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  2. Human muscle system | Functions, Diagram, & Facts | Britannica

    www.britannica.com/science/human-muscle-system

    Human muscle system, the muscles of the human body that work the skeletal system, that are under voluntary control, and that are concerned with movement, posture, and balance. Broadly considered, human muscle—like the muscles of all vertebrates—is often divided into striated muscle, smooth muscle, and cardiac muscle.

  3. Chemically, the human body consists mainly of water and of organic compounds —i.e., lipids, proteins, carbohydrates, and nucleic acids. Water is found in the extracellular fluids of the body (the blood plasma, the lymph, and the interstitial fluid) and within the cells themselves. It serves as a solvent without which the chemistry of life ...

  4. human skeleton, the internal skeleton that serves as a framework for the body. This framework consists of many individual bones and cartilages. There also are bands of fibrous connective tissue —the ligaments and the tendons —in intimate relationship with the parts of the skeleton. This article is concerned primarily with the gross ...

  5. The heart consists of several layers of a tough muscular wall, the myocardium. A thin layer of tissue, the pericardium, covers the outside, and another layer, the endocardium, lines the inside. The heart cavity is divided down the middle into a right and a left heart, which in turn are subdivided into two chambers.

  6. Human eye, specialized sense organ in humans that is capable of receiving visual images, which are relayed to the brain. The anatomy of the eye includes auxiliary structures, such as the bony eye socket and extraocular muscles, as well as the structures of the eye itself, such as the lens and the retina.

  7. Human reproductive system | Definition, Diagram & Facts |...

    www.britannica.com/science/human-reproductive-system

    gamete. viviparity. fertility. human reproductive system, organ system by which humans reproduce and bear live offspring. Provided all organs are present, normally constructed, and functioning properly, the essential features of human reproduction are (1) liberation of an ovum, or egg, at a specific time in the reproductive cycle, (2) internal ...

  8. thoracic vertebra. rib cage, in vertebrate anatomy, basketlike skeletal structure that forms the chest, or thorax, and is made up of the ribs and their corresponding attachments to the sternum (breastbone) and the vertebral column. The rib cage surrounds the lungs and the heart, serving as an important means of bony protection for these vital ...

  9. Human ear, organ of hearing and equilibrium that detects and analyzes sound by transduction and maintains the sense of balance. Anatomically, the ear has three distinguishable parts: the outer, middle, and inner ear. Learn about the anatomy and physiology of the human ear in this article.

  10. human anatomy - Students | Britannica Kids | Homework Help

    kids.britannica.com/students/article/human-anatomy/272852

    To understand the human body it is necessary to know the structure of its parts, what they do, and how they work together. Anatomy is the scientific study of the structure of living things. The study of how the structures function is known as physiology. A major subdivision of anatomy is human anatomy, which focuses on structures of the human body.

  11. pelvis, in human anatomy, basin-shaped complex of bones that connects the trunk and the legs, supports and balances the trunk, and contains and supports the intestines, the urinary bladder, and the internal sex organs.The pelvis consists of paired hipbones, connected in front at the pubic symphysis and behind by the sacrum; each is made up of three bones—the blade-shaped ilium, above and to ...