Biology- Heart and Blood vessels

• Open circulatory system


  • Blood leaves the blood vessels and flows around the cells of the animals body before going back into the blood vessel
• Closed Circulatory System


  • Blood remains in a Continuous system of blood vessels (doesn't leave system)
• Advantages of Closed Systems

  • Blood can be pumped faster allowing nutrients (oxygen) to get to cells faster
  • Blood flow can be regulated by an increase or decrease of blood flow to certain areas of the body
• Artery

  Carries blood away from the heart, blood under high pressure, thick walls, small lumen
• Vein

  • Blood under low pressure
  • Thin walls
  • Large lumen
  • carries blood to heart
• Vessel Walls

  • Outer Layer: tough collagen prevents vessels from over expanding
  • Middle layer: consists of muscles and elastic fibres. Allows the vessels to be more opened or closed
  • Inner Layer: consist of endothelium, a layer of living cells that help regulate blood vessel function (capillaries have singular endothelium layer)
• Lumen


  The opening inside of the blood vessels
• Capillaries


  • Connect arteries to veins and allow for exchange of materials between the blood and body issue
  • Their walls are a singular layer of endothelium
• The Heart


  • Muscular organ that expands and contracts to move blood around the body
  • Located between the lungs, slightly to the Left side
  • Made of cardiac muscle
• Blood Circulation


  1. The heart acts as a double pump sending blood through two circuits

  2. Pulmonary Circuit - blood is pumped to the Lungs to pick up oxygen, then back to the heart

  3. Systemic Circuit - blood with oxygen is pumped around the body, gains CO₂ and returns to the heart
• Blood Supply


  • Heart muscles are supplied with blood from the Coronary (cardiac) arteries, and blood leaves the heart via the Coronary veins
  • Blockage of the coronary arteries is a common cause for a heart attack (cardiac arrest)
• Control of Headbeat


  1. Pacemaker (SA node) sends impuse that causes atria to contract

  2. This pulse stimulates AV node to send impulses down septum to ventricles

  3. Ventricles recieve impulse and Contract
• Pulse


  Alternate expansion and contraction of the arteries
• Blood Pressure


  • Force exerted by the blood against the walls of blood vessels
  • Systole when heart chambers contract
  • Diastole when heart chambers relax
• Portal System


  • Blood pathway that begins and ends in capillaries
  • Example: hepatic portal vein that connects stomach and intestines to liver
• Smoking


  • Damages the heart & blood vessels
  • Increase heart attack rate
  • Increase blood pressure
  • Overworked heart
  • Increase risk of blood clots and cancer
• Animal fats

  Can cause blocked arteries
• High salt intake

  Increase blood pressure
• Overweight

  Increases blood pressure & heat attacks
• Aerobic Exercise 


  • Is good for heart health
  • Strengthens heart
  • Improves circulation
  • Reduces weight
• Stages of heartbeat


  1. Blood enters heart

  2. Blood pumped from atria to ventricles

  3. Blood leaves heart