(MOS) Levels of Organization Lesson

Levels of Organization Lesson

An organism is any living thing that possesses the characteristics of life. Animals, plants, fungi, and even bacteria are organisms. The cell is the basic structural and functional unit in an organism. All living things are made up of at least one or more cell. Recall that a cell contains structural units within the cytoplasm called organelles. These organelles such as the nucleus and cell membrane help keep the organism alive. Each organelle carries out a specialized function or activity such as removing waste and releasing energy. A group of similar specialized cells that perform a particular function are called a tissue.

The human body consists of four different types of tissues: nervous, muscle, connective, and epithelial tissue. Epithelial tissue is made up of tightly packed cells that can cover the inner and outer surface of the body. Skin cells are probably the most common type of epithelial tissue. They provide protection, sensory perception, and absorption for the delicate structures and organs beneath the skin. Epithelial tissue can also be found in the lining of internal organs such as the kidneys, trachea, and digestive tract. The most abundant type of tissue in your body is connective tissue. It can provide support, protection, and framework for your body. Adipose tissue can be found in various parts of the body, around the eyeballs and abdominal region. The adipose tissue provides insulation to conserve heat, store energy, and a protective cushion. Fibrous connective tissues are essential in connecting body parts with tendons or ligaments. Cartilage, bone, and blood tissue are also types of connective tissue.

Muscle tissues consist of certain types of muscle cells that are responsible for movement.

The three types of muscle tissues are skeletal, smooth, and cardiac. Nerve cells that make up nervous tissue are found in the brain, spinal cord, and nerves. Hundreds of neurons send electrical messages from various parts of your body to your brain and vice versa. Nerve tissues allow an organism to sense and respond to a stimulus which enables your body to make adjustments to its environment. Muscle contractions, sensory, memory and reasoning are processes controlled by nervous tissues.

A group of tissues that can perform a particular function is called an organ. Your stomach, lungs, kidneys, and heart are organs. Your heart is made up of cardiac tissue as well as connective and epithelial tissue. A group of organs that work together to perform a certain task such as transporting blood and oxygen make up an organ system. The circulatory system transports blood and nutrients throughout the body.

The organs that make up the circulatory system are the heart, blood vessels, arteries, and veins. The major systems that make up the human body are the respiratory, digestive, excretory, circulatory, nervous, skeletal, muscle, and reproductive systems. The combinations of the organ systems help provide protection, oxygen, and energy that are essential to the human body.

Although multicellular organisms can have hundreds of different types of specialized cells, their cells are almost always found working together in organized groups.

 

See description of diagram Links to an external site.

 

The following segment from the video Understanding Cells: Cells Working Together-Tissues and Organs explore this concept by focusing on what tissues and organs are and how they work together to form the organ systems in our body.

 

 

 

Levels of Organization Review

Now it is time to review the levels of the organization. Watch a presentation about the levels of organization in multicellular organisms and the arrangement of the necessary cellular components that make up such living things.

 

 

Complete the matching activity below to review your key terms.

 

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