1. From Cells to Body Systems Human Biology 11

2. Understanding Cells Cells are the building blocks of life There are trillions of cells in the human body Our body cells are specialized, which means that each type of cell has a different function Each cell contains organelles which allow the cell to work properly If the organelles do not work properly, the cell will die

3. Cells Build Tissues Tissues are groups of specialized cells that work together to perform a certain task There are 4 different types of tissues that are found in the human body: –Epithelial –Connective –Nerve –Muscle

4. Epithelial Tissue This tissue forms a film-like covering Its purpose is to cover the surfaces of many different organs in the body

5. Connective Tissue This is the most common type of tissue This separates and supports other cells and tissues It can also act as a site of attachment for cells and other tissues Collagen is the main protein in connective tissue

7. Nerve Tissue This tissue is responsible for sending messages to the brain and throughout the entire body

8. Muscle Tissue This tissue is able to contract and expand Its purpose is to allow movement

9. Tissues Build Organs Organs are groups of specialized tissues that perform certain tasks Each body organ has a specific shape and is made up of different types of tissues to perform a certain job The heart, as an example, is mostly muscle tissue – WHY? The heart also contains nerve tissue and is covered in epithelial tissue (pericardium)

10. Organs in the Human Body

11. Organs Build Systems Body systems are groups of specialized organs that perform a specific function Some organs belong to more than one particular body system

12. Organization of the Human Body CELLS TISSUES ORGANS BODY SYSTEMS