Chapter 10 THE NERVOUS SYSTEM

OBJECTIVES 1.Describe the functions and structures of the nervous system. 2.Identify the major divisions of the nervous system and describe the structures of each by location and function. 3.Identify the medical specialists who treat disorders of the nervous system. 4.Recognize, define, spell, and pronounce terms related to the pathology and diagnostic and treatment procedures of the nervous system. 5.Recognize, define, spell, and pronounce terms related to the pathology and diagnostic and treatment procedures of the mental health disorders.

Key Word Parts Ambul/o Cephal/o Concuss/o Contus/o Echo- Encephal/o -esthesia Klept/o Mening/o Myel/o Narc/o Neur/i, neur/o -phobia Psych/o Somn/o

Structures of The Nervous System Coordinates and controls all bodily activities. 1.Brain 2.Spinal Cord 3.Nerves 4.Sensory Organs

Sensory Organs Receive external stimulation and transmit it to the sensory neurons.

Three Parts of Nervous System Central Nervous System (CNS) –Brain and spinal cord Peripheral Nervous System (PNS) –12 pairs of cranial nerves –31 pairs of spinal nerves Autonomic Nervous System (ANS) –Peripheral nerves and ganglia on either side of the spinal cord

The Nerves One or more bundles of neuron cells (impulse carrying fibers) that connect the brain and the spinal cord with other parts of the body. –Tract –Ganglion –Plexus –Innervation –Receptors –Stimulus –Impulse

Reflexes Automatic, involuntary response to some change. –Heart rate –Breathing –Blood pressure Coughing, sneezing and reactions to pain stimuli

Neuron The basic part Of the nervous system

Types of Neurons basic cell of the nervous system A -Afferent neurons Sensory neurons They emerge from the skin or sense organs and carry impulses toward the brain and spinal cord. C -Connecting neurons Associative neurons They carry impulses from one neuron to another. E -Efferent neurons Motor neurons They carry impulses away from the brain and spinal cord and toward the muscles and glands.

Neuron Parts Dendrites - receive impulses and conduct them to the cell body Axon – conducts impulses away from the nerve cell Terminal end fibers – lead the nervous impulse away from the axon and toward the synapse.

Synapse – the space between two neurons Neurotransmitter – chemical messenger that transmit messages between nerve cells 30 neurotransmitters have been identified Neuroglia – glial cells, supportive and connective cells (nerve cells)

Neurotransmitters and their functions: 1.Acetylcholine – released at some synapses in the spinal cord and at neuromuscular junctions, it influences muscle actions. 2.Dopamine – released in the brain thought to cause some forms of psychosis and abnormal movements such as Parkinson’s disease. 3.Endorphins – released within the spinal cord; inhibits pain impulses. 4.Serotonin – released in the brain; has roles in sleep and pleasure recognition.

The Central Nervous System Brain and the spinal cord are protected by the: –Meninges Dura mater Arachnoid membrane Pia mater –Cerebrospinal fluid (CSF) – clear, colorless, watery fluid Nourish, cool, and cushion the brain and spinal cord from shock or injury

Three Layers of Meninges (brain) Dura Mater –Thick, tough, outermost membrane –Epidural space –Subdural space Arachnoid Membrane –Subarachnoid space Contains cerebrospinal fluid Pia Mater –Nearest to the brain and spinal cord –Connective tissue with rich supply of blood vessels

Structures of the Brain Cerebrum- responsible for the highest level of thought. Thalamus - monitors sensory stimuli by suppressing some and manifying others. Hypothalamus – controls vital body functions. Cerebellum – coordinates muscular activity for smooth and steady movements. Pons – nerves cross over so that one side of the brain controls the opposite side of the body. Medulla oblongata – controls the basic vital functions of life.

The Brainstem Midbrain Pons –Nerves that control the left side of the body are found in the right side and vice versa Medulla Oblongata –Lowest part of the brainstem

The Cerebrum the largest and upper-most portion of the brain responsible for all thought, judgment, memory, association, and discrimination Divided into left and right hemisphere –Each hemisphere divided into four lobes Frontal lobe – motor functions Parietal lobe – receives and interprets nerve impulses from the sensory receptors Occipital lobe – controls eyesight Temporal lobe – control the senses of hearing and smell

Regulatory Functions of the Hypothalamus Regulates heart rate, BP, respiratory rate, and digestive tract activity. Regulate emotional responses and behavior. Regulate body temperature. Regulate food intake by controlling hunger sensations. Regulate water balance and thirst. Regulate sleep-wake cycles. Regulate endocrine system activity.

Autonomic controls the involuntary actions of the body. Sympathetic prepares the body for emergency and stressful situations by increasing the breathing rate, heart rate, and blood flow to muscles. Parasympathetic returns the body to normal after a stressful response.

. The Spinal Nerves 31 pairs of spinal nerves extending from the spinal cord Receptors –Eyes, ears, skin, nose, and taste buds Reflex –Autonomic, involuntary response to some change

The Peripheral Nervous System – 12 Cranial Nerves I.Olfactory II.Optic III.Oculomotor IV.Trochlear V.Trigeminal VI.Abducens VII. Facial VIII.Acoustic IX. Glossopharyngeal X. Vagus XI. Accessory XII. Hypoglossal

Medical Specialties Related to the Nervous System Anesthesiologist Anesthetist Neurologist Neurosurgeon Psychiatrist Psychologist

Pathology of the Nervous System (see the text) Head and Meninges –Cephalalgia –Migraine Headache –Encephalocele –Hydrocephalus –Meningocele –meningitis

Disorders of the Brain Alzheimer’s disease Cognition Encephalitis Parkinson’s disease Tetanus

Brain injuries Amnesia Concussion Cerebral contusion Cranial hematoma

Altered States of Consciousness Conscious Syncope Lethargy Stupor Coma Delirium Dementia

Strokes CVA Transient ischemic attack (TIA) Ischemic stroke Cerebral thrombosis Aphasia Hemorrhagic stroke (bleed)

Sleep Disorders Insomnia Narcolepsy Somnambulism Somnolence

Spinal Cord Myelitis Myelosis Multiple sclerosis Poliomyelitis Postpolio Radiculitis (pinched nerve) Spinal cord injuries

Nerves Amyotrophic lateral sclerosis(Lou Gehrig’s disease) Bell’s palsy Guillain-Barre syndrome Peripheral neuropathy Tic douloureux Sciatica High Spirited: Dr. William Kuhlman now must communicate with a pencil and paper because of the effects of ALS, or Lou Gehrig's disease. Although Kuhlman's mind is as sharp as ever, he can't talk and barely has use of his hands.

Abnormal Sensations Causalgia Hyperesthesia Paresthesia Cerebral Palsy

Epilepsy Grand mal epilepsy Petit mal epilepsy Epileptic aura

Mental Health Developmental Disorders Substance-Related Disorders Schizophrenia and other Psychotic Disorders Mood Disorders Panic Disorders Anxiety Disorders Phobias Somatoform Disorders Impulse-control disorders Personality Disorders Other conditions

Diagnostic Procedures of the Nervous System Computed tomography or CAT scan MRI Echoencephalography Electroencephalography (EEG) Encephalography Myelography LOC

Treatment Procedures of the Nervous System Medications to Treat Mental Disorders –Tranquilizers –Antidepressant –Antipsychotic –Psychotropic drugs Pain control –Transcutaneous electronic nerve stimulation (TENS) –Analgesic –Nonnarcotic analgesics –Narcotic analgesics Sedative and Hypnotic meds –Hypnotic –Barbiturate –Amobarbital –Phenobarbital –Anticonvulsant Anesthesia –Topical, local, regional –Epidural –Spinal –General

Treatment… Brain and Head –Electroshock therapy (ECT) –Lobectomy –Thalamotomy Nerves –Neurectomy –Neuroplasty –Neurorrhaphy –Neurotomy

Key Word Parts Ambul/o Cephal/o Concuss/o Contus/o Echo- Encephal/o -esthesia Klept/o Mening/o Myel/o Narc/o Neur/i, neur/o -phobia Psych/o Somn/o

The Nervous System THE END