NERVOUS SYSTEM & SPECIAL SENSES By: Alyce Baughman and Jessica Woodruff Period 3

FUNCTION OF THE SYSTEM -Main function is to control the operation and movements of the body based on the sensory information it gathers, both internally and externally FUNCTIONS INCLUDE: -To maintain your consciousness -To help you respond to your senses -To help coordinate what you sense and feel -To allow learning and memory -To control other body systems

NEURON -Includes a cell body, dendrites, and an axon -Dendrites and the cell body provide receptive surfaces -Axon arises from the cell body and can be enclosed in a myelin sheath and a neurilemma -Either multipolar, bipolar, or unipolar

SYNAPSE -Junction between 2 neurons -Presynaptic neuron carries an impulse into a synapse; post- synaptic neuron responds -Axons have synaptic knobs at distal ends, which secrete neurotransmitters -Neurotransmitter released when nerve impulse reaches end of axon-Neurotransmitter reaching the postsynaptic neuron membrane may trigger nerve impulse

STRUCTURES OF THE BRAIN -Composed of100 billion multi-polar neurons -Multi-polar neurons communicate with one another and with neurons in other parts of nervous system -Subdivided into the cerebrum, diencephalon, brainstem, and cerebellum

FUNCTIONS OF THE BRAIN

CENTRAL NERVOUS SYSTEM(CNS) -Nerves of the brain and spinal cord -Central core of the body

PERIPHERAL NERVOUS SYSTEM -Cranial nerves arising from the brain -Spinal nerves arising from the spinal cord -Sensory neurons running from stimulus receptors that inform the CNS of the stimuli - Motor neurons running from the CNS to the muscles and glands, called effectors, that take action.

CNS AND PNS

CENTRAL VERSES PERIPHERAL

AUTONOMIC NERVOUS SYSTEM -Functions independently(autonomously) and without conscious effort -Regulates the visceral activities that maintain homeostasis -Reflexes controlled from the nerve centers in the brain and spinal cord

SUB-LEVELS SympatheticParasympathetic -Responds to stressful and emergency conditions -Leave the spinal cord and synapse in paravertebral ganglia -Most active under ordinary conditions -Begin in the brainstem and sacral region of the spinal cord and synapse in ganglia near viscera

SOMATIC SENSES -Senses we feel with our bodies -Include sensations of touch and pressure, pain and temperature, and our muscle senses (proprioception) Example: If you feel someone touch your arm or face

SENSE OF TASTE & SMELL -The perception of chemicals in the air or in our food -Tastants, chemicals in foods, are detected by taste buds -Taste buds consist of special sensory cells -When stimulated, these cells send signals to specific areas of the brain, which make us conscious of the perception of taste. -Specialized cells in the nose pick up odorants, airborne odor molecules -Odorants stimulate receptor proteins found on hairlike cilia at the tips of the sensory cells -Initiates a neural response. *Ultimately, messages about taste and smell converge, allowing us to detect the flavors of food*