Chapter 14: Bones, Muscles and Skin Section 1: Body Organization and Homeostasis p. 468 – p.473

Body Organization How the body systems work together to keep you alive

Levels of Organization in the Body The levels of organization in the human body consist of: – Cells – the basic unit of structure and function in living things – Tissues – a group of similar cells that work together to perform the same function – Organ – A structure in the body that processes materials necessary for the body to survive – Organ system – A group of organs that work together to perform a major function in the body – Organism – A complete, living thing

homeostasis Our internal environment stays the same in spite of changes on the outside Keeping things in balance

Homeostasis The maintenance of stable internal condition in an organism even when the outside environment changes Like body temperature Sugar Iron Calcium

Cell The basic unit of structure and function in a living things. A human being contains 100 trillion cells.

Cell Membrane The cell membrane forms the outside boundary of the cell. It is picky about what it allows into and out of the cell. One could say, “It is selectively permeable.”

Nucleus It is the control center of the cell. It directs all the cell’s activities. It contains the information that determines the cell’s form and function.

Cytoplasm The material within the cell apart from the nucleus. The clear, jellylike substance containing the cell’s structures and organelles.

Tissue A group of similar cells that perform the same function. The human body contains four basic types of tissue: – Muscle Tissue – Nervous Tissue – Connective Tissue – Epithelial Tissue

Muscle Tissue Muscle tissue can contract or shorten. By doing this, muscle tissue makes parts of your body move.

Nervous Tissue Nervous tissue carries electrical messages back and forth between the brain and other parts of the body. It controls the brain messages and responses from the brain.

Connective Tissue Connective tissue provides support for your body and connects all its parts. Bone tissue and fat are connective tissues.

Epithelial Tissue The surfaces of your body, inside and out are covered by epithelial tissue. Some epithelial tissue, such as your skin, protects the delicate structures that lie beneath it. The lining of your digestive system consists of epithelial tissue that allows you to absorb the nutrients in your food.

Organ An organ is a structure that is composed of different kinds of tissue. Your stomach, heart, brain and lungs are all organs. An organ performs a specific job.

Organ System Each part of your body is part of an organ system. An organ system is a group of organs that work together to perform a major function to sustain the body. Check page 471 in your textbook

Stress The reaction of your body to potentially threatening, challenging, or disturbing events.

Summary What information was helpful to me? Is there something interesting that I may look back at in this section?