The Nervous System
Essential Questions The Nervous System What does the nervous system do? How do the parts of the nervous system work together?
Functions of the Nervous System The part of an organism that gathers, processes, and responds to information is called the nervous system. The nervous system receives information from the five senses: vision, hearing, smell, taste, and touch. The nervous system can receive information, process it, and respond in less than one second.
Neurons The basic functioning units of the nervous system are called nerve cells, or neurons. Neurons help different parts of your body communicate with each other. Neurons are made of three parts: dendrites, a cell body, and an axon.
Parts of a Neuron
Parts of a Neuron and their functions A dendrite receives information from another nerve cell or body cell. A cell body processes the information. An axon sends the information to another cell.
3 types of Neurons Sensory neurons send information about your environment to your brain or spinal cord. Motor neurons send information from your brain or spinal cord to tissues and organs in your body. Interneurons connect sensory and motor neurons.
3 types of Neurons
Synapse The connection between two neurons is called a synapse. Chemical signals carry information between neurons.
Neurons and Synapses
Neurons and Synapses
The Central Nervous System The central nervous system (CNS) is made up of the brain and the spinal cord. The CNS receives, processes, stores, and transfers information. The brain is the control center of the body which receives information, processes it, and sends out a response. The brain also stores some information as memories.
The Central Nervous System (cont.) The part of the brain that controls memory, language, and thought is the cerebrum. The cerebrum is the largest, most complex part of the brain. It processes touch and visual information. The cerebellum is the part of the brain that coordinates voluntary muscle movement, balance, and posture.
The area of the brain that controls involuntary functions, sneezing, coughing, and swallowing is the brain stem.
The Central Nervous System (cont.) The spinal cord is a tube-like structure of neurons that extend to other areas of the body. Neurons in the spinal cord send information back and forth between the brain and other body parts. Bones called vertebrae protect the spinal cord.
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The Peripheral Nervous System The peripheral nervous system (PNS), is made of sensory and motor neurons that transmit information between the CNS and the rest of the body. The PNS is made of two parts: the somatic system and the autonomic system. The somatic system controls skeletal muscles.
The Peripheral Nervous System (cont.) Neurons of the somatic system communicate between the CNS and skeletal muscle to cause voluntary movements. The autonomic system controls smooth (visceral) muscle and cardiac muscle and regulates involuntary actions.