nervous system Flashcards
overall function of the nervous system
Coordinate the body’s systems by receiving and sending information; maintaining homeostasis
what does the nervous system include
Brain, Spinal cord, Nerves
CNS
brain and spinal cord
PNS
Nerves throughout the body
31 pairs of spinal nerves
12 pairs of cranial nerves
sensory receptors
ends of peripheral neurons that gather information by detecting changes inside and outside the body
systems of the nervous system (2)
somatic and autonomic
somatic
skeletal and voluntary
autonomic
Smooth muscles, Glands, Involuntary, Parasympathetic (rest and digest), sympathetic (fight or flight)
neurons
mass of nerves cells that transmit information
what makes up a neuron
dendrites, Chromatophilic substance, myelin, nodes of Ranvier, axon, nucleus
microglial cells
Immune function; digest debris, kills bacteria
Oligodendrocytes
make myelin sheath that provides insulation around the axons
(In the CNS)
Astrocytes
connect blood vessels to neurons
Ependymal Cells
forms membranes around tissue
Schwann cells
form the insulating myelin sheath around the neurons in the PNS
how do nerve impulses travel
(8 steps)
- Neuron membrane maintains resting potential
- Threshold stimulus is received
- Sodium channels open
- Sodium ions diffuse inward, depolarizing the membrane
- Potassium channels open
- Potassium ions diffuse outward, repolarizing the membrane
- The resulting action potential causes a local bioelectric current that stimulates the membrane.
- Wave of action potentials travel the length of the axon as a nerve impulse
depolarization
loss of the difference in charge between the inside and outside of the plasma membrane of a muscle or nerve cell due to a change in permeability and migration of sodium ions to the interior
synapse
junction between two communicating neurons
Nerve pathway
dendrites, cell body, along axon, synapse, dendrite
Excitatory
increase membrane permeability, increases chance for threshold to be achieved
inhibitory
decrease membrane permeability, decrease chance for threshold to be achieved
ALS: Amyotrophic Lateral Sclerosis
Progressive degeneration of nerve cells in the spinal cord and brain
Myasthenia Gravis
Autoimmune disorder in which antibodies destroy neuromuscular connections
Epilepsy
Excessive electrical activity within networks of neurons in the brain
MS Multiple Sclerosis in neuron
Myelin around the nerve fibers is lost (autoimmune) and forms scar tissue called sclerosis
nerve
bundles of axons, cordlike bundle of nerve fibers
Sensory fibers/Afferent fibers
Bring sensory information to the CNS
Motor fibers/Efferent fibers:
Carry impulses from the CNS to effectors
meninges
layered membranes that lie between the bony coverings and soft tissues of the CNS.
They protect the brain and spinal cord.
Dura mater (outermost)
Arachnoid mater (midde)
Pia mater (innermost)
functions of spinal cord
conducting nerve impulses
Serves as the center for spinal reflexes
major parts of the brain
Cerebrum, diencephalon, brain stem, cerebellum
cerebrum
Divided into a left and right cerebral hemisphere
The corpus callosum connects the two hemispheres
Provides higher brain functions, Stores memory and uses reason, Intelligence & Personality arise from here
the lobes of the brain (4)
frontal, parietal, temporal, occipital
diencephalon
Located between the hemispheres and above the midbrain
includes thalamus, hypothalamus, optic tract, optic chiasma, infundibulum, posterior pituitary gland, mammillary bodies, pineal gland
thalamus
produces general awareness (pain, touch, temperature)
hypothalamus
regulates (heart rate, blood pressure, body temp, etc.)
brainstem
Bundle of nervous tissue that connects the cerebrum to the spinal cord
includes midbrain, pons, medulla oblongata
midbrain
includes reflex centers (eye movement, auditory reflex)
pons
relay sensory information to the higher brain centers
medulla oblangata
cardiac, vasomotor, and respiratory centers
cerebellum
Large mass of tissue that is located below the occipital lobes of the cerebrum and posterior to the pons and medulla oblongata
Communicates with other parts of the CNS
cranial nerves (12 pairs)
I. olfactory
II. optic
III. oculomotor
IV. trochlear
V. trigeminal
VI. abducens
VII. facial
VIII. vestibulocochlear
IX. glossopharyngeal
X. vagus
XI. accessory
XII. hypoglossal
olfactary nerve
smell
optic nerve
vision
oculomotor nerve
most muscles in the eye
trochlear nerve
moves eyelid
trigeminal nerve
main sensory nerve in the face
abducens nerve
controls lateral rectus (eye)
facial nerve
facial expression
vestibulocochlear nerve
hearing and balance
glossopharyngeal nerve
pharynx and tongue
vagus nerve
controls the organs in the abdominal cavity
accessory nerve
shoulder muscles
hypoglossal nerve
speech
sections of the spinal cord
cervical (8)
thoracic (12)
lumbar (5)
sacral (5)
coccygeal (1)
dorsal root
contains the cell bodies of sensory neurons
ventral root
contains the axons of the motor neurons
plexuses
main portions of the spinal nerves combine to form complex networks.
cervical plexuses
Deep in the neck
Contain phrenic nerves (control diaphragm)
brachial plexuses
Deep in the shoulders
Supply muscles of the arms and hands
lumbosacral plexuses
Lumbar region of the back
Controls lower extremities
analgesia
loss or reduction in the ability to sense pain but no loss of consciousness
analgesic
pain relieving drug
anesthesia
loss of feeling
aphasia
disturbance or loss of the ability to use and understand words
apraxia
impairment in the ability to complete tasks
ataxia
Partial or complete inability to coordinate voluntary movements
cerebral palsy
Partial paralysis and lack of muscular coordination due to cerebrum damage
coma
unconscious condition
cordotomy
surgical procedure that severs a nerve tract in the spinal cord to relieve pain
craniotomy
Surgical procedure that opens part of the skull
electroencephalogram (EEG)
recording of the brain’s electrical activity
encephalitis
inflammation of the brain and meninges, produces drowsiness
epilepsy
disorder of disturbed brain impulses
hemiplegia
paralysis of one side of the body including limbs
huntington’s disease
inherited disease which causes dance like movements and personality changes
laminectomy
surgical removal of the posterior arch of the vertebrae to relieve a pressing disc
monoplegia
paralysis of a single limb
multiple sclerosis in the brain
loss of myelin throughout the brain and spinal cord
neuralgia
sharp, recurring pain associated with a nerve
neuritis
inflammation of the nerve
paraplegia
paralysis in both lower limbs
quadriplegia
paralysis of all four limbs