How the heart works?

Answer 1

The heart is a muscle which works like a pump to send blood throughout your body. It is divided in to right and left sides separated by a septum. Your heart has four chambers a right atrium and ventricle and a left atrium and ventricle, your heart has four valves that regulate the flow of blood through the heart, its chambers and the arteries. The right and lefts sides of the heart work together to pump blood. The right side of the heart pumps blood from your heart to your lungs through the pulmonary artery. The left side of your heart pumps blood to other parts of your body through the aorta. A pumping cycle begins when blood from your body that is low in oxygen or (deoxygenated blood) returns through the superior and inferior vena-cavae to fill your hearts right atrium, when the right atrium is full with blood it contracts the tricuspid valve opens and blood is pumped in to the right ventricle of your heart this is called atrial systole. When the right ventricle is full with blood, the tricuspid valve closes this prevents blood from flowing back in to the right atrium. Full with blood your hearts right atrium contracts the pulmonic valve opens and blood it pumped in to your pulmonary artery and on to your lungs. This is called ventricular systole, the pulmonary valve quickly closes to prevent blood from flowing back in to the right ventricle. Oxygen rich blood ( oxygenated blood) returns from the lungs through the pulmonary veins and has filled your hearts left atrium. Your hearts left atrium contracts the mitral valve opens and blood is pumped in to the left ventricle. This occurs at the same time a new contraction is taking place in your hearts right atrium. When your hearts left ventricle is full with blood the mitral valve closes this prevents blood from flowing back in to the left atrium. Your hearts left ventricle contracts and the aortic valve between your left ventricle and aorta opens, the contraction pumps oxygen rich blood in to your aorta and on to the rest of your body, the aortic valve quickly closes to prevent blood from flowing back in to the left ventricle. This occurs at the same time a new contraction is taking place in your hearts right ventricle meanwhile your hearts atria have filled with blood and the cycle continues.

Phases of the cardiac cycle:

1) diastole: oxygenated blood flows in to the left atrium through the four pulmonary veins and deoxygenated blood enters the right atrium through the vena cave.

2) atrial systole: the ventricles relax. Pressure rises in the atria which forces the mitral and tricuspid valve open and the blood is pumped in to both ventricles.

3) Ventricular systole: the last phases of the heart beat cycle: the ventricles contract and blood is pumped in to the circulation. Heart valves The heart has four valves (mitral, pulmonic, aortic and tricuspid) The valves open and close in response to pressure changes. Each valve opens and closes once per heart beat. The mitral and tricuspid valves are located between the atria and the ventricles. The pulmonic and aortic valves are located in each ventricle. The aortic valve is located in the left ventricle, and the pulmonic valve is in the right ventricle and it connects to the pulmonary arteries and then in to the lungs.

Blood supply to the heart The heart needs oxygenated blood to survive. The heart receive its own supply of blood the coronary arteries which rap over the surface of the heart. The coronary ostium, an opening in the aorta feeds blood in to the coronary arteries, during systole when the LEFT ventricle is pumping blood the coronary ostium is open enabling blood to fill the coronary arteries. During diastole when the LEFT ventricle is filling with blood the coronary ostium is covered with blood. With tachycardia ( fast heart rhythm) less blood flows in to the coronary arteries and less blood will be sent through the circulatory system.

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Electrical system of the heart

Your heart is a muscle which works continually much like a pump. Each beat of your heart is set in motion by an electrical signal from within your heart muscle. The electrical activity is recorded by an electrocardiogram know as a ECG or EKG. Each beat of your heart begins with an electrical signal from the sinoatrial node also know as the SA node. The SA node is located in your hearts right atrium. When your hearts right atrium is full with blood the electrical signal spreads across the cells of your hearts right and left atria. This signal causes the atria to contract or squeeze. This pumps blood through the open valves from the atria in to both ventricles the P wave on the ECG marks the contraction of your hearts atria. The signal arrives at the atrioventricular or AV node near the ventricles here it is slowed for an instant to allow your heart right and left ventricles to fill with blood. On the ECG this interval is represented by the start of the line segment between the P and Q wave. The signal is released and moves next to the bundle of his located in your hearts ventricles from the bundle of his the signal fibbers divide in to left and right bundle branches which run through your hearts septum. On the ECG this is represented by the Q wave. The signal leaves the left and right bundle branches through the purkinje fibbers that connect directly the cells of the walls of your hearts ventricles. The signal spreads quickly across your hearts ventricles. As the signal spreads across the cells of the ventricle walls both ventricles contract but not exactly the same moment the left ventricle of your heart contracts an instant before the right ventricle. On the ECG the R wave marks the contraction of your hearts left ventricle. The S wave marks the contraction of your hearts right ventricle. The contraction of your hearts right ventricle pushes blood through the pulmonary valve to your lungs. The contraction of your hearts left ventricle pushes blood through the aortic valve to the rest of your body. As the signal passes the walls of your hearts ventricles relax and await the next signal. On the ECG the T wave marks the point in which your hearts ventricles are relaxing this process continues over and over. The sympathetic nerves speed up heart rate while the paraspathetic nerves slow it down- two sets of chemicals - neropinephrine and epinephrine are highly influenced by this system. These two sets of chemicals do several things. They work to maintain normal blood pressure and they help to speed up heart rate. These sets of chemicals are found in the blood. ____________________________________________________________________ Information about the cardiac cells.

The heart cannot pump unless and electrical impulse occurs first as electrical impulses are transmitted, cardiac cells undergo phases of depolarization and repolarisation. Depolarization means electrical changes- and repolarisation means- REST/ relaxes. Cardiac cells at rest are considered polarized- meaning that no electrical activity takes place. The transmission of electrical impulse depends upon five characteristics of cardiac cells. 0 through to 5. 0-5 phases of cardiac cells:

0: the cell receives an impulse from another cell and is depolarized

1: phase one is early rapid repolarisation

2:phase two is a period of slow repolarisation

3:phase three the cell undergoes rapid repolarisation

4:phase four the cell is ready for another stimulus.

The heart cells produce electrical impulses on their own. The cells membrane separates different concentrations of irons such as sodium and potassium this helps to create a more negative charge inside the cell. Different cells to the heart.

The SA node: The sinoatrial node also known as the sinus node or the SA node, is located in the top right hand corner of the heart. normally the SA node begins the hearts electrical discharge. When the hearts right atrium is full with blood, the SA node is activated. The electrical discharge the spreads through the atria through the intermodal track and the Bachman's bundle. The AV node: The AV node or more properly called the junctional point is responsible for delaying the electrical discharge by .00.4 seconds which allows enough time for the ventricles to fill with blood. The HIS-bundle: The bundle of his continues the rapid discharge on the way to the ventricles. From the bundle of his - the signal fibbers divide in to left and right bundle branches which run through your hearts septum. The purkije fibbers: finally the electrical current moves up to the purkije fibbers forcing the ventricles to contract. NOTE: The electrical signal spreads faster down the left bundle branch than the right bundle branch which is why the left ventricle of the heart contacts slightly before the right ventricle does. _____________________________________________________________________ A look at heart rhythms

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Normal sinus rhythm:

If the SA node is controlling the heart and the rhythm is regular and steady the heart is said to be in sinus-rhyme. The SA node discharges impulses at a rate of 60-100 times per minuet which is NORMAL. Your heart rate ( HR) is the number of times your heart beats per minuet- or the number of electrical impulses the SA node produces each minuet.

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Escape rhythm:

If the SA node fails to discharge an impulse then other cells will take over as the pacemaker. For example if atria pacemaker cells take control of the hearts depolarization sequence then the rhythm is described as an atria escape. Junctional escape: If the SA node fails to discharge and the AV junction takes over as the hearts pacemaker the rhythm is described as Junctional escape. Ventricular escape: If the SA node fails to discharge and no atrial or juntional escape kicks in then a ventricular escape will take control of the heart. Escape rhythms are NOT primary disorders and they sometimes occur during sleep. If the SA node slows down to below 60 BPM then bryadicardia occurs. Bryadicardia is a heart beat below 60 BPM. If the SA rate slows down too much then escape rhythms can occur.

Pacemaker discharge rate: The SA node discharges at a rate of 60- 100 times a minuet If the AV junction takes over as the pacemaker then it can discharge a rate of 40-60 times each minuet. If a ventricular focus takes over as the hearts pacemaker it can only discharge at a rate of 20/40 times each minuet. Very slow heart beats can be dangerous, if ventricular cells act as the heart pacemaker for a long time then it can lead to brain damage due to lack of oxygen and blood around the body. Ventricular, atrial and juctional escapes CAN be single beats. Sinus tachycardia If the SA node discharges impulse greater than 100/min then sinus tachycardia is present. Tachycardia is important for two reasons. Firstly less blood will flow through the coronary ostium and into the coronary arteries and less blood can flow through the circulation.

If the rate is very fast 200/min or more, less blood will flow around the body and less oxygen can get to the cells of the body. Sinus bryadicardia: Sinus bryadicardia is a heart rate slower than 60 BPM/ min. It can occur during sleep and usually causes no problems. If the heart rate gets very low 40-50/min then treatment will have to be given.

Maximal heart rate: Maximal heart rate is the highest number of times per minuet that the heart can beat safely ( although sinus tachycardia risk are present) pushing your heart beyond this number is VERY dangerous because its as fast as the heart can beat without going in to fibrillation. Fibrillation Fibrillation is life- threatening IF IN THE VENTRICLES.

There are two types of fibrillation atrial fibrillation ( AF) and ventricular fibrillation (VF) Atrial fibrillation During atrial fibrillation AF- the atria contact very rapidly and irregularly this happens when the electrical signal begins in a different part of the atrium than the SA node. Abnormal electrical signals tend to begin near the left pulmonary veins rather than in the SA node. AF also can happen if the signal is conducted abnormally, the abnormal electrical signal causes the walls of the atria to quiver rapidly or fibrillate instead of contracting normally. As result the atria don't work effectively and don't pump all their blood in to the ventricles. If all the blood does not flow in to the ventricles the blood that remains pools in the atria, if blood pools in the atria clots can form. This increases the risk of stroke because part of a clot can break off and travel to the brain. During AF the ventricles continue to contract from the hearts electrical activity, however the abnormal signals travelling from the atria through the AV node makes the ventricles beat faster than normal, This can lead to heart failure a condition where the heart cannot pump enough blood to meet the bodies needs. There IS effective treatment available for this condition.

Ventricular fibrillation

Ventricular fibrillation also known as V-fib happens when electrical signals in the ventricles become very rapid as a result, the ventricles quiver and are NOT able to pump blood to the lungs and the rest of the body. V-fib can happen during or after a heart attack or in a heart that is damaged from another condition, because the heart is NOT able to pump blood when it is in V-fib sudden cardiac death is often a result unless a person gets emergency medical care right away. Fibrillation be caused by: * Heart conditions * Heart attacks * Other arrhythmia - heart rhythm disorder such as SVT * If you exceed your maximal heart rate during exercise During AF the atria quiver at a rate of 300- 600 times per minuet. During V-fib the heart can quiver uselessly at a rate of 300-600 times per minuet within a few minuets the heart stops so the HR or heart rate would be 0/ min. Your chances of surviving AF are very good as long as you get treatment for it. Your chances of surviving VF are VERY small if you are outside a hospital.

On an ECG with atrial fibrillation abnormal and rapid P waves are seen On an ECG with ventricular fibrillation small rapid waves are seen, but you cannot make out P waves or the QRS complex or T waves. Asytole Cardiac asytole is ventricular standstill. No blood is being pumped and the heart has stopped beating- no escape rhythms can take over as the pacemaker for the heart- this usually leads to brain death. Treatment for this includes: CPR

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Eptopical heartbeats.

Eptopical heartbeats also known as extra systoles can occur in healthy people. Here are different types of extra systoles:

PAC:

PAC stands for premature atrial contraction. PAC originate outside of the SA node, this is usually caused by an irritable spot within the atrial tissue mass. Sometimes atrial escape occurs when it does not need to which makes the atria contract prematurely. PAC lead to a loss in atrial contraction so less blood will flow in to the ventricles.

PVC:

PVC stands for premature ventricular contraction. PVCS do NOT affect the SA node. They are caused when cells in the ventricular muscle discharges too soon. On an ECG PVCS which look similar are called uniform and they are caused by a particular irritable spot within the ventricular muscle. PVCS that look different to one another are called multiform PVCS. PVCS which occur every other normal heartbeat are called bigeminy PVCS can occur in runs of 3 or more. PVCS are important because they reduce cardiac out-put and less blood flows through to the coronary arteries.

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Answer 2

The heart is a muscle which works like a pump to send blood throughout your body. It is divided in to right and left sides separated by a septum. Your heart has four chambers a right atrium and ventricle and a left atrium and ventricle, your heart has four valves that regulate the flow of blood through the heart, its chambers and the arteries. The right and lefts sides of the heart work together to pump blood. The right side of the heart pumps blood from your heart to your lungs through the pulmonary artery. The left side of your heart pumps blood to other parts of your body through the aorta. A pumping cycle begins when blood from your body that is low in oxygen or (deoxygenated blood) returns through the superior and inferior vena-cavae to fill your hearts right atrium, when the right atrium is full with blood it contracts the tricuspid valve opens and blood is pumped in to the right ventricle of your heart this is called atrial systole. When the right ventricle is full with blood, the tricuspid valve closes this prevents blood from flowing back in to the right atrium.

Full with blood your hearts right atrium contracts the pulmonic valve opens and blood it pumped in to your pulmonary artery and on to your lungs. This is called ventricular systole, the pulmonary valve quickly closes to prevent blood from flowing back in to the right ventricle. Oxygen rich blood ( oxygenated blood) returns from the lungs through the pulmonary veins and has filled your hearts left atrium. Your hearts left atrium contracts the mitral valve opens and blood is pumped in to the left ventricle.

This occurs at the same time a new contraction is taking place in your hearts right atrium. When your hearts left ventricle is full with blood the mitral valve closes this prevents blood from flowing back in to the left atrium. Your hearts left ventricle contracts and the aortic valve between your left ventricle and aorta opens, the contraction pumps oxygen rich blood in to your aorta and on to the rest of your body, the aortic valve quickly closes to prevent blood from flowing back in to the left ventricle. This occurs at the same time a new contraction is taking place in your hearts right ventricle meanwhile your hearts atria have filled with blood and the cycle continues.

Phases of the cardiac cycle

1) diastole: oxygenated blood flows in to the left atrium through the four pulmonary veins and deoxygenated blood enters the right atrium through the vena cave.

2) atrial systole: the ventricles relax. Pressure rises in the atria which forces the mitral and tricuspid valve open and the blood is pumped in to both ventricles.

3) Ventricular systole: the last phases of the heart beat cycle: the ventricles contract and blood is pumped in to the circulation.

Heart valves

The heart has four valves (mitral, pulmonic, aortic and tricuspid)

The valves open and close in response to pressure changes. Each valve opens and closes once per heart beat. The mitral and tricuspid valves are located between the atria and the ventricles. The pulmonic and aortic valves are located in each ventricle. The aortic valve is located in the left ventricle, and the pulmonic valve is in the right ventricle and it connects to the pulmonary arteries and then in to the lungs.

Blood supply to the heart. The heart needs oxygenated blood to survive. The heart receive its own supply of blood the coronary arteries which rap over the surface of the heart. The coronary ostium, an opening in the aorta feeds blood in to the coronary arteries, during systole when the LEFT ventricle is pumping blood the coronary ostium is open enabling blood to fill the coronary arteries. During diastole when the LEFT ventricle is filling with blood the coronary ostium is covered with blood. With tachycardia (fast heart rhythm) less blood flows in to the coronary arteries and less blood will be sent through the circulatory system.

Electrical system of the heart. Your heart is a muscle which works continually much like a pump. Each beat of your heart is set in motion by an electrical signal from within your heart muscle. The electrical activity is recorded by an electrocardiogram know as a ECG or EKG. Each beat of your heart begins with an electrical signal from the sinoatrial node also know as the SA node. The SA node is located in your hearts right atrium. When your hearts right atrium is full with blood the electrical signal spreads across the cells of your hearts right and left atria. This signal causes the atria to contract or squeeze. This pumps blood through the open valves from the atria in to both ventricles the P wave on the ECG marks the contraction of your hearts atria. The signal arrives at the atrioventricular or AV node near the ventricles here it is slowed for an instant to allow your heart right and left ventricles to fill with blood. On the ECG this interval is represented by the start of the line segment between the P and Q wave. The signal is released and moves next to the bundle of his located in your hearts ventricles from the bundle of his the signal fibbers divide in to left and right bundle branches which run through your hearts septum. On the ECG this is represented by the Q wave. The signal leaves the left and right bundle branches through the purkinje fibbers that connect directly the cells of the walls of your hearts ventricles. The signal spreads quickly across your hearts ventricles. As the signal spreads across the cells of the ventricle walls both ventricles contract but not exactly the same moment the left ventricle of your heart contracts an instant before the right ventricle. On the ECG the R wave marks the contraction of your hearts left ventricle. The S wave marks the contraction of your hearts right ventricle.

The contraction of your hearts right ventricle pushes blood through the pulmonary valve to your lungs. The contraction of your hearts left ventricle pushes blood through the aortic valve to the rest of your body. As the signal passes the walls of your hearts ventricles relax and await the next signal. On the ECG the T wave marks the point in which your hearts ventricles are relaxing this process continues over and over.

The sympathetic nerves speed up heart rate while the paraspathetic nerves slow it down- two sets of chemicals - neropinephrine and epinephrine are highly influenced by this system.

These two sets of chemicals do several things. They work to maintain normal blood pressure and they help to speed up heart rate. These sets of chemicals are found in the blood.

____________________________________________________________________

Information about the cardiac cells.

The heart cannot pump unless and electrical impulse occurs first as electrical impulses are transmitted, cardiac cells undergo phases of depolarization and repolarization. Depolarization means electrical changes- and repolarization means- REST/ relaxes. Cardiac cells at rest are considered polarized- meaning that no electrical activity takes place.

The transmission of electrical impulse depends upon five characteristics of cardiac cells.

0 through to 5.

0-5 phases of cardiac cells:

0: the cell receives an impulse from another cell and is depolarized

1: phase one is early rapid repolarisation

2:phase two is a period of slow repolarisation

3:phase three the cell undergoes rapid repolarisation

4:phase four the cell is ready for another stimulus

The heart cells produce electrical impulses on their own. The cells membrane separates different concentrations of irons such as sodium and potassium this helps to create a more negative charge inside the cell.

Different cells to the heart.

The SA node:

The sinoatrial node also known as the sinus node or the SA node, is located in the top right hand corner of the heart. normally the SA node begins the hearts electrical discharge. When the hearts right atrium is full with blood, the SA node is activated. The electrical discharge the spreads through the atria through the intermodal track and the Bachman's bundle.

The AV node: The AV node or more properly called the junctional point is responsible for delaying the electrical discharge by .00.4 seconds which allows enough time for the ventricles to fill with blood.

The HIS-bundle: The bundle of his continues the rapid discharge on the way to the ventricles. From the bundle of his - the signal fibbers divide in to left and right bundle branches which run through your hearts septum.

The purkije fibbers: finally the electrical current moves up to the purkije fibbers forcing the ventricles to contract.

NOTE: The electrical signal spreads faster down the left bundle branch than the right bundle branch which is why the left ventricle of the heart contacts slightly before the right ventricle does.

_____________________________________________________________________

A look at heart rhythms

Normal sinus rhythm: If the SA node is controlling the heart and the rhythm is regular and steady the heart is said to be in sinus-rhyme. The SA node discharges impulses at a rate of 60-100 times per minuet which is NORMAL. Your heart rate ( HR) is the number of times your heart beats per minuet- or the number of electrical impulses the SA node produces each minuet.

Escape rhythm:

If the SA node fails to discharge an impulse then other cells will take over as the pacemaker. For example if atria pacemaker cells take control of the hearts depolarization sequence then the rhythm is described as an atria escape.

Junctional escape:

If the SA node fails to discharge and the AV junction takes over as the hearts pacemaker the rhythm is described as Junctional escape.

Ventricular escape: If the SA node fails to discharge and no atrial or juntional escape kicks in then a ventricular escape will take control of the heart.

Escape rhythms are NOT primary disorders sometimes during sleep the SA node slows down to below 60 BPM and bryadicardia occurs. Bryadicardia is a heart beat below 60 BPM. If the SA rate slows down too much then escape rhythms can occur.

Pacemaker discharge rate:

The SA node discharges at a rate of 60- 100 times a minuet

If the AV junction takes over as the pacemaker then it can discharge a rate of 40-60 times each minuet.

If a ventricular focus takes over as the hearts pacemaker it can only discharge at a rate of 20/40 times each minuet. Very slow heart beats can be dangerous, if ventricular cells act as the heart pacemaker for a long time then it can lead to brain damage due to lack of oxygen and blood around the body.

Ventricular, atrial and juctional escapes CAN be single beats.

Sinus tachycardia

If the SA node discharges impulse greater than 100/min then sinus tachycardia is present. Tachycardia is important for two reasons. Firstly less blood will flow through the coronary ostium and into the coronary arteries and less blood can flow through the circulation. If the rate is very fast 200/min or more, less blood will flow around the body and less oxygen can get to the cells of the body.

Sinus bryadicardia:

Sinus bryadicardia is a heart rate slower than 60 BPM/ min. It can occur during sleep and usually causes no problems. If the heart rate gets very low 40-50/min then treatment will have to be given.

Maximal heart rate:

Maximal heart rate is the highest number of times per minuet that the heart can beat safely ( although sinus tachycardia risk are present) pushing your heart beyond this number is VERY dangerous because its as fast as the heart can beat without going in to fibrillation.

Fibrillation: there are two types if fibrillation atrial and ventricular.

Atrial fibrillation:

Atrial fibrillation is where the atria contact very rapidly and irregularly, this happens when the electrical impulses begin in a different part of the atrium than the SA node. Abnormal electrical signals tend to begin near the left pulmonary veins, rather than in the SA node. The electrical signals become irregular and make the atria quiver fast or fibrillate. As a result the atria don't pump blood effectively and don't pump all their blood in to the ventricles. If all the blood does not flow in to the ventricles then the blood that remains pools in the atria. If blood pools in the atria clots can form, this increase the risk of stroke because part of a clot can break off and travel to the brain via the blood stream. You should get hospital treatment quickly, atrial fibrillation is common and people do live with this, symptoms include: palpitations, breathlessness and fainting.

Ventricular fibrillation:

Ventricular fibrillation also known as V-FIBB happens when electrical signals in the ventricles become very rapid. As a result the ventricular fibrillate and cannot pump blood to the lungs and the rest of the body. This leads to cardiac death and asystole if not treated very quickly

Asytole

Cardiac asytole is ventricular standstill. No blood is being pumped and the heart has stopped beating- no escape rhythms can take over as the pacemaker for the heart- this usually leads to brain death. Treatment for this includes: CPR

Etopical heartbeats.

Etopical heartbeats also known as extra systoles can occur in healthy people.

Here are different types of extra systoles:

PAC:

PAC stands for premature atrial contraction. PAC originate outside of the SA node, this is usually caused by an irritable spot within the atrial tissue mass. Sometimes atrial escape occurs when it does not need to which makes the atria contract prematurely. PAC lead to a loss in atrial contraction so less blood will flow in to the ventricles.

PVC

PVC stands for premature ventricular contraction. PVCS do NOT affect the SA node. They are caused when cells in the ventricular muscle discharges too soon. Premature ventricular contracts do not affect the SA node.

On an ECG PVCS which look similar are called uniform and they are caused by a particular irritable spot within the ventricular muscle.

PVCS that look different to one another are called multiform

PVCS which occur every other normal heartbeat are called bigeminy

PVCS can occur in runs of 3 or more.

PVCS are important because they reduce cardiac out-put and less blood flows through to the coronary arteries.

it just works because it pumps and keeps you alive

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The heart periodically contracts. The contraction starts in the upper right quadrant, near the atria. They contract and force blood into the ventricles. A short time later the ventricles contract, forcing blood into the body and lungs.