| A | B |
|---|
| Neurons | Functional units of the nervous system |
| Neuroglia | These protect the neurons and account for half of the volume of the nervous system |
| Central Nervous System (CNS) | Consists of the spinal cord and brain |
| Peripheral Nervous System (PNS) | All the neural tissue outside the CNS |
| Cranial nerves | Connected to the brain |
| Spinal nerves | Connected to the spinal cord: 31 pairs |
| Nerves | Responsible for carrying sensory information and motor commands. Cannot reproduce themselves |
| Afferent | This division of the PNS brings sensory information to the CNS from receptors in peripheral tissues and organs |
| Efferent | This division of the PNS carries motor commands from the CNS to muscles and glands |
| Receptors | Sensory structures that either detect changes in the internal environment or respond to the presence of specific stimuli |
| Somatic Nervous System | This controls skeletal muscle contractions and is a division of the efferent nervous component |
| Autonomic Nervous System | Provides automatic regulation of smooth and cardiac muscles and glandular secretions at the subconscious level |
| Parasympathetic and Sympathetic Divisions | Have antagonistic effects, two divisions of the Autonomic Nervous System |
| Synapse | Specialized site where the neuron communicates with another cell. Two cells meet at every one of these. |
| Neurotransmitter | A chemical necessary for communication between cells at a synapse. |
| Chemical | Most abundant type of synapse |
| Presynaptic cell | Sends the messsage |
| Postsynaptic cell | Receives the message |
