HEART AND CIRCULATORY SYSTEM (Part-I)

Blood comes into the right atrium from the body, moves into the right ventricle and is pushed into the pulmonary arteries in the lungs. After picking up oxygen, the blood travels back to the heart through the pulmonary veins into the left atrium, to the left ventricle and out to the body's tissues through the aorta.

A typical heart has two upper and two lower chambers. The upper chambers, the right and left atria, receive incoming blood. The lower chambers, the more muscular right and left ventricles, pump blood out of the heart. The heart valves are gates at the chamber openings. They blood flowing in the right direction.

The aorta is the largest and main artery of the body, through which oxygenated blood flows outside the heart. It serves to circulate oxygenated blood to all the tissues of the body.

The aorta is the largest and main artery of the body, through which oxygenated blood flows outside the heart. It serves to circulate oxygenated blood to all the tissues of the body.

Capillaries are the smallest blood vessels which have one cell thick walls that allows diffusion between the blood and cells to occur. Nutrients and oxygen from the blood diffuse through the capillary walls into the tissues that need it.

Capillaries are the smallest blood vessels which have one cell thick walls that allows diffusion between the blood and cells to occur. Nutrients and oxygen from the blood diffuse through the capillary walls into the tissues that need it.

Visible swollen veins in the lower layer of the skin, which are often blue or purple in colour, are called varicose veins. These arise due to valves not closing properly. Varicose veins usually appear on the thighs, feet, and ankles. Usually they are not painful, but sometimes they are itchy and painful.

In a closed circulatory system, blood is completely enclosed in blood vessels of various sizes and thicknesses and circulates from one organ to another. A closed circulatory system is found in all vertebrates and some invertebrates.

Christiaan Neethling Barnard (8 November 1922 - 2 September 2001) was a South African cardiac surgeon who performed the world’s first human-to-human heart transplant operation. On 3 December 1967, Barnard transplanted the heart of accident victim Denise Darvall into the chest of 54-year-old Louis Washkansky, with Washkansky regaining full consciousness and being able to talk easily with his wife, before dying eighteen days later of pneumonia, largely brought on by the anti-rejection drugs that suppressed his immune system.

The human heart is divided into four chambers: the right and left atriums, as well as the right and left ventricles. The NPPA gene in humans encodes atrial natriuretic peptide (ANP), also known as atrial natriuretic factor (ANF), a natriuretic peptide hormone secreted by the cardiac atria. The major function of ANP is to reduce the volume of extracellular fluid (ECF) via enhancing renal sodium excretion.