Levels of Organization

The Body’s Organization  The human body is organized into different levels of organization: from the smallest unit, the cell, to the largest unit, the organ system.  These organization levels consist of cells, tissues, organs, and organ systems.  The human body is organized into different levels of organization: from the smallest unit, the cell, to the largest unit, the organ system.  These organization levels consist of cells, tissues, organs, and organ systems.

The Body’s Organization (cont.)  In other words, we begin with cells, cells are organized into tissues (like muscle or nerve tissue), several tissues are organized into organs (like the heart or lungs), and organs are organized into organ systems like the digestive system which consists of several organs like the stomach, intestines, liver, and gall bladder.

Cells Are the basic unit of structure and function in a living thing. Are the basic unit of structure and function in a living thing.

TissuesTissues  Are a group of similar cells that perform the same function.  *The body contains four types of tissue: muscle, nerve, connective (bone, fat), and epithelial (ex. Skin).  Are a group of similar cells that perform the same function.  *The body contains four types of tissue: muscle, nerve, connective (bone, fat), and epithelial (ex. Skin).

Organs Organs Are structures composed of different kinds of tissue and they perform a specific job like the heart pumps blood.Are structures composed of different kinds of tissue and they perform a specific job like the heart pumps blood.

Organ Systems Are a group of organs that work together to perform a major function. For example, the organs in the respiratory system function together, allowing us to breathe.Are a group of organs that work together to perform a major function. For example, the organs in the respiratory system function together, allowing us to breathe. *Organ systems work together to help maintain homeostasis.*Organ systems work together to help maintain homeostasis. Are a group of organs that work together to perform a major function. For example, the organs in the respiratory system function together, allowing us to breathe.Are a group of organs that work together to perform a major function. For example, the organs in the respiratory system function together, allowing us to breathe. *Organ systems work together to help maintain homeostasis.*Organ systems work together to help maintain homeostasis.

Organ Systems