It comprises living cells and extracellular materials, organized into tissues, organs, and systems.
It is primarily composed of water and organic compounds, lipids, proteins, carbohydrates, and nucleic acids.
Water, making up about 60% (varies by age) of body weight, is crucial for life's chemical processes, found in both extracellular fluids and within cells, serving as a vital solvent.
The skin and related structures form the integumentary system, safeguarding the body from harmful invaders and chemicals while also preventing water loss.
Comprising skeletal muscles and bones (about 206 in adults), the musculoskeletal system facilitates body movement and shields internal organs.
Incorporating breathing passages, lungs, and respiratory muscles, the respiratory system acquires vital oxygen from the air for cellular metabolism and expels waste carbon dioxide.
The circulatory system, comprising the heart, blood, and vessels, circulates fluid throughout the body, furnishing cells with oxygen and nutrients while removing waste like carbon dioxide and toxic compounds.
The digestive system comprises the mouth, esophagus, stomach, and intestines, breaks down food into usable nutrients, absorbing them into the bloodstream, and eliminates the remaining waste as feces.
Consisting of kidneys, ureters, bladder, and urethra, the excretory system filters toxins and waste from the blood for elimination.
The nervous system formed by sensory organs, brain, spinal cord, and nerves transmits sensory data, integrates it, and triggers appropriate muscular or glandular responses.
Composed of hormone-secreting glands and tissues, the endocrine system coordinates body processes via a chemical communication network.
The reproductive system, encompassing male or female sex organs, plays a crucial role in facilitating reproduction.
In males, this system includes structures such as the testes, which produce sperm, and in females, it comprises the ovaries, which produce eggs.
