Bio

• The heart is a muscular organ that pumps blood around the body
• The heart has 4 chambers:

  • 2 upper chambers called atria
  • 2 lower chambers called ventricles
• The 2 sides of the heart are separated by a thick muscular wall called the septum
• The septum prevents oxygenated blood in the left side from mixing with deoxygenated blood in the right side
• Deoxygenated blood returns to the right atrium of the heart from all parts of the body
• Blood passes into the right ventricle and is pumped to the lungs where it absorbs oxygen and releases carbon dioxide
• Diastole is when the heart muscles relax:

  • Deoxygenated blood from the body enters the right atrium
  • Oxygenated blood from the lungs enters the left atrium
• Systole is when the heart muscles contract:

  • The atria contract forcing blood into the ventricles
  • When full, the ventricles contract, forcing blood out of the heart
• Valves in the heart ensure blood flows in one direction and prevent backflow
• Arteries:

  • Carry blood away from the heart
  • Most carry oxygenated blood (exception is pulmonary artery)
  • Have thick walls with a thick muscle layer to withstand high blood pressure
  • Have a relatively small inside diameter or lumen
  • Blood flow is at high pressure and no valve is present
• Veins:

  • Carry blood to the heart
  • Most carry deoxygenated blood (exception is pulmonary vein)
  • Have thinner walls with less muscle, resulting in lower blood pressure
  • Have a wider inside diameter or lumen
  • Blood flow is slow, and valves are present to prevent backflow
• Capillaries:

  • Arteries subdivide into arterioles and then into a network of blood capillaries
  • Capillaries have walls that are one cell thick, allowing for the exchange of oxygen and glucose with cells
  • Waste products like carbon dioxide and urea diffuse out of cells into capillaries
  • Capillaries join to form venules, which then combine to form veins that carry blood back to the heart
• Blood consists of a liquid part called plasma

  The solid part is mostly made up of blood cells

  Plasma is about 90% water

  Plasma contains 

  Nutrients obtained by the digestion of food which are taken to the cells of the body

  Waste products such a uria

  Proteins such as antibodies

  Hormones

  The mass of blood cells contains a mixture of both red and white blood cells 

  It also contains plateletes 

  plateletes look like fragments of red blood cells

  They are essential for th clothing process
• Red blood cells transport oxygen around the body

  it contains a pigment called hamglobin which contains iron

  a shortage of red blood cells causes aniemia a condi cause by low iron

  lymphocytes release chemicals antibodes that destroy bacteria
• White blood cells

  fight any infections

  they are 2 type phogocytes and lymphocytes

  phogocytea enclose bacteria into the cells and digest them and kill dem