The Heart

The Pathway of the Blood  Through the heart, beginning at the vena cava

 anterior (inferior) vena cava is at the bottom  superior vena cava is at the top

 blue blood (deoxygenated) enters the right atrium  right atrium contracts  blue blood is sent through the AV valve to the right ventricle

 right ventricle contracts sending blood through the semilunar valve out the pulmonary artery  blood goes to the lungs

 The arteries branch into arteriolles  capillaries surround the alveoli in the lungs allowing the oxygen to diffuse into the lungs

 red blood returns oxygenated to the heart through the pulmonary veins

 Oxygenated (red) blood comes from the lungs through the Pulmonary VEIN

 red blood enters the left atrium  left atrium contracts  forces blood through the AV valve into the left ventricle

 left ventricle is the heart’s most muscular chamber  contraction of the left ventricle sends blood through the semilunar valve out the aorta

 the aorta is the largest ARTERY in the body  it sends oxygen rich blood to the body

 arteries branch smaller into arterioles and eventually into capillaries

 capillaries transfer oxygen to tissues (greatest surface area) and extract CO2 from tissues into the blood

 after picking up the CO2, capillaries become venuoles and veins which lead back to the heart

 deoxygenated (blue) blood returns to the heart through the vena cava (main vein)

Quick Question?!  What is the only blood vessel in which diffusion can occur?

Heartbeat  Systole and Diastole phases  Lub Dub of the Heart

Diastole  relaxation where the atria or ventricle fills with blood

Systole  ventricle or atrial contraction to eject blood from the chamber

Lub Dub  lub dub is caused by the slamming close of valves in the heart

 Systole  ventricles contract sending blood out of the heart  high pressure forces the AV valve to close

 AV valves closing cause the LUB  semilunar valves are opened by high pressure blood leaving the ventricles

 Diastole  atria and ventricle relax and fill with blood  low pressure opens the AV valve

 Blood outside the heart causes high pressure and the semilunar valve slams shut  Producing the DUB sound

 when the atria contracts (atrial systole) the blood is forced into the ventricle  AV valve remains open and the semilunar remains closed

Cardiac Output  Cardiac output is the volume of blood pumped by the heart in one minute, which is equal to the produce of stroke volume and heart rate

Example A typical human male has a stroke volume of 70mL per beat and a resting heart rate of 72 beats per minute.  a. Calculate the cardiac output. Express your answer in liters per minute.  b. Calculate the volume of blood that would be pumped in ONE DAY based upon the cardiac output.

Work to Get Done!  Complete Topic 2 Practice Questions (pg 11 booklet)  Work on your lab write up!