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# Ch 11 Nervous System Homeostasis - balance. To remain in balance the various organ systems of the body must work together. The nervous system consists of the brain, spinal cord, and nerves; constantly receives signals about changes within the body as well the external environment. The body has...

# Ch 11 Nervous System Homeostasis - balance. To remain in balance the various organ systems of the body must work together. The nervous system consists of the brain, spinal cord, and nerves; constantly receives signals about changes within the body as well the external environment. The body has two organ systems dedicated to coordinating the activities of the trillions of cells making up the human form. - Endocrine system - employs chemical messengers called hormones to communicate with cells. - Nervous system - uses electrical signals to transmit messages at lightning speed. The nervous system has three essential roles - **Sensing** - the nervous system uses sense organs and nerve endings to detect changes both inside and outside the body - **Integrating** - the nervous system processes the information received, relates it to past experiences, and determines what response is appropriate - **Responding** - the nervous system issues commands to muscles and glands to initiate changes based on its information ## Divisions of the Nervous system - **Central Nervous System** - consists of the brain and spinal cord - **Peripheral Nervous system** - consists of the vast network of nerves throughout the body ## Nervous System Cells Two types of cells make up the nervous system: Neurons and Neuroglia