 What system sends messages in the form of electrical signals?

 Objectives:  Identify levels of structural organization within the human body  Analyze four kinds of body tissue  List the bodies major organs  Evaluate the importance of endothermy in maintaining homeostasis.

 Four levels of organization  Cells  Tissues  Organs  Organ Systems

 Tissue-group of cells that work together to perform a specific function.  4 Types of Tissues  Epithelial  Connective  Nervous  Muscle

 Epithelial-lines most body surfaces and protects other tissue from damage and dehydration.  Nervous-consists of nerve cells and carry information throughout the body.  Connective-support, protect, and insulate the body  Muscle-enables the movement of body structure by muscle conratcion.

 Example: The function of the spongy tissue in the lung is to take in oxygen and release carbon dioxide.

 Organ-collection of tissues that carry on a specialized function in the body.  Example: the function of the lung is to take oxygen from the air and deliver it to the blood and take carbon dioxide from the blood and deliver it to the air.

 Undifferentiated cells that give rise to all of the cell types in the body.  Immortal and divide indefinitely  Stem cells come from embryos  Why is stem cell research controversial?

 A group of organs that work together to carry out major activities or processes

 Human body contains four large fluid filled spaces to house organs  Thoracic  Cranial  Abdominal  Spinal