Neuron Nerve Cell Cell Body Cytoplasm Nucleus Axon

Neuron (Nerve Cell) • Cell Body – Cytoplasm – Nucleus • Axon – Carry messages away from the cell body to other neurons • Dendrites – Carry messages to the cell body

Types of Neurons Receptor Cells Receives information from a stimulus • • For example - your finger gets hit by a hammer Sensory Neurons – Carry the impulse to the spinal cord • • Travels the length of the arm to the spinal cord Interneurons – Impulse is transmitted to the brain and the motor neurons via synapses • • Travels to the brain to register pain and out to the finger Motor neurons – Sends the processed information back to finger • Carries impulse to the effector cells in the fingers, hand arm

Nerve Impulses • 120 meters per second = speed at which impulses travel in the body. • Synapse – gap between two neurons (axon and dendrite) – Impulse travels from one neuron to the next by sending chemicals across a gap to activate the next neuron.

Reflex Arc 1. Hand touches open flame or hot burner 2. Impulse travels to spinal cord 3. Impulse sent to brain and back to hand. 4. Hand pulls back before pain is registered by brain 3. 2. 1. 4.

Nervous System • Two major divisions 1. Central Nervous System (CNS) • brain and spinal cord 2. Peripheral Nervous System • motor and sensory neurons

Central Nervous System

Development of the brain Conception - newborn

Sagittal Section of Brain cerebrum Corpus callosum cerebellum pons Medulla oblongata

Inferior view of Brain Olfactory Lobes Frontal lobe of the cerebrum Medulla oblongata cerebellum

Regions of the Brain • Cerebrum - thought and reasoning – – • • Frontal - thinking, talking, remembering, moving Parietal - touching Occipital - seeing Temporal – tasting, smelling, hearing Cerebellum – coordination of muscular movements Medulla Oblongata – involuntary responses Pons – band of nerves linking the medulla and the cerebellum Olfactory – sense of smell

Spinal Cord

Peripheral Nervous System • Consist of the neurons (receptor and motor) which lead to and from the central nervous system • Two divisions – Sensory Somatic – Autonomic