2. Defination
• Circulatory system : The circulatory
system, also called
the cardiovascular system or
the vascular system, is an organ
system that permits blood to circulate
and transport nutrients (such as amino
acids and electrolytes), oxygen, carbon
dioxide, hormones, and blood cells to
and from the cells in the body to
provide nourishment and help
in fighting diseases, stabilize
temperature and pH, and
maintain homeostasis.
4. HEART
• The heart is a muscular organ in most animals, which pumps blood through the blood
vessels of the circulatory system.
• The heart pumps around 5.7 litres of blood in a day throughout the body.
• The heart is situated at the centre of the chest and points slightly towards the left.
• On average, the heart beats about 100,000 times a day, i.e., around 3 billion beats in
• The average male heart weighs around 280 to 340 grams (10 to 12 ounces). In
around 230 to 280 grams (8 to 10 ounces).
• An adult heart beats about 60 to 100 times per minute, and newborn babies heart
than an adult which is about 90 to 190 beats per minute.
6. Internal structure of heart
• Left atrium
• Right atrium
• Left ventricle
• Right ventricle
• Atria are thin, less muscular walls and smaller than ventricles. These are the blood-receiving chambers that are fed by the large veins.
• Ventricles are larger and more muscular chambers responsible for pumping and pushing blood out to the circulation. These are connected to larger
arteries that deliver blood for circulation.
• The right ventricle and right atrium are comparatively smaller than the left chambers. The walls consist of fewer muscles compared to the left portion,
and the size difference is based on their functions. The blood originating from the right side flows through the pulmonary circulation, while blood arising
from the left chambers is pumped throughout the body.
• Valves are flaps of tissues that are present in cardiac chambers between the veins. They prevent the backflow of blood. Examples include the
atrioventricular valves, tricuspid valves, mitral valves and the semilunar valves.
8. • The blood vessels typically comprise the following:
• Veins supply deoxygenated blood to the heart via inferior and superior vena cava, and it
eventually drains into the right atrium.
• Capillaries are tiny, tube-like vessels which form a network between the arteries to veins.
• Arteries are muscular-walled tubes mainly involved in supplying oxygenated blood away
from the heart to all other parts of the body. Aorta is the largest of the arteries and it
branches off into various smaller arteries throughout the body.
