Blood

• Functions of the Blood:

  1. transport of gases, nutrients, and waste products
  2. transport of processed molecules
  3. transport of regulatory molecules
  4. regulation of pH and osmosis
  5. maintenance of body temperature
  6. protection against foreign substances
  7. clot formation
• composition of the blood: plasma, buffy coat, red blood cells
• plasma: water, proteins, nutrients, hormones, etc.
• buffy coat: platelets, white blood cells
• hematocrit: red blood cells
• normal blood for males: 37%-47% hematocrit

  normal blood for females: 42%-52%
• anemia: depressed hematocrit %
• polycythemia: elevated hematocrit %
• Hemopoiesis is the proliferation and differentiation of the formed elements of blood.
• red blood cells are disk-shaped, with edges thicker than the center of the cell
• the biconcave shape of RBCs allow gases to move more rapidly into and out of the RBC as compared to a flat disc of the same size
• RBCs live for 120 days in males, and 110 days in females
• primary function of RBCs: transport oxygen from lungs to various tissues of the body and help transport carbon dioxide from tissues to lungs
• hemoglobin: pigmented protein responsible for rbc's red color
• 1 protein chain (globin) is bound to 1 heme (red pigmented molecule)
• 1 rbc contains many molecules of hgb, allowing for transport of sufficient oxygen to the cells of the body. hgb picks up oxygen in the lungs and releases oxygen in other tissues
• arterial: oxygenated blood (hgb bound to oxygen), bright red color
• venous: deoxygenated blood (hgb not bound to oxygen), dark red color
• rbc production depends on the presence of several vitamins and minerals
• vitamin B12 (cobalamin) and B9 (folate): for cell division that produces new rbcs
• iron: hgb production
• old/abnormal/damaged rbc's are removed through phagocytosis in the spleen and liver (components are either recycled or excreted from the body)
• white blood cells are spherical cells without hgb
• white blood cells are larger than rbcs
• white blood cells have a nucleus
• white blood cells functions:

  1. protect the body against invading microorganisms and other pathogens
  2. remove dead cells and debris from the tissues by phagocytosis
• white blood cells are not similar in shape
• types of WBCs:

  1. neutrophil
  2. basophil
  3. eosinophil
  4. lymphocyte
  5. monocyte
• neutrophil: most common; with 3-4 lobes; phagocytize microorganims
• basophil: least common; large granules that stain blue or purple; releases histamine and heparin
• eosinophil: granules that stain bright red; with 2-lobed nucleus; associated with allergies and parasitic infection
• lymphocyte: smallest wbc; important role in immune response
• monocyte: largest wbc; this becomes a macrophage once it leaves the blood and enter the tissues
• platelets: minute fragments of cells consisting of small amount of cytoplasm surrounded by a cell membrane
• platelets are produced in the red bone marrow from megakaryocyte (large cells)
• platelets: small fragments break off from the megakaryocytes and enter the blood as platelets
• function of platelets: clot formation, thereby preventing blood loss
• ABO blood grouping: used to categorize human blood
• ABO blood grouping uses antigen on the surface of red blood cells
• 2 antigens in the surface of rbc: type A & type B