(AP) Blood + Circulation

• Human beings are approximately 70% water by body weight
• Where is the water in the human body

  • Tissue Fluid (surrounds cells)
  • Lymph (within lymph vessels) • Blood vessels
• Blood is a liquid connective tissue required by the body to maintain homeostasis
• Blood functions


  • Transport (of gases, wastes, and nutrients)
  • Clotting (to seal injuries) • Infection Fighting
• The average person has about 5 to 6 liters of blood
• Main parts of blood


  • Plasma (the liquid portion of blood)
  • Formed Elements (the solid part of blood)
• Plasma


  Makes up about 55% of blood volume, contains water and organic and inorganic substances
• Plasma constituents


  • Fibrinogen
  • Albumin
  • Globulins
  • Clotting factors
  • Respiratory gases
• Formed Elements


  The solid part of blood
• Formed Elements


  • Red Blood Cells (Erythrocytes)
  • White Blood Cells (Leukocytes)
  • Platelets (Thrombocytes)
• Red Blood Cells (Erythrocytes)


  • Transport oxygen, formed in bone marrow, over 95% of formed elements
• White Blood Cells (Leukocytes)


  • Fight infection, formed in bone marrow and lymphoid tissue
• Types of White Blood Cells (Leukocytes)


  • Granular (Neutrophils, Eosinophils, Basophils)
  • Agranular (Monocytes, Lymphocytes)
• Platelets (Thrombocytes)


  • Function in blood clotting from fragmentation of large cells called megakaryocytes
• Cholesterols a lipid that is insoluble in plasma. It must be carried by proteins
• HDL (high-density lipoprotein)


  Better than LDL for binding with cholesterol, according to some studies, in the prevention of atherosclerosis
• Blood proteins


  Contribute to the viscosity of blood (blood is thicker than water), which aids in transport
• Blood proteins


  Contribute to osmotic pressure which maintains blood volume
• If you increase water


  Osmotic pressure decreases
• Hemoglobin


  Oxygen is carried by hemoglobin which is made of 2 alpha and 2 beta chains, each containing a heme group which attaches to oxygen
• Hemoglobin


  • It is an excellent carrier of oxygen because it weakly binds with oxygen in the cool, neutral conditions in the lungs and easily gives up oxygen in the warm, acidic tissues
• Hemoglobin is always contained in red blood cells
• Since hemoglobin is a red pigment, red blood cells appear red. This colour can change based on what the hemoglobin is attached to
• Oxyhemoglobin


  Hemoglobin bound to oxygen
• Reduced hemoglobin


  Hemoglobin that has lost its oxygen is dark purple
• Carbon Monoxide (CO)


  A poison found in car exhaust, it binds to hemoglobin better than oxygen, and stays bound for several hours regardless of the environmental conditions. CO poisoning can lead to death
• At the venous end of a capillary, the blood pressure is lower than the osmotic pressure, so water, ammonia, and carbon dioxide tend to diffuse out of the bloodstream
• At the arterial side of a capillary, the blood pressure is higher than the osmotic pressure and therefore water, oxygen, and glucose tend to leave the bloodstream
• Carbonic anhydrase enzyme


  Speeds up the reaction of CO2 and water to form carbonic acid, which then dissociates
• The H+ released by the above reaction could wreak havoc on blood pH. To prevent this, the H+ is picked up by hemoglobin (becoming HHb) so that pH is maintained
• Red blood cells


  • They are biconcave disk-shaped cells without a nucleus, made by cells called erythroblasts in red bone marrow
• There are close to 30 trillion blood cells in an adult. Each cubic millimeter of blood contains from 4 1/2 to 5 1/2 million red blood cells and an average total of 7,500 white blood cells
• Red blood cell formation


  Stem cells continuously divide in red bone marrow, producing red blood cells which then lose their nucleus and become much smaller
• Erythropoietin


  A chemical produced by the kidneys that, when combined with globulin from the liver, causes the bone marrow to produce more red blood cells
• Red blood cells live for only 120 days and then are destroyed in the liver and spleen. The iron is recovered from the hemoglobin and sent to the bones, while the heme portion is chemically degraded and is excreted by the liver in the bile
• Blood clotting


  1. Platelets clump at the site of the puncture and partially seal the leak

  2. Platelets and injured tissues release the enzyme prothrombin activator

  3. Prothrombin is converted to thrombin

  4. Thrombin severs two short amino acid chains from each fibrinogen molecule

  5. These activated chains join end to end to form long fibrin threads

  6. Fibrin threads entangle red cells and platelets in the damaged area and form the framework of the clot
• Calcium ions (Ca2+) are necessary for the conversion of prothrombin to thrombin
• Vitamin K is required for the production of prothrombin
• Clotting takes place faster at warmer temperatures


  Than cold because it is controlled by enzymes
• Serum


  Plasma from which the fibrinogen has been removed due to clotting