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Introduction to blood Fluid component of blood “Formed elements” Function of blood Maintenance of blood volume. Total volume of blood is ~5.5 liters About 55% is plasma; rest is cells Most are red cells (RBCs) Cells are specialized to carry oxygen full of hemoglobin; no organelles
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Introduction to blood Fluid component of blood “Formed elements” Function of blood Maintenance of blood volume
Total volume of blood is ~5.5 liters About 55% is plasma; rest is cells Most are red cells (RBCs) Cells are specialized to carry oxygen full of hemoglobin; no organelles 4-6 million RBCs per cc for males; 4-5 million for females What factors affect RBC count and activity?
Insufficient red cell production and/or oxygen delivery- anemia Causes: iron deficiency (most common) vitamin B12, folic acid (pernicious anemia) hemolytic anemia sickle cell anemia blood loss bone marrow disease infections
All blood cells are formed in the bone marrow Red blood cells White blood cells (leukocytes) neutrophils lymphocytes monocytes eosinophils basophils Platelets (megakaryocytes)
Leukocytes help fight infection Phagocytes neutrophils monocytes/macrophages phagocytes Inflammation neutrophils infiltrate site monocytes/mactrophages help control immune reactions basophils release chemicals involved in inflammation, allergy
White cell counts is normally 5000-10000/cc Leukocytosis- elevated cell count Leukopenia- count is depressed Differential- neutrophils 50-75% lymphocytes 20-40% monocytes 5-10% eosinophils 1-3% basophils 0-1%
Hemostasis (clotting; stoppage of blood loss) Platelets- plug formation; can repair small wounds Clotting factors (coagulation)
What’s in plasma? water nutrients plasma proteins albumins alpha and beta globulin gamma globulin (antibodies) all except gamma globulins are formed in the liver maintain osmotic pressure (and thus blood volume) gases; wastes
Red blood cell antigens and blood typing Antigen: a molecule that is recognized as foreign by the immune system Lots of these: several different types of antigens found on red blood cells (RBCs) ABO system especially important Four blood types: A, B, AB, O A and B are dominant, O is recessive
People with type A blood can tolerate type A blood from other individuals But type A people make antibodies to type B antigens People with type AB can tolerate all blood types: universal recipient (of CELLS) People with type O blood can donate to all but have antibodies to both A and B antigens: universal donor (of CELLS)
Rh antigen is also important People either have the antigen or do not Rh-negative people will develop antibodies to the Rh antigen if they are exposed to the Rh-positive blood If a Rh-negative woman becomes pregnant with a Rh-positive fetus she may make antibodies to the fetus’ RBCs This can be prevented with RhoGAM
Implications for: blood transfusions Blood type antigen antibody A A anti-B B B anti-A AB A, B neither O neither anti-A and B
Transfusions are preferred between people of the same blood type If blood is properly processed and administered: A can receive from A and O B from B and O AB from AB, A, B and O O only from type O- but can donate to everyone else Rh-positive can receive from negative and positive Rh-negative only from negative
Blood types are inherited In some parts of the world some blood types are more common than others In U.S.: ~45% are O, ~40% are A, 12% are B, and about 3% are AB about 85% are Rh-positive
Roles of blood oxygen transport nutrient transport waste transport transport of other essential molecules (antibodies, hormones, etc.) regulation (temperature, metabolism, etc.) fighting infection