Human Anatomy & Physiology (9th Edition)

Published by Pearson
ISBN 10: 0321743261
ISBN 13: 978-0-32174-326-8

Chapter 1 - The Human Body: An Orientation - Review Questions - Page 21: 1


The six levels of structural organization of the human body are chemical, cellular, tissue, organ, organ system, and organismal levels.

Work Step by Step

The Six Levels of Structural organization: Level 1: Chemical. This is the level of the operation of atoms and molecules .Atoms are the smallest units of matter. At this level atoms combine to form molecules ; in turn. molecules can combine to form organelles. Level 2: Cellular (cells) .Organelles like plasma membrane, nucleus, ribosome, endosplasmic reticulum, and golgi body combine to form cells.. Cells are the smallest units that can carry out all the essential functions of life Level 3: Tissue(s) A tissue is a group of similar cells that work together to carry out special functions. The major human tissues are epithelium, connective tissue, muscular tissue, and nervous tissue. Major functions of tissues: Epithelium covers and lines surfaces. Connective tissue supports and protects softer tissues. Muscular tissue effects movement. Nervous tissue is responsible for internal communication and environmental awareness. Level 4: Organ(s). An organ is a complex structure that comprises at two or more tissues. Organs are dedicated to carrying out specific functions . Examples are heart( pumps blood around circulatory system) ; kidneys ( remove and excrete wastes from the blood) ; brain (responsible for consciousness and coordination of body's activities) ; small intestine (absorption of digested nutrients). Level 5: Organ System : The organ system comes next in the hierarchy. An organ system is a group of organs that work together for a common physiological purpose. The main organ systems of the human body are integumentary, muscular, nervous, (skin) cardiovascular, skeletal, endocrine, lymphatic, reproductive, and digestive system. Categories of immunological system, and urinary system are sometime used in the healthcare professions to complete this listing. Level 6: Organismal. This is the level of the total organism. It comprises all the structures that make up a human body. At this level all structures work together to maintain life and reproduce.
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