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  2. Composition of the human body - Wikipedia

    en.wikipedia.org/wiki/Composition_of_the_human_body

    Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...

  3. Axoplasm - Wikipedia

    en.wikipedia.org/wiki/Axoplasm

    Axoplasm is the cytoplasm within the axon of a neuron (nerve cell). For some neuronal types this can be more than 99% of the total cytoplasm. [1]Axoplasm has a different composition of organelles and other materials than that found in the neuron's cell body or dendrites.

  4. Calcium metabolism - Wikipedia

    en.wikipedia.org/wiki/Calcium_metabolism

    Calcium regulation in the human body. [6]The plasma ionized calcium concentration is regulated within narrow limits (1.3–1.5 mmol/L). This is achieved by both the parafollicular cells of the thyroid gland, and the parathyroid glands constantly sensing (i.e. measuring) the concentration of calcium ions in the blood flowing through them.

  5. Calcium in biology - Wikipedia

    en.wikipedia.org/wiki/Calcium_in_biology

    Calcium regulation in the human body [38] Different tissues contain calcium in different concentrations. For instance, Ca 2+ (mostly calcium phosphate and some calcium sulfate) is the most important (and specific) element of bone and calcified cartilage. In humans, the total body content of calcium is present mostly in the form of bone mineral ...

  6. 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]

  7. Metabolism - Wikipedia

    en.wikipedia.org/wiki/Metabolism

    Metabolism (/ m ə ˈ t æ b ə l ɪ z ə m /, from Greek: μεταβολή metabolē, "change") is the set of life-sustaining chemical reactions in organisms.The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the conversion of food to building blocks of proteins, lipids, nucleic acids, and some carbohydrates; and the ...

  8. Blood - Wikipedia

    en.wikipedia.org/wiki/Blood

    The average adult has a blood volume of roughly 5 litres (11 US pt) or 1.3 gallons, [10] which is composed of plasma and formed elements. The formed elements are the two types of blood cell or corpuscle – the red blood cells, (erythrocytes) and white blood cells (leukocytes), and the cell fragments called platelets [12] that are involved in ...

  9. Red blood cell - Wikipedia

    en.wikipedia.org/wiki/Red_blood_cell

    Red blood cells (RBCs), referred to as erythrocytes (from Ancient Greek erythros 'red' and kytos 'hollow vessel', with -cyte translated as 'cell' in modern usage) in academia and medical publishing, also known as red cells, [1] erythroid cells, and rarely haematids, are the most common type of blood cell and the vertebrate's principal means of delivering oxygen (O 2) to the body tissues—via ...