Chap12_2401 - 1 NERVOUS TISSUE Chapter 12 Anatomy and...

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1 NERVOUS TISSUE Chapter 12 Anatomy and Physiology
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2 NERVOUS TISSUE The Nervous System is made up of the Brain , Spinal Cord , Nerves , and Sensory Receptors . It is responsible for sensory perceptions, mental activities, and stimulating muscle movements and the secretions of many glands. FUNCTIONS OF THE NERVOUS SYSTEM 1. Sensory input 2. Integration 3. Homeostasis 4. Mental activity 5. Control of muscle and glands DIVISIONS OF THE NERVOUS SYSTME Two Principal divisions of the Nervous System 1. Central Nervous System (CNS) - The control center for the entire nervous system. -Consists of the Brain and Spinal Cord . (Various sorts of incoming sensory information are integrated and correlated; thoughts and emotions are generated; and memories are formed and stored . Most nerve impulses that stimulate muscles to contract and glands to secrete originate here.) 2. Peripheral Nervous System (PNS) – Is external to the CNS.
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3 Consists of: a. Sensory Receptor – Ending of nerve cells or separate, specialized cells that detect temperature, pain, touch, pressure, light, sound, odors, and other stimuli. Location: Skin, muscles, joints, internal organs, eyes, and ears. b. Nerve – Is a bundle of axons and their sheaths that connects the CNS to sensory receptors, muscles and glands. (i) 12 Pairs of Cranial Nerves – Originate from the Brain. (ii) 31 Pairs of Spinal Nerves – Originate from Spinal Cord. c. Ganglion – Is a collection of neuron cell bodies located outside the CNS. d. Plexus – Is an extensive network of axons and, in some cases, also neuron cell bodies located outside the CNS. Two Subcategories of PNS : 1) Sensory (Afferent) Division – Transmits electric signals, called action potentials , from the sensory receptors to the CNS. -Called the Input Component. 2) Motor (Efferent) Division – Transmits action potentials from the CNS to effector organs, such as muscles and glands. -Called the Output component.
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Motor (Efferent) Division is divided into : 1) Somatic Nervous System (SNS) – Transmits action potentials from the CNS to skeletal muscles. Skeletal muscles are voluntarily controlled through the somatic nervous system. 2) Autonomic Nervous System (ANS) – Transmits action potential from the CNS to smooth muscle, Cardiac muscle, and certain glands. Are subconsciously or involuntarily controlled by the ANS. Autonomic Nervous System (ANS) is subdivide into : 1) Sympathetic Division – Prepares the body for physical activity. 2) Parasympathetic Division – Regulates resting or vegetative functions, such as digesting food or emptying the urinary bladder. Usually, the two divisions have opposing reactions. CELLS OF THE NEERVOUS SYSTEM Nervous System is made up of: (1) Neurons - Receive stimuli and conduct action potential. (2)
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This note was uploaded on 03/10/2012 for the course BIOL 2403 taught by Professor Campbell during the Spring '12 term at Texas Pan American.

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Chap12_2401 - 1 NERVOUS TISSUE Chapter 12 Anatomy and...

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