Heart blood & circulation colstons


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Heart blood & circulation colstons

  1. 1. Blood & circulation Colston’s School
  2. 2. Circulation  Your body resembles a large roadmap, There are routes or “arteries” that take you downtown to the “heart” of the city.
  3. 3. 3 Major Parts of the Circulatory system • Blood Vessels - routes blood travels • Heart – pumps or pushes blood through body • Blood – carries important “ *stuff ” through body * Stuff – includes oxygen, food, & waste
  4. 4. Blood Vessels : One Way Streets • Blood Vessels resemble very long and skinny tunnels that are all through your body.
  5. 5. 3 Types of Blood Vessels Arteries Capillaries Tissue fluid forms here Arteries get smaller and become arterioles Veins emerging from capillaries are venules Veins
  6. 6. • The Heart – 4 chambers ( or compartments ) • 2 upper chambers : Left Atrium Right Atrium • 2 lower chambers : Left Ventricle Right Ventricle
  7. 7. Lub If you listen to your heartbeat, it makes a lub dub sound. The lub is when blood is pushed out of the heart into the body and the dub is the reloading of the heart with more blood ready to push it out to the body Dub
  8. 8. Blood Flow through the Human Body Blood with little oxygen is pumped from the Right Atrium through a valve to the Right Ventricle and through another valve into the Pulmonary Artery. The Pulmonary Artery sends it to the Lungs to pick up Oxygen. It’s sent from the Lungs through Pulmonary Veins to the Left Atrium through a valve to the Left Ventricle. The Left Ventricle sends it through a valve to the Aorta. The Aorta is a series of branches that sends oxygenated blood throughout the body.
  9. 9. Heart Beat • • • • • • Effectively the heart is a double pump It beats from top to bottom Atria beat first, then the ventricles This beat is carefully coordinated A pacemaker sets the beat Cardiac muscle is special – myogenic and once kick started beats by itself.
  10. 10. Coordinating the Pump: Electrical Signal Flow
  11. 11. Electrical conduction in the Heart • The Sinoatrial node (SA node), is a group of autorhythmic cells (main pacemaker of the heart) in the right atrium near the entry of the superior vena cava. • An internodal pathway connects the SA node to the atrioventricular node (AV node), a group of autorhythmic cells found near the floor of the right atrium. • From the AV node action potentials move into fiber known as the bundles of his or atrioventricular bundle. The bundle passes from the AV node into the wall of the septum between the ventricles.
  12. 12. Electrical conduction in the Heart • A short way down the septum the bundle divides into left and right bundle branches. • These fibers continue downward to the apex where they divide into many small purkinje fibers that spread outward among the contractile cells.
  13. 13. The pacemaker - SAN
  14. 14. • If the electrical signals from the atria were conducted directly into the ventricles, the ventricles would start to contraction at the top. Then the blood would be squeezed downward and trapped at the bottom of the ventricle. • The apex to base contraction squeezes blood toward the arterial opening at the base of the heart. • The AV node also delays the transmission of action potentials slightly, allowing the atria to complete their contraction before the ventricles begin their contraction. This AV node delay is accomplished by slowing conduction through the AV node cells.
  15. 15. Ventricular Pressure Note pressure changes in Aorta as blood enters. The value is always under ventricles as energy and pressure is lost via blood friction. Pressure in Aorta varies as ventricle pressure increases. As blood leaves heart and enters Aorta pressure increases .
  16. 16. Electrocardiogram (ECG) • Composite of all action potentials of nodal and myocardial cells detected, amplified and recorded by electrodes on arms, legs and chest
  17. 17. Electrical Activity of the Heart Einthoven's triangle P-Wave – atria QRS- wave – ventricles T-wave – repolarization
  18. 18. • Heart Rate can be determined using a Stethoscope 400 300 200 200 50 30 100 28 0 376 9 70 40 cam el cat cow ele p gre hant yw hal e hum an lion mo use Heartbeats per minute Average Heart Rate of some Mammals Mammals
  19. 19. Heart Facts • Hold out your hand and make a fist. If you're a kid, your heart is about the same size as your fist, and if you're an adult, it's about the same size as two fists. • Your heart beats about 100,000 times in one day and about 35 million times in a year. During an average lifetime, the human heart will beat more than 2.5 billion times. • Give a tennis ball a good, hard squeeze. You're using about the same amount of force your heart uses to pump blood out to the body. Even at rest, the muscles of the heart work hard--twice as hard as the leg muscles of a person sprinting.