circulatory system

• why is the human heart a double circulatory system?

  blood flows through two circuits.
• what does the first circuit do in heart?

  carries oxygenated blood around the body.
• what does second circuit in heart do?

  carries deoxygenated blood to the lungs to pick up more oxygen.
• why does heart need its own blood supply?

  it is a muscle
• What supplies the heart with its own source of oxygenated blood and glucose.

  coronary arteries
• From vena cana deoxygynated blood enters the heart from body then its pumped from right ventricicle to lungs throygh pulmonary artery
• what does deoxygenated blood needs to go to the lungs?

  supplies body with oxygen
• oxygenated blood enters heart through pulmonary veins then the left ventricle pumps blood through the aorta to rest of the body
• Each side of heart has atrium what does it do?

  receives blood and pumps it to the ventricle
• what do valves stop?

  blood from flowing backwards
• the atrium and ventricle on left side of heart has thicker walls then right so they can pump blood around the whole body
• what acts as natural pacemaker?

  group of cells in right atrium controlling natural resting heart rate
• what is cardiac output?

  volume of blood pumped by heart ever minute depends on heart rate and stroke volume
• what is stoke volume?

  volume of heart pumped by 1 heartbeat
• cardia output(cm^3/min) = heart rate(bpm) x stroke volume(cm^3)