2 Division of Labor & The First Level Within multi-cellular organisms there is division of labor. Division of labor means that the work (labor) of keeping the organism alive is divided (division) among the different parts of the body. Each part has a job to do and as each part does its special job, it works in harmony with all the other parts.The arrangement of specialized parts within a living thing is sometimes referred to as levels of organization. Cells of course, are the first level of organization.
3 Cells: LOTS of Different Kinds. Here are two examples Cells: LOTS of Different Kinds! Here are two examples. Can you guess what kind?Muscle CellsSkin Cells
5 Second Level: Tissues Tissues are the second level of organization. In any multi-cellular organism, cells rarely work alone. Cells that are similar in structure and function are usually joined together to form tissues.Tissues are the second level of organization.There are four basic/major types of tissues in the human body: Muscle tissue, nerve tissue, connective tissue, and epithelial tissue
6 Let’s Look Again…Here are the cells we saw before, but you can see that, in each type, they look similar. Muscle cells working together make muscle tissue, and skin cells make up a special type of epithelial tissue.
7 Taken One At A Time….Connective tissue connects and supports parts of the body. Blood, fat, ligaments, cartilage, bones, and tendons are all connective tissues.Nerve tissue carries messages back and forth between the brain and every other part of the body. The brain, spinal cord, and nerves are made up of nerve tissue.Epithelial tissue covers and lines the surfaces of your body and organs, inside and out. They primarily serve as protective barriers. Skin is one example.Muscle tissue can contract, or shorten. Because of this, muscle tissue makes parts of your body move.
8 Level Three: Organs When a bunch of different types of tissues work together, they form an ORGAN. There are many organs in the body. How many can you name??
9 Level Four: Organ Systems Each organ in your body is part of an organ system, a group of organs that work together to perform a major function.For example, your heart is part of your circulatory system, which carries oxygen and other materials throughout your body. Besides the heart, blood vessels are organs that work in your circulatory system.
10 The nervous system detects and interprets information from the environment outside the body and from within the body; controls most body functions.The immune system fights disease.The excretory system removes wastes.The endocrine system controls many body processes by means of chemicals, like hormones.
11 The muscular system enables the body to move; moves food through the digestive system, and keeps the heart beating.The skeletal system supports and protects the body, and works with the muscular system to allow movement; makes and stores blood cells and stores some other materials.
12 The digestive system takes food into the body, breaks the food down into smaller particles, and absorbs the digested materials.The respiratory system takes oxygen into the body and eliminates carbon dioxide.The reproductive system produces sex cells that can unite with other sex cells to create offspring; controls male and female characteristics.
13 Let’s Review…. 1st Level: Cells working together form 2nd Level: Tissues, which can form3rd Level: Organs, which work together to form4th Level: Organ Systems, which work together to form5th Level: Organisms!