Anatomically, breathing is facilitated by the respiratory system, which includes the lungs, airways, and muscles involved in the process. When we inhale, the diaphragm, a dome-shaped muscle below the lungs, contracts and flattens, while the external intercostal muscles between the ribs contract, causing the rib cage to expand. This action creates negative pressure in the thoracic cavity, allowing air to rush into the lungs through the trachea and bronchial tubes. During exhalation, the diaphragm and intercostal muscles relax, reducing the volume of the thoracic cavity. This causes the lungs to compress, expelling carbon dioxide from the alveoli, up the airways, and out through the nose or mouth. This rhythmic process of inhalation and exhalation continues automatically, controlled by the respiratory center in the brainstem, ensuring a constant supply of oxygen for cellular functions and the removal of waste carbon dioxide from the body.

Oxygen from the air enters our body and oxygenates our tissues through a process called respiration. When we inhale, air enters the body through the nose or mouth, passing through the trachea and into the lungs. Within the lungs, the air reaches millions of tiny air sacs called alveoli, where gas exchange occurs. Oxygen in the alveoli diffuses across the thin walls of the alveoli and capillaries into the bloodstream, which is then pumped by the heart to various parts of the body through arteries. Cells utilize oxygen for cellular respiration, a process that produces energy for essential functions. Simultaneously, the cells release carbon dioxide, which diffuses into the capillaries and binds to hemoglobin to be transported back to the lungs. In the lungs, the carbon dioxide is released from the hemoglobin and exhaled during exhalation. This continuous process of gas exchange ensures that our body tissues receive a constant supply of oxygen, vital for sustaining life and enabling cellular functions. 

The heart, a vital organ in the circulatory system, works as a powerful pump to deliver oxygen and nutrients throughout the body. Anatomically, it is a muscular organ located in the chest cavity, slightly tilted to the left. It consists of four chambers: two atria and two ventricles, separated by valves. Deoxygenated blood returns to the right atrium through the superior and inferior vena cava. When the right atrium contracts, blood flows through the tricuspid valve into the right ventricle. The right ventricle then contracts, pushing the deoxygenated blood into the pulmonary artery, which transports it to the lungs for oxygenation. Oxygenated blood returns to the left atrium via the pulmonary veins. As the left atrium contracts, blood flows through the bicuspid (mitral) valve into the left ventricle. The left ventricle contracts, pumping the oxygen-rich blood through the aortic valve into the aorta, the main artery, for distribution throughout the body. This rhythmic cycle of contractions and relaxations, coordinated by the heart's electrical system, sustains the continuous circulation of blood, supplying oxygen and nutrients to body tissues and organs while removing waste products.

High blood pressure, or hypertension, strains the heart by making it work harder to pump blood against increased resistance in the blood vessels. This can lead to left ventricular hypertrophy, reducing the heart's efficiency and oxygen delivery to tissues. Hypertension also promotes arterial damage and atherosclerosis, narrowing blood vessels and increasing the risk of heart attacks and strokes. Managing blood pressure is crucial to preserve heart health and prevent cardiovascular complications.