Nervous System

The Nervous System directs complex processes (seeing, hearing, tasting, feeling, responding). It regulates the internal environment and links to external environment. It directs the organs in the body so that they don’t act independently of each other; without a Nervous System, there’d be chaos inside.

Central nervous system controls

The central nervous system (CNS - brain, spinal cord) controls the entire body. Neurons receive and transmit biochemical information, and are classified as either sensory or motor. Glial cells (or neuroglia) provide structural support for the neurons. One type of neuroglia, called astrocytes, helps form the blood-brain barrier which prevents or slows the flow of unwanted substances into the brain tissue. They also help seal off damaged nerve tissue. Smaller microglia in brain and spinal cord act during inflammation or injury.

The Nervous System coordinates the activities that bring about a response to stimulus with these activities:

• Reception - information is gathered from external environment at receptors
• Transmission - information is delivered by sensory neurons to the CNS
• Integration - appropriate response is determined
• Response - nerve impulse is dispatched via motor neurons to effectors (muscles, glands) that will regenerate a response to the stimulus

Spinal cord coordinates with brain

The spinal cord nerve coordination consists of coordinating reflexes and networking to the brain. The brain is the organizing and processing center of the Nervous System (consciousness, sensation, memory, coordination). The cerebral cortex (outer layer of brain), the highest order region of brain, controls speech and thought process, interprets information from senses, controls voluntary responses, reduces inhibitions and dulls senses.

The limbic system controls emotions and memory. The cerebellum controls movement (voluntary and involuntary muscles—balance). The hypothalamus controls sexual arousal and performance. The pituitary gland signals the kidneys to excrete more or less water, increasing or decreasing urination, dehydrating or hydrating the body. The brain stem / medulla controls what you don’t need to think about (breathing, heart rate, circulation). (Source: Anatomy and Physiology: The Easy Way, Alcamo & Krumhardt)