore, someone with Rh+ blood can receive both Rh+ and Rh- transfusions, but those with Rh- can only receive Rh- blood
• Rh incompatibility occurs when a woman who is Rh-negative becomes pregnant with a baby with Rh-positive blood


  With Rh incompatibility, the woman's immune system will produce antibodies that can attack the baby's red blood cells
• Antigen


  Foreign protein
• We tolerate our own "self" antigens
• Antibodies


  The "recognizers" that bind foreign antigens
• Blood typing


  Using antibodies that will cause blood with certain proteins to clump (agglutination) and lyse
• Rhesus factor / Rh factor


  A certain type of protein found on the outside of blood cells. People are either Rh-positive (they have the protein) or Rh-negative (they do not have the protein). The majority of people, about 85%, are Rh-positive.
• A person with the Rh positive factor


  Will not make anti-Rh antibodies
• Those with Rh negative factor


  Will produce the antibodies
• Someone with Rh+ blood


  Can receive both Rh+ and Rh- transfusions, but those with Rh- can only receive Rh- blood
• RH Incompatibility in Pregnancy

  A woman who is Rh-negative becomes pregnant with a baby with Rh-positive blood. The woman's immune system reacts and creates Rh antibodies. These antibodies help drive an immune system attack against the baby, which the mother's body views as a foreign object.