Chapter 15, Section 1 Body Organization and Homeostasis Wednesday, January 27, 2010 Pages 472 -- 479

Objectives Identify the levels of organization in the body. Identify and describe the four basic types of tissue in the human body. Define homeostasis and describe its importance to the body.

Vocabulary Words Cell Cell membrane Nucleus Cytoplasm Tissue Muscle tissue Nerve tissue Connective tissue Epithelial tissue Organ Organ system Homestasis Stress

Levels of Organization The levels of organization in the human body is made up of cells, tissues, organs, and organ systems. Smallest is the cell. Largest is the organ system.

Cells Basic unit of structure and function in a living thing. Carry on the processes that keep organisms alive. Inside the cells, molecules from digested food undergo chemical reaction that provide energy. Cells get rid of waste products, grow and reproduce.

Tissues A group of similar cells that perform the same function. The human body contains four basic types of tissue. Muscle tissue Nerve tissue Connective tissue Epithelial tissue

Muscle Tissue Muscle tissues can contract or shorten. This makes parts of your body move.

Nerve Tissue Carries messages back and forth between the brain and every other part of the body. The brain is made up mostly of nerve tissues.

Connective Tissue Provides support for your body and connects all its parts. Examples include: Bone -- supports the body and protects the internal organs. Fat -- pads parts of the body, provides insulation, and stores energy.

Epithelial Tissue Covers the surfaces of your body, inside and out. Serves as a layer of protection. Absorb or release substances such chemicals used in digestion.

Organs and Organ Systems An organ is a structure that is composed of different kinds of tissue. An organ performs a specific function. Its job is more complex than that of tissues. Each organ in the body is part of an organ system. An organ system is a group of organs that work together to perform a major function.

Circulatory System Carries needed materials to the body cells. Carries wastes away from body cells. Helps fight disease.

Digestive System Takes food into the body. Breaks food down. Absorbs digested materials.

Endocrine System Controls many body processes -- such as the intake of sugar by cells -- by means of chemicals.

Excretory System Removes wastes.

Immune System Fights disease.

Muscular System Enables the body to move. Moves food through the digestive system. Keeps the heart beating.

Nervous System Detects and interprets information from the environment outside the body and from within the body. Controls most body functions.

Reproductive System Produces sex cells that can unite with other sex cells to create offspring. Controls male and female characteristics.

Respiratory System Takes oxygen into the body and eliminates carbon dioxide.

Skeletal System Supports the body, protects it, and works with muscles to allow movement. Makes blood cells and stores some materials.

Skin Protects the body. Keeps water inside the body. Helps regulate body temperature.

Homeostasis Body’s tendency to keep an internal balance. Systems of the body working together. It is the process by which an organism’s internal environment is kept stable in spite of changes in the external environment.

Stress and Homeostasis Stress is the reaction of your body and mind to threatening, challenging, or disturbing events.

More blood goes to the brain. Pupils of eyes widen to take in more light. Hearing ability increases. Heart rate increases. Sweating increases. Digestive System slows. Muscles tense. Blood receives more energy-producing substances. Body cells release energy faster.

Physical Responses to Stress The body will respond within seconds after experiencing stress. This is called the alarm stage. The body will release a chemical called adrenaline into the bloodstream.

Adrenaline Adrenaline gives a boost of energy and causes changes in the body. Adrenaline prepares the body to take quick action. Breathing quickens and sends more oxygen to the body cells to provide energy for the muscles. The heart will beat faster and increases the flow of blood.

Fight or Flight This is the reaction caused by adrenaline. The body prepares you to either fight the stressor or to take flight and escape. The body system will work together to respond to the stressor

Homework Workbook 15.1 (1/29) Vocabulary quiz 15.1 (1/29)