Welcome to this informational website, all about the cardiovascular system. The cardiovascular system is one of the 11 organ systems in the human body. This system transports materials througout the body via blood pumped by the heart, including oxygen, carbon dioxide, nutrients, and waste.
Here, you can gain knowledge about many aspects of the cardiovascular system, including the anatomy and physiology of it, in addition to information about blood vessels and blood pressure. Common homeostatic imbalances are also included, with reasons as to why they occur.
Interesting statistics and facts are included as well, about heart disease, heart attacks, and more.
If you would like to gain even more knowledge about the heart, or you would like to contribute somehow, information about helpful organizations/resources are available, such as the renowned American Heart Association.
Comment boxes are also available if you should have any questions regarding any of the information presented, or anything having to do with the circulatory system.
Enjoy. :)
Thursday, February 26, 2009
Helpful Organizations
Spotlight: The American Heart Association
The American Heart Association is a national voluntary health agency whose mission is to build healthier lives, free of cardiovascular disease and stroke. The association's impact goal is to reduce coronary heart disease, stroke and risk by 25 percent by 2010. The American Heart Association hopes to help reduce death rates from heart diseases, the prevalence of smoking, rates of high blood cholesterol, rates of physical inactivity, and rates of uncontrolled high blood pressure. In addition, this organization is determined to eliminate the growth of obesity and diabetes.
To achieve these goals, the American Cancer Association is composed of countless volunteers that help participate in events that promote health through things such as physical activity, eating healthy, and more. Fundraising and collecting donations are also tasks completed every day by volunteers, that all go toward research and other outlets that benefit the community and the wellness of society.
To contact the American Heart Association,
Email AHA at Review.personal.info@heart.org
Phone: 1-800-AHA-USA1
Mail: 7272 Greenville Ave. Dallas, TX 75231
To donate to the AHA, you can make a monetary contribution that is for memorial, tribute, or general purposes.
A Few Interesting Statistics and Facts
Did You Know?
Every 34 seconds a person in the United States dies from heart disease.
More than 2,500 Americans die from heart disease each day.
Every 20 seconds, a person in the United States has a heart attack.
At least 250,000 people die of heart attacks each year before they reach a hospital.
Studies show that under-educated people are more likely to suffer heart attacks.
Almost 6 million hospitalizations each year (in the United States) are due to cardiovascular disease.
Since 1900, Cardio Vascular Disease has been the number 1 killer in the United States for every year but 1918.
Every 33 seconds, a person dies from Cardiovascular Disease in the United States.
Research has proved that smoking cigarettes is a leading cause and accelerator of heart disease. Smoking causes or accelerates heart disease by many different mechanisms.
Smoking speeds up the progression of atherosclerosis, alters lipid profile, increases heart muscle oxygen demand by 10%, reduces coronary artery blood flow due to adrenaline release, and alters the clotting mechanism with aggregation of blood platelets, just to name a few.
(Mama's Health. Com)
Every 34 seconds a person in the United States dies from heart disease.
More than 2,500 Americans die from heart disease each day.
Every 20 seconds, a person in the United States has a heart attack.
At least 250,000 people die of heart attacks each year before they reach a hospital.
Studies show that under-educated people are more likely to suffer heart attacks.
Almost 6 million hospitalizations each year (in the United States) are due to cardiovascular disease.
Since 1900, Cardio Vascular Disease has been the number 1 killer in the United States for every year but 1918.
Every 33 seconds, a person dies from Cardiovascular Disease in the United States.
Research has proved that smoking cigarettes is a leading cause and accelerator of heart disease. Smoking causes or accelerates heart disease by many different mechanisms.
Smoking speeds up the progression of atherosclerosis, alters lipid profile, increases heart muscle oxygen demand by 10%, reduces coronary artery blood flow due to adrenaline release, and alters the clotting mechanism with aggregation of blood platelets, just to name a few.
(Mama's Health. Com)
Common Homeostatic Imbalances of the Cardiovascular System
Myocardial Infarction
Also known as a heart attack or coronary, myocardial infarctions occur when coronary arteries are blocked. The infarct is formed from a prolonged angina. Heart cells die, which causes the heart to become blocked, and ventricles begin to beat at their own rate. Rate is much slower than usual. This is caused by damage to AV node, and ventricles are no longer controlled by the SA node.
Ischemia
Ischemia is damage to the SA node, which results in slower heart rate. There is a lack of an adequate blood supply to the heart muscle, and may lead to fibrillation (rapid uncoordinated shuddering of the heart muscle). It is the major cause of death from heart attacks, because the heart cannot function as a pump any longer.
Hypotension
Also known as low blood pressure, hypotension is defined as dizziness and temporary low blood pressure, which occurs when people rise suddenly. Usually the elderly are most commonly afflicted by this disorder because the sympathetic nervous system reacts slower when aged. Therefore, there is a reduced blood delivery to the brain.
Hypertension
Also known as high blood pressure, hypertension is defined as a condition of sustained arterial pressure of 140/90. It slowly strains the heart and damages arteries. The heart is forced to pump against increased resistance, and the myocardium enlarges. Therefore, blood vessels are ravaged, which causes small tears in the endocardium.
Atherosclerosis
This occurs when the walls of vessels thicken from objects and protrude inside. It is affected in the aorta and coronary arteries most often.
Congenital Heart Disorders
CHD accounts for half of infant deaths from congenital defects. It is caused by internal infection and ingested drugs during pregnancy in the first three months. Disorders include ductus ateriosus, septal openings, and structural abnormalities of the heart.
Also known as a heart attack or coronary, myocardial infarctions occur when coronary arteries are blocked. The infarct is formed from a prolonged angina. Heart cells die, which causes the heart to become blocked, and ventricles begin to beat at their own rate. Rate is much slower than usual. This is caused by damage to AV node, and ventricles are no longer controlled by the SA node.
Ischemia
Ischemia is damage to the SA node, which results in slower heart rate. There is a lack of an adequate blood supply to the heart muscle, and may lead to fibrillation (rapid uncoordinated shuddering of the heart muscle). It is the major cause of death from heart attacks, because the heart cannot function as a pump any longer.
Hypotension
Also known as low blood pressure, hypotension is defined as dizziness and temporary low blood pressure, which occurs when people rise suddenly. Usually the elderly are most commonly afflicted by this disorder because the sympathetic nervous system reacts slower when aged. Therefore, there is a reduced blood delivery to the brain.
Hypertension
Also known as high blood pressure, hypertension is defined as a condition of sustained arterial pressure of 140/90. It slowly strains the heart and damages arteries. The heart is forced to pump against increased resistance, and the myocardium enlarges. Therefore, blood vessels are ravaged, which causes small tears in the endocardium.
Atherosclerosis
This occurs when the walls of vessels thicken from objects and protrude inside. It is affected in the aorta and coronary arteries most often.
Congenital Heart Disorders
CHD accounts for half of infant deaths from congenital defects. It is caused by internal infection and ingested drugs during pregnancy in the first three months. Disorders include ductus ateriosus, septal openings, and structural abnormalities of the heart.
Blood Pressure
Blood pressure is the pressure blood exerts against the inner walls of vessels. Ventricles contract and arteries expand, causing continuous movement to areas of lower pressure. The pressure changes from high to low pressure. Blood flow is dependent upon elasticity and the recoil of arteries.
Blood pressure is measured usually with a sphygmomanometer, which observes the contract, relax, rise, and fall of blood pressure. The two arterial measurements are systolic and diastolic pressure, measured in millimeters of mercury (mm Hg). With the auscultatory method, pressure in the brachial artery is measured.
Blood Vessels
There are three coats, which include the tunic intima, tunica media, and tunica externa. Arteries are thicker walls close to the pumping action of heart, which must expand. The walls must be strong and stretchy. The aorta is the largest vein in the body. Veins are thinner walls further from heart, which contain valves to prevent backflow. Capillaries are one layer thick and allow blood and tissue exchange.
Physiology of the Heart
Heart Works Hard
The heart pushes the body’s supply of approx. 6000 quarts of blood through blood vessels daily.
Setting the Basic Rhythm
Cardiac muscle cells contract spontaneously and independently, and occur in a regular and continuous way. Cardiac muscle can beat independently. Muscle cells in different areas of heart have different rhythms. Atrial cells contract 60 times per minute, while ventricular cells contract 20-40 times per minute. The heart needs a unifying control system or else the heart would be uncoordinated and inefficient.
Regulating heart activity
The intrinsic conduction system (nodal system) is built into the heart tissue and sets basic rhythm. It is composed of tissue that is a cross between muscle and nervous tissue. It causes heart muscle depolarization from the atria to the ventricles. The intrinsic conduction system enforces contraction of 75 beats per minute.
The intrinsic conduction system contains the sinoatrial node (SA), which is located in the right atrium. It starts each heartbeat and pace for the whole heart, which is why it is often called the ‘pacemaker.’ It also contains the atrioventricular (AV) node, located in the junction of the atria and ventricles. The atrioventricular (AV) bundles and bundle branches are located in the interventricular septum. Purkinje fibers spread within the muscle of the ventricular walls.
Cardiac Output
Cardiac output (CO) is the amount of blood pumped out by each side of the heart in one minute. It is the product of heart rate (HR) and stroke volume (SV)
The average adult cardiac output is HR (75 bpm) x SV (70 ml/beat), which amounts to 5250 ml/min. The entire blood supply passes through the body once each minute. CO varies with demands of the body, and increases when SV increases, the hearts beat faster, or both. It decreases when either or both decreases.
Regulation of Stroke Volume
The more the heart muscle is stretched, the stronger the contraction. Venous return is the amount of blood entering the heart and defending its ventricles. It prevents the back up of blood circulation by forcing the ventricle that pumps less blood to pump out an equal amount. When the volume or speed of the blood flow increases, the stroke volume and face increases as well.
Neural (ANS) Controls
The sympathetic nervous system stimulates the SA and AV nodes, as well as the cardiac muscle itself during physical or emotional stress. The heart beats more rapidly. The parasympathetic nervous system slows and steadies the heart during non crisis times.
Effects of Hormones and Ions on Heart Activity
Epinephrine mimics the effect of sympathetic nerves, and epinephrine and thyroxine both increase heart rate. Reduced levels of ionic calcium
depress the heart if found in the blood. It causes prolonged contractions that the heart may stop entirely. The excess or lack of potassium and/or sodium modifies heart activity, which may include deficit of potassium ions in the blood. When this occurs, the heart beats feebly and abnormal rhythms appear.
The heart pushes the body’s supply of approx. 6000 quarts of blood through blood vessels daily.
Setting the Basic Rhythm
Cardiac muscle cells contract spontaneously and independently, and occur in a regular and continuous way. Cardiac muscle can beat independently. Muscle cells in different areas of heart have different rhythms. Atrial cells contract 60 times per minute, while ventricular cells contract 20-40 times per minute. The heart needs a unifying control system or else the heart would be uncoordinated and inefficient.
Regulating heart activity
The intrinsic conduction system (nodal system) is built into the heart tissue and sets basic rhythm. It is composed of tissue that is a cross between muscle and nervous tissue. It causes heart muscle depolarization from the atria to the ventricles. The intrinsic conduction system enforces contraction of 75 beats per minute.
The intrinsic conduction system contains the sinoatrial node (SA), which is located in the right atrium. It starts each heartbeat and pace for the whole heart, which is why it is often called the ‘pacemaker.’ It also contains the atrioventricular (AV) node, located in the junction of the atria and ventricles. The atrioventricular (AV) bundles and bundle branches are located in the interventricular septum. Purkinje fibers spread within the muscle of the ventricular walls.
Cardiac Output
Cardiac output (CO) is the amount of blood pumped out by each side of the heart in one minute. It is the product of heart rate (HR) and stroke volume (SV)
The average adult cardiac output is HR (75 bpm) x SV (70 ml/beat), which amounts to 5250 ml/min. The entire blood supply passes through the body once each minute. CO varies with demands of the body, and increases when SV increases, the hearts beat faster, or both. It decreases when either or both decreases.
Regulation of Stroke Volume
The more the heart muscle is stretched, the stronger the contraction. Venous return is the amount of blood entering the heart and defending its ventricles. It prevents the back up of blood circulation by forcing the ventricle that pumps less blood to pump out an equal amount. When the volume or speed of the blood flow increases, the stroke volume and face increases as well.
Neural (ANS) Controls
The sympathetic nervous system stimulates the SA and AV nodes, as well as the cardiac muscle itself during physical or emotional stress. The heart beats more rapidly. The parasympathetic nervous system slows and steadies the heart during non crisis times.
Effects of Hormones and Ions on Heart Activity
Epinephrine mimics the effect of sympathetic nerves, and epinephrine and thyroxine both increase heart rate. Reduced levels of ionic calcium
depress the heart if found in the blood. It causes prolonged contractions that the heart may stop entirely. The excess or lack of potassium and/or sodium modifies heart activity, which may include deficit of potassium ions in the blood. When this occurs, the heart beats feebly and abnormal rhythms appear.
Anatomy of the Circulatory System
The Heart
Location and Size
The heart is the size of a person’s fist: hollow, cone-shaped, and weighs less than a pound. It is enclosed within the inferior mediastinum and middle cavity of thorax. The apex is located at the left hip and rests on diaphragm. The heart is located within the fifth intercostal, where a stethoscope is placed.
Coverings
Coverings of the heart include the pericardium (double sac of serous membrane), the epicardium (visceral pericardium, located at the external surface of the heart), parietal pericardium (continuous at the heart base), fibrous pericardium (reinforced by dense connective tissue, protects heart), and serous fluid (produced by serous pericardial membrane).
Layers
There are three layers, which are the epicardium, myocardium, endocardium. The epicardium is the external surface of the heart. The myocardium are thick bundles of cardiac muscle that contract. The endocardium are thin sheets of endothelium that line heart chambers
Chambers and Associated Great Vessels
There are four chambers or cavities, which include two atria and two ventricles. They help blood flow smoothly. The superior atria are receiving chambers. Blood flows into atria under low pressure from veins and continues on to fill ventricles. The inferior ventricles are discharging chambers. Blood is pumped out and into circulation
Systemic vs. Pulmonary Circuits
Pulmonary arteries carry blood to lungs. Oxygen is picked up and CO2 is unloaded. Pulmonary circulation occurs from the right side of heart to lungs, to left side of heart. It carries blood to lungs, then back to heart. Systemic circulation occurs from the left side of heart through body tissues, and back to right side of heart. It supplies oxygen and nutrient-rich blood to all organs.
Major Valves
The atrioventricular valve prevents backflow into atria when ventricles contract It is comprised of a bicuspid valve (2 flaps), tricuspid valve (3 flaps), and chordae tendinae (anchors flaps). Semilunar valves guard bases of two large arteries leaving the vent. There are pulmonary and aortic semilunar valves.
Location and Size
The heart is the size of a person’s fist: hollow, cone-shaped, and weighs less than a pound. It is enclosed within the inferior mediastinum and middle cavity of thorax. The apex is located at the left hip and rests on diaphragm. The heart is located within the fifth intercostal, where a stethoscope is placed.
Coverings
Coverings of the heart include the pericardium (double sac of serous membrane), the epicardium (visceral pericardium, located at the external surface of the heart), parietal pericardium (continuous at the heart base), fibrous pericardium (reinforced by dense connective tissue, protects heart), and serous fluid (produced by serous pericardial membrane).
Layers
There are three layers, which are the epicardium, myocardium, endocardium. The epicardium is the external surface of the heart. The myocardium are thick bundles of cardiac muscle that contract. The endocardium are thin sheets of endothelium that line heart chambers
Chambers and Associated Great Vessels
There are four chambers or cavities, which include two atria and two ventricles. They help blood flow smoothly. The superior atria are receiving chambers. Blood flows into atria under low pressure from veins and continues on to fill ventricles. The inferior ventricles are discharging chambers. Blood is pumped out and into circulation
Systemic vs. Pulmonary Circuits
Pulmonary arteries carry blood to lungs. Oxygen is picked up and CO2 is unloaded. Pulmonary circulation occurs from the right side of heart to lungs, to left side of heart. It carries blood to lungs, then back to heart. Systemic circulation occurs from the left side of heart through body tissues, and back to right side of heart. It supplies oxygen and nutrient-rich blood to all organs.
Major Valves
The atrioventricular valve prevents backflow into atria when ventricles contract It is comprised of a bicuspid valve (2 flaps), tricuspid valve (3 flaps), and chordae tendinae (anchors flaps). Semilunar valves guard bases of two large arteries leaving the vent. There are pulmonary and aortic semilunar valves.
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