Lecture about the Nervvous System

1. The Nervous System By WILLIAM M. BANAAG, R.N.

2. 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.

3. 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 moment—a 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.

4. Structural Classification of the Nervous System: Central Nervous System (CNS): Consists of the brain and the spinal cord, which act as the integrating and command centers of the nervous system. They interpret incoming sensory information and issue instructions based on past experience and current conditions. Peripheral Nervous System (PNS): It is the part of the nervous system outside the CNS. They link all parts of the body by carrying impulses from the sensory receptors to the CNS and from the CNS to the appropriate glands or muscles. It consists mainly of the nerves that extend from the brain and spinal cord. Cranial Nervescarry impulses to and from the brain. Spinal Nervescarry impulses to and from the spinal cord.

5. 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

6. Central Nervous system (CNS) THE BRAIN Cerebral Hemispheres: The two cerebral hemispheres (the left and the right side) form the largest apart of the brain, called the cerebrum Its surface, called cerebral cortex, is convoluted and exhibits elevated ridges called gyri, which are separated by shallow grooves called sulci. It also has deeper grooves called fissures, which separate large regions of the brain. Each cerebral hemisphere is divided by some fissures and sulci into a number of lobes which are named for the cranial bones that lie over them. The cerebral hemispheres are involved in logical reasoning, moral conduct, emotional responses, sensory interpretation, and the initiation of voluntary muscle activity. sulci fissure gyri

7. 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.”

8. Functional Areas of the Cerebral Hemispheres The cerebral hemispheres has three (3) types of functional areas… Sensory areas Motor areas Association areas

9. Functional Areas of the Cerebral Hemispheres Sensory Areas: receive and interpret sensory impulses Primary somatosensory area (Areas 1, 2 & 3) - receives impulses from somatic sensory receptors for touch, pain, and temperature. Primary visual area (Area 17) – receives visual input concerning shape, color, and movement. Primary auditory area (Area 41 & 42) – interprets the basic characteristics of sounds such as pitch and rhythm. Primary gustatory area (Area 43) – receives impulses related to taste.

10. Functional Areas of the Cerebral Hemispheres Motor Areas: control muscular movement Primary motor area (Area 4) – controls voluntary contractions of specific muscles or group of muscles on the opposite side of the body (e.g. finger maneuver) Motor speech area or Brocha’s area (Area 44) – involves in the translation of thoughts into speech. It is located in only one cerebral hemisphere (usually the left). Damage to this area causes inability to say words properly—you know what you want to say, but you can’t vocalize the word.

11. 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 interpret sensations It permits you to: determine the exact shape and texture of an object without looking at it; determine the orientation of one object to another as they are felt; sense the relationship of one body part to another. It stores memories of past sensory experiences—thus you can compare sensations with previous experiences. Visual association area (Areas 18 & 19) – it relates present to past visual experiences with recognition and evaluation of what is seen.

12. Functional Areas of the Cerebral Hemispheres Premotor area (Area 6) It deals with learned motor activities of a complex and sequential nature, for example, to write a word. It controls learned skilled movements and serves as a memory bank for such movements. Frontal eye field area (Areas 8) – it controls voluntary scanning movements of the eyes—like for instance, searching for a word in a dictionary. Auditory association (Wernicke’s) area (Area 22) It determines if a sound is a speech, music, or noise; It also interprets the meaning of speech by translating words into thoughts. Gnostic (gnosis = knowledge) area (Areas 5, 7, 39 & 40) It integrates sensory interpretations from the association areas and impulses from other areas so that a common thought can be formed from the various sensory inputs. It then transmits signals to other parts of the brain to cause the appropriate response to the sensory signal.

14. Spoken and written language

15. Numerical and scientific skills

18. STM lasts seconds to hours and is limited to 7 or 8 pieces of information

20. Rehearsal– repeating or rehearsing material enhances memory

22. YES!

23. Prove It Yourself… Improve Your Memory The following techniques take advantage of the brain’s storage and retrieval mechanisms: Concentrate. Paying attention increases brain activity—promoting 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.

24. 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.

25. Peripheral Nervous system (PNS) Nerve:Nerve is a bundle of neuron fibers found outside the CNS. Cranial nerves: Cranial nerves are 12 pairs of nerves that extend from the brain to serve the head and neck region, except the Vagus nerve, which extend into the thorax and abdomen. Spinal nerves: Spinal nerves are 31 pairs of nerves formed by the union of the dorsal and ventral roots of the spinal cord on each side.

26. Peripheral Nervous system (PNS) The PNS has two (2) functional divisions… Sensory or Afferent Division: Consists of nerve fibers that convey impulses to the central nervous system from sensory receptors located in various parts of the body. Sensory fibers that deliver impulses from the skin, skeletal muscles, and joints are called somatic (soma = body) sensory fibers. Sensory fibers that transmit impulses from the visceral organs are called visceral sensory fibers, or visceral afferents. The sensory division keeps the CNS constantly informed of events going on both inside and outside the body. Motor or Efferent Division: Carries impulses from the CNS to effector organs, muscles and glands.

27. Peripheral Nervous system (PNS) Motor Division: The Somatic Nervous System (SNS): Allows us to consciously, or voluntarily, control our skeletal muscles. This subdivision is often referred to as the voluntary nervous system, however, skeletal muscle reflexes are also initiated involuntarily by fibers of this same subdivision. The Autonomic Nervous System (ANS): Regulates events that are automatic, or involuntary, such as the activity of smooth muscles and glands. This subdivision is commonly called the involuntary nervous system

28. Peripheral Nervous system (PNS) Motor Division (Autonomic Nervous System): Sympathetic (stimulates) It is the “fight or flight” subdivision, which prepares the body to cope with some threats Its activation results in increased heart rate and blood pressure. Parasympathetic (inhibits) It is the “housekeeping” system and is in control most of the time. This division maintains homeostasis by seeing that normal digestion and elimination occur and that energy is conserved.

29. Nervous System

30. 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 arcand involve both CNS and PNS structures.

31. Reflex Arc Five (5) Basic Element of Reflex Arc Receptor Sensory neuron Integration center Motor neuron Effector

32. 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.

33. That’s all… Thank you for listening.