BIO10004 WK8

• Blood


  Specialized connective tissue that transports gas, nutrients, hormones, wastes, regulates pH and ions, restricts fluid loss, defends against toxins and pathogens, and sustains body temperature
• Components of blood


  • Plasma (55%)
  • Red blood cells (41%)
  • White blood cells and platelets (4%)
• Plasma proteins


  Albumins, globulins, fibrinogen
• Albumins


  Major contributors to plasma osmolarity and osmotic pressure, transport fatty acids, thyroid hormones, some steroid hormones, and other substances
• Globulins


  Include antibodies (immunoglobulins) that aid in body defense and transport globulin that binds small ions, hormones, and substances
• Fibrinogen

  Aids in blood clotting
• Formed elements


  Red blood cells, white blood cells, platelets
• Hemopoiesis


  Process that produces formed elements
• Platelets


  Make blood sticky and aid in blood clotting
• Blood is specialized connective tissue
• Blood temperature is 38 degrees
• Blood is 5x more viscous than water resulting from interactions among dissolved proteins, formed elements, and water in plasma
• Blood is slightly alkaline at pH of 7.35-7.45
• Myeloid stem cells and lymphoid stem cells

  Population stem cells
• Role of blood


  • Transports oxygen from lungs to tissues and carbon dioxide from tissues to lungs
  • Distributes nutrients absorbed by digestive tract or released from storage
  • Carries hormones from endocrine glands to target cells
  • Carries waste produced by tissues to kidneys for excretion
• Red blood cells


  Produced in bone marrow, take a week to mature, stimulated by hypoxia, iron is recycled at end of life cycle, have a biconcave shape and flexible plasma membrane that gives them a large surface-area-to-volume ratio, enables them to form stacks and bend/flex to enter small capillaries, are unnucleated and retain only the cytoskeleton
• Hemoglobin


  Contains iron that allows it to pick up oxygen from air and deliver it throughout the body, each red blood cell contains about 280 million Hb molecules, roughly 98.5% of oxygen carried by blood is bound to Hb, amount of oxygen bound to Hb depends on oxygen content of plasma
• Blood type


  Determined by surface antigens A, B, and Rh on red blood cells, immune system ignores these antigens on own red blood cells but has antibodies that will attack "foreign" red blood cells with different antigens, leading to agglutination
• Blood type determination


  1. Surface antigens A, B, and Rh

  2. Rh-positive gene is dominant over Rh-negative gene
• White blood cell types

  • Neutrophils
  • Eosinophils
  • Basophils
  • Monocytes
  • Lymphocytes (T cells, B cells, NK cells)
• Neutrophils


  50-70% of white blood cells, 12 μm in diameter, highly mobile, attack and digest marked pathogens
• Eosinophils


  1. 4% of white blood cells, attack objects coated with antibodies, release enzymes that reduce inflammation
• Basophils


  Less than 1% of white blood cells, 8-10 μm in diameter, migrate to injury sites and discharge granules containing histamine and heparin to enhance inflammation
• Monocytes


  1. 8% of white blood cells, remain in circulation for 24 hours before entering tissues to become aggressive phagocytic macrophages
• Lymphocytes


  20-40% of white blood cells, continuously migrate between bloodstream and tissues, T cells responsible for cell-mediated immunity, B cells responsible for humoral immunity, NK cells carry out immune surveillance
• Blood clotting (hemostasis)


  1. Vascular phase (endothelial cells contract and expose basement membrane, release chemical factors, become "sticky")

  2. Platelet phase (platelet plug formation)

  3. Coagulation phase (extrinsic pathway)
• Platelets


  Release chemicals for clotting process, clump up at site of injury to form a platelet plug, reduce size of vessel wall break using filaments myosin and actin
• Two major structures of the lymphatic system

  • Lymph nodes
  • Spleen
• Lymphatic system


  Consists of lymph, lymphatic vessels and lymphoid organs
• Lymph vessels


  Carry lymph from peripheral tissue to venous system
• Types of lymphatics


  • Lymph capillaries
  • Superficial lymphatics
  • Deep lymphatics
• Superficial lymphatics


  Located in the subcutaneous layer deep to the skin; in the areolar tissues of the mucous membranes lining the digestive, respiratory, urinary, and reproductive tracts; and in the areolar tissues of the serous membranes lining the pleural, pericardial, and peritoneal cavities
• Deep lymphatics


  Larger lymphatic vessels that accompany deep arteries and veins supplying skeletal muscles and other organs of the neck, limbs, and trunk, and the walls of visceral organs
• Lymphatic trunks


  Where superficial and deep lymphatics converge to form larger vessels
• Thoracic duct and right lymphatic duct


  Two large collecting vessels that lymphatic trunks form into
• Lymphoid tissue


  Connective tissue
• Tonsils


  Lymphoid nodules consisting of five tonsils
• Lymph nodes


  Small lymphoid organs ranging in diameter from 1 mm to 25 mm, greatest number located in the neck, axillae, and groin, defend against bacteria and other invaders
• Lymphatic system


  Supports the circulatory system by draining excess fluids and proteins from tissues back into the bloodstream, preventing tissue swelling
• Innate immune system


  Nonspecific responses