Nervous+System

__**Nervous System** __  Function: A vast collection of cells helps coordinate all other body functions to maintain homeostasis and to enable the body to respond to changing conditions. Feeling, thinking, remembering, moving, and being aware of the world require activity from the nervous system. Nerve cells within these organs communicate with each other and with muscles and glands using electrochemical signals called nerve impulses. Each impulse gives out a relatively short-term effect on its target. Some nerve cells are specialized sensory receptors that detect changes inside and outside the body. Other nerve cells transmit and receive nerve impulses which stimulate the brain or spinal cord to contract or to secrete products.
 * very thorough, especially homeostatic mechanisms. I like the graphic, too~Mrs. Rohland **


 * Characteristics of Life -**

Movement: Nerve cells throughout the body act as receptors and transmitters giving and taking information to the brain. This is how we move. Nerve impulses are sent to the brain and the brain sends a signal back and you move. It all happens so fast, its hard to believe any information is being sent to and from the brain.

Responsiveness: Receptors in the body alert the brain when conditions change inside and outside of the body. The information is sent to the brain and the brain reacts accordingly. The changes are made to adapt to the new body conditions.

Respiration: While running it is easy to tell when you're breathing heavy. Our lungs want more oxygen. We know this because the information is sent from the nerve cells up to our brain which sends impulses throughout the body to obtain more oxygen, remove carbon dioxide, and release energy from foods that are being digested.

Digestion: Our bodies need energy constantly, nerve impulses are sent from the brain to the stomach which is already breaking down foods. The foods are broken down into simpler forms which can be used and absorbed as energy.


 * Organs, Locations, Relativity:**

The brain, spinal cord, nerves, and sense organs are all part of the nervous system. These organs are located in the cranial cavity, and the vertebral canal. A example of how this system interacts with other systems is that the brain is constantly receiving and giving out information to other systems when and how to function to maintain homeostasis. Without the brain none of the other systems would be able to function.


 * Metabolism -**

The reactions of metabolism enable us to acquire and use energy to fuel life processes. Multiple systems are important for maintaining metabolism all of which get the needed information from the nervous system and the brain due to the receptors of the body transmitting information throughout the body and to the stomach to break down the foods for nutrients and energy.


 * Homeostasis -**

The nervous system plays a key role in homeostasis. Receptors provide information about specific conditions in the internal environment. This information is sent to the brain and the brain begins to adapt to the changing internal environment. Body parts function only when the concentration of water, nutrients, and oxygen and the conditions of heat and pressure remain within certain limits. When one of these exceeds or drops below the limit the information is sent to the brain and the brain responds. For example, if a person is becoming overheated, the brain's temperature control center triggers a series of changes that help to promote loss of body heat. Sweat glands in the skin secrete perspiration, and as the fluid evaporates from the skin it takes the heat with it and the skin is cooled.