Notmanyfeedbackmechanismsinthebodyarebasedonpositivefeedback. Positivefeedback
speeds up the direction of change, which leads to increasing hormone concentration, a state
that moves further away from homeostasis.
Lesson Summary
- The levels of organization in the human body include: cells, tissues, organs, and organ
systems. A tissue is a group of cells that work together. An organ is made of two or
more tissues that work together. Organs that work together make up organ systems. - There are four tissue types in the body: epithelial tissue, connective tissue, muscle
tissue, and nervous tissue. There are 12 major organ systems in the body. Organs and
organ systems work together to maintain homeostasis.
Review Questions
- What is homeostasis?
- What are the four levels of organization in an organism?
- What is the difference between a tissue and an organ?
- List the four types of tissues that make up the human body.
- A classmate says that all four tissue types are never found together in an organ.
- Why do you think an organ is able to do many more jobs than a single tissue can?
- Identify the organ system to which the following organs belong: skin, stomach, brain,
lungs, and heart. - Give an example of how two organ systems work together to maintain homeostasis.
Further Reading / Supplemental Links
Vocabulary
cardiovascular system Thebodysystemthatincludetheheart, blood, andbloodvessels.
connective tissue Tissue that is made up of different types of cells that are involved in
structure and support of the body; includes blood, bone, and cartilage.
epithelial tissue A tissue that is composed of layers of tightly packed cells that line the
surfaces of the body; examples of epithelial tissue include the skin, the lining of the
mouth and nose, and the lining of the digestive system.