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.