The Nervous System
Functions of the Nervous System Control center for all body activities Responds and adapts to changes that occur both inside and outside the body (Ex: pain, temperature, illness)
A system that controls all of the activities of the body. Nervous System A system that controls all of the activities of the body. The nervous system is made of: The brain The spinal cord The nerves The senses
The nervous system also allows you to react to a stimulus. A stimulus is a change in the environment. Example: A hot stove Or… tripping over a rock
Your reactions are automatic. Automatic Automatic means that you do not have to think about your reactions. Example: If a bug flies by your eye, you will blink.
Two Major Divisions of the Nervous System
Central Nervous System The Central Nervous System is made of the brain and the spinal cord. The Central Nervous System controls everything in the body.
Links the brain to the rest of the body Nervous System The Peripheral Nervous System is made of the nerves and the sense organs. Links the brain to the rest of the body Nerves Sense organs
Messages carried throughout the body by nerves. Nerve Impulse Messages carried throughout the body by nerves.
Cells of the Nervous System Neurons : microscopic nerve cells that make up the brain, spinal cord, and nerves - 30,000 neurons can fit on a pinhead
Anatomy of a Neuron Each neuron contains: - Cell body with nucleus - Dendrites : fibers that receive messages from other neurons - Axons : fibers that send messages to other neurons
Neurons do NOT touch; there is a gap between them called a synapse Messages are sent across the synapses by special chemicals called neurotransmitters
Communication Between Neurons The use of neurotransmitters causes an electrical current There is enough electrical current in the brain to power a flashlight
The Central Nervous System * The Central Nervous System controls all of the body’s activities. * The Central Nervous System is made of two main organs. 1. The brain 2. The spinal cord
The Spinal Cord * The spinal cord sends messages to the brain. * The spinal cord is the part of the nervous system that connects the brain to the rest of the nervous system.
The Brain * The brain controls everything in the body. * The brain is made of more than 10 billion nerves! * The brain is divided into three parts and is protected by the skull.
The Four Parts of the Brain 1. The Cerebrum 2. The Cerebellum The Brain Stem The Diencephalon
* The Cerebrum is the largest part of the brain. 1. The cerebrum controls your thinking. 2. The cerebrum controls your memory. 3. The cerebrum controls your speaking. 4. The cerebrum controls your movement and identifies the information gathered by your sense organs.
* The cerebellum is below and to the back of the cerebrum. 1. The cerebellum controls you balance. 2. The cerebellum controls your posture.
The Brain Stem * The Brain Stem connects the brain to the spinal cord. * The nerves in the brain stem control your heartbeat, breathing, and blood pressure.
The Vertebrae * The vertebrae are the many bones that protect the nerves in the spinal cord.
The Diencephalon relays sensory information (from your 5 senses) between brain regions. It controls many autonomic functions of the peripheral nervous system.
The Peripheral Nervous System
Peripheral Nervous System carries messages between the central nervous system and the rest of the body. connects the Central Nervous System to the rest of the body. Controls sensory and mobile action.
Peripherals Nervous System The peripheral nervous system is made of the nerves and the sense organs. Nerves Eye Ear Tongue Skin
Automatic Nervous System The peripheral nervous system controls: the body’s activities that you don’t think about. activities in your small intestine, your breathing, and your heartbeat.