1.5-Human Structure

the body's structural hiearchy

The organsim is composed of organ systems, organ systems are composed of organs, organs are composed of tissues, tissues are composed of cells, cells are composed partly of organelles, organelles are composed of molecules, and molecules are composed of atoms

organ system

a group of organs with a unique collective function, such as circulation, digestion, or respiration (the body has 11 organ systems)

tissue

a mass of similar cells and cell products that forms a discrete region of an organ and preforms a specific function (types of tissue: epithelial, connective, muscular, and nervous)

organism

a single, complete individual

organ

a structure composed of two or more tissue types that work together to carry out a particular function

molecules

composes organelles and other cellular components

organelles

microscoping structures in a cell that carry out its individual functions, such as mitochondria, lysosomes, and centrioles

atoms

smallest particles with unique chemical identities; a molecule is composed of at least two atoms

holism

the complentary theory that there are 'emergancy properties' of the whole organsim that can not be predicted from the properties of its seperate parts

macromolecules

the largest molecules, such as protiens, fats, and DNA

cells

the smallest units of an organism that carry out all the basic functions of life; nothing simpler than a cell is considered alive

cytology

the study of cells

histology

the study of tissues

reductionism

the theory that a large, complex system such as the human body can be understood by studying its simpler components