Mid Unit Summary

The circulatory system is the system is the system that transports nutrients and oxygen through out your body and transports waste products out of your body. The heart is at the center of this complex system. The heart the pump for the system that is vital for life. The layers of the heart include the pericardium (not actually part of the heart), the epicardium, the myocardium, and the endocardium. The pericardium is the sac surrounding the heart for protection, restriction, and lubrication. The epicardium is the outer epithelial tissue that is attached to the pericardium. The myocardium is the cardiac muscle that is responsible for the heart's contractions. The Endocardium is the inner connective tissue that allows the blood to smoothly flow through and has the valves open and close smoothly. The blood flow though the heart goes from the vena cava to the right atrium, through the tricuspid valve to the right ventricle then out through the pulmonary valve to the pulmonary artery.  After the blood exchanges oxygen for carbon dioxide the blood return through the pulmonary vein where it enters the left atrium then goes through the bicuspid valve to the left ventricle. It exits through the aortic valve to the aorta and travels out to the body. (see "Box Heart" for visual) The right atrium and right ventricle hold deoxygenated blood, where as the left atrium and ventricle hold oxygenated blood; these 4 caverns are called the chambers of the heart. The hear pumps blood through it in an electric current system of nodes. The SA Node initiates the beat, when it travels to the AV Node the atria contract and push the blood to the ventricles. The ventricles then contract and push blood out of the heart. The valves prevent back flow into the atria. Then the whole heart relaxes in diastole.
The circulatory system is made mainly of the heart, arteries and veins. A vein is a blood vessel that carries blood to the hear, where as arteries carry it away. Venuoles are smaller veins and arterioles are smaller arteries. The artirioles branch off and surround cells in capillaries to deliver nutrients and oxygen to the cells. It also includes blood, which fills the whole closed system. There are various specific blood vessels in this system. The accessory organs of the circulatory system include the liver, lungs, kidneys, intestines, bone marrow, and spleen. Each help to filter/ clear of toxins or provide with new cells or nutrients. Blood pressure is the amount of pressure when the ventricles contract over when the whole heart relaxes.
Plaque build up in the arteries can be life threatening. This condition, called atherosclerosis, happens when the inflammatory response occurs on a worn artery wall. The result is plaque. High levels of LDL can contribute to this because the LDL will congregate around the cite. The plaque can break off and cause a blood clot, leading to a heart attack or stroke. A heart attack starts with restricted blood flow to the heart that then causes an irregular heart beat called fibrillation. In this phase the heart can be reset. Then the person goes into cardiac arrest, where the heart stops beating. Parts or the entire heart (and person) can die in a heart attack due to the cardiac arrest phase. An EKG reads the electrical signals in the heart and can tell if a heart attack is happening.  Cardiovascular disease is the number one killer in America. Healthy lifestyle can drastically reduce the risk of atherosclerosis and other cardiovascular conditions. An angiography is when die is put in the blood stream to see places where plaque has built up and can put a risk factor on a heart attack for that person. An aneurysm is when the artery wall is weakened. It can swell and bulge out and eventually rupture, leading to death.
Blood is made of plasma, a watery fluid with nutrients dissolved in it, and blood cells. Blood cells include WBC and RBC. RBC carry the oxygen to the cells. A blood type is the antigens on the RBC. The WBC help fight infections. Neutrophils fight bacteria and have globbed nuclei.   Basophils act in an allergy and are puffy. Eosinphils fight the parasites and are orange. Lymphocytes help cause an immune response when needed.It has a dark nucleus. Monocytes have antigens to attack microbes. Platelets help clot the blood. An increase in the number of WBC may indicate what type of microbe is invading the body; this is called the WBC differencial.