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  2. Respiration (physiology) - Wikipedia

    en.wikipedia.org/wiki/Respiration_(physiology)

    In physiology, respiration is the transport of oxygen from the outside environment to the cells within tissues, and the removal of carbon dioxide in the opposite direction to the environment by a respiratory system. [1]

  3. Biological roles of the elements - Wikipedia

    en.wikipedia.org/wiki/Biological_roles_of_the...

    A large fraction of the chemical elements that occur naturally on the Earth's surface are essential to the structure and metabolism of living things. Four of these elements (hydrogen, carbon, nitrogen, and oxygen) are essential to every living thing and collectively make up 99% of the mass of protoplasm. [1]

  4. Breathing - Wikipedia

    en.wikipedia.org/wiki/Breathing

    Real-time magnetic resonance imaging of the human thorax during breathing X-ray video of a female American alligator while breathing. Breathing (spiration [1] or ventilation) is the rhythmical process of moving air into and out of the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring in oxygen.

  5. Cardiorespiratory fitness - Wikipedia

    en.wikipedia.org/wiki/Cardiorespiratory_fitness

    Cardiorespiratory fitness can be increased by means of regular physical activity and exercise. The medical community agrees that regular physical activity plays an important role in reducing risk of cardiovascular disease, stroke, hypertension, diabetes, and a variety of other morbid conditions.

  6. Oxygen - Wikipedia

    en.wikipedia.org/wiki/Oxygen

    Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium. [68] About 0.9% of the Sun's mass is oxygen. [19] Oxygen constitutes 49.2% of the Earth's crust by mass [69] as part of oxide compounds such as silicon dioxide and is the most abundant element by mass in the Earth's crust.

  7. List of systems of the human body - Wikipedia

    en.wikipedia.org/wiki/List_of_systems_of_the...

    This is an accepted version of this page This is the latest accepted revision, reviewed on 31 January 2025. List of organ systems in the human body Part of a series of lists about Human anatomy General Features Regions Variations Movements Systems Structures Arteries Bones Eponymous Foramina Glands endocrine exocrine Lymphatic vessels Nerves Organs Systems Veins Muscles Abductors Adductors ...

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    Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!

  9. Breathing gas - Wikipedia

    en.wikipedia.org/wiki/Breathing_gas

    A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas. Other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed habitats such as scuba equipment, surface supplied diving equipment, recompression chambers, high-altitude mountaineering, high-flying aircraft, submarines ...