Jimmy Buckley Caitlin Pigott Remy Pontes Hunter Sleeper Shmo CHen CARDIOVASCULAR SYSTEM

THE HEART A heart is the size of a fist and weighs less than a pound It is located within the bony thorax and is in between the lungs There are 3 walls of the heart: (from out to in) Epicardium Myocardium Endocardium There are 4 chambers: 2 atria and 2 ventricles The right ventricle goes to lungs, the left goes to all other organs There are 2 atria that hold blood going into the heart and empties into the right and left The inner ventricles are the actual pumps that cause circulation

CIRCULATION There are 2 processes of circulation that pump blood from the heart to the body and back The blood enters the heart and goes through a process called pulmonary circulation to collect oxygen The oxygen is gathered and prepared to be pumped to the rest of the body The blood is pumped out to the rest of the body and then brought back through a process called systemic circulation The oxygen is deposited throughout the body and the blood is brought back to the heart to collect more oxygen A cardiac cycle is one complete heartbeat, this includes both circulation processes Each cycle is about 0.8 seconds and there are about 75 cycles per minute

PULMONARY CIRCULATION Oxygen-poor blood enters the heart through superior and inferior venae cavae It is pumped through pulmonary arteries on the right side Blood is then brought to the lungs where carbon dioxide is unloaded and oxygen is picked up The now oxygen-rich blood is brought to the left side of the heart through 4 pulmonary veins

SYSTEMIC CIRCULATION Blood is returned to the left side and is then pumped out of the heart into the aorta Systemic arteries then bring the blood to the rest of the body where the oxygen is delivered Blood comes back to the right atrium (which is now oxygen-poor) through systemic veins and empty its cargo into superior or inferior vena cava

THE HEART’S FUNCTION The body contains about 6 quarts of blood, which is pumped about 1000 times per day There are control systems to keep the heart coordinated and functioning properly There are 2 control systems: Nerves of the autonomic nervous system Intrinsic conduction system

CONTROL SYSTEMS The nerves of the autonomic nervous system act as brakes and accelerators to increase and decrease heart rate The intrinsic conduction system is made up of a unique tissue that is built into the heart tissue It causes depolarization that enforces a contraction rate of 75 beats per minute The SA node is crescent shaped node that sets the pace for each contraction. It starts each beat and then sends the impulse through the atria to the AV node. The AV node then stalls the impulse to allow the contraction to complete and then sends the impulse out. Damage to the AV node can cause an irregular heart beat rate called heart block. Pacemakers are used to correct the slower heartbeats after the SA node is damaged. Fibrillation (rapid uncoordinated shuddering of the heart muscle) can occur when there is a lack of blood supply.

HEART BEATS There are two sounds that can be heard by a beating heart, called heart sounds It sounds like “lub” and “dup”. There is a pause and then it repeats “lub” is long and loud; “dup” is short and sharp A heart murmur is an abnormal heart beat A heart with a murmur can still be healthy, but it may indicate valve problems The amount of blood that is pumped out by each side of the heart in one minute is called cardiac output Congestive heart failure occurs when circulation is too slow to pump efficiently