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