(a) Hypertension The high blood pressure can harm heart, brain kidneys and eyes. High blood pressure is most common disease affecting the heart and blood vessels, Blood pressure is considered normal at 120/80. When it goes beyond 140 mm Hg and 90 mm Hg it is called hypertension or high blood pressure.

Causes of Hypertension

(i) Blockage in the coronary heart vessels.

(ii) Tobacco smoking speeds up heart rate. It constrict blood vessels and raises blood pressure.

(b) Coronary Artery Disease (CAD) It is caused due to the deposition of fatty substances on the arterial wall causing atherosclerotic plaques. The lumen of artery decreases, thus obstructing the blood flow and sometimes completely blocks the artery resulting into thus, heart attack.

The diagrammatic presentation of heart with labelled SAN, AVN, AV bundles bundle of His and purkinje fibres in heart is show as follows