Health Supplement Selection and Cardiovascular Health: An Analysis of the Functions of the Nine Major Systems in the Human Body

No one wants to be sick; everyone desires health and longs for longevity. Many people need and take health supplements because they perceive some health issues, but haven't yet reached the point of needing medical attention. Lacking guidance from doctors or professionals, they often feel lost and unsure how to choose when purchasing health supplements, leading to hearsay, blind faith, and even being scammed. If consumers possess some basic knowledge of life sciences and medical health, they can rely on themselves rather than others. Faced with a dazzling array of health supplements, they can make targeted choices based on their health needs, rationally discern quality, and take control of their own health.

Currently, a large proportion of health supplement consumers suffer from the "three highs"—hypertension, hyperglycemia, and hyperlipidemia. Therefore, this chapter will focus on the cardiovascular system, introducing the composition and function of the major systems in a healthy body, and how they coordinate to regulate blood pressure, blood sugar, and blood lipids to maintain normal health levels.

I. The Nine Major Systems of the Human Body

The human body has nine major systems: the musculoskeletal system, digestive system, respiratory system, urinary system, reproductive system, endocrine system, immune system, nervous system, and circulatory system. Each system is composed of related organs that work together to perform a series of specific physiological functions.

The musculoskeletal system consists of bones, joints, and skeletal muscles. Skeletal muscles are attached to bones and contract and relax under the control of the nervous system. When skeletal muscles contract, they pull on the bones using joints as fulcrums, changing their position, thus enabling us to perform daily exercise or labor. The digestive system is responsible for the ingestion, digestion, and absorption of food, including the entire digestive tract from the mouth, esophagus, stomach, intestines to the anus, and the large and small digestive glands inside and outside the digestive tract. The respiratory system is responsible for gas exchange between the body and the external environment,

including the nose, pharynx, larynx, trachea, and lungs. The urinary system, composed of the kidneys, ureters, bladder, and urethra, primarily functions to excrete metabolic waste and excess fluid, maintaining the body's internal environment balance and stability. The reproductive system's function is to reproduce and form and maintain secondary sexual characteristics. The endocrine system includes the thyroid gland, parathyroid glands, adrenal glands, pituitary gland, pineal gland, pancreas, thymus, and gonads. Their functions include transmitting information, working with the nervous system to regulate growth, development, and various metabolic processes, maintaining internal environment stability, influencing behavior, and controlling reproduction. The immune system is the body's most important defense system against pathogens and various toxic and harmful substances, composed of the bone marrow, thymus, spleen, lymph nodes, and tonsils. The nervous system, including the brain, spinal cord, and peripheral nerves, is responsible for controlling and regulating the activities of other systems, maintaining harmony between the body and the external environment.

The circulatory system (also known as the cardiovascular system) is the vital center of the nine major systems; it is a closed and intricate system of tubes composed of the heart and blood vessels. The heart is the engine of the system, providing power, while blood vessels are the conduits through which blood is transported. Through the rhythmic contraction and relaxation of the heart, blood is propelled to circulate continuously in the blood vessels in a specific direction; this is called blood circulation. It transports nutrients absorbed from the digestive tract and oxygen inhaled from the lungs to various tissues and organs, and carries metabolic waste products into the bloodstream via the same pathway, excreting them through the lungs and kidneys. It also transports heat to all parts of the body to maintain body temperature and delivers hormones to target organs to regulate their function. Blood circulation is one of the most important functions for human survival. Because of blood circulation, all the functions of blood can be realized, and the blood volume can be adjusted and distributed to meet the needs of active organs and tissues, thus ensuring the relative homeostasis of the internal environment and the normal functioning of metabolism. Once blood circulation stops, life activities cannot proceed normally, ultimately leading to death.