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The Nervous System. Objectives. Identify the principle parts of the nervous system Describe the cells that make up the nervous system Describe what starts and stops a nerve impulse (action potential) The role of neurotransmitters Compare the functions of the CNS & PNS
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Objectives • Identify the principle parts of the nervous system • Describe the cells that make up the nervous system • Describe what starts and stops a nerve impulse (action potential) • The role of neurotransmitters • Compare the functions of the CNS & PNS • Identify the principle parts of the brain
Principle Parts of Nervous System • Central nervous system (CNS): “command central” • Components: brain and spinal cord • Functions: receives, processes, and transfers information • Peripheral nervous system (PNS): “messengers” • Components: nerves outside CNS • Sensory neurons: carry information toward the CNS • Motor neurons: carry information away from CNS
Motor Division: 2 parts • Somatic - under conscious control (movement of skeletal muscles) • Autonomic – unconscious control (smooth muscle, cardiac, glands)
Autonomic divisions: 2 parts • Sympathetic – flight or fight • Parasympathetic – conserves energy, promotes nonemergency functions
Cells of the Nervous SystemCommunicators/messengers • Neurons: specialized cells for communication: • Cell adaptations: cell body, axon, dendrites • Types: sensory, interneurons, motor neurons
Sensory neurons - INPUT • Of PNS transmit impulses to the CNS • Specialized to respond to specific stimuli like light or pressure • Impulses are electrical –as they travel they cause depolarization and repolarization of membrane potential = measurable difference in voltage across a cell membrane
Interneurons - INTERGRATION • Of CNS transmit impulses between components of CNS • Receives information from sensory neurons, • Integrates/interprets information and • Influences the functioning of other neurons
Motor neurons - OUTPUT • Of PNS transmit electrical impulses away from the CNS to muscles and glands
Neuron Structure • Cell body – BATTERY - nucleus, DNA, mitochondria, etc • Dendrites – SENSORS - extension of cell body (soma) = info receivers/receptors • Axon – WIRING – long, slender tube of cell membrane specialized to conduct electric impulses • Axon terminals & axon bulbs (plugs & lights) – connections to tissues or other neurons
Neuron adaptations • Sensory neural axons originate from a dendrite • Interneurons and motorneurons axons originate from axon hillock (cone shaped area of soma)
