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  2. Respiratory system - Wikipedia

    en.wikipedia.org/wiki/Respiratory_system

    The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies greatly, depending on the size of the organism, the environment in which it lives and its evolutionary ...

  3. Human body - Wikipedia

    en.wikipedia.org/wiki/Human_body

    The human body is composed of elements including hydrogen, oxygen, carbon, calcium and phosphorus. These elements reside in trillions of cells and non-cellular components of the body. The adult male body is about 60% total body water content of some 42 litres (9.2 imp gal; 11 US gal).

  4. Human digestive system - Wikipedia

    en.wikipedia.org/wiki/Human_digestive_system

    The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body. The process of digestion has three ...

  5. Anatomy - Wikipedia

    en.wikipedia.org/wiki/Anatomy

    Anatomy (from Ancient Greek ἀνατομή (anatomḗ) ' dissection ') is the branch of morphology concerned with the study of the internal structure of organisms and their parts. [1] Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its beginnings in prehistoric ...

  6. Cell (biology) - Wikipedia

    en.wikipedia.org/wiki/Cell_(biology)

    The cell is the basic structural and functional unit of all forms of life. Every cell consists of cytoplasm enclosed within a membrane; many cells contain organelles, each with a specific function. The term comes from the Latin word cellula meaning 'small room'. Most cells are only visible under a microscope.

  7. Nervous system - Wikipedia

    en.wikipedia.org/wiki/Nervous_system

    Anatomical terminology. [edit on Wikidata] In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine ...

  8. Organelle - Wikipedia

    en.wikipedia.org/wiki/Organelle

    Organelle. In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name organelle comes from the idea that these structures are parts of cells, as organs are to the body, hence organelle, the suffix -elle being a diminutive. Organelles are either separately enclosed within their own lipid ...

  9. Organ system - Wikipedia

    en.wikipedia.org/wiki/Organ_system

    There are 11 distinct organ systems in human beings, [2] which form the basis of human anatomy and physiology. The 11 organ systems: the respiratory system, digestive and excretory system, circulatory system, urinary system, integumentary system, skeletal system, muscular system, endocrine system, lymphatic system, nervous system, and ...