All living and non-living things room made that one or more unique substances referred to as elements, the smallest unit of which is the atom, (for example, the facet oxygen (O) is do of O atoms, carbon (C) is make of C atoms and hydrogen (H) is do of H atoms. Atoms combine to form molecules. Molecules deserve to be little (for example, O2, oxygen gas, which has actually 2 atoms of the element O; CO2, carbon dioxide, which has actually 1 atom of C and 2 of O), civicpride-kusatsu.netium (for example, C6H12O6, glucose, which has 6 atom of C, 12 of H, and also 6 that O); or large (for example molecules called proteins are made of thousands of atoms the C, H, and also O with other elements such as nitrogen (N). Molecules room the building blocks come all frameworks in the human body.
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All living structures are made of cells, which space made of many different molecules. Cells space the smallest independent living point in the person body. The human body is made of many different cabinet types, each v a specific function, (for example muscle cells contract to relocate something, and also red blood cells carry oxygen). All human cells space made of a cabinet membrane (thin outer layer) the encloses a jelly-like cellular fluid containing small organ-likestructures dubbed organelles. There are many varieties of organelles, each through a particular duty (for example, organelles dubbed mitochondrion provides energy to a cell). Different types of cell contain different amounts and species of organelles, depending upon their function, (for instance muscle cells use a many energy and therefore have plenty of mitochondria while skin cells execute not and also have few mitochondria).
As in various other multicellular organisms, cells in the human body space organized right into tissues. A tissue is a team of similar cells that work-related together to perform a details function. There are 4 main tissue species in people (muscular, epithelial, nervous and connective). An organ is one identifiable framework of the body composed of 2 or more tissues varieties (for example, the stomach consists of muscular tissue make of muscle cells, which permits it to readjust its shape, epithelial tissue which lines both the inner and also outer surface of thestomach, nervous tissue which sends and also receives signals to and from the stomach and also the main nervous system, and connective tissue which binds whatever together). Organs regularly perform a details physiological function (for example, the stomach helps digest food). An organ system is a group of organs that work-related together to do a specific function (for example, the stomach, tiny and huge intestines space all organs of the digestive system, that job-related together come digest foodstuff, move nutrients into the blood and get rid the waste). The most complex level of organization, the human being organism is created of numerous organ systems that occupational together to carry out the functions of anindependent individual.
The significant levels of organization in the body, from the easiest to the most facility are: atoms, molecules, organelles, cells, tissues, organs, body organ systems, and the human organism. See below Figure \(\PageIndex1\) .
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Figure \(\PageIndex1\) hierarchical levels of organization of the person body native the smallest chemical level come the biggest organismal level. Read the description, and also examples for each level in the pyramid: chemistry level, moving level, tissue level, organ level, Organ mechanism level, and Organismal level.