what is cardiac output?
914123
Cardiac output is the volume of blood being pumped by the heart, in particular a ventricle in a minute. It is equal to the heart rate multiplied by the stroke volume.\n\nSo if there are 70 beats per minute, and 70 ml blood is ejected with each beat of the heart, the cardiac output is 4900 ml/minute. This value is typical for an average adult at rest, although cardiac output may reach up to 30 liters/minute during extreme exercise.\n\nWhen cardiac output increases in a healthy but untrained individual, most of the increase can be attributed to increase in heart rate. Change of posture, increased sympathetic nervous system activity, and decreased parasympathetic nervous system activity can also increase cardiac output. Heart rate can vary by a factor of approximately 3, between 60 and 180 beats per minute, whilst stroke volume can vary between 70 and 120 ml, a factor of only 1.7.
1084888
A pulmonary valve is one in your heart.  It is a valve that opens and closes as your heart beats,.  When the heart beat pushs the blood out, valve closes, when heart beats the blood into the heart the valve opens.  I hope this helps.  The thump thump thump you hear when your heart beats is this exact motion, value opens and closes, thump thump thump!  Thats what a "heart beat" is!
686559
Blood pressure is the pressure exerted by the blood on the walls of the blood vessels. Unless indicated otherwise, blood pressure refers to systemic arterial blood pressure, i.e., the pressure in the large arteries delivering blood to body parts other than the lungs, such as the brachial artery (in the arm). The pressure of the blood in other vessels is lower than the arterial pressure. Blood pressure values are universally stated in millimetres of mercury (mm Hg), and are always given relative to atmospheric pressure—the absolute pressure of the blood in an artery with mean arterial pressure stated as 100 mm Hg, on a day with atmospheric pressure of 760 mm Hg, is 860 mm Hg.\n\nThe systolic pressure is defined as the peak pressure in the arteries during the cardiac cycle; the diastolic pressure is the lowest pressure (at the resting phase of the cardiac cycle). The mean arterial pressure and pulse pressure are other important quantities.
1078725
Systole refers to the active, ejection phase of the cardiac cycle, when the heart muscle forcefully contracts, ejecting blood out of the ventricles into the pulmonary artery and aorta. Diastole refers to the passive, relaxation phase of the cardiac cycle, when the heart's muscular walls relax, allowing the ventricles to fill with blood from the atria, pulmonary veins and vena cavae, in preparation for the next cycle.\n    Ventricular contraction during systole causes blood to leave the heart under high pressure, which is propagated as a pressure (pulse) wave throughout the arterial system. If our arteries were rigid pipes, then when the heart muscle relaxed during ventricular diastole, the blood pressure within the arteries would also drop close to zero. But since our arteries have walls that are highly elastic, the walls stretch and increase in diameter in response to the high pressure pulse wave of systole. Then during diastole, the arterial walls snap back to "normal" like a rubber band that's actively stretched (systole) and then allowed to passively return to normal (diastole). This passive contraction of the arterial walls, due to their elasticity, maintains positive pressure within the arteries during diastole, maintaining blood flow throughout the entire cardiac cycle. Thus, arterial blood pressure varies throughout the cardiac cycle: The maximum is the systolic pressure, and the minimum is the diastolic pressure.
396031
As the heart increase in size, the surface area increase by the square, while the internal volume increases by the cube.\nExample: internal volume = Length * Width * height\n\nAs the internal volume increases the amount of blood pumped per heart beat (stroke volume) increases.\n\nThe actual “strength” of the heart is unchanged. Cardiac myosites are essentially unchanged between different mammal species. \n\nWell trained athletes tend to have a health heart hypertrophy (enlarged heart) and have heart beats in the 40’s-50’s BPM while the average adults range in the 60’s-80’s.\n\nAs an end product of all of this, large animals tend to have slower metabolic rates because while it may be possible for a 6 oz bird to eat its weight in insects a day a large animal like a dog can not be expected to do so.
64374
The above answer is correct, but the cardiovascular system is not just the heart. That's the "cardio", but the "vascular" part is all of the arteries, veins, and capillaries that distribute the blood throughout the body.\nThe respiratory system does indeed oxygenate the blood, but is also responsible for eliminating carbon dioxide from the body as well. As the body uses oxygen for metabolism, it produces carbon dioxide. If this is not eliminated from the body fairly quickly, it builds up, and without going into alot of detail, you die.
848153
heart rate is defined as the number of beats( systoles) the heart produces per unit of time( ussually per minute).\nBlood pressure is the pressure exert by the blood to the vessel´s walls( the arteries and the veins).
76097
blood, fluid pumped by the heart that circulates throughout the body via the arteries, veins, and capillaries (see circulatory system; heart). An adult male of average size normally has about 6 quarts (5.6 liters) of blood. The blood carries oxygen and nutrients to the body tissues and removes carbon dioxide and other wastes. The colorless fluid of the blood, or plasma, carries the red and white blood cells, platelets, waste products, and various other cells and substances
138406
I'm not sure what you need to know about this subject.\n\nCoronary arteries supply blood to the heart muscle. \nThe coronary arteries regulate the supply of blood to your heart muscle depending on how much oxygen your heart needs at the time, as indicated by:\n\n    * The number of times your heart beats per minute (heart rate).\n    * Your blood pressure.\n    * The force of your heart's contractions.\n    * The thickness of your heart muscle.\n\nSecond link discusses coronary artery disease.
667354
The Cardiovascular System\n\n\n The cardiovascular system and the lymphatic system form what is collectively called the circulatory system. Together, these systems transport oxygen, nutrients, cell wastes, hormones, and many other substances to and from all cells in the body. The trillions of cells in the human body take up nutrients and excrete wastes every minute of every day. Although the pace of this exchange may increase with activity or slow with rest, it happens continuously. If it stops, so does life. Of the two systems, the cardiovascular system is the primary transport operator; the lymphatic system aids it in its function.\n\n\nDesign: Parts of the Cardiovascular System\n\nCardiovascular comes from the Greek word cardia, meaning "heart," and the Latin vasculum, meaning "small vessel." The basic components of the cardiovascular system are the heart, the blood vessels, and the blood. The system can be compared to a large muscular pump (the heart) that sends a fluid (blood) through a series of large and small tubes (blood vessels). As blood circulates through the increasingly intricate system of vessels, it picks up oxygen from the lungs, nutrients from the small intestine, and .....
540634
This is a complex question involving many components in a heartbeat. Firstly, I'll assume that your question means the chambers of the heart is empty, but not the coronary vessels supplying the heart to keep the heart muscle alive. (Or else the heart muscles would just die and the heart stops.)\n\nA heartbeat is stimulated by several factors, and those related to your question are blood pressure and blood volume.\nIn the situation where all the blood rush out of the heart, the blood pressure would remain nearly unchanged as the slight increase in blood volume is not significant. However, blood volume is partly detected by receptors in the heart itself (if the heart stretch more, blood volume is higher) Now that the heart is empty, it would tend to slow down its beating and wait for blood to fill it before it beat again.\nThe effect is gradual, so theoretically, the heart would beat slower and slower until it stops.\n\nHowever in reality, it is impossible for the heart to become empty without the heart dying as the coronary arteries and veins are attached directly into the heart.
634762
Airway, Breathing, Circulation
1146904
because these are the only two measurements done with a routine manual blood pressure reading.  now if on a blood pressure monitoring machine, there is a mean or average blood pressure.  however, the basics are the top number or systolic and bottom number or diastolic.  the systolic is the heart when working or contracting; the diastolic is the heart at rest.  a high diastolic is more significant due to the fact that a hi diastolic creates more pressure in the arteries to move the blood to vital organs.
126528
blood pressure.  The viscosity factor is present in the flow equations.  The flow number is than in the equation governing cardiac output.  You see viscosity affect blood pressure, but the equations relate it to the amount of energy needed during each stroke of the heart.
429801
the heart generates its own electrical impulses to stimulate the heart to beat . It is the SA node in the atria and the AV node in the ventricles. \n\nWhen patients have been diagnosed as brain dead - and on a ventilator ( a breathing machine )  - their heart is still beating - because the heart has its own built-in battery pack, so to speak .
311612
The top number is the systolic rate,the bottom number is the diastolic rate.\n\nSystolic pressure (the higher,first #) measures the force that the blood exerts on the artery walls as the heart contracts to pump the blood.\n\nDiastolic pressure (the lower second #) is the measurement of force as the heart relaxes to allow blood to flow to the heart.
937883
Our heart is a pump, a very efficient one. The whole body consists of various circuits. And there are valves which control the flow of blood. Since the heart pumps blood, that is, it sends the blood at a certain pressure, the flood flows to various body parts and back, whatever the body position is, horizontal or vertical. This applies to the lowest part of our bodies (foot) too, when we stand up.