O RGANIZATION OF L IFE Chapter 3, Section 1 Pages Cell Heart muscle cell Tissue Heart muscle tissue Organ Heart Organ system Circulatory system Organism Human

C ELLS : S TARTING OUT S MALL Most cells are too small to be seen without a microscope You might have one of the world’s largest cells in your refrigerator (an egg)!

C ELLS : S TARTING OUT S MALL Like a chicken, you too began as a single cell.

C ELLS : S TARTING OUT S MALL Not all of your cells look or act the same. You have about 200 different kinds of cells, and each type is specialized to do a particular job.

C ELLS : S TARTING OUT S MALL Some are bone cells, some are blood cells, and others are skin cells. When someone looks at all of those cells together, they see you.

T ISSUES : C ELLS W ORKING IN T EAMS When you look closely at your clothes, you can see that threads have been grouped together to make cloth that has a function.

T ISSUES : C ELLS W ORKING IN T EAMS In the same way, cells are grouped together to make a tissue that has a function. A tissue is a group of cells that work together to perform a specific job in the body. The material around and between cells is also part of the tissue.

O RGANS : T EAMS W ORKING T OGETHER When two or more tissues work together to perform a specific job, the group of tissues is called an organ. Some examples of organs are your stomach, intestines, heart, lungs, and skin.

O RGANS : T EAMS W ORKING T OGETHER Plants also have different kinds of tissues that work together. A leaf is a plant organ that contains tissue that traps light energy to make food. Other examples of plant organs are stems and roots.

O RGAN S YSTEMS : A G REAT C OMBINATION Organs work together in groups to perform particular jobs. These groups are called organ systems. Each system has a specific job to do in the body.

O RGAN S YSTEMS : A G REAT C OMBINATION Your digestive system’s job is to break down food into very small particles so it can be used by all of your body’s cells.

O RGAN S YSTEMS : A G REAT C OMBINATION Your nervous system’s job is to transmit information back and forth between your brain and the other parts of your body.

O RGAN S YSTEMS : A G REAT C OMBINATION Organ systems in plants include leaf systems, root systems, and stem systems

O RGAN S YSTEMS : A G REAT C OMBINATION The organs in an organ system depend on each other. If any part of the system fails, the whole system is affected.

O RGAN S YSTEMS : A G REAT C OMBINATION Failure of one organ system can affect other organ systems. If your digestive system stopped converting food to energy, none of the other organ systems would have energy to function.

O RGANISMS : I NDEPENDENT L IVING Anything that can live on its own is called an organism All organisms are made up of at least one cell.

O RGANISMS : I NDEPENDENT L IVING If a single cell is living on its own, it is called a unicellular organism. Most unicellular organisms are so small that you need to use a microscope to see them.

O RGANISMS : I NDEPENDENT L IVING You are a multicellular organism. This means that you can exist only as a group of cells and that most of your cells can survive only if they remain a part of your body.

O RGANISMS : I NDEPENDENT L IVING When you fall down on a sidewalk and scrape your knee, the cells you leave behind on the sidewalk are not able to live on their own.