?HISTORY OF THE CIRCULATORY SYSTEM: DISCOVERY OF THE BASICS The most basic principles of the Circulatory system took thousands of years to uncover. An Egyptian papyrus dating back to 1500BC correctly correlated the character and frequency of the pulse with the patient’s health status. Hippocrates (460-355BC) and his pupils also drew accurate conclusions regarding the nature of blood flow. The goal of this review is to examine the events that led to discovery of blood circulation.
The Ancient Greeks, including Hippocrates and Galen viewed the cardiovascular system as comprising two distinct networks of arteries and veins. Galen claimed that the liver produced blood that was then distributed to the body in a centrifugal manner, whereas air was absorbed from the lung into the pulmonary veins and carried by arteries to the various tissues of the body. Arteries also contained blood. This was an open-ended system in which blood and air simply dissipated at the ends of veins and arteries according to the needs of the local tissue.
Blood was not seen to circulate but rather to slowly ebb and flow. This view would hold sway for 15 centuries until 1628 when William Harvey published his momentous 72-page book, On the Motion of the Heart and Blood in Animals. Harvey employed experiment and deductive logic to show that arteries and veins are functionally, if not structurally, connected in the lung and the peripheral tissues, and that blood circulates. The mechanical force of the heart replaced Galen’s elusive attractive powers.
PARTS OF THE CIRCULATORY SYSTEM
The heart, blood, and blood vessels make up the cardiovascular component of the circulatory system. It includes the pulmonary circulation, a “loop” through the lungs where blood is oxygenated. It also incorporates the systemic circulation, which runs through the rest of the body to provide oxygenated blood. The Heart -The Heart is an amazing organ. The heart beats about 3 BILLION times during an average lifetime. It is a muscle about the size of your fist. The heart is located in the center of your chest slightly to the left.
It’s job is to pump your blood and keep the blood moving throughout your body. It is your job to keep your heart healthy and there are three main things you need to remember in order to keep your heart healthy. Exercise on a regular basis. Get outside and play. Keep that body moving (walk, jog, run, bike, skate, jump, swim). Eat Healthy. Remember the Food Pyramid and make sure your eating your food from the bottom to top. Don’t Smoke! Don’t Smoke! Don’t Smoke! Don’t Smoke! Don’t Smoke! -The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs.
In the human heart there is one atrium and one ventricle for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: left atrium, left ventricle, right atrium and right ventricle. The right atrium is the upper chamber of the right side of the heart. The blood that is returned to the right atrium is deoxygenated (poor in oxygen) and passed into the right ventricle to be pumped through the pulmonary artery to the lungs for re-oxygenation and removal of carbon dioxide.
The left atrium receives newly oxygenated blood from the lungs as well as the pulmonary vein which is passed into the strong left ventricle to be pumped through the aorta to the different organs of the body. Coronary circulation Coronary circulatory system provides a blood supply to the myocardium (the heart muscle). It arises from the aorta by two coronary arteries, the left and the right, and after nourishing the myocardium blood returns through the coronary veins into the coronary sinus and from this one into the right atrium. Back flow of blood through its opening during atrial systole is prevented by the Thebesian valve.
The smallest cardiac veins drain directly into the heart chambers. Pulmonary circulation The pulmonary circulatory system is the portion of the cardiovascular system in which oxygen-depleted blood is pumped away from the heart, via the pulmonary artery, to the lungs and returned, oxygenated, to the heart via the pulmonary vein. Oxygen deprived blood from the superior and inferior vena cava, enters the right atrium of the heart and flows through the tricuspid valve(right atrioventricular valve) into the right ventricle, from which it is then pumped through the pulmonary semilunar valve into the pulmonary artery to the lungs.
Gas exchange occurs in the lungs, whereby CO2 is released from the blood, and oxygen is absorbed. The pulmonary vein returns the now oxygen-rich blood to the left atrium. Systemic circulation Systemic circulation is the circulation of the blood to all parts of the body except the lungs. Systemic circulation is the portion of the cardiovascular system which transports oxygenated blood away from the heart through the aorta from the left ventricle where the blood has been previously deposited from pulmonary circulation, to the rest of the body, and returns oxygen-depleted blood back to the heart.
Systemic circulation is, distance-wise, much longer than pulmonary circulation, transporting blood to every part of the body. THE BLOOD VESSELS There are three types of blood vessel Arteries are blood vessels that carry oxygen rich blood AWAY from the heart.
Remember, A A Arteries Away, A A Arteries Away, A A Arteries Away. Capillaries are tiny blood vessels as thin or thinner than the hairs on your head. Capillaries connect arteries to veins. Food substances(nutrients), oxygen and wastes pass in and out of your blood through the capillary walls. -Veins.
ARTERIOLES Just like arteries, arterioles carry blood away from the heart and out to the tissues of the body. In addition to this “supply train” function, arterioles are very important in blood pressure regulation. Venules Venules are small blood vessels whose function is to collect blood from the capillary beds. The vessels then unite to form veins which transport the deoxygenated blood to the heart. Veins transport blood under less pressure than arteries, which have thin lumens. Blood vessels that carry deoxygenated blood from the capillaries back to the vein.