1. Levels of Organization
The Human Body

2. Levels of Organization in the Human Body
There is more to the human body than individual cells
Scientists organize multicellular structures into five basic levels, beginning with the smallest unit and ending with the largest
Cells
Tissues
Organs
Organ Systems
Organism

3. Cells
Remember… A cell is the basic unit of structure and function in a living thing
Cells perform the basic processes that keep organisms alive
Each type of specialized cell has a particular structure and chemical makeup that enable it to perform a specific task

4. Tissues
A tissue is a group of similar cells that perform the same function
The human body contains four basic types of tissue:
Muscle tissue
Nerve tissue
Connective tissue
Epithelial tissue

5. Tissues Muscle tissue can contract (shorten) to produce movement
This tissue is what makes parts of your body move
Nerve tissue carries impulses (messages) back and forth between the brain and every other part of your body
It also processes information and regulates the body’s response to its environment

6. Tissues
Connective tissue serves to support, bind together, and protect other tissues & organs
Bone, fat, tendons, ligaments, and cartilage are all connective tissue
Epithelial tissue consists of protective sheets of tightly packed cells connected by special junctions
The skin and the lining of stomach and lungs are epithelial tissues

7. Organs
An organ is a structure that is made up of different kinds of tissue that work together
An organ’s job is usually more complex than that of a tissue
For example, the lungs are organs composed of all four types of tissues
Muscle & connective tissue expand and contract the lungs
Nervous tissue sends messages to tell the tissues when to expand and contract
Epithelial tissue forms the inner lining of the lungs

8. Organ Systems Two or more organs working together form an organ system
The different organ systems all work together and depend on each other
For example, when you ride a bike…
Muscular and skeletal systems steer and push the pedals
Nervous system directs your arms and legs
Respiratory, digestive, and circulatory systems work together to fuel your muscles

9. Organism Together, all of the organ systems make up an entire organism
For you, or any other organism, to stay alive, all of the systems must interact and work together
As a result, anything that harms one organ or organ system will affect the health of the entire body