1-07-Nervous_System - The Nervous system Responding to...

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The Nervous system Responding to stimuli All animals have to be able to respond to environmental stimuli (things we are able to sense in our environment) o Sensory receptors- detect stimulus o Motor receptors- respond to it The nervous system links sensations and the responses o This consists of neurons and neuroglia (supporting cells) Types of neurons Vertebrates have three types of neurons o Sensory neurons : afferent neurons which carry impulses to central nervous system (CNS) o Motor neurons : efferent neurons that carry impulses from CNS to effectors such as muscles and glands o CNS is made of interneurons which are association neurons that link sensory and motor neurons Provide complex reflexes and associative functions (learning and memory) Nervous system organization The CNS consist of the brain and spinal cord which is the information processing center The peripheral nervous system (PNS) consists of sensory and motor neurons
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o Somatic NS stimulates voluntary responses such as skeletal muscles o Automatic NS stimulates responses that do not require conscious control Stimulates smooth and cardiac muscles Affects digestion, respiration, salivation, sexual arousal, etc. Neuron anatomy Neurons have a common and basic structure o Cell body – enlarged part containing nucleus Thin projections from the body Two types of projections: dendrites and axon o Dendrites – short, cytoplasmic extensions that receive stimuli (as a finger) o Axon- single, long extension that conducts impulses away from the cell body (as an arm) Supporting cells are wrapped multiple times around the axon— this layered membrane forms a myelin sheath Neuron anatomy figure
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Neurons are supported both structurally and functionally by cells called neuroglia o Schwann cells and oligodendrocytes produce myelin sheaths (coding on a wire) that surround the axon o Functions to aid the transmission of nerve impulses, supply with nutrients and 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
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This note was uploaded on 04/11/2011 for the course BIO 111 taught by Professor Dr. bos during the Winter '10 term at Purdue University-West Lafayette.

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1-07-Nervous_System - The Nervous system Responding to...

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