Bài giảng Medical Assisting - Chapter 27: The Nervous System

Objectives: 27-1 Explain the difference between the central nervous system and the peripheral nervous system. 27-2 Describe the functions of the nervous system. 27-3 Describe the structure of a neuron. 27-4 Describe the function of a nerve impulse and how a nerve impulse is created. 27-5 Describe the structure and function of a synapse. 27-6 Describe the function of the blood-brain barrier.

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ChapterPowerPoint® to accompany Second EditionRamutkowski  Booth  Pugh  Thompson  WhickerCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Medical Assisting Chapter 271Objectives:27-1 Explain the difference between the central nervous system and the peripheral nervous system.27-2 Describe the functions of the nervous system.27-3 Describe the structure of a neuron.27-4 Describe the function of a nerve impulse and how a nerve impulse is created.27-5 Describe the structure and function of a synapse.27-6 Describe the function of the blood-brain barrier.The Nervous System2Objectives:27-7 Describe the structure and functions of meninges.27-8 Describe the structure and functions of the spinal cord.27-9 Define reflex and list the parts of a reflex arc.27-10 List the major divisions of the brain and give the general functions of each.27-11 Describe the differences between the somatic nervous system and autonomic nervous system. The Nervous System3Objectives:27-12 Explain the two divisions of the autonomic nervous system.27-13 Explain the functions of the cranial and spinal nerves.27-14 Describe the location and function of cerebrospinal fluid.27-15 Describe various disorders of the nervous system and how they are diagnosed and treated.The Nervous System4Introduction Nervous system is a highly complex system divided into two major parts;Central nervous system (CNS) Peripheral nervous system.Controls all other organs systems and is important for maintaining balance within those systems.Disorders of the nervous system are numerous and often very difficult to diagnose and treat because of the complexity of this system. 5General Functions of the Nervous SystemDetect and interpret sensory information, Make decisions about the sensory information that is received, Carry out motor functions based on the decisions made.For example, if you feel pain, your brain might decide you need to move away from the painful stimulus. 6Neuron Structure Transmit electrochemical messages called nerve impulses to other neurons and effectors (muscles or glands)Neurons lose their ability to divide When destroyed by disease, they cannot be replaced 7Neuron Structure (cont.)Neurons have cell body processes called nerve fibers that extend from the cell body. Dendrites - short - function is to receive information (nerve impulses) for the neuron Axons - long - function is to send information (nerve impulses) away from the cell body.8Nerve Impulse Nerve impulse is the flow of electric current along the axon membrane At rest, or in its polar state, more sodium (Na+) is on the outside of the membrane, which makes the outside positive and the inside negative.When sodium moves into the cell, the membrane depolarizes, which means that the inside becomes more positive. The membrane repolarizes when potassium (K+) and later sodium move to the outside of the cell membrane.9Synapse Synaptic knobs contact dendrites, cell bodies and the axons of other neuronsSynaptic knob is contacting is called a postsynaptic structure. Within synaptic knobs are vesicles or small sacs that contain chemicals called neurotransmitters. When the nerve impulse reaches the synaptic knobs, the neurotransmitters are released onto postsynaptic structures.10Neurotransmitters Functions: Causes muscles to contract or relax Causes glands to secrete products Activates neurons to send nerve impulses, inhibiting neurons from sending nerve impulses.11Apply Your KnowledgeWhat is the function of a dendrite?12Apply Your Knowledge -Answer Dendrite’s function is to receive information (nerve impulses) for the neuron. What is the function of a dendrite?13Central Nervous System Includes the spinal cord and brain. Has a blood-brain barrier:Barrier prevents certain substances from entering the tissues of the CNS Tight capillaries form the blood-brain barrier. Meninges are membranes that protect the brain and spinal cord.14Cerebrospinal fluid Location: Between the arachnoid mater and pia mater is an area called the subarachnoid space Function: Cushions the CNS 15Spinal CordSlender structure that is continuous with the brain Descends into the vertebral canal and ends around the level of the first or second lumbar vertebra.31 spinal segments: 8 cervical segments 12 thoracic segments 5 lumbar segments 5 sacral segments1 coccygeal segment  16Spinal Cord (cont.)Name the spinal segments and tell how many of each segment are present on the spinal cord.8 cervical segments 12 thoracic segments 5 lumbar segments 5 sacral segments1 coccygeal segment  17Spinal Cord – Gray and White Matter Gray matter - inner tissue with darker color contains neuron cell bodies and their dendritesdivisions are called horns and the divisions of the white matter are called columns (funiculi)columns contain groups of axons called nerve tracts central canal runs down the entire length of the spinal cord through the center of the gray matter White matter - the outer tissue contains myelinated axons18Spinal Cord - Ascending and Descending Tracts Function of the spinal cord is to carry sensory information to and from the brain Ascending tracts - carry sensory information up to the brain Descending tracts - carry motor information down from the brain to muscles and glands 19Spinal Cord ReflexesFunction of the spinal cord is to participate in reflexes Reflex - a predictable, automatic response to stimuli Receptor Sensory NeuronsEffectorsMotor NeuronsInterneurons 20Apply Your KnowledgeWhat are the descending tracts of the spinal cord?21Apply Your Knowledge -AnswerDescending tracts carry motor information down from the brain to muscles and glands What do the descending tracts of the spinal cord do?22The Brain Four Parts: Cerebrum Diencephalons Brain stem Cerebellum 23The Brain - CerebrumLargest part of the brain Two halves cerebral hemispheres Thick bundle of nerve fibers called the corpus callosum connect the two hemispheres LobesFrontal Parietal Temporal Occipital CortexVentricles 24The Brain - DiencephalonsThalamus - relay station for sensory information that heads to the cerebral cortex for interpretation Hypothalamus - maintains balance by regulating many vital activities such as heart rate, blood pressure, and breathing rate. Located between the cerebral hemispheres and is superior to the brain stem 25The Brain - Brain stemMidbrain - controls both visual and auditory reflexes Pons - regulates breathing Medulla oblongata - controls many vital activities such as heart rate, blood pressure, and breathing Connects the cerebrum to the spinal cord26The Brain - Cerebellum Inferior to the occipital lobes of the cerebrumPosterior to the pons and medulla oblongata Coordinates complex skeletal muscle contractions that are needed for body movements 27Apply Your KnowledgeThe patient has had trauma to the pons of the brain. What type of problems would you see in the patient?28Apply Your Knowledge -AnswerThe patient could not breath without assistance.The patient has had trauma to the pons of the brain. What type of problems would you see in the patient?29Preventing Brain and Spinal Cord InjuriesAlways wear appropriate protective gear while playing any sport.Avoid diving headfirst into unknown waters.Always wear your safety belt.Follow safety rules on playgrounds.Make sure children use car seats that are appropriate for their age and weight.Be familiar with ways to get help quickly in emergencies.Follow traffic rules and signs while walking, biking, or driving.30Peripheral Nervous SystemConsists of nerves that branch off the CNS. These nerves are called peripheral nerves and are classified in 2 types:Cranial nerves Spinal nerves 31Cranial Nerves – 12 SetsI.   Olfactory nerves carry smell information to the brain for interpretation.II.  Optic nerves carry visual information to the brain for interpretation.III. Oculomotor nerves are found within the muscles that move the eyeball, eyelid and iris. IV. Trochlear nerves act in the muscles that move the eyeball.32Cranial Nerves (cont.)V.  Trigeminal nerves carry sensory information from the surface of the eye, the scalp, facial skin, the lining of the gums, and the palate to the brain for interpretation. They also are found within the muscles needed for chewing.VI. Abducens nerves act in the muscles that move the eyeball.33VII. Facial nerves are found in the muscles of facial expression as well as in the salivary and tear glands. These nerves also carry sensory information from the tongue. VIII. Vestibulocochlear nerves carry hearing and equilibrium information from the inner ear to the brain for interpretation.Cranial Nerves (cont.)34IX. Glossopharyngeal nerves carry sensory information from the throat and tongue to the brain for interpretation. They also act in the muscles of the throat.X. Vagus nerves carry sensory information from the thoracic and abdominal organs to the brain for interpretation. These nerves are also found within the muscles in the throat, stomach, intestines and heart.Cranial Nerves (cont.)35XI. Accessory nerves are found within the muscles of the throat, neck, back, and voice box.XII. Hypoglossal nerves are found within the muscles of the tongue.  Cranial Nerves (cont.)36Spinal NervesSpinal nerves are peripheral nerves that originate from the spinal cord.  31 pairs of spinal nerves: 8 pairs of cervical nerves (C1 through C8) 12 pairs of thoracic nerves (T1 through T12) 5 pairs of lumbar nerves (L1 through L5) 5 pairs of sacral nerves (S1 through S5) One pair of coccygeal nerves (Co)37Somatic and Autonomic Nervous Systems Consists of nerves that connect the CNS to skin and skeletal muscle.Somatic nervous system - “voluntary” nervous system because it controls skeletal muscles, which are under voluntary control. Autonomic nervous system consists of nerves that connect the CNS to organs and other structures such as the heart, stomach, intestines, glands, blood vessels, and bladder (among others) - “involuntary” nervous system. 38Neurologic TestingTypical neurologic examination: State of consciousness Reflex activity Speech patterns Motor patterns 39Diagnostic ProceduresLumbar Puncture Magnetic Resonance Imaging (MRI). Positron Emission Tomography (PET) Scan Computerized Tomography (CT) Scan Electroencephalogram (EEG) X Ray Common diagnostic procedures40Reflex Testing Biceps reflex - The absence of this reflex may indicate spinal cord damage in the cervical region. Knee reflex - The absence of this reflex may indicate damage to lumbar or femoral nerves. Abdominal reflexes - These reflexes are used to evaluate damage to thoracic spinal nerves.41Apply Your KnowledgeWhat is the somatic nervous system?42Apply Your Knowledge -AnswerSomatic nervous system (“voluntary”) nervous system because it controls skeletal muscles, which are under voluntary control What is the somatic nervous system?43Diseases and Disorders of the Nervous SystemAlzheimer's Disease - a progressive, degenerative disease that occurs in the brain. Amyotrophic Lateral Sclerosis (ALS) - a fatal disorder characterized by the degeneration of neurons in the spinal cord and brain.Bell's Palsy is a disorder in which facial muscles are very weak or totally paralyzed. 44Diseases and Disorders of the Nervous System (cont.)Brain Tumors and Cancers - abnormal growths in the brain Epilepsy and Seizures - occur when parts of the brain receive a burst of electrical signals that disrupt normal brain functioning.Guillain-Barré Syndrome - a disorder in which the body's immune system attacks part of the peripheral nervous system. 45Diseases and Disorders of the Muscular SystemHeadaches affect almost everyone at some point in their life Tension HeadachesClusterMigraine Multiple Sclerosis (MS) - a chronic disease of the central nervous system in which myelin is destroyed.Stroke - brain cells die due to an inadequate blood flow. 46Diseases and Disorders of the Muscular System (cont.)Meningitis is an inflammation of the meninges.Neuralgias are a group of disorders commonly referred to as nerve pain Parkinson's Disease is a motor system disorder Sciatica occurs when the sciatic nerve is damaged.47Apply Your KnowledgeThe doctor has told your patient she has had a stroke. How would you explain this to the family?48Apply Your Knowledge -AnswerA stroke happens when brain cells are damaged or die due to an inadequate blood flow. The doctor has told your patient she has had a stroke. How would you explain this to the family?49Summary Medical Assistant Functions of the nervous system include detecting and interpreting sensory information, making decisions about that information, and responding to and carrying out motor functions based on those decisions. Knowledge of this system is essential when assisting the physician during a neurologic exam.50End of ChapterEnd of Chapter 51