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Nervous System. Chapter 14 Medical Terminology. Nervous System. System of conducting tissues (nerves) that receive information from the environment and control both voluntary and involuntary functions of the body and consciousness. Cellular Anatomy. Two types of cells: Neurons
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Nervous System Chapter 14 Medical Terminology
Nervous System • System of conducting tissues (nerves) that receive information from the environment and control both voluntary and involuntary functions of the body and consciousness
Cellular Anatomy • Two types of cells: • Neurons • Transmit impulses (conduct) • Sensory neurons (afferent) • Motor neurons (efferent) • Mixed (both afferent and efferent) • Neuroglia • Supporting cells
Neurons: Structure • Cell body • Nucleus, cytoplasm, organelles • Dendrites • Projections of the cell body • Receive and carry impulses • Axons • Single, long projections from cell body • Also transmit impulses
Neurons: Structures • Myelin sheath • Covering outer layer of axon • Lipid layer • White color • Makes up the white matter in CNS • Acts as an insulator • Speeds up impulse transmission in the axon
More about myelin • Unmyelinated structures • Appear gray, gray matter • CNS and spinal column • Peripheral nerve (PNS) • Schwann cell = myelin sheath • Neurilemma/neurolemma = this thin layer • Node of Ranvier = space between Schwann cells
Neurons: Other terms • Synapse • Space between neurons • Between axon terminal and dendrites of adjacent neurons • Axon terminal • Neurotransmitter
Neuroglia: Four Types Astrocytes star shaped support cells for neurons form capillary sheaths (BBB) Oligodentrocytes help in CNS myelin development Microglia: phagocytes
Neuroglia: Four Types • Ependyma • Ciliated cells • Line cavities in CNS (ventricles) • Help CSF circulation
Nervous System Anatomy • Central Nervous System (CNS) • Brain • Spinal Cord • Peripheral Nervous System (PNS) • 12 pairs of cranial nerves (CN I-XII) • From basilar surface of brain • 31 pairs of spinal nerves • From spinal cord
CNS Anatomy: Brain Meninges three protective membranes around CNS Cerebrum corpus callosum structures connecting hemispheres gyri (gyrus) = folds or convolutions sulci (sulcus) =fissues, furrows
CNS Anatomy: Brain • Lobes of the brain: • Frontal • Parietal • Temporal • Occipital • Insula
Brain Anatomy • Cerebral Cortex • Thin outer layer • Gray matter due to millions of cell bodies • Rest of cerebrum is myelinated axons (white) • Cerebrum: Functions • Sensory perception, interpretation • Voluntary movement, language, memory • Emotional aspects of behavior
Other Structures in the Brain: • Cerebellum • Posterior aspect • Coordinates and refines movement • Balance and equilibrium
Other Brain Structures • Diencephalon (interbrain) • Thalamus • Receives & transmits all sensory info except smell to the cerebrum • Transmits impulses from cerebrum to efferents • Hypothalamus • Coordinates autonomic impulses • Temperature regulation • Control of endocrine system
Other Brain Structures: • Brainstem: control of respiration, cardiac activity • Pathway between brain and spinal column • Midbrain (mesencephalon) • Medulla (oblongata) • pons
CNS structures: Spinal Cord • Ascending tracts • Bring sensory input to CNS • Descending tracts • Send impulses to muscles, end organs • Cross-section: • Gray matter-inner part of cord • White matter—outer part of cord • Spinal cavity • Spinal nerves exit from intervertebral spaces • Cauda equina
CNS: Meninges • Dura • Outermost, very fibrous • Subdural space: filled with serous fluid • Arachnoid • Thinner, looks like a spider web • Subarachnoid space: contains CSF • Pia • Innermost layer, also thin • Contains blood vessels and lymphatics
Peripheral Nervous System (PNS) • Cranial Nerves • Spinal Nerves • Somatic Nervous system (SNS) • Autonomic Nervous system (ANS)
PNS: Cranial Nerves • Exit mostly from base of the brain • Named and denoted by I through XII • Mostly involve facial, eye, mouth movement and sensation and the special senses of hearing, taste, sight • Are afferent, efferent, and mixed nerves
PNS: Spinal Nerves • Exit from spinal cord and go to muscles and organs • Each has two attachments to spinal cord: • Anterior root: motor fibers • Posterior root: sensory fibers
Somatic Nervous System (SNS) • Voluntary functions • Mostly supplies skeletal muscles
Autonomic Nervous System (ANS) • Supplies nerves (ennervates) involuntary functions • Ennervates glands, smooth & cardiac muscles, etc • Sympathetic system • Fight or flight • Parasympathetic system • Functions that are the opposite, resting
Medical Word Elements • Cerebro: cerebrum • Cranio: cranium or skull • Encephalo: brain • Kinesio: movement • Ganglio: knot or mass (a ganglion) • Narco: sleep, stupor • Neuro: nerve
Medical word elements: • Radiculo: nerve root (radiculopathy) • Theco: sheath (intrathecal) • Tono: tension (tonometry, dystonic)
Medical Word Elements • Others are from anatomic structure names • Ventriculo: ventricles • Thalamo: thalamus • Myelo: spinal cord or bone marrow • Meningo: meninges • Glio: neuroglial tissue • Dentro: treee-like
Suffixes: Neuro • -algia or algesia: pain • -asthenia or –paresis: weakness, disability • -esthesia: feeling • -kinesia: movement • -lepsy: seizure (epilepsy, narcolepsy) • -phasia: speech • -plegia: paralysis
Suffixes: Neuro • -plexy: stroke • -taxia: coordination (ataxia) • -trophy: development
Prefixes: Neuro • Contra- = against/opposite • Pachy- = thick • Para- = near • Syn- = together, joined
Neurological Pathology • Common symptoms: • Pain (head, neck, back, periphery) • Abnormal movements • Gait abnormalities • Disturbances of special senses • Speech abnormalities • Altered level of consciousness • Focal weakness • seizures
Bell’s Palsy • Facial paralysis (unilateral usually)) • Involves CN VII • Herpes viral infection • Usually transient • Facial weakness and numbness, problems with blink reflex and speech
Cerebrovascular Disease • Cerebrovascular accident (CVA) or stroke • Focal loss of function due to loss of blood supply • Lasts more than 24 hours • Causes: • Ischemic: due to thrombus or carotid emboli (75%) • Hemorrhagic (25%) • Extrinsic compression of blood vessel (rare)
Cerebrovascular Disease • Typical CVA symptoms: • Anterior stroke: • Hemiparesis or hemiplegia • Aphasia or dysphasia • Partial loss vision/ visual field • Posterior stroke: • Balance problems, ataxia, vertigo
Cerebrovascular Disease • Transient Ischemic Attack (TIA) • Focal symptoms like a CVA, lasting less than 24 hours • Typical symptoms: weakness or clumsiness of upper extremity, visual field loss, hemiparesis of the face, paresthesias of upper extremities • Indicates risk of CVA within next year
Seizure Disorders • Nerve conduction dysrhythmias • Epilepsy = chronic seizure disorder • Generalized Sz (gran mal, tonic clonic) • Movements of entire body • unconsciousness • Partial Sz (focal) (Jacksonian) • Petit mal (absence Sz)
Seizure Disorders: Causes • Congenital anomalies • Brain injury • Metabolic disease • Brain tumors • Genetic disorders • Vascular anomalies
Seizures: • Are often the symptom of the disease • Status epilepticus • Life-threatening • Lengthy or muliple Sz • Electroencephalography • Magnetoencephalography • Rx: antiepileptic meds
Parkinson Disease • Parkinsonism also • A movement disorder • Progressive neurological disease affected the movement control centers of the brain • Deficiency of dopamine, a neurotransmitter in the brain • Rx: L-dopa administration
Parkinson Disease • Symptoms: • Bradykinesia or hypokinesia • Uncontrollable shaking of head • Shuffling gait, pill rolling of fingers • Tremors • Some stiffness, • Mask-like facial expressions
Multiple Sclerosis (MS) • Progressive demyelinating disease of CNS • Impeding nerve conduction • Disease of young adults, usually females • Autoimmune disease suspected, fatal • Symptoms: • Tremors, bradykinesias • Visual disturbances, muscle weakness
Alzheimer Disease • Progressive, fatal neurological degenerative disease of the elderly • Memory loss, cognitive dysfunction, anxiety, decline in social skills and ADL • Plaques develop in cerebral cortex • Common cause of senile dementia in US • Some medications slow progress of disease
Mental Illnesses • Alterations in behavior, mood, thought • Some general terminology: • Phobia • Delusion • Hallucinations • Obsessive compulsive disorders (OCD) • Psychiatrist or clinical psychologist
Categories of Mental Illnesses • Affective (mood) disorders • Mania • Depression • Manic-depressive disorder (bipolar disorder) • Eating disorders • Anorexia nervosa • Bulimia nervosa
Categories of Mental Illnesses • Anxiety disorders • Panic attacks • Attention-deficit hyperactivity disorder (ADHD) • Schizophrenia (thought disorder)
Neuro Oncology • Most intracranial neoplasms are primary brain tumors • Papilledema = classic sign of intracranial tumor, slowly rising ICP • Metastatic tumors to brain • Fairly common, slower growing than their primary tumors, more easily resected than primary CNS tumors
Neuro Infections • Meningitis • Bacterial = most rapid, meningococcal • Viral or fungal • Encephalitis • Usually viral • Brain or Spinal Cord abscesses • Usually bacterial • Parasitic also possible
Intracranial Hemorrhages • Epidural hemorrhage • Subdural hemorrhage • Subarachnoid hemorrhage • Intracerebral hemorrhage
Epidural Hemorrhage • Arterial bleeding • Often involves parietal skull fracture • Disrupts the middle meningeal artery • Famous “lucid interval” symptoms • Usual symptoms: headache, unconsciousness, unilateral weakness or abnormal reflexes
Subdural Hemorrhage • Venous bleeding from the bridging veins • Slower bleed • Symptoms: similar to EDH but no lucid interval
Subarachnoid Hemorrhage • Thin filmy layer of blood around the brain and cord • May be spontaneous or due to trauma • Symptoms and Signs: • “the worst headache of my life” • Sudden onset • Nuchal rigidity • Photophobia, nausea, vomiting