The Nervous System Health Science 1 Ms. Marta Valdes, Instructor Organs and Divisions of the Nervous System
Central nervous system (CNS)brain and spinal cord Peripheral nervous system (PNS)all nerves Division Flowchart Neuron Neuron-basic cell of the nervous system consist of 3 main parts dendrites: conduct impulses to cell body of neuron cell body & axon: conducts impulses away from cell body of neuron 3 main types of nerve cells
Sensory neuron Interneuron Motor neuron Sensory neurons Functionsensory: conduct impulses to the spinal cord and brain Carries impulses from receptors e.g. pain receptors in skin to the CNS( brain or spinalcord) Interneuron Carries impulses from sensory nerves to motor nerves.
Interneuron: conduct impulses from sensory neurons to motor neurons Carries impulses from sensory nerves to motor nerves. Glia Cell Glia (neuroglia) - Support cells, bringing the cells of nervous tissue together structurally and functionally Disorders of the Nervous System
Disorders of nervous tissue Multiple sclerosischaracterized by myelin loss in central nerve fibers and resulting conduction impairments Tumors General name for nervous system tumors is neuroma Most neuromas are gliomas, glial tumors Normal & Partially Destroyed Myelin by Multiple Sclerosis Nerves Nervebundle of peripheral axons White matterbrain or cord tissue composed primarily of myelinated axons (tracts) Gray matterbrain or cord tissue composed primarily of cell bodies and unmyelinated fibers Nerves Nerve coveringsfibrous connective tissue
Endoneuriumsurrounds individual fibers within a nerve Perineuriumsurrounds a group (fascicle) of nerve fibers Epineuriumsurrounds the entire nerve Nerve Impulses Definitionself-propagating wave of electrical disturbance that travels along the surface of a neuron membrane Mechanism A stimulus triggers the opening of Na+ channels in the plasma membrane of the neuron Inward movement of positive sodium ions leaves a slight excess of negative ions outside at a stimulated point; marks the beginning of a nerve impulse Impulse Pathway The Synapse Definitionchemical compounds released from axon terminals (of a presynaptic neuron) into a synaptic cleft Neurotransmitters bind to specific receptor molecules in the membrane of a postsynaptic neuron, opening ion channels and thereby stimulating impulse conduction by the membrane Transmission of Impulse (conduction)Through the Synapse with Neurotransmitters The Synapse (Neurotransmitters)
Names of neurotransmitters Acetylcholine-1st neurotransmitter to be identified, lowers heart rate Catecholamines - norepinephrine, dopamine, and serotonin Endorphins-"endorphin rush" refers to feelings of exhilaration brought on by pain, danger, or other forms of stress Enkephalins- regulate "the neural processes of encoding and processingnoxious stimuli that have the potential to damage tissue Nitric oxide (NO)-signaling moleculeinvolved in many physiological and pathological processes (nitroglycerine) Example Parkinsons diseasecharacterized by abnormally low levels of dopamine in motor control areas of the brain; patients usually exhibit involuntary trembling and muscle rigidity Depression -characterized by abnormally low levels of serotonin. Signs of Parkinsons Disease Central Nervous System
Divisions of the brain Brainstem Consists of three parts of brain; named in ascending order, they are the medulla oblongata, pons, and midbrain Functiongray matter in the brainstem functions as reflex centers (for example, for heartbeat, respirations, and blood vessel diameter); sensory tracts in the brainstem conduct impulses to the higher parts of the brain; motor tracts conduct from the higher parts of the brain to the spinal cord Divisions of the Brain Central Nervous System
Diencephalon Structure and function of the hypothalamus Consists mainly of the posterior pituitary gland, pituitary stalk, and gray matter Acts as the major center for controlling the ANS; therefore, helps control the functioning of most internal organs Controls hormone secretion by anterior and posterior pituitary glands; therefore it indirectly helps control hormone secretion by most other endocrine glands Contains centers for controlling appetite, wakefulness, pleasure, etc. Central Nervous System
Structure and function of the thalamus Dumbbell-shaped mass of gray matter in each cerebral hemisphere Relays sensory impulses to cerebral cortex sensory areas In some way produces the emotions of pleasantness or unpleasantness associated with sensations Central Nervous System
Cerebellum Second largest part of the human brain Helps control muscle contractions to produce coordinated movements so that we can maintain balance, move smoothly, and sustain normal postures Recent evidence shows the cerebellum may also have wider coordinating effects, assisting the cerebrum and other regions of the brain Central Nervous System
Cerebrum Largest part of the human brain Outer layer of gray matter is the cerebral cortex; made up of lobes; composed mainly of dendrites and cell bodies of neurons Interior of the cerebrum composed mainly of white matter (that is nerve fibers arranged in bundles called tracts) Functions of the cerebrummental processes of all types, including sensations, consciousness, memory, and voluntary control of movements Central Nervous System
BRAIN DISORDERS Destruction of brain tissue Cerebrovascular accident (CVA)hemorrhage from or cessation of blood flow through cerebral blood vessels; a stroke Cerebral palsycondition in which damage to motor control areas of the brain before, during, or shortly after birth causes paralysis (usually spastic) of one or more limbs Central Nervous System
Dementiasyndrome that includes progressive loss of memory, shortened attention span, personality changes, reduced intellectual capacity, and motor control deficit Alzheimer disease (AD)brain disorder of the middle and late adult years characterized by dementia Huntington disease (HD)inherited disorder characterized by chorea (purposeless movement) progressing to severe dementia HIV (also causes AIDS) can infect neurons and thus cause dementia Central Nervous System
Seizure disorders Definition Seizuresudden burst of abnormal neuron activity that results in temporary changes in brain function Epilepsymany forms, all characterized by recurring seizures Petit mal Grand mal Electroencephalogram (EEG)graphic representation of voltage changes in the brain used to evaluate brain activity Central Nervous System
Spinal cord Outer part is composed of white matter made up of many bundles of axons called tracts; interior composed of gray matter made up mainly of neuron dendrites and cell bodies Functions as the center for all spinal cord reflexes; sensory tracts conduct impulses to the brain, and motor tracts conduct impulses from the brain Central Nervous System
Coverings and fluid spaces of the brain and spinal cord Coverings Cranial bones and vertebrae Cerebral and spinal meningesthe dura mater, arachnoid mater, and the pia mater Fluid spacessubarachnoid spaces of meninges, central canal inside cord, and ventricles in brain Peripheral Nervous System
Cranial nerves Twelve pairsattached to undersurface of the brain Connect brain with the neck and structures in the thorax and abdomen Spinal nerves Structurecontain dendrites of sensory neurons and axons of motor neurons Functionconduct impulses necessary for sensations and voluntary movements Peripheral Nervous System
Peripheral nerve disorders Neuritisgeneral term referring to nerve inflammation Sciatica is inflammation of the sciatic nerve that innervates the legs Neuralgia, or muscle pain, often accompanies neuritis Trigeminal neuralgiarecurring episodes of stabbing pain along one or more branches of the trigeminal (fifth cranial) nerve in the head Bells palsyparalysis of facial features resulting from damage to the facial (seventh cranial) nerve Peripheral Nervous System
HERPES ZOSTER OR SHINGLES Viral infection caused by chickenpox virus that has invaded the dorsal root ganglion and remained dormant until an episode of shingles Usually affects a single dermatome, producing characteristic painful plaques or vesicles Autonomic Nervous System
Autonomic nervous systemmotor neurons that conduct impulses from the central nervous system to cardiac muscle, smooth muscle, and glandular epithelial tissue; regulates the bodys automatic or involuntary functions Autonomic neuronspreganglionic autonomic neurons conduct from spinal cord or brainstem to an autonomic ganglion; postganglionic neurons conduct from autonomic ganglia to cardiac muscle, smooth muscle, and glandular epithelial tissue Autonomic Nervous System
Autonomic or visceral effectorstissues to which autonomic neurons conduct impulses (i.e., cardiac and smooth muscle and glandular epithelial tissue) Autonomic Nervous System
Composed of two divisions: the sympathetic system and the parasympathetic system Autonomic conduction paths Consist of two-neuron relays (i.e., preganglionic neurons from the central nervous system to autonomic ganglia, synapses, postganglionic neurons from ganglia to visceral effectors) In contrast, somatic motor neurons conduct all the way from the CNS to somatic effectors with no intervening synapses Autonomic Nervous System
Sympathetic nervous system Function Serves as the emergency or stress system, controlling visceral effectors during strenuous exercise and strong emotions (anger, fear, hate, or anxiety) Group of changes induced by sympathetic control is called the fight-or-flight response Autonomic Nervous System
Parasympathetic nervous system Function Dominates control of many visceral effectors under normal, everyday conditions Divisions of the ANS Sympathetic - fight or flight
Catabolic (expend energy) Mass activation prepares for intense activity. Heart rate (HR) increases. Bronchioles dilate. Blood [glucose] increases. Parasympathetic - feed & breed, rest & digest Maintain homeostasis Normally not activated as a whole, stimulation of separate parasympathetic nerves. Relaxing effects: Decreases heart rate. Dilates visceral blood vessels. Increases digestive activity. Dual innervations of many organs having a brake and an accelerator provides more control Activity: Paras. vs. Symp. Autonomic Nervous System
Autonomic neurotransmitters Cholinergic fibersrelease acetylcholine Adrenergic fibersrelease norepinephrine (noradrenaline) Autonomic Nervous System
Autonomic nervous system as a whole Regulates the bodys automatic functions in ways that maintain or quickly restore homeostasis Many visceral effectors are doubly innervated (that is, they receive fibers from parasympathetic and sympathetic divisions and are influenced in opposite ways by the two divisions) Autonomic Nervous System
Disorders of the autonomic nervous system Stress-induced disease Prolonged or excessive response to stress can disrupt normal functioning throughout the body Examples of stress-induced conditions Heart disease Digestive problems Reduced resistance to disease Tumors Neuroblastomahighly malignant tumor of the sympathetic nervous system, primarily affecting young children Neurological Conditions
Multiple sclerosis Cerebral Palsy Bells palsy Migraine ADHD Wernicke-Korsakoff Syndrome Alzheimer's Disease Encephalitis Epilepsy Syncope Febrile Seizures Parkinsons Disease Phineas Cage CHOOSEA TOPIC FROM THE LIST OR ON YOUR OWN Research and write a 3 page APA 6th edition research paper. I will explain the rules for writing in APA. You can find additional information and an example of the format in the class website