Circulatory System

• Functions of the Circulatory System


  • Transport materials such as waste, nutrients, hormones, enzymes, lymph, antibodies, carbon dioxide and oxygen
  • Regulate body temperature
  • Help fight disease
  • Aid in digestion
• Components of Blood


  • 55% Plasma
  • 45% Formed Elements

  
• Plasma


  Mostly water and also contains proteins
• Formed Elements


  • Red Blood Cells (R.B.C's)
  • White Blood Cells (W.B.C's)
  • Platelets

  
• Red Blood Cells (R.B.C's)

  • Carry oxygen, carbon dioxide and enzymes throughout the bloodstream

  
• White Blood Cells (W.B.C's)

  • Work together to fight infection. The blood carries white blood cells to parts of the body that might contain pathogens.

  
• Platelets


  • "Sticky" proteins that prevent blood loss by forming plugs in blood vessels
• Blood Vessels


  • Arteries
  • Venules
  • Capillaries
• Arteries


  • Branch into smaller vessels known as "arterioles" and they carry blood away from the heart

  
• Venules


  • Smaller veins that lead to larger veins and they carry blood towards the heart

  
• Capillaries


  • Bridged between the arteries and veins, can carry oxygenated blood and deoxygenated blood, the tiniest blood vessels in which rich blood cells deliver oxygen and nutrients to cells and pick up waste from cells

  
• All Arteries carry oxygenated blood except the Pulmonary Arteries (carry blood away from the heart, to the lungs) which carry deoxygenated blood

  
• All Veins carry deoxygenated blood except Pulmonary Veins (carry blood from the lungs to the heart from the lungs), they carry oxygenated blood

  
• Gas Exchange at the Lungs

  1. Exchange of oxygen and carbon dioxide occurs at the alveoli of the lungs

  2. The gases simply diffuse across the alveolar membrane

  3. Pulmonary arteries deliver deoxygenated blood to the lungs, where carbon dioxide is released and exhaled

  4. Pulmonary veins take freshly oxygenated blood from the lungs and bring it to the heart for circulation

  
• The Heart


  • The heart is a double pump because one half of the heart (the right ventricle) sends blood through the lungs, the other half of the heart (the left ventricle) sends blood through the body

  
• Direction of Blood Flow

  • LUNGS → HEART → BODY (repeat)
  • BODY → HEART → LUNGS (repeat)

  
• Red Blood Cells


  • Shaped as biconcave discs
  • Lack a nucleus & cannot reproduce (average lifespan = about 120 days)
  • Transport hemoglobin (each RBC has about 280 million hemoglobin molecules)
  • Can transport oxygen and carbon dioxide
  • Make up approximately 40% of our blood

  
• Hemoglobin


  A polypeptide that is attached to red blood cells and helps to transport oxygen and carbon dioxide, composed of globin (made up of 4 highly folded polypeptide chains) + 4 heme groups (with iron), each molecule can carry 4 molecules of oxygen

  
• Red Blood Cell Disorders

  • Anemia (not enough red blood cells and/or hemoglobin, leading to fatigue)
  • Iron-deficiency anemia (not enough iron to properly transport oxygen)
  • Sickle cell anemia (red blood cells are shaped like sickles and do not properly function)

  
• White Blood Cells


  • The largest type of blood cell, responsible for fighting infections, typically have a short life cycle (from a few days to a few weeks), typically accounts for 4% of our blood
• Types of White Blood Cells

  • Monocyte
  • Eosinophil
  • Basophil
  • Lymphocytes
  • Neutrophil

  
• Platelets


  • The smallest of the blood cells, made up of proteins that can stick to one another and form a clot in blood vessels to stop bleeding, important for hemostasis (prevention of blood loss from a broken blood vessel)
• Buildup of cholesterol and fat in blood vessels

  Blood cannot flow properly, can result in a clot if platelets get stuck between the cholesterol and the artery to create a blockage, leading to heart attack or stroke