Grade 8 Science: Cells, Tissues, Organs & Systems

Characteristics of Systems

• Made up of individual parts that work together as a whole
• Often connected to one or more systems
• If one part of a system is missing or damaged, the system will not function well or may not function at all

Levels of Organization

• Cells
• Tissues
• Organs
• Organ Systems
• Organisms

Tissues

• Groups of similar cells
• Found in all multicellular organisms
• Examples: Muscle tissue, nerve tissue, epithelial tissue, etc.

Organs

• Groups of tissues
• Made up of two or more types of tissues
• Distinct structures that perform specific functions
• Examples: Lungs, kidneys, heart, etc.

Organ Systems

• A group of organs that perform activities that help the body as a whole
• Examples:

Digestive System

• Consists of: Mouth, Esophagus, Stomach, Small Intestine, Large Intestine, Liver, Gall Bladder, Pancreas
• Function: To take in and break down food, absorb nutrients, and eliminate solid waste

Circulatory System

• Consists of: Heart, Arteries, Veins, Capillaries
• Function: To transport blood, nutrients, gases, and wastes

Nervous System

• Consists of: Brain, Spinal cord, Nerves, Sense organs
• Function: To detect changes in the environment and to signal these changes to the body which then carries out a response

Respiratory System

• Consists of: Nasal cavity, Trachea, Lungs
• Function: To control breathing, and exchange gases in lungs and tissues

Excretory System

• Consists of: Lungs, Kidneys, Urinary bladder
• Function: To remove liquid and gas wastes from the body

Muscular System

• Consists of: Muscle tissue connected to bones throughout the body
• Function: Not specified in the text