Human Body Organization

1. Human Body Organization

2. Levels of Organization in Humans • Trillions of cells in the human body are organized in levels that work together to help the body function properly • LEQ 1: In order from simplest to most complex, the levels of organization in humans are: • Cells • Tissues • Organs • Organ Systems

3. Cells • Cells are the basic unit of structure and function in living things • Each of your cells carries out the processes that keep you alive • In humans, cells are specialized for specific jobs • Examples: • Nerve cells carry information from one part of the body to another • Red blood cells carry oxygen • Bone cells help support your body

4. Cells • Although cells are specialized to carry out specific jobs, each type of cell needs other cells to do its work • Example: muscle cells can move the body only if they can get enough oxygen to release energy; they depend on red blood cells to deliver this oxygen

5. Tissues • The second level of organization in humans is the tissue • Tissue: a group of specialized cells that work together to perform a specific function

6. Types of Tissue • The human body contains four main types of tissue • Nerve tissue: carries impulses back and forth between the brain and the body • Muscle tissue: contracts and shortens, making body parts move • Three types of muscle tissue: cardiac muscle, smooth muscle, and skeletal muscle

7. Types of Tissue • Epithelial tissue: covers surfaces of the body; inside the body, epithelial tissue serves as a lining for internal organs and forms a layer of skin outside the body • Connective Tissue: connects all parts of the body and provides support • Examples: tendons, ligaments, cartlidge

8. Organs • The third level of organization in humans is organs • Organ: a group of two or more kinds of tissue that work together to perform a specific function • Example: The heart is made up of all four types of tissue; the stomach is made up of epithelial, muscle, and connective tissue

9. Organ Systems • The fourth level of organization in humans is the organ systems • Organ system: a group of two or more organs that work together to perform a specific function • There are eleven organ systems in the human body • All of the systems work together to keep you alive

10. Human Organ Systems • Circulatory System: transports oxygen, nutrients, and other materials to cells; transports wastes away from cells • Digestive: breaks down food into nutrients the body can use; disposes of solid waste • Endocrine: secretes hormones that regulate body functions • Excretory: removes waste

11. Human Organ Systems • Immune: protects against disease • Integumentary: provides a barrier between the body and the environment; prevents water loss • Muscular: moves the body; moves materials through the body • Nervous: detects and responds to changes in the environment; transmits information throughout the body

12. Human Organ Systems • Reproductive: produces offspring • Respiratory: Exchanges gases between the body and the external environment • Skeletal: Supports and moves the body; protects internal organs