<p><img src="levels-of-organization_57603a2e39313.jpg" style="float: right; margin: 10px;" id="" title="" /></p> <p><span style="font-size: 16px;">Let's take a little time to review the levels of organization in the human body. There are five levels of organization in the human body.</span></p> <ul> <li><span style="font-size: 16px; line-height: 22.4px;">Cells</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Tissues</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Organs</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Organ systems</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Organism</span></li> </ul> <p><span style="font-size: 16px; line-height: 22.4px;">Specialized cells develop from a single <span style="background-color: #ccffff;">zygote</span>. Zygote's begin by dividing into embryonic stem cells. These cells can become any type of specialized cell in the body. </span></p> <p><span style="font-size: 16px; line-height: 22.4px;"><span style="background-color: #ccffff;">Determination</span> - happens after the first few divisions, and this is when cells are committed to becoming a particular type of specialized cell. </span></p> <p><span style="font-size: 16px; line-height: 22.4px;"><span style="background-color: #ccffff;">Differentiation</span> - occurs after determination and is the process where committed cells acquire the specialized structure and functions they will need. </span></p> <p><span style="font-size: 16px; line-height: 22.4px;"><span style="background-color: #ccffff;">Specialized cells</span> function together in tissues, organs, organ systems, and the whole organism. <span style="background-color: #ccffff;">Tissues</span> are groups of similar cells working together. <span style="background-color: #ccffff;">Organs</span> are different tissues working together, and <span style="background-color: #ccffff;">organ systems</span> involve two or more organs working together. An <span style="background-color: #ccffff;">organism</span> is all organ systems working together. </span></p> <p><img src="organsystem_57603ab2b4f9f.jpg" width="354" height="263" style="float: right; margin: 10px;" id="" title="" /></p> <p><span style="font-size: 16px; line-height: 22.4px;">There are 11 major organ systems in the human body that you will be studying over the next few weeks.</span></p> <ul> <li><span style="font-size: 16px; line-height: 22.4px;">Circulatory</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Digestive</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Endocrine</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Excretory</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Immune</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Integumentary</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Muscular</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Nervous</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Reproductive</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Respiratory</span></li> <li><span style="font-size: 16px; line-height: 22.4px;">Skeletal</span></li> </ul>