HUMAN HEART STRUCTURE & ANATOMY I Simple and Easy Note

HUMAN HEART STRUCTURE & ANATOMY

 I Simple and Easy Note
(Student Level)

By learningcentury.blogspot.com

HUMAN HEART

1)     Human heart is derived from the Greek word “Cardium”.

2)     It is a conical, muscular pumping organ.

3)     LOCATION: It is present in the chest cavity, behind the breast bone sternum between the two lungs.

4)     It is on the left side because the left chamber of the heart i-e left ventricle is the largest chamber.

STRUCTURE OF HUMAN HEART:

The structure of the Human heart can easily be discussed under the following headings.

1)  PERICARDIUM:

a.      Heart is covered by a tough double membrane called pericardium.

b.      It protects the heart from overextension.

c.      Both membranes of pericardium separated by a small cavity filled with pericardial fluid, which lubricates the heart during movement.

2)  SEPTUM:

a.       The heart of birds and mammals has two sides left and right sides, which are divided by a septum (wall).

3)  CHAMBERS OF THE HEART:

a.       Each side of the heart is divided into an upper and lower chamber.

b.      Each upper chamber is called atrium and each lower chamber is called ventricle.

c.       So, there are two atria (left and right) and two ventricles (left and right).

d.      The atria are thin-walled and the ventricles are thick-walled.

4)  VALVES OF THE HEART:

a.       Right atrium communicates with the right ventricle through a valve called tricuspid valve (having three flaps of muscles).

b.      Left atrium opens into the left ventricle through a bicuspid valve (having two flaps)

c.       Bicuspid valve is also known as mitral valve.

d.      These valves control the blood flow and prevent blood from flowing back to atria.

e.       A semilunar valve is present between each ventricle and large vessels.

f.        Semilunar valves prevent blood from flowing back into the ventricles.

CIRCULATION OF BLOOD IN HEART CHAMBERS

OR

FUNCTION OF HUMAN HEART

1.      In birds and mammals, the oxygenated and de-oxygenated blood is completely separated.

2.      De-oxygenated blood remains on the right side and oxygenated blood on the left side of the heart.

3.      The right side of the heart receives de-oxygenated blood from the body and sends it to the lungs.

4.      While the left side receives oxygenated blood from the lungs and sends it to the body.

5.      It means that the human heart works as a double pump.

6.      The right atrium receives deoxygenated blood from the whole body through vena cava (largest veins).

7.      This blood is pumped to the right ventricle through the tricuspid valve.

8.      When the right ventricle contracts, the deoxygenated blood is pumped to the lungs through pulmonary arteries.

9.      The oxygenated blood from the lungs comes back to the left atrium through the pulmonary vein.

10.  From here, this oxygenated blood is pumped to the left ventricle via a bicuspid valve.

11.  When the left ventricle contracts the oxygenated blood is pumped into the aorta the largest artery which distributes it to the whole body through a network of arteries.

PULMONARY CIRCULATION

LOW-PRESSURE CIRCULATION:

The flow of blood from the heart to lungs and then from lungs to heart is called pulmonary circulation.

1.      The blood in the pulmonary circulation is at a lower pressure than the blood in systematic circulation.

2.      Due to low pressure in pulmonary circulation, blood flows in the lungs at slow speed.

3.      It gives sufficient time for gaseous exchange to occur in the lungs.

SYSTEMATIC CIRCULATION

HIGH-PRESSURE CIRCULATION:

The flow of blood from the heart to the body tissues and then from body tissues to heart is called systematic circulation.

1.      The blood in systematic circulation is at higher pressure.

2.      Due to high pressure in systematic circulation, blood can reach all body parts.

Q: WHAT IS CARDIAC CYCLE?

A: CARDIAC CYCLE:

       

        HEART BEAT:

1.      One contraction and relaxation of the heart is called the cardiac cycle.

2.      It makes one heartbeat.

3.      SYSTOLE: contraction of the heart is termed as systole.

4.      DIASTOLE: relaxation of the heart is termed as diastole.

5.      One complete cycle takes 0.8 seconds.

6.      Normal rate of heart beat in a healthy human being is 72 times per minute, this is also called heart rate.

A) SYSTOLE:

1.      first phase is called systole.

2.      It occurs when both ventricles contract to pump the blood into pulmonary arteries and aorta.

3.      Due to this contraction, tricuspid and bicuspid valves close and semilunar valves open.

4.      During systole “LUBB” sound is produced due to the closing of tricuspid and bicuspid valves.

     B) DIASTOLE:

1.      The second phase is called diastole.

2.      It occurs immediately after systole when both atria relaxed so that blood enters the atria.

3.      Due to this, tricuspid and bicuspid valves open and semilunar valves close.

4.      Contraction of the atria fills the ventricles.

5.      During diastole “DUBB” sound is produced due to the closing of semilunar valves.

Q: WHAT IS PULSE?

A: PULSE:

1.      Heart rate can be measured by feeling the pulse.

2.      A pulse is a series of expansion waves in an artery caused by the contractions of the left ventricle.

3.      When the ventricle contracts blood rushes through the arteries.

4.      The elastic walls of arteries expand.

5.      The arteries in wrists are close to the surface.

6.      Therefore, a pulse can be felt easily here.

7.      Pulse rate is an easy way to understand the condition of the heart.

 

YOUR PRECIOUS COMMENT WILL BE HIGHLY APPRECIATED.

THANKS FOR VISITING OUR SITE.