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The Circulatory System NATALIA JANZEN AND HEATHER CARPENTER Draw This No, it doesn’t have to be pretty, or colorful, or proportionate. But, you will understand more of all of the cardiovascular stuff we are about to throw at you if you have an idea of what the heart looks like. http://ibguides.com/biology/notes/the-transport-system The Function of the Cardiovascular System Many believe that the purpose of the circulatory system is to pump blood Though not entirely inaccurate, the main function of the circulatory system is to pump different things in the blood, namely: Oxygen/Carbon Nutrients Hormones Antibodies Urea Heat Dioxide The Big Picture https://www.youtube.com/watch?v=9fxm85Fy4sQ A Summary of the Big Picture Arteries = leave the heart Arteries= high pressure blood Veins = enter the heart Veins = low pressure blood Right = deoxygenated blood Left = oxygenated blood Atria = collect blood Ventricles = pump blood out Right 1. The right atrium collects blood from the superior and inferior vena cava 2. Blood flows through the atrioventricular valves into the right ventricle, where the semilunar valves are closed 3. 4. The right atrium contracts, closing the atrioventricular valves to prevent backflow The closed valves create a rise in pressure in the right ventricle, causing the semilunar valves to open 5. Blood flows from the right ventricle to the pulmonary artery 6. A contraction of the right ventricle closes the semilunar valves, preventing backflow, and starting the process all over again The Little Picture: How the Heart Pumps Blood 1. 2. 3. 4. 5. 6. Left The left atrium collects blood from the pulmonary veins Blood passes through the atrioventricular valves into the left ventricle, where the semilunar valves are closed The left atrium contracts, closing the atrioventricular valves to prevent backflow The closed valves create a rise in pressure in the left ventricle, causing the semilunar valves to open Blood flows from the left ventricle to the aorta A contraction of the left ventricle closes the semilunar valves, preventing backflow, and starting the process all over again The Even Littler Picture: How the Heart Pumps Blood https://www.youtube.com/watch?v=oHMmtqKgs50 Impulses from the medulla in the brain control heart rate by sending electrical signals to the sinoatrial node The sinoatrial node sends electrical impulses to the rest of the heart to stimulate contraction Contraction is stimulated in the atria first, by the sinoatrial node Contraction of the ventricles occur second, as the electrical impulse passes through the atrioventricular node There is a delay between the reception and dispersion of the electrical signal at the atrioventricular node This allows for atrial systole (a fancy way of saying the contraction), before the ventricles also contract The contractions of the valves are what we hear as heart beats – there are two separate ones https://www.youtube.com/watch?v=EA2DY0tjpFI The Microscopic Picture: Cardiac Muscles & More Purkinje Fibers: carry electrical impulses from the bundle branches to the myocardium (muscle tissue of the heart) The muscle tissue is made of cardiac muscles The structure of cardiac muscles allow for the quick dispersion of electrical impulses throughout the heart Cardiac muscles are made of individual muscles cells, called cardiomyocytes Cardiomyocytes connect to form intercalated discs, which work together as the syncytium Electrical resistance in intercalated discs is extremely low, allowing for the free flow of ions, and the quick transmission of electric signals http://en.wikipedia.org/wiki/Electrical_conduction_system_of_the_heart http://www.meddean.luc.edu/lumen/meded/Histo/HistoIm ages/hl3A-48.jpg Order of Electric Impulse Signals 1. sinoatrial node 2. atrioventricular node 3. atrioventricular bundle 4. left and right bundle branches 5. Purkinje fibers 6. myocardium 7. syncytium 8. intercalated discs 9. cardiomyocytes What happens when all of that doesn’t work properly? Arrhythmia Arrhythmia occurs when the normal sequence of electrical impulses does not work properly This causes the heart to beat too fast, too slow, or too erratically, which interrupts blood flow Pacemakers Pacemakers are small devices that are put in a patients chest (usually), that send out electrical impulses in order to regulate heartbeat Used to treat arrhythmia Defibrillators Defibrillators are often used in life-threatening situations, such as cardiac arrest It delivers an electrical shock to the heart in order to stop any cardiac dysrhythmia and lets the body restore the proper heart rate with the sinoatrial node. The Rest of the Cardiovascular System THE FLOW OF BLOOD THROUGHOUT THE BODY The Arteries: Function and Description Remember that the arteries are responsible for any blood flow away from the heart The arteries convey blood at high pressure from the ventricles to the tissues of the body The aorta is the largest artery in the body and is the thickest of the blood vessels in the body. It runs the length of the body’s trunk. This includes the aortic arch, a 180 degree turn in the aorta at the top of the heart, where the blood is pumped into the artery. It branches off into three different arteries The Arteries: Structure Arteries have a thick outer layer of longitudinal collagen and elastic fibers that help prevent leaks and bulges They have thick walls that help them withstand the high pressure Arteries have thick layers of circular elastic fibers and muscle fibers that help them move the blood after each heart contraction These fibers and muscles cells help regulate the blood pressure between pump cycles Narrow lumen (the inside or hollow part of a tubular structure) helps maintain the high blood pressure in the arteries. The Capillaries: Function and Description The blood vessel that assists in transporting blood through the body’s tissues They connect the arteries and the veins The arteries bring oxygen rich blood into the capillaries The veins take deoxygenated blood out of the capillaries Capillaries are found in a bundle of cells known as capillary networks The Capillaries: Structure The capillary wall is about one cell thick The thickness aides the capillary’s permeability, because diffusion only has to occur over a very small space Because of the high permeability of a capillary, and the fact that its wall is easy t diffuse across, diffusion happens a lot in the capillaries The capillaries often exchange materials between cells in tissue and blood in the capillaries through pores in the walls of the capillary Plasma leaks out of blood to form tissue fluid Phagocytes can also escape, and are beneficial in fighting infection The lumen of the capillaries is extremely small/narrow More capillaries can fit into small spaces, which increases the surface area for diffusion The Veins: Function and Description Veins are responsible for blood flow into the heart They collect blood that is at low pressure from the tissues of the body and return it to the atria of the heart There are valves present among veins that prevent the backflow of blood throughout the body The Veins: Structure The walls of veins are thin layers of a few circular elastic fibers and muscle fibers Veins can become flat when pressed against by other muscles This helps push the blood along towards the heart There is only a small layer of longitudinal collagen and elastic fibers on the vein walls Blood does not flow in pulses, so the vein walls do not need to be thick in order to move the blood along The low pressure in the veins means they are less likely to burst Veins have wide lumens, in order to maintain a low blood pressure and accommodate a large amount of slow-moving blood at once. http://www.majordifferences.com/2013/02/differen ce-between-artery-and-vein.html#.VS-QBsJFDIU http://leavingbio.net/circulatory%20system/circul atory%20system.htm http://alexalex.wikispaces.com/Transportation+ System Summary of Blood flow by Vessels throughout the Body heart arteries capillary networks veins heart https://www.youtube.com/watch?v=VVJJHw_Ocp4 http://antranik.org/wp-content/uploads/2012/05/bloodflow-of-the-heart.jpg?9873a6 What happens when that doesn’t work? Coronary Artery Disease CAD is caused by a buildup plaque in the arteries due to a condition known as atherosclerosis The cholesterol in food can deposit into blood vessel walls, creating a plaque buildup This buildup creates blockages in the blood flow system of the body, which could lead to blood clots or heart attacks The plaques cause the artery walls to be sticky, so any non-liquid elements of blood have a greater chance of sticking to the plaque and building it more A person is most at-risk for blood clots and heart attacks during physical activity, because there is not enough time for the blood cells to circumvent the plaque in order to supply the muscles with oxygen-rich blood CAD is usually the result of a cholesterol-laden diet Height as a factor? Research What happens when that doesn’t work? Hypertension Hypertension is just another way of saying high blood pressure Blood pressure is determined by the amount of blood your heart pumps and the amount of resistance to blood flow in the arteries High blood pressure is the result of the heart pumping more blood than into narrower arteries Hypertension generally develops over several years and can be the effect of medications, substance abuse, or an unhealthy diet It is usually treated with medication Thrombosis The forming of a blood clot inside of a blood vessel Can result in hypoxia (oxygen deprivation), and, more seriously, in anoxia (complete oxygen deprivation, resulting in loss of tissue) Skills and Applications THE WAY IB WANTS YOU TO USE THIS INFORMATION Heart Rate How to measure heart rate Place two fingers on the side of the neck over the jugular Count how many beats you experience in one minute The normal resting heart rate for adults are anywhere from 60-100 beats per minute The harder your body is working (physical exertion ect.) the higher the heart rate will be Abnormal: Above 100 beats per minute = Tachycardia Below 60 beats per minute = Bradycardia Blood Pressure Systolic Higher of the two numbers (the top #) Measures the pressure in the arteries when the heart muscle contracts Normal = less then 120 Diastolic The bottom number Measures the pressure in the arteries between heart beats when the heart is resting Normal = less than 80