The human body is a complex organism. It is made of trillions of individual cells, all working together to perform the physiological functions of a living thing. Cells represent the basic unit of structure and function within the body. Different types of cells are arranged into layers called tissues, and tissues are arranged into organs. Multiple organs work together as an organ system to perform a specific function within an organism's body. There are eleven organ systems in the human body. These organ systems carry out many physiological processes. One fundamental process is the maintenance of homeostasis, a state of equilibrium within the system.
At A Glance
- When scientists study the complexities of the human body, they analyze its structure and how its structure is related to how the body functions.
- The structure of the human body is organized into six different levels that are comprised of chemicals, cells, tissues, organs, organ systems, and the organism.
- The integumentary, skeletal, and muscular, organ systems are responsible for protecting the body and allowing it to move.
- The electrical and chemical signals of the nervous system and the chemical signals of the endocrine system send information throughout the body.
- The respiratory and digestive systems acquire resources to generate energy, while the reproductive system is required for sexual reproduction.
- The cardiovascular, lymphatic, and urinary systems move and eliminate resources throughout the body.
Homeostasis is the ability of the body to maintain a relatively stable internal environment despite changes that occur in the external environment.
- A negative feedback mechanism lessens or counteracts the original action of a stimulus on the body.
- A positive feedback mechanism amplifies a stimulus, thereby increasing the original action of stimulus on the body.