the heart & blood vessels

• The double Circulatory system

  A) Lungs

  B) Aorta

  C) Pulmonary artery

  D) vena cava

  E) pulmonary vein

  F) rest of the body

  
• Types of blood vessels - each designed for specified functions within the circulatory system.

  A) artery

  B) capillaries

  C) vein

  
• Why is the heart described as an organ?

  It's made up of different tissues that perform specific functions.
• Circulatory system



  An organ system that:

  • transports food and oxygen to body tissues.
  • Transports waste substances out of cells.

  The components are:

  • blood - carries the oxygen and nutrients.
  • blood vessels - holds the blood
  • Heart - pumps the blood to keep it moving through the vessels.
• The journey of blood around the body

  Body tissues ➔ vena cava ➔ right atrium ➔ valve -> right ventricle ➔ valve -> pulmonary artery ➔ lungs ➔ pulmonary vein ➔ left atrium ➔ valve -> left ventricle ➔ valve -> aorta ➔ body tissues
• Heart


  • Central pump of the circulatory system, maintaining flor of blood throughout the body.
  • Supplies oxygenated blood to tissues and organs.
  • Returns deoxygenated blood to the lungs.
  • Walls made of muscle tissue that contract to pump blood.
  • Contains valves to prevent backflow.

  
• Label the heart:

  A) vena cava

  B) right atrium

  C) valves

  D) right ventricle

  E) pulmonary artery

  F) pulmonary vein

  G) left atrium

  H) valves

  I) left ventricle

  J) aorta

  
• Coronary arteries:

  • Small Arteries that branch off the aorta to supply The heart its own supply of oxygenated blood.
  • It encircles the heart, so the muscle tissue gets all of the oxygen & nutrients to function effectively.
  • This causes the heart muscles to contract.

  
• Pacemaker

  • A group of cells in the RIGHT ATRIUM act as a natural PACEMAKER.
  • It produces small electrical impulses, which spread through the muscular walls of the heart, causing them to contract.
  • It controls the heartbeat

  
• Artificial pacemaker

  • When a natural pacemaker does NOT work properly.
  • They can implant an ARTIFICIAL pacemaker, which is a small device that is placed under the skin with a wire that carries electrical current down to the heart, telling it to contract regularly.

  
• Arteries - has a pulse - organ

  • carries OXYGENATED blood AWAY from the heart under HIGH PRESSURE, because the blood has been forced out of the heart for the ventricles has contracted (squeezed).
  • Their walls have a thick middle layer, containing both muscle and elastic tissue:
  • The thick muscle tissue provides strength to withstand high blood pressure.
  • The thick elastic tissue allows the arteries to regain shape, so it can maintain the high blood pressure.
  • The LUMEN (the interior passage of a blood vessel) is narrow to maintain high blood pressure.

  
• Capillaries


  • Their lumen are tiny.
  • But there're so many of them that a total cross-sectional area (the area of all the capillaries added together) are huger than arteries.
  • meaning there's a lower blood pressure and flows more slowly to give the blood time to exchange things with the tissues.

  
• On each side of the heart, the atrium and ventricle are separated by a valve, which prevents the blood from flowing backwards.
• The order blood flows through the blood vessels:

  Heart ➔ arteries ➔ capillaries ➔ veins ➔ heart
• Veins - don't have a pulse - organ

  Capillaries eventually join up again and form veins.

  • Carries deoxygenated blood from the body / lungs back to the heart at a lower pressure.
  • Has a wide lumen to carry more blood.
  • thin walls with small layer of elastic fibres & smooth muscle, because they carry blood at a much lower pressure, so it doesn't need to be strong.
  • Contain valves to prevent the blood from flowing backwards.

  
• Rate of an enzyme reaction = 1000 / time
• Rate of blood flow = volume / time
• If the coronary artery gets blocked, then the cells in the heart may run short of oxygen, which can cause a cardiac arrest or heart attack.

  
• Double circulatory system


  Two separate circuits that work together.

  • both circuits have the heart at its centre, which pumps blood.
  • One circuit pumps blood to the LUNGS.
  • The other circuit pumps blood to the REST OF THE BODY.

  It separates the oxygenated blood and the deoxygenated blood.

  
• The movement of blood around the body:

  • Blood flows into the right atrium from the vena cava and the left atrium from the pulmonary vein.
  • Both atria contract, pushing blood through the valves and into the relaxed ventricles.
  • Ventricles contract, forcing blood through the valves and into the pulmonary artery (from the right ventricle) and aorta (from left ventricle) and out of the heart
  • It then flows to the organs through the arteries, and returns through the veins.
  • At the same time, more blood will enter the now-relaxed atria.
  • The cycle repeat.

  
• blood pressure 


  a measure of force of the blood against the walls of the blood vessels.
• The aorta is the blood vessel that transport blood at the highest pressure from the heart to the body.

  
• The heart is a double pump:

  Right ventricle of the heart pumps blood to the lungs and left ventricle of the heart pumps blood to the body.
• The wall of the left ventricle is much thicker than the wall of the right ventricle because it is has to pump blood further and at a high pressure than the right ventricle.

  
• valves 


  Used to maintain correct direction of blood and prevent backflow of blood.

  
• The blood in the vena cava is different than the aorta:

  • It's at a lower pressure
  • It carries deoxygenated blood
  • Has a greater concentration of carbon dioxide

  A) Right lung

  
• Capillaries - tissue


  When arteries transported blood to parts of the body, it divides into smaller blood vessels till it reaches to capillaries:

  • It exchanges nutrients & oxygen with cells and takes away waste products (CO2) with the tissues.
  • Their walls are one cell thick for a short diffusion path, so substances can get in and out more quickly.
  • Capillary walls are permeable, so substances are able to move through them.
  • Capillaries carry blood at a low pressure.
  • Has a small lumen to slow blood flow, so substances have time to diffuse in and out of the blood.

  
• An athlete recorded his heart rate when he went for a cycle. He noticed that his heart rate and breathing rate increased for the first ten minutes and then stayed at a steady rate.


  His heart rate increased because:

  • The blood was pumped faster, so it carried oxygen and glucose for respiration to provide energy to his muscles.

  His breathing rate increased because:

  • The muscles needed more energy for respiration, so the blood needed to carry more oxygen, so the ventilation rate increased.
• Blood in the pulmonary vein would contain more oxygen and less carbon dioxide than blood in the pulmonary artery.

  Because by the time blood reaches the pulmonary vein, gases have been exchanged in the lungs, whereas in the pulmonary artery, gas exchange has not yet taken place.
• Differences in the composition of the blood in the arteries and veins:


  Arteries has:

  • more oxygen
  • more glucose
  • more amino acids / fatty acids
  • less carbon dioxide
  • less lactic acid