1/21/2014. Learning Objectives. Vocabulary (p. 225) Structure and Function. Figure 19-1A & B Divisions of the Nervous System. Central Nervous System

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1 CHAPTER 19 NERVOUS SYSTEM Learning Objectives Define at least six (6) terms relating to the nervous system Describe the function of the nervous system Identify at least 10 structures of the nervous system Describe at least five (5) disorders of the nervous system Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 1 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 2 Vocabulary (p. 225) Structure and Function Cerebrospinal Fluid Dementia Epilepsy Intracranial Ischemia Meninges Neurotransmitter Reflex Senile YOU HAVE 15 minutes TO FINISH The nervous system is divided into two major structures: Central nervous system (CNS) Peripheral nervous system (PNS) The function of the nervous system is: To sense, interpret, and respond to internal and external environmental changes to maintain a steady state in the body s homeostasis Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 3 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 4 Figure 19-1A & B Divisions of the Nervous System Central Nervous System Central nervous systems includes: Brain Spinal cord Coordinates body s full nervous system Contains nerves that control connections between impulses coming to and from the brain and the rest of the body Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 5 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 6 1

2 Figure 19-1A Central Nervous System Peripheral Nervous System Peripheral nervous system consists of: 12 pairs of cranial nerves Originate in the brain 31 pairs of spinal nerves Act independently from the brain in some reflex reactions Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 7 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 8 Figure 19-1B Peripheral Nervous System Table 19-1 Functions of the Peripheral Nervous System Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 9 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 10 Organs of the Peripheral Nervous System Organs of the peripheral nervous system contain: Afferent (sensory) neurons Carry messages from the sensory cell of the body to the brain Figure 19-2 The Spinal Reflex Arc Efferent (motor) neurons Carry messages from the brain to the body organs or parts Classified as somatic (voluntary) or automatic (involuntary) Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 11 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 12 2

3 Divisions of the Nervous System (PLEASE COPY) Figure 19-3 The Autonomic Nervous System Sympathetic system The sympathetic nerves are stimulated in situations that require action such as the fight-orflight reaction Parasympathetic system The parasympathetic nervous system functions in response to normal, everyday situations Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 13 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 14 Neurons Neurons Basic structural unit of the nervous system is the nerve. Nerve is bundle of fibers that carries impulses Nerve fibers consist of neuron cells Three main types of neurons: Afferent Efferent Interneuron Each carries messages, or impulses, to and from the body s organs Important parts of a neuron Dendrites Receive impulses and transmit them to cell body Cell body transmits impulses to the axon Axon transmits impulse away from cell body to dendrite of next neuron Myelin (white matter) White, fatty substance covering the axon Arranged in bundles called Schwann cells Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 15 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 16 Figure 19-4 Neuron Neuroglia (Glia) Special nervous tissue cells that act as glue to support, bind, repair, and protect neurons Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 17 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 18 3

4 Synapse Space between two neurons Impulses from one neuron are transmitted across the synapse to another neuron by a chemical called a neurotransmitter Ganglia Groups of nerve tissue Increased ability to transmit impulses because they are clustered together in the ganglion Two most common neurotransmitters: Acetylcholine (helps transmit nerve impulses) Norepinephrine (vasoconstrictor) Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 19 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 20 Plexus Plexus and Dermatome Four major networks of interwoven spinal nerves (cervical, brachial, lumbar, and sacral) Provide impulses to specific regions of the body Dermatomes Spinal nerves that control sensations on the skin surface Brain Largest structure of the nervous system and one of the largest organs of the body Brain weighs about 2 to 3 pounds The brain is covered by three layers of membranes called meninges: Dura mater Arachnoid Pia mater Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 21 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 22 Figure 19-5 The Brain Lobes of the Brain Frontal: personality, behavior, memory, reasoning, and emotion Parietal: Understanding speech or choosing words Temporal: Hearing & understanding speech and printed words; memory of music & visual scenes Occipital: vision Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 23 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 24 4

5 Parts of the Brain Parts of the Brain Cerebrum: Largest area; divided into two hemispheres Reasoning & senses Cerebellum: Directs coordination, muscle tone, and equilibrium Hypothalamus Regulates & coordinates activity of the ANS Controls hormone secretion & appetite Thalamus Sensory Brainstem: Heartbeat, respiration, and blood pressure Pons, medulla, midbrain Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 25 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 26 Figure 19-6 The Parts of the Brain Table 19-2 Functions of the Brain Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 27 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 28 Assessment Techniques Electroencephalography (EEG) Lumbar puncture Myelography Nerve conduction velocity Computed tomography (CT) Positron emission tomography (PET) Magnetic resonance imaging (MRI) Alzheimer s A form of senile dementia Cerebrovascular accident Commonly called a stroke or CVA, Down syndrome A genetic disorder caused by the presence of an extra chromosome Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 29 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 30 5

6 Encephalitis An inflammation of the brain caused by a virus, bacteria, or chemical agent Guillain-Barré syndrome Progressive muscular weakness that may lead to paralysis; it may appear shortly after a viral immunization or infection Migraine headaches Vascular headaches of unknown cause; the pain results from the narrowing of blood vessels in the brain Sinus headaches From the swelling of the membranes that line the sinus cavities Headache The muscles around the occipital area of the brain constrict the blood flow to the area Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 31 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 32 Intracranial tumors Usually involve neuroglia, blood vessels, or membranes rather than neurons Meningitis A serious inflammation of the meninges caused by a bacterium, virus, or fungus Meningocele A birth defect that occurs when the membranes covering the brain or spinal cord protrude through a congenital defect in the skull or spinal column Multiple sclerosis From a defect in electrical transmission of the neurons caused by degeneration of the myelin sheath Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 33 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 34 Parkinson s disease Results from degeneration of certain brain cells Sciatica Pressure on the sciatic nerve or other nerves in to your leg; Cause is usually a rupture of an intervertebral disk Spina bifida A birth defect involving a malformed spinal column resulting from neural tube defects Seizure Result from injury, infection, or epilepsy Over 40 different types Petit mal Lapse of consciousness for several seconds Grand mal Series of distinctive tonic & clonic spasms that last several minutes Tonic: muscles contracted rigidly Clonic: involuntary muscle movements Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 35 Copyright 2007 by Mosby, Inc., an affiliate of Elsevier Inc. 36 6