What is the circulatory system?

The circulatory system removes waste products i.e., carbon dioxide and carries oxygen, nutrients and hormones to different parts of the body.

What is the circulatory system made up of?

    • The circulatory system is the system consists of :
    • Heart (hollow muscular organ/pump)
    • Systems of tubes(arteries, veins and capillaries)
    • Lungs (for purification of blood)
    • Blood( holds the oxygen and distributes to the body and then holds carbon dioxide back to heart and then to lungs to get rid of it)

What do you mean by double circulation?

    • Double circulation means that blood passes through the heart twice in a complete circulation.
    • Double circulation happens in two steps:
    • Pulmonary circulation: when blood is deoxygenated and collected by heart from the whole body and received by lungs to get the blood oxygenated.

Blood in pulmonary circulation enters into the lungs with low pressure as lungs are near to the heart and cells of the lungs are very delicate and fragile.

    • Systemic circulation: now the heart collects oxygenated blood from lungs and distributed to the whole body with the help of blood vessels.

Blood in systemic circulation enters with high pressure as blood has to disperse in whole huge human body.

Pulmonary and systemic circulation

 What is the difference between single circulation and double circulation of blood?

What are  the advantages of Double circulation of blood?

    • It helps to keep the oxygenated and deoxygenated blood in the body.
    • It maintains the high blood pressure to carryout different essential processes in body.
    • It helps the pure blood to reach every cell and tissue of the blood.

External Structure of Human Heart:

    • Fist- sized present under the rib cage.
    • Conical shaped organ with a pointed apex towards the diaphragm.
    • Muscular organ located in the chest cavity, to the left of breast bone (sternum), between two lungs.
    • It is connected with blood vessels to carry out its function.
    • Heart is enclosed in a tough fibrous membrane called
    • Pericardium prevents heart from over distention and damage due to friction.

Internal Structure of Human Heart:

Consist of 4 chambers:

    • Right atrium : thin walled
    • Left atrium: thin walled
    • Right ventricle: thick walled
    • Left ventricle: thickest of all chambers.

Valves of Heart:

    • tricuspid valve: present between right atrium and right ventricle
    • bicuspid or mitral valve: present between left atrium and left ventricle
    • semilunar valves: present in pulmonary artery and aorta.

Four Valves present in Human Heart

Cardiac muscles:

    • Involuntary muscles.
    • Walls of the heart is made up of cardiac muscles which respire aerobically so do not get tired throughout the life.

Chordae tendineae:

    • Cord like
    • They attach the tricuspid and bicuspid valves with the walls of their respective ventricles to permit easy flow of blood from atrium to ventricles.

Internal structure of Human Heart

Veins and Arteries:

    • Coronary artery: Supply nutrient and oxygen to heart muscles and emerges from the aortic arch/aorta.
    • Superior vena cava: receives deoxygenated blood from upper body; head, neck, upper chest and arms to the heart
    • Inferior vena cava: receives deoxygenated blood from lower half body.
    • Pulmonary artery: send deoxygenated blood from right ventricle to lungs for oxygenation. This is the only artery in our whole body that contain deoxygenated blood.
    • Pulmonary vein: receive oxygenated blood from lungs and push it in left atrium. This is the only vein in our whole body that contain oxygenated blood.
    • Aorta/aortic arch: this is the biggest artery in the whole body that receives oxygenated blood from left ventricle and distributes the blood in whole body.

Main Veins and Arteries in Human Heart:

Conducting system of Heart:

Sinoatrial Node/sinus Node ( SA node):

    • Present in right atrium.
    • Produce electrical impulse.
    • Causes to contract

Atrioventricular Node ( AV node):

    • Present between right atria and ventricle.
    • Act like a gate that slows the electrical impulse before it enters into
    • This delay gives the atria to contract.

Atrioventricular Bundle (Bundle of His):

    • Conducted the electrical impulse from AV node to septum between ventricles and then to the right and left ventricles.

Purkinje Network/fibers:

    • Purkinje fibers and Bundle of His transmit the electrical impulse to right and left ventricles and causes them to contract.

Electrical impulses in Human Heart

Working of Heart in Human Body:

Test yourself:

    • What do you mean by circulatory system?
    • Name the organs involved in a circulatory system.
    • Why does blood circulates through heart?
    • How many chambers a human heart has?
    • How many valves are present in a human heart?
    • What is a double circulatory system?
    • What is the difference between tricuspid and bicuspid valves?
    • Why does tricuspid valve contain three flaps?
    • What is SA and AV node?
    • What is the function and location of SA and AV node?
    • What is the difference between pulmonary and systemic circulation?
    • What are the main arteries and veins of human heart?
    • What is the main function of coronary artery?
    • What are the advantages of double circulation?
    • What is the function of purkinje fibers?
    • Where are the purkinje fibers located?
    • What are the bundles of His?
    • What is the main difference between purkinje fibers and bundles of His?
    • What is an aorta and what is its function?
    • Why is the arch of aorta biggest artery in body?

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