Cardiovascular system

• different types of blood vessels in the body:

  1. arteries
  2. capillaries
  3. veins
• Artery

  • thick , muscular walls ( withstand high pressure of blood )
  • elastic walls
  • small lumen
  • carries blood away
• veins

  • carry blood towards
  • thin walls
  • large lumen
  • contains valves prevent back flow of blood
• Capillary's

  • diffusion of gasses
  • very thin walls , one cell thick
  • very small lumen - one cell at a time can pass through it
  • walls made out of semi - permeable membrane
• red blood cells – these transport oxygen around the body
• white blood cells - these fight infection
• platelets - these clot to prevent blood loss during injury
• plasma - this is the liquid part of blood
• cardiovascular system has three main functions:

  1. transport of oxygen, carbon dioxide and nutrients
  2. clotting of open wounds
  3. regulation of body temperature
• In the heat, blood vessels close to the surface of the skin enlarge. This process is called vasodilation .This allows more heat to be lost from the blood.
• In the cold, blood vessels at the skin's surface close. This process is called vasoconstriction and takes blood away from the surface of the skin to help prevent it from losing heat.
• systolic value – blood pressure while the heart is squeezing
• diastolic value – blood pressure while the heart is relaxing
• average blood pressure for an adult is 120/80 mmhg
• Heart rate (HR) is the number of times the heart beats in one minute
• Stroke volume (SV) is the amount of blood pumped out of the ventricles each time they contract.
• average resting SV is approximately 70 ml.
• cardiac output

  Q = HR × SV