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Human Heart Working Explained : Notes on Class 10th Biology

HUMAN HEART

 

      • The heart is a hollow, muscular organ, roughly of the size of one’s fist (12 x 9 cm.).
      • Its average weight is about 500 gm. in males and about 250 gm. in females.
      • The heart is reddish-brown in color and somewhat conical in form.

It is located almost in the middle of the thoracic cavity close to its front wall and between the lungs

Structure of Human Heart

      • Human heart is four-chambered.
      • The two little smaller upper chambers are called atria and the larger lower chambers are called ventricles.
      • Both are separated by coronary sulcus.
      • The left atrium is smaller than the right atrium and is separated by a thin muscular wall called interatrial septum.
      • The left and right ventricles are separated by thick walled inter ventricular septum.

Path way for deoxygenated blood

Deoxygenated blood is carried to the right atrium by: superior vena cava (from the upper region of body)

      • a coronary sinus (from nearby heart tissues)
      • inferior vena cava (from the lower part of the body).
      • This blood is then passed to the right ventricle through the opening of the tricuspid valve having three flaps.
      • The deoxygenated blood from the right ventricle is carried by pulmonary artery to the lungs where it is oxygenated.

Path way for oxygenated blood

      • The oxygenated blood is then passed into the left atrium through the pulmonary vein.
      • The blood then flows to left ventricle through opening of bicuspid valves (with two flaps)
      • The oxygenated blood is then pumped into the aorta on opening of the aortic semilunar valve.
      • The blood is prevented from flowing back to atria from their respective ventricles by the presence of chordae tendineae which are attached to the lower chamber.
      • Aorta further branches to form left subclavian artery (supply blood to arms),
      • common carotid artery (supply oxygen rich blood to near by heart tissues),
      • brachiocephalic artery (supplies blood to brain and head)
      • renal artery (supply blood to kidney
      • mesenteric artery (supply blood to intestine)
      • femoral artery (supply blood to lower portion of body)
      • common iliac artery (supply blood to back of the body)

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