Chapter 7

Chapter 7 - The Nervous system Responding to stimuli - All...

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The Nervous system Responding to stimuli - All animals must be able to respond to environmental stimuli o Sensory receptors = detect stimulus o Motor effects = respond to it - The nervous system links sensation and the responses o Consists of neurons and neuroglia (supporting cells) Types of neurons - Vertebrates have 3 types of neurons o Sensory neurons (afferent neurons) carry impulses to central nervous system (CNS) o Motor neurons (efferent neurons) carry impulses from CNS to effectors (muscles and glands) o CNS made of interneurons (association neurons) that link sensory and motor neurons Provide complex reflexes and associate functions (learning and memory) Nervous system organization - The CNS consists of the brain and spinal cord - The peripheral nervous system (PNS) consists of sensory and motor neurons o Somatic NS stimulates voluntary responses (skeletal muscles) o Automatic NS stimulates responses that do not require conscious control
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Stimulates smooth and cardiac muscles Affects digestion, respiration, salivation, sexual arousal, etc. Neuron anatomy - Neurons have a common basic structure o Cell body = enlarged part containing nucleus Thin projections from body Two types of projections: dendrites and axon o Dendrites = short, cytoplasmic extensions that receive stimuli o Axon = single, long extension that conducts impulses away from cell body Supporting cells are wrapped multiple times around axon – layered membrane forms a myelin sheath Neuron anatomy figure
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Neuroglia - Neurons are supported both structurally and functionally by cells called neuroglia o Schwann cells and oligodendrocytes produce myelin sheaths surrounding axons o Function to aid the transmission of nerve impulse, supply with nutrients, carry away waste o In the CNS, oligodendrocytes produce the myelin sheath o Schwann cells produce the myelin in the PNS - In the PNS, myelinated axons are bundled to form nerves Resting Potential - An electrical potential exists across every cell’s plasma membrane
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This note was uploaded on 10/24/2011 for the course BIOL 111 taught by Professor Dr.zielinski during the Spring '08 term at Purdue.

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Chapter 7 - The Nervous system Responding to stimuli - All...

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