Heart

The Sacred Heart is a medieval symbol of Christ

they are in the heart of humans only

A human heart is divided into 4 compartments: A right and left Atrium (Auricle) and 2 similar Ventricles.

Valves prevent the backflow of blood.

The heart beats faster during physical exercise, anxiety, and emotional stress. This is because the body needs to have more oxygen and glucose to deal with tougher activities and feelings like these.

Between 60 and 100 during 'normal' activities. During sports, running etc. heartbeat may temporarily - and safely - go up to between 160 (if you are somewhat older) and 200 beats per minute.

its not really in the heart its emotionally... uless your having hard good sex then your heart will beat faster as your moving quickly.

Aortic valve stenosis can occur because of a birth defect in the formation of the valve. Calcium deposits may form on the valve with aging, causing the valve to become stiff and narrow. Stenosis can also occur as a result of rheumatic fever.

The sternum is anterior to the heart (in front of the heart). It may also be called superficial or ventral to the heart.

Muscle tetany occurs in muscles without absolute refractory period. The stimulus for contraction comes before the preceding contraction/relaxation is over leading to multiple action potentials without a refractory period. It does not occur in cardiac muscle because it has absolute refractory period during which the muscle cannot be excited, thus making tetany impossible

If your heartbeat speeds up slightly then this is respiratory sinus arrhythmia - this is normal, healthy heart-rate variation and is nothing to worry about. It is an indicator of health.

Some are quite painful, some are totally painless, some have only sympathetic symptoms (flush, sweating).

The innervation to the heart is not consistent from person to person. Some people have diseases which alter the innervation to the heart, and with age we are more likely to not have pain with heart attacks.

cardiovascular, circulatory and respiratory.

the heart is its own organ if you mean system it is part of the cardiovascular system.

Right ventricle to the lungs

Left ventricle to the body

because you get crazy just like when you run

As blood is pumped out of the heart it first goes up into the biggest artery in the body called the aorta. It has nerves in it that measure blood pressure called baroreceptors. Then the blood goes up through the carotid arteries in the neck which have more baroreceptors and another kind that measures the carbon dioxide content in blood. These are called chemoreceptors. Both of these nerve receptors send their information to a part of the brain known as the medulla oblongata which has two regulatory regions called the cardio-acceleratory and the cardio-inhibitory centers. Both of these control mechanisms are linked to the sinoatrial node at the top of the right side of the heart. This is where the electrical impulse that starts every heart beat cycle is generated. If the heart needs to pump out more blood, or increase cardiac output, a message is sent to the senatorial node to make it accelerate and cause the heart beat faster. If it needs to slow down, or decrease cardiac output, a message is sent to inhibit the sinoatrial node which then makes the heart beat slower. As blood is pumped out of the heart it first goes up into the biggest artery in the body called the aorta. It has nerves in it that measure blood pressure called baroreceptors. Then the blood goes up through the carotid arteries in the neck which have more baroreceptors and another kind that measures the carbon dioxide content in blood. These are called chemoreceptors. Both of these nerve receptors send their information to a part of the brain known as the medulla oblongata which has two regulatory regions called the cardio-acceleratory and the cardio-inhibitory centers. Both of these control mechanisms are linked to the sinoatrial node at the top of the right side of the heart. This is where the electrical impulse that starts every heart beat cycle is generated. If the heart needs to pump out more blood, or increase cardiac output, a message is sent to the senatorial node to make it accelerate and cause the heart beat faster. If it needs to slow down, or decrease cardiac output, a message is sent to inhibit the sinoatrial node which then makes the heart beat slower.

The blood vessels in the pulmonary circulation carry the blood through the lungs to pick up oxygen and get rid of carbon dioxide, while the blood vessels in the systemic circulation carry the blood throughout the rest of our body.

In order to make one round trip through all the major arteries and veins in your body, it can take up to about 60 seconds to make one complete trip. Since you have about 24,000 to 48,000 miles of blood vessels - if you include the capillaries - then it would take much longer for your blood to make one complete circulatory trip.

Interesting question, but your blood is constantly being circulated. the average person has 5 L of blood in the body and during each beat that blood is circulated. but if you're asking how much blood fills the heart in one beat I'm not too sure.

The surgeon told me 3 days. I returned to work after 5 days because the bruising where they inserted the catheters was quite painful, and I need to move around a lot for my job.

There are several reasons. But the one big reason accompanying them all is that the body is essentially getting excited, all the muscles are being used further and therefore those muscles need blood, so the heart pumps faster

Another reason is that sexual excitement is controlled by the sympathetic nervous system which also speeds up heart rate.

Same as your and my heart, they gather blood from the veins, put it into the frogs single ventricle, and pump it out to the lungs and body.

Venous valves .