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Introduction to Anatomy & Physiology The Nervous System
Packet #34 Chapter #29
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Anatomy & Physiology Introduction
Study of structure and relationship between body parts Physiology Study of the function of the body parts and the body as a whole
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Anatomy & Physiology Study Areas
Cytology The study of cells at microscopic level Histology Study of tissue at microscopic level
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The Nervous System
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Introduction The nervous system has three main functions Sensory Input
Integration Sensory Output
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Introduction II Radically symmetric invertebrate organisms utilize nerve nets and radial nervous systems Cnidarians have a nerve net of cells scattered throughout the body. There is no central control organ Echinoderms, such as star fish , typically have a radial nervous system. Nerve ring Nerves that extend to various parts of the body Bilateral nervous systems are characteristic of bilaterally symmetrical animals
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The Human Nervous System
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Nerves Neurons Basic functional units of the human nervous system
Three categories of neurons Sensory Interneurons Motor neurons
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Neurons II Sensory (Afferent) Neurons
Receives stimuli from environment Transmits impulses from skin and other sensory organs towards the CNS Ears; eyes; nose; tongue
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Nerves III Interneurons Motor (Efferent) Neurons
Interprets impulses brought by sensory neurons Submits “commands” to the motor neurons Leads back to effector organs Motor (Efferent) Neurons Transmit impulses from the CNS to effectors Target cells that produce some kind of response Muscles Glands
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Parts of the Human Nervous System
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Human Nervous System I The human nervous system can be divided into two major categories The Central Nervous System The Peripheral Nervous System
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The Central Nervous System
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Introduction The central nervous system is composed of two main parts: - The Brain The Spinal Cord
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Brain Cerebrum Cerebellum Medulla Contains center for learned behavior
Center for thought, memory and reasoning Cerebellum Controls balance & muscular activities Medulla Controls involuntary functions Heartbeat; breathing; blood pressure
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Spinal Cord The spinal cord, in addition to helping move messages to the brain, allows the organism to reflex rapidly and involuntary in response to a stimulus The message only travels through the spinal cord and not the brain The Reflex Arc Pathway traveled by nerve impulses during a reflex
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Peripheral Nervous System
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Peripheral Nervous System
The PNS includes all nerves, of all types, that branch through the body from the CNS Consist of all nerves outside of the brain and spinal cord Has two divisions Somatic Nervous System Autonomic Nervous System
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Somatic Nervous System
Consists of motor neurons that stimulate skeletal muscles Control actions at voluntary skeletal muscle.
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Autonomic Nervous System
Include only motor neurons that control the activities of Organs Glands Various involuntary muscles Cardiac and smooth muscle Two parts Sympathetic Nervous System Parasympathetic Nervous System The somatic nervous system controls voluntary actions while the autonomic nervous system controls involuntary actions
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Sympathetic Nervous System
Prepare the body for action Prepare body for situations requiring alertness or strength or situations that arouse fear anger, excitement or embarrassment (fight or flight) Responses that serve to fight of or retreat from danger
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Parasympathetic Nervous System
Activates “calm” functions Stimulates the processes of digestion, urination and defecation Reduces blood pressure, heart and respiratory rates Conserves energy through relaxation and rest
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The Nervous System Overview
Central Nervous System Brain Cerebrum Cerebellum Medulla Spinal Cord Peripheral Nervous System Somatic (Voluntary) Autonomic (Involuntary) Sympathetic Action Parasympathetic Calm
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