FUNCTIONS OF THE NERVOUS SYSTEM
1. COORDINATE
VOLUNTARY ACTIVITIES, E.G., SPEECH, MUSCLE MOVEMENT, TASTE, SEE RESPOND TO
DANGER
2. INVOLUNTARY
ACTIVITIES - E.G., HORMONE SECRETION, BRAIN FUNCTION
ANATOMY AND PHYSIOLOGY
MAJOR
DIVISIONS
CENTRAL NERVOUS SYSTEM
1. BRAIN
2. SPINAL CORD
PERIPHERAL NERVOUS SYSTEM
1. CRANIAL
NERVES - 12 PAIRS IN THE HEAD AND NECK, MAINLY VOLUNTARY MOVEMENTS
2. SPINAL
NERVES - 31 PAIRS CARRYING MESSAGES BETWEEN THE SPINAL CORD AND CHEST, ABDOMEN,
EXTREMITIES; MAINLY VOLUNTARY MOVEMENTS
3. AUTONOMIC
NERVOUS SYSTEM - INVOLUNTARY/AUTOMATIC FUNCTIONS
a. SYMPATHETIC
- STIMULATION IN TIMES OF STRESS, E.G., INCREASED HEART RATE, DILATED AIRWAYS,
INCREASE BLOOD PRESSURE, SLOW DIGESTION
b. PARASYMPATHETIC
- BALANCE FOR SYMPATHETIC REACTIONS, I.E., SLOW HEART RATE, LOWER BLOOD
PRESSURE
NEURON - INDIVIDUAL NERVE CELL (MICROSCOPIC);
PARENCHYMAL TISSUE NERVE - BUNDLES OF NEURONS (MACROSCOPIC)
DENDRITES -
BRANCHING FIBERS OF NEURON WHICH RECEIVE A STIMULI CAUSING CHANGE IN ELECTRICAL
CHARGE AND BEGINS NERVOUS IMPULSE (ONE DIRECTION ONLY)
CELL BODY - CONTAINS CELL NUCLEUS
AXON - CARRIES IMPULSE AWAY FROM CELL BODY
MYELIN SHEATH - FATTY TISSUE COVERING SOME AXONS; GIVES WHITE COLOR
NEURILEMMA - COVERS MYELIN SHEATH OF
PERIPHERAL NERVES
TERMINAL END FIBERS - AT END OF THE AXON
SYNAPSE - SPACE BETWEEN NEURONS
NEUROTRANSMITTER - FACILITATES TRANSFER OF
NERVE IMPULSES FROM ONE NEURON TO ANOTHER, E.G., ACETYLCHOLINE, EPINEPHRINE
(ADRENALIN), DOPAMINE
AFFERENT - CARRY IMPULSES FROM SKIN, EYE, ETC. TO BRAIN AND
SPINAL CORD
EFFERENT - CARRY IMPULSES FROM BRAIN AND
SPINAL CORD TO ORGANS
NEUROGLIA - INTERSTITIAL TISSUE; SUPPORTIVE AND
CONNECTIVE, PROTECTION, DO NOT TRANSMIT NERVOUS IMPULSES
1. ASTROCYTES
(ASTROGLIA) - STAR SHAPED, TRANSPORT H2O AND SALTS
2. MICROGLIAL
- VERY SMALL WITH BRANCHING PROCESSES; PHAGOCYTES
3. OLIGODENDROGLIA
- SCANTY DENDRITES; RESPONSIBLE FOR
a. PRODUCTION
OF MYELIN
b. ASSOCIATED
WITH BLOOD VESSELS HELPING REGULATION OF PASSAGE OF HARMFUL MATERIALS INTO THE
BRAIN
"BLOOD-BRAIN BARRIER"
BRAIN
CEREBRUM - LARGEST PART; THOUGHT,
JUDGEMENT, MEMORY, PERCEPTION, MOTOR IMPULSES
MENINGES - 3
LAYERS OF CONNECTIVE TISSUE SURROUNDING THE BRAIN AND SPINAL CORD
1. DURA
MATER - OUTERMOST THICK, TOUGH LAYER CONTAINING CHANNELS FOR BLOOD TO ENTER
BRAIN TISSUE
2. SUBDURAL
SPACE - MANY BLOOD VESSELS BELOW DURA
3. ARACHNOID
MEMBRANE - WEB LIKE ALLOWING SPACE FOR FLUID BETWEEN 2ND AND 3RD MEMBRANE
4. SUBARACHNOID
SPACE - CONTAINS CSF
5. PIA
MATER - DELICATE LAYER OF CONNECTIVE TISSUE CLOSEST TO RICH SUPPLY OF BLOOD
VESSELS
THALAMUS - RELAY CENTER FOR SENSATIONS,
E.G., PAIN
HYPOTHALAMUS - CONTROLS BODY TEMPERATURE,
SLEEP, APPETITE, FEAR, PLEASURE
CEREBELLUM - BELOW POSTERIOR CEREBRUM; AIDS
COORDINATION OF VOLUNTARY MOVEMENT AND MAINTAINS BALANCE, POSTURE, MUSCLE TONE
PONS - BRIDGE OF NERVE FIBERS CONNECTING
CEREBELLUM AND CEREBRUM
MEDULLA OBLONGATA - NERVE CROSS OVER AT
BASE OF BRAIN REGULATING RESPIRATION AND HEART RATE, VASOMOTOR IMPULSES
SPINAL CORD
EXTENDS FROM MEDULLA TO L2 ENDING IN FAN OF NERVES
(CAUDA EQUINA)
CARRIES NERVES AFFECTING LIMBS AND TRUNK
GRAY MATTER - INNER SECTION CONTAINING CELL
BODIES AND DENDRITES
WHITE MATTER - NERVE FIBER TRACTS WITH
MYELIN SHEATHS
PATHOLOGICAL
CONDITIONS
HYDROCEPHALUS - ACCUMULATION OF CEREBRAL
SPINAL FLUID (CSF) CAUSING ENLARGED HEAD.
CATHETER (SHUNT) PLACED IN BRAIN TO DRAIN FLUID INTO PERITONEUM
SPINA BIFIDA
DEGENERATIVE,
MOVEMENT AND SEIZURE DISORDERS
ALZHEIMER'S DISEASE - DETERIORATION OF
MENTAL CAPACITY (DEMENTIA). ASSOCIATED
WITH PATHOLOGICAL LESIONS: PLAQUE DEPOSITS AND NEUROFIBRILLARY TANGLES IN THE
BRAIN.
AMYOTROPHIC LATERAL SCLEROSIS (ALS) -
PROGRESSIVE DISORDER IN ADULTS, PARTICULARLY MEN. DEGENERATION OF MOTOR NEURONS IN THE SPINAL CORD AND BRAIN STEM
(CNS). SYMPTOMS INCLUDE WEAKNESS IN
SKELETAL MUSCLES, DYSPHAGIA, DYSPHASIA, DYSPNEA, ATROPHY LEADING TO
QUADRIPLEGIA.
EPILEPSY (SEIZURE) - ABNORMAL EXCESSIVE
ELECTRICAL DISCHARGE IN THE BRAIN.
DIAGNOSIS: EEG
MULTIPLE SCLEROSIS - DESTRUCTION OF MYELIN
SHEATH WITH REPLACEMENT BY SCLEROTIC (HARD)PLAQUES PREVENTS CONDUCTION OF NERVE
IMPULSES THROUGH AXON. SYMPTOMS:
PARESTHESIA, MUSCLE WEAKNESS, UNSTEADY GAIT, PARALYSIS, ETC.
MYASTHENIA GRAVIS (MUSCLE WEAKNESS) -
ANTIBODIES BLOCK ACETOCHOLINE FROM TRANSMITTING IMPULSES FROM NERVES TO
MUSCLES, e.g., MUSCLE CONTRACTIONS FAIL.
INFECTIOUS DISORDERS
MENINGITIS - INFLAMMATION OF THE MENINGES
CAUSED BY BACTERIA OR VIRUSES. SYMPTOMS: FEVER, HEADACHE, STIFF NECK.
BRAIN TUMORS
GLIOMAS - NEUROGLIAL CELLS PRESENTING AS
ASTROCYTOMAS OR OLIGODENDROGLIOMA, ETC.
MENINGIOMAS - USUALLY BENIGN AND SURROUNDED
BY A CAPSULE. CAN CAUSE PRESSURE AND DISTORTION OF THE BRAIN.
VASCULAR DISORDERS
CEREBRAL VASCULAR ACCIDENT
LABORATORY TESTS
CEREBROSPINAL FLUID ANALYSIS (CSF) -
EVALUATE CELLS, BACTERIA, GLUCOSE, ETC. WHICH MAY BE PRESENT INDICATING
DISEASE.
X-RAY PROCEDURES
MYELOGRAPHY - CONTRAST MEDIUM INJECTED INTO
SUBARACHNOID SPACE THROUGH LUMBAR PUNCTURE DEMONSTRATES NEOPLASMS/SLIPPED
DISKS. CT AND MRI LESS INVASIVE.
ECHOENCEPHALOGRAPHY - ULTRASOUND IN HEAD
MRI - SEE TEXT
RADIOACTIVE STUDIES
BRAIN SCAN - INTRAVENOUS RADIOACTIVE
MATERIALS ABSORBED INTO BRAIN. LEAK ACROSS BLOOD-BRAIN BARRIER IF A LESION.
OTHER PROCEDURES
ELECTROENCEPHALOGRAPHY - DEMONSTRATES
ABNORMAL ELECTRICAL ACTIVITY IN THE BRAIN, E.G., SEIZURES, TUMORS
LUMBAR (SPINAL) PUNCTURE - WITHDRAW CSF FOR
DIAGNOSIS, MEASURE PRESSURE, GIVE MEDICATIONS OR CONTRAST MEDIUM.