Detects changes in the body Make decisions Stimulate muscles or glands to respond Works by sending an electrical signal known as an action potential through the cells of the nervous system, which are called neurons

Abbreviated CNS Consists of Brain and Spinal Cord

Abbreviated PNS Consists of cranial and spinal nerves Further divided into Sensory Division and Motor Division

Signals sent to the CNS from PNS Various senses – sight, hearing, touch (temperature, pressure, etc.), taste, smell

Signals sent from CNS to PNS Carry out effectors- actions that result in an effect happening Skeletal, smooth, cardiac muscle movement and glandular secretion Further divided into Somatic Nervous System and Autonomic Nervous System

Voluntary effectors, such as breathing and skeletal muscle contraction

Involuntary effectors, such as heartbeat, smooth muscle contraction, secretion of hormones and enzymes

Cell Body Nucleus Dendrites Axon hillock Axon Myelin Sheath Schwann Cells Nodes of Ranvier Axon Terminal Synaptic Knob

Myelinated neurons appear white Unmyelinated neurons appear gray 3 purposes – Protects axon – Insulates axon – Speeds rate of transmission Schwann Cells enclose, but do not wrap around myelin sheath

Multipolar – found mostly in the brain and spinal cord Bipolar – found in eyes, nose, and ears Unipolar – connect PNS with CNS

Sensory Neurons – Sensory Divison Interneurons – Relays info between neurons in brainand spinal cord Motor Neuron – Motor Division

Cells of the nervous system that perform other functions apart from transmitting impulses

Astrocytes – structural support, mop up excess ions and neurotransmitters, induce synapse formation Oligodendrocytes – creates myelin Microglia – structural support and phagocytosis Ependyma – forms a membrane for which substances can diffuse from the fluid of the brain to the cerebrospinal fluid

Schwann Cells – protect axons, speed neurotransmition Satellite Cells – Support ganglia (clusters of neurons)

Presynaptic neuron – the neuron carrying the message Postsynaptic neuron – the neuron receiving the message Synaptic Cleft – separates the 2 cells – Synaptic knob of presynaptic neuron connected with dendrite or cell body of postsynaptic neuron