red blood cells

• Red blood cells (RBC) - erythrocytes
• Shape: bioconcave disk

  • increased surface area for gas exchange
  • cell membrane close to hemoglobin
  • lose nuclei as they mature to carry more oxygen
• • cannot perform protein synthesis of cell division
  • lose mitochondria too
  • can only perform glycolysis for ATP
  • do not use the oxygen they carry
• hemoglobin: protein complex that binds to oxygen

  • heme: red pigment containing iron, binds oxygen
  • globin: 4-part protein complex, can bind to carbon dioxide

  gives RBC their color
• oxyhemoglobin: hemoglobin bound to oxygen, bright red

  deoxyhemoglobin: hemoglobin not bound to oxygen, dark red
• red blood cell production: erythropoiesis

  • produced in red bone marrow in adults
  • produced from hematopoietic stem cells
• triggered by erythropoietin hormone produced by kidney and liver in response to oxygen deficiency
• dietary needs

  • B-complex vitamins: B12 and folic acid for DNA synthesis
  • iron for hemoglobin synthesis
• Red blood cell destruction

  • macrophages destroy RBC, primarily in the liver and spleen
  • hemoglobin is broken down into amino acids and iron to be recycled
• heme decomposes into biliverdin (green) and bilirubin (yellow) pigments; released as bile pigments

  • degraded pigment leaves as stercobilin (brown) and urobilin (yellow)
• average lifespan of a RBC is 120 days
• walls of the heart

  • epicardium: “on the heart”, outer layer that protects the heart by reducing friction
  • myocardium: “muscle heart”, cardiac muscle
  • endocardium: “inside the heart”, inner layer containing purkinje fibers
• chambers of the heart

  • atria: “entryway”, upper chambers that receive blood returning to the heart
• auricles: “small ears”, increase atrial volume

  • ventricles: ”underside”, lower chambers that receive blood from atria and contract to force blood out
• septum: separates right and left sides of the heart
• blood flow through the heart

  • blood returns to the right atrium
• • superior vena cava: deoxygenated blood from upper body
  • inferior vena cava: deoxygenated blood from lower body
  • coronary sinus: deoxygenated blood from the heart
• blood pumped from right atrium to right ventricle

  • passes through tricuspid valve
  • 3 cusps close to prevent backflow
• blood pumped from right ventricle to pulmonary circuit

  1. passes through pulmonary semilunar valve
  2. pulmonary trunk
  3. pulmonary arteries (left and right)
  4. deoxygenated blood travels to lungs