The Nervous System Coach Book: Pgs

The Main Idea: Your body carries out many complex activities to keep you alive and healthy. These activities must be controlled to keep the body working properly. Most of the body functions are controlled and coordinated by your nervous system.

Importance of Nervous System You could not move without your nervous system, or think, feel pain, or taste any of your favorite foods!

Any internal or external change that causes a response is called a stimulus. (plural stimuli) The nervous system controls the body’s functions and its responses to stimuli. The nervous system is composed of three main structures: the brain, the spinal cord, and the many nerves throughout your body.

The Central and Peripheral Nervous System: The central nervous system is made up of the brain and the spinal cord. The peripheral nervous system consists of the many nerves that communicate between the central nervous system and the rest of the body. Both parts of the nervous system are involved in both voluntary and involuntary actions.

Neurons Your nervous system is like a giant computer, with wires and electrical circuits sending and receiving messages.

Neurons Nerve cells, or neurons, branch out from the brain and the spinal cord. Many neurons form bundles of fibers called nerves. These nerves form a network through which messages in the form of electrical signals can travel to all parts of the body. The electrical signals carried by neurons are called impulses.

Notice that the neuron is made up of three main PARTS: dendrites, a cell body, and an axon. Structure of a typical nerve cell. Axon Dendrites Cell body

Neurons continued… Impulses travel through neurons in only one direction. An impulse is transmitted from the axon of the one neuron to the dendrite of another. The dendrite carries the impulse to the cell body. The axon then carries the impulse away from the cell body to the next neuron. ONLY

Types of Neurons There are 3 main TYPES: sensory neurons, motor neurons, and interneurons. 1.Sensory neurons - carry impulses from the sense organs to the spinal cord and brain. –Sense organs are parts of your body that take in information from the external world. –Most of your sense organs are centralized in your head. (eyes, ears, nose, & taste buds)

Types of Neurons continued… –Your body’s largest sense organ is your skin. –Once information is sent to the brain to process, your brain decides how the body will respond. 2. Motor neurons carry impulses from the brain and spinal to the muscles and glands. 3. Interneurons, carry impulses between sensory neurons and motor neurons.

Central Nervous System The central nervous system is the control center of the body. It includes the brain and spinal cord. The thick column of nerve tissue that links the brain to most of the nerves is the spinal cord.

Central Nervous System The brain controls most functions in the body. The brain is located in the head and is protected by the skull.

Protecting the Brain 3 layers of connective tissue cover the brain. The space between the middle layer and inner layer is filled with a watery fluid that helps protect it. The skull also protects the brain. Fun Facts!!!

Parts of the brain: 1.Cerebrum - largest part of the brain. –Interprets input from the senses, controls movement, and carries out complex mental processes like learning. - Certain areas of it are associated with smell, touch, taste, hearing, and vision. - Other areas control movement, speech, written language and abstract thought.

Parts of the Brain cont… 2. Cerebellum - 2 nd largest part of brain. -Coordinates the actions of your muscles and helps you keep your balance. 3. The brain stem controls your involuntary actions like breathing and your heartbeat.

The Spinal Cord The spinal cord is a bundle of nerves that links the peripheral nerves and the brain. The spinal cord runs down the center of your back and is protected inside a column of bones, the vertebrae. Central Nervous System

Central Nervous System continued… The brain and the spinal cord are connected by the brain stem. The brain stem is the part of your nervous system that controls your body’s involuntary responses. Involuntary responses are those that are not under your conscious control and happen automatically. (ex. Heartbeat)

Reflexes Most responses are controlled by the brain. However, a reflex is controlled by the spinal cord. A reflex is a rapid, involuntary response to a stimulus. An example, if you touch a really hot object with your hand. The impulse is sent to the spinal cord immediately. The spinal cord responds by sending impulses to your arm muscles to cause you to quickly pull away your hand.