week 2 (circulatory system)

• The heart is a unique structure made of cardiac muscle that can beat continuously without getting tired
• Heart


  • About the size of a fist, located between the lungs in the center of the chest
  • Pumps blood continuously around the body
• The heart begins beating about 5-6 weeks after conception
• Blood clotting


  1. Platelets stick to exposed collagen fibers, forming a plug

  2. Thromboplastins convert fibrinogen into fibrin, forming a fibrous mesh that traps blood cells and strengthens the platelet plug

  3. Fibrinolysis eventually reabsorbs the clot as the wound heals
• Plasma


  The liquid part of blood that carries cells and platelets, and contains nutrients, waste, and other substances
• The circulatory system is like a complex arrangement of highways, avenues and lanes connecting all the cells together in a neighborhood
• Circulatory system


  Also known as the cardiovascular system, functions with other body systems to deliver different materials in the body
• Role of the circulatory system

  • Circulates vital elements and nutrients like oxygen
  • Transports waste away from the body in the form of carbon dioxide
• Parts of the circulatory system

  • Heart
  • Blood vessels
  • Arteries
  • Veins
  • Capillaries
  • Blood
• Heart


  A specialized cardiac muscle that pumps blood throughout the body
• Arteries


  Blood vessels that carry oxygenated blood away from the heart to the cells, tissues and organs
• Veins


  Blood vessels that carry deoxygenated blood back to the heart
• Capillaries


  The smallest blood vessels that connect arteries and veins, found in organs to allow diffusion of materials and gases
• Components of blood


  • Red blood cells
  • White blood cells
  • Platelets
  • Plasma
• Red blood cells


  Responsible for carrying oxygen and carbon dioxide
• White blood cells


  Part of the immune system, fight infection and foreign bodies
• Platelets


  Responsible for blood clotting
• Plasma


  Main component of blood, consists mainly of water with proteins, ions, nutrients and wastes
• Types of blood circulation

  • Pulmonary circulation
  • Systemic circulation
  • Coronary circulation
• Pulmonary circulation


  Movement of blood from the heart to the lungs and back to the heart
• Systemic circulation


  Movement of blood from the heart to the rest of the body except the lungs
• Coronary circulation


  Movement of blood through the tissues of the heart
• The circulatory system performs other functions such as maintaining internal balance, body temperature, and fighting foreign material
• The circulatory system and respiratory system work together to transport nutrients, gases and other molecules to and from different parts of the body
• The heart starts beating 22 days after conception and beats about 100,000 times a day, pumping about 2,000 gallons of blood
• If the heart stops beating for 4-6 minutes, it can cause brain cell death, and after 10 minutes it can result in serious organ damage and death
• Atria


  The two upper chambers of the heart that receive blood from different parts of the body
• Right atrium


  Receives deoxygenated blood from the body
• Left atrium


  Receives oxygenated blood from the lungs
• Ventricles


  The lower chambers of the heart that pump blood out of the heart
• Right ventricle


  Pumps deoxygenated blood to the lungs
• Left ventricle


  Pumps oxygenated blood to the rest of the body
• Superior vena cava


  Vein that brings deoxygenated blood from the upper body to the right atrium
• Inferior vena cava


  Vein that brings deoxygenated blood from the lower body to the right atrium
• Pulmonary artery


  Blood vessel that transports deoxygenated blood from the right ventricle to the lungs
• Aorta


  The largest artery that carries oxygenated blood from the left ventricle to the rest of the body
• Septum


  The dividing wall between the right and left sides of the heart
• Valves


  Structures that prevent blood from flowing backwards between the atria and ventricles
• Heart valves


  • Tricuspid valve
  • Pulmonary valve
  • Mitral or bicuspid valve
  • Aortic valve
• Blood flow through the heart

  1. Deoxygenated blood enters right atrium

  2. Flows to right ventricle

  3. Pumped to lungs through pulmonary artery

  4. Oxygenated blood returns to left atrium

  5. Flows to left ventricle

  6. Pumped to body through aorta