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First look at the systems

Even though each organ has its own specific function, the human body is made up of several systems, where organs work together as a unit to perform certain tasks, and ensure the body keeps functioning. There are eleven major organ systems overall, each of which plays a different role.

Integumentary, Muscular and Skeletal Systems

The integumentary system provides the body protection from the environment. It waterproofs, cushions and shields the underlying deeper tissues. Moreover, it excretes wastes, regulates temperature, and serves as an anchor for sensory receptors.  It consists of skin, hair, exocrine glands, subcutaneous fat and nails.

The muscular and skeletal systems provide locomotion, structural support and internal organ protection. The muscular system includes all skeletal muscles, while the cardiac and smooth muscles are excluded, but are involved in other organ systems. The skeletal system on the other hand, is composed of bones, cartilage, ligaments and tendons.

Nervous, Cardiovascular and Lymphatic Systems

The nervous system is responsible for the coordination of voluntary and involuntary actions and processing information from both external and internal stimuli. It consists of two parts, the central nervous system (CNS) formed by the brain and spinal cord, and the peripheral nervous system (PNS) formed mainly of nerves that connect the CNS to all body parts.

The cardiovascular system circulates blood around the body, delivering oxygen, nutrients and other vital substances to every cell and tissue, and carrying the waste products away. Its essential components are blood, heart, and blood vessels.

The lymphatic system maintains the balance of fluid in the blood versus the tissues. Lymph is formed from the leakage of clear fluid from the blood vessels into the surrounding tissues. The lymphatic system makes sure that the lymph returns to the heart. Lymph also carries lymphocytes and white blood cells, which makes it a vital part of the immune system. In addition, it also facilitates the absorption of fats and fat-soluble nutrients from the digestive system. The lymphatic system consists of a network of lymphatic vessels, lymph nodes, and lymph organs (spleen, thymus, and bone marrow).

Respiratory, Endocrine, Digestive, Urinary and Reproductive Systems

The respiratory system is the principle site for gas exchange between the external environment and the circulatory system in the body. Oxygen is absorbed into the bloodstream while carbon dioxide and gaseous metabolic wastes are removed from the circulation. As a result, the acid-base balance is maintained as part of homeostasis. The respiratory system is also involved in vocalization, and has other metabolic and immune functions. It consists of the nose, sinuses, pharynx, larynx, trachea, bronchi, bronchioles, lungs and diaphragm.

The endocrine system provides chemical communications within the body via hormones secreted by various glands. These hormones regulate growth, metabolism, and sexual development and function. The major glands of the endocrine system are the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus, and adrenal glands. This system is regulated through feedback control.

The digestive or alimentary system is involved in mechanical and chemical processes that involve the breaking down of food and providing of nutrients for the body. It also excretes wastes from the body. The digestive system includes the mouth, pharynx, esophagus, stomach, small and large intestine, as well as the accessory organs of digestion.

The urinary or renal system has various functions. It removes waste products, controls blood volume, maintains blood pressure, and regulates blood pH and electrolyte balance. The kidneys, ureters, bladder and urethra are all parts of the urinary system.

The reproductive or genital system’s purpose is sexual reproduction. It allows the combination of genetic material between two individual in order for the possibility of an offspring. This system is comprised of both primary sex organs that produce gametes (testes and ovaries) and secondary sex organs, which are also essential for reproduction (ducts, glands, penis, and uterine tube, uterus, vagina)

Although each system is an entity of its own, the functions of the body’s organ systems overlap. So the body cannot properly function without the cooperation of all systems. In some cases, the failure of one could lead to severe disability or death.

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