The Nervous System By WILLIAM M. BANAAG, R.N..
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Transcript of The Nervous System By WILLIAM M. BANAAG, R.N..
The Nervous System By WILLIAM M. BANAAG, R.N. The Nervous System
The Nervous System is the master controlling and communicating
system of the body. The Nervous System CONTROLS and COORDINATES ALL
ESSENTIAL FUNCTIONS of the Human Body. Function of the Nervous
System
SENSORY FUNCTION: Nervous system uses its millions of sensory
receptors to monitor changes occurring both inside and outside of
the body.Those changes are called STIMULI, and the gathered
information is called Sensory Input. INTEGRATIVE FUNCTION: The
Nervous System process and interprets the sensory input ad makes
decisions about what should be done at each momenta process called
Integration. MOTOR FUNCTION:The Nervous System then sends
information to muscles, glands, and organs (effectors) so they can
respond correctly, such as muscular contraction or glandular
secretions. Structural Classification of the Nervous System:
Central Nervous System (CNS): Consists of the brain and the spinal
cord, which actas the integrating and command centers of thenervous
system. They interpret incoming sensory information andissue
instructions based on past experience andcurrent conditions.
Peripheral Nervous System (PNS): It is the part of the nervous
system outside theCNS. They link all parts of the body by carrying
impulsesfrom the sensory receptors to the CNS and fromthe CNS to
the appropriate glands or muscles. It consists mainly of the nerves
that extend fromthe brain and spinal cord. Cranial Nerves carry
impulses to and from thebrain. Spinal Nerves carry impulses to and
from the spinalcord. Central Nervous system (CNS)
THE BRAIN The brain is located within the cranial cavity of the
skull and consists of the cerebral hemispheres, diencephalon, brain
stem, and cerebellum. Central Nervous system (CNS)
THE BRAIN Cerebral Hemispheres: The two cerebral hemispheres (the
left and the rightside) form the largest apart of the brain, called
thecerebrum Its surface, called cerebral cortex, is convolutedand
exhibits elevated ridges called gyri, which areseparated by shallow
grooves called sulci.It alsohas deeper grooves called fissures,
which separatelarge regions of the brain. Each cerebral hemisphere
is divided by some fissuresand sulci into a number of lobes which
are named forthe cranial bones that lie over them. The cerebral
hemispheres are involved in logicalreasoning, moral conduct,
emotional responses,sensory interpretation, and the initiation of
voluntarymuscle activity. sulci fissure gyri Point to Remember
Pathways of nerve impulses are crossed pathways meaning that the
Left side of the brain controls the RIGHT side of the body, and the
Right side of the brain controls the LEFT side of the body.
Functional Areas of the Cerebral Hemispheres
The cerebral hemispheres has three (3) types of functional areas
Sensory areas Motor areas Association areas Functional Areas of the
Cerebral Hemispheres
Sensory Areas:receive and interpret sensory impulses Primary
somatosensory area(Areas 1, 2 & 3) - receivesimpulses from
somatic sensoryreceptors for touch, pain, andtemperature. Primary
visual area (Area 17) receives visual input concerningshape, color,
and movement. Primary auditory area (Area 41& 42) interprets
the basiccharacteristics of sounds such aspitch and rhythm. Primary
gustatory area (Area43) receives impulses related totaste.
Functional Areas of the Cerebral Hemispheres
Motor Areas:control muscular movement Primary motor area (Area 4)
controls voluntary contractions ofspecific muscles or group
ofmuscles on the opposite side ofthe body (e.g. finger maneuver)
Motor speech area or Brochasarea (Area 44) involves in
thetranslation of thoughts intospeech. It is located in only one
cerebralhemisphere (usually the left). Damage to this area causes
inabilityto say words properlyyou knowwhat you want to say, but you
cantvocalize the word. Functional Areas of the Cerebral
Hemispheres
Association Areas:deal with more complex, integrative functions
such as memory, emotions, reasoning, will, judgement, personality
traits, and intelligence. Somatosensory association area(Areas 5
& 7) Its role is to integrate and interpretsensations It
permits you to:determine the exactshape and texture of an object
withoutlooking at it; determine the orientationof one object to
another as they arefelt; sense the relationship of one bodypart to
another. It stores memories of past sensoryexperiencesthus you can
comparesensations with previous experiences. Visual association
area (Areas 18 &19) it relates present to past
visualexperiences with recognition andevaluation of what is seen.
Functional Areas of the Cerebral Hemispheres
Premotor area (Area 6) It deals with learned motor activities of
acomplex and sequential nature, for example,to write a word. It
controls learned skilled movements andserves as a memory bank for
such movements. Frontal eye field area (Areas 8) itcontrols
voluntary scanning movements ofthe eyeslike for instance, searching
fora word in a dictionary. Auditory association (Wernickes)
area(Area 22) It determines if a sound is a speech, music, ornoise;
It also interprets the meaning of speech bytranslating words into
thoughts. Gnostic (gnosis = knowledge) area (Areas5, 7, 39 &
40) It integrates sensory interpretations fromthe association areas
and impulses from otherareas so that a common thought can beformed
from the various sensory inputs. It then transmits signals to other
parts ofthe brain to cause the appropriate responseto the sensory
signal. Brain Lateralization Left side control Right side
control
On gross examination, the brain appears the same on both sides,
however there are functional differences LEFT HEMISPHERE RIGHT
HEMISPHERE Left side control Musical and artistic awareness Space
and pattern perception Insight Imagination Generating mental images
to compare spatial relationship Right side control Spoken and
written language Numerical and scientific skills Reasoning Look at
the chart and say the COLOR not the word.
YELLOWBLUEORANGEBLACK RED
GREENPURPLEYELLOWREDORANGEGREENBLACKMAGENTACYANBROWNPINK Left Right
Conflict Your right brain tries to say the color but your left
brain insists on reading the word. Memory is the storage and
retrieval of information
Stages of Memory Short-term memory (STM, or working memory) a
fleeting memory of the events that continually happen STM lasts
seconds to hours and is limited to 7 or 8 pieces of information
Long-term memory (LTM) has limitless capacity Transfer from STM to
LTM Factors that affect transfer of memory from STM to LTM include:
Emotional state we learn best when we are alert, motivated, and
aroused Rehearsal repeating or rehearsing material enhances memory
Association associating new information with old memories in LTM
enhances memory Can you improve your ability to learn and remember
new information? YES! Prove It Yourself Improve Your Memory The
following techniques take advantage of the brains storage and
retrieval mechanisms: Concentrate.Paying attention increases brain
activitypromoting consolidation of information into long-term
memory. Minimize Interference.Go where it is quiet. A noisy
environment will impair your ability to concentrate. Break down
large amount of information into smaller topic.Give yourself time
to review each topic, and take a break in between. Rephrase
material in your own words.Restate the information in a way that
makes sense to you personally. Test yourself.Create outlines or
diagrams. Use practice and review questions when they are
available. Central Nervous System (CNS)
THE SPINAL CORD The spinal cord is a reflex center and conduction
pathway which is found within the vertebral canal. It extends from
the foramen magnum to L1 or L2. Peripheral Nervous system
(PNS)
Nerve:Nerve is a bundle of neuron fibers found outside the CNS.
Cranial nerves: Cranial nerves are 12 pairs of nervesthat extend
from the brain to servethe head and neck region, exceptthe Vagus
nerve, which extend intothe thorax and abdomen. Spinal nerves:
Spinal nerves are 31 pairs of nervesformed by the union of the
dorsaland ventral roots of the spinal cordon each side. Peripheral
Nervous system (PNS)
The PNS has two (2) functional divisions Sensory or Afferent
Division: Consists of nerve fibers that conveyimpulses to the
central nervous systemfrom sensory receptors located invarious
parts of the body. Sensory fibers that deliver impulsesfrom the
skin, skeletal muscles, andjoints are called somatic (soma =body)
sensory fibers. Sensory fibers that transmit impulsesfrom the
visceral organs are calledvisceral sensory fibers, or
visceralafferents. The sensory division keeps the CNSconstantly
informed of events going onboth inside and outside the body. Motor
or Efferent Division: Carries impulses from the CNS toeffector
organs, muscles and glands. Peripheral Nervous system (PNS)
Motor Division: The Somatic Nervous System (SNS): Allows us to
consciously, orvoluntarily, control our skeletalmuscles. This
subdivision is often referredto as the voluntary nervoussystem,
however, skeletal musclereflexes are also initiatedinvoluntarily by
fibers of this samesubdivision. The Autonomic NervousSystem (ANS):
Regulates events that areautomatic, or involuntary, such asthe
activity of smooth muscles andglands. This subdivision is commonly
calledthe involuntary nervous system Peripheral Nervous system
(PNS)
Motor Division (Autonomic Nervous System): Sympathetic (stimulates)
It is the fight or flight subdivision,which prepares the body to
cope withsome threats Its activation results in increasedheart rate
and blood pressure. Parasympathetic (inhibits) It is the
housekeeping system and isin control most of the time. This
division maintains homeostasis byseeing that normal digestion
andelimination occur and that energy isconserved. Nervous System
Reflex Reflexes are programmed, rapid, predictable, and involuntary
responses to stimuli. Reflexes may be inborn or learned (acquired)
Reflexes occur over neural pathways called reflex arc and involve
both CNS and PNS structures. Reflex Arc Five (5) Basic Element of
Reflex Arc Receptor
Sensory neuron Integration center Motor neuron Effector Reflex
Types of Reflexes
Somatic Reflexes include all reflexes that stimulate the skeletal
muscle (e.g. When you quickly pulled your hand away from a hot
object, a somatic reflex is working). Autonomic Reflexes regulate
the activity of smooth muscles, the heart, and glands
(i.e.Secretion of saliva and changes in the size of the eye
pupils); autonomic reflexes regulate such body functions as
digestion, elimination, blood pressure and sweating. Thats all
Thank you for listening.