The nervous system with questions

Nursing

1. The Nervous System Lecture #5

2. The Nervous System Is Responsible For: Allowing us to interact w/ environment Regulation of activities involving internal organs ‘Driving’ the other sys. of the body Network composed of complex structures, that transmit signals: Electrically Chemically … b/w the body’s organs, tissues & brain

3. Organization of the Nervous System

4. Organization of the Nervous System Central Nervous System: comprised of the Brain & Spinal Cord

5. Organization of the Nervous System Peripheral Nervous System (PNS) pathways are differentiated : Afferent pathways (sensory): ascending. sensory impulses toward CNS Efferent pathways (motor): descending. motor impulses away from CNS Somatic NS : voluntary control (i.e. skeletal muscle contraction) Autonomic NS : involuntary control (i.e. subconscious reg. of body’s internal environment: resp., HR, digestion)

6. Autonomic NS : Sympathetic NS: Nerves originating from thoracic & lumbar regions of spinal column Parasympathetic NS: Nerves originating from the brain & sacrum

7. 2 Basic Cells w/in the N. System Neuron Primary cell of N.Sys . Fxnal unit of N.Sys . Different types ( Neuroglial Cells) Supporting cells: Structural support Nutrition Schwann Cells Astrocytes Microglial Cells

8. 100 Billion neurons present in our NS ~7 miles of axons (connections) One neuron connects with 10,000 other neurons (on average) Some of the more important connections are up to 6ft long Therefore increased metabolic demands! Many diseases that affect energy affect the Nervous System. Organ of consciousness, emotions, behavior, intellect & humanity.

9. The Neuron Can work alone, or in units Detect environmental changes & initiate body responses to maintain a dynamic steady state ( Homeostasis ) Structures differ, so that each neuron is adaptable to perform specialized fxns . { differentiated } Cannot regenerate entirely Cell division stops at birth: (G1)

10. 3 Parts to a Neuron: Cell Body : Soma Dendrites : thin processes / extensions: carries impulses toward cell body

11. The Three Parts to a Neuron 3. Axon : projection away from cell body. Carries impulses away from it. Covered with myelin (lipid insulating layer - called ‘myelin sheath’ ). Increases the velocity of impulse transmission Diameter of axon also influences impulse transmission velocity. De- myelinating Diseases: MS & Guillain-Barre Syndrome

12. Integrating the INPUT with the OUTPUT The NS has only 3 main (overlapping) jobs: Sensory Input : Informing the CNS: Organizing what is happening inside & outside the body Allows info from body receptors (i.e. Skin) to create an impulse that shoots up to the Spinal Cord & then to the brain

13. Integrating the INPUT with the OUTPUT Integration : CNS makes ‘sense’ of received input from around the body. i.e. Interneurons: neuron (nerve cell) sits b/w a sensory fiber & a motor fiber. Interneurons bring an impulse / stimulus to the CNS, and back to the nerves that can make an action happen

14. Integrating the INPUT with the OUTPUT Motor Output : The stimulation of muscles to move The stimulation of glands to secrete substances i.e. Motor fibers- are ‘action making’ nerves

15. Transmission of the Nerve Impulse Impulses have a domino-like effect When a neuron get a signal, it passes it onto the next neuron; which passes it onto the next neuron; which passes it onto the next neuron; etc. def . Nerve-a long collection of neurons Entire impulse passes through a neuron in about 7 milliseconds How? The Action Potential

16. Transmission of the Nerve Impulse The Action Potential When neuron at rest : ‘ resting membrane potential’ Cell membrane is Polarized More Na + outside; More K + inside When a stimulus reaches resting neuron: Gated Na + channels open on the surface of membrane Na + rushes into the cell Inside of the cell becomes (+) This Depolarizes the cell Creates an ACTION POTENTIAL Transmits the stimulus ALL–or–NONE: need to overcome threshold

17. Transmission of the Nerve Impulse The Action Potential Movement of K + Outside the Cell: K + gates open, cause K + to escape outside Na + gates close Closing of K + gates: More K + outside the cell than Na + inside the cell The cell is now in a HYPERPOLARIZED STATE

18. Transmission of the Nerve Impulse The Action Potential Refractory Period : puts everything back to normal K + returns inside & Na + returns outside Because of the Na + /K + Pump! During refractory period, the neuron DOES NOT respond to ANY incoming stimuli

19. Transmission of the Nerve Impulse: The Synaptic Cleft This is the gap that separates the axon of one neuron & the dendrites of another. Neurons NEVER touch each other! How does the signal get transmitted? The depolarization wave reaches the end of the axon & causes Ca 2+ ion channels to open , on the presynaptic neuron Ca 2+ enters the presynaptic axonal terminal & fuses with the NT vesicles ( synaptic vesicles ) NT then gets released into the synapse

20. Transmission of the Nerve Impulse The Synaptic Cleft NT binds with protein receptors on the dendrites of the postsynaptic neuron. (NTs have specific receptors) 2 things can now occur. The NT can: stimulate Na + channels to open. This continues the impulse [EPSP] stimulate K + channels to open. This hyper-polarizes the cell & stops the impulse [IPSP] The NT then goes back to the presynaptic neuron & gets recycled for the next impulse transmission

21. Sympathetic Response Cardiovascular Increases in: B/P ; HR ; Contractility ; B.flow to Skeletal Muscles. Respiratory Efficiency Increases: Bronchial dilation ; RR increases Pupil Dilation & Sweating Increase Piloerection Shunting of blood way from GI Tract. Shunting of blood away from kidneys. Glyconeogenesis & Glycogenolysis . Release of Corticosteroids. Suppression of Immune & Inflammatory responses.

22. Sympathetic Transmission Termination Once NEpi has been released in the synaptic cleft it must be removed. Effective recycling of NEpi . Enzymatic metabolization by: Monoamine oxidase (MAO) Catechol-o- methyltransferase (COMT)

23. Click on right answer to go to next page The nurse monitors for which clinical manifestations in the client receiving a medication that stimulates the sympathetic division of the autonomic nervous system? a. Decreased heart rate, decreased force of contraction b . Increased heart rate, increased force of contraction c. Decreased heart rate, increased force of contraction d. Increased heart rate, decreased force of contraction

24. Correct Answer is B Stimulation of the sympathetic nervous system initiates the fight-or-flight response, increasing both the heart rate and force of contraction .

25. Parasympathetic Response Increase motility and secretions in the GI tract to promote digestion and absorption. Relaxation of GI/GU sphincters - evacuation of wastes. Decrease HR, B/P & contractility- to conserve energy & provide rest to the heart Bronchial Constriction & Increased secretions from bronchial mucosa. Pupillary constriction, thereby decreasing light entering eye (decreases stimulation of the retina).

26. Parasympathetic Transmission Termination Once ACh has been released in the synaptic cleft it must be removed. Effective recycling of Ach. Enzymatic metabolization by: Acetylcholinesterase

27. Click on correct answer to move to next slide: In preparation for magnetic resonance angiography, the nurse asks the client which question ? a. “Have you had a recent blood transfusion?” b. “Do you have allergies to iodine or shellfish?” c. “Do you have a history of urinary tract infections?” d. “Do you currently use oral contraceptives?”

28. Correct Answer :B Allergies to iodine and/or shellfish need to be explored because the client may have a similar reaction to the dye used in the procedure. In some cases, the client may need to be premedicated with antihistamines or steroids before the test.

29. Neurotransmitters >30 NTs: NEpi & Epi ACh Dopamine Histamine Serotonin AAs (i.e. GABA) Enkephalins Endorphins

30. Thinking about your Brain The brain weighs only 3 pounds & requires 15-20% of the total CO Different parts of your brain are responsible for different fxns Major parts of brain: Cerebrum Cerebellum Brain Stem Diencephalon 4 connective cavities of the brain (ventricles)

31. Cerebrum Largest part of brain Controls consciousness Divided in L / R halves called Cerebral Hemispheres Each 1/2 has 4 lobes: Frontal Parietal Temporal Occipital

32. Cortex ( cerebrum’s outer layer )- is gray The ‘curvy bumps’ are called gyri Shallow grooves that separate the gyri are called sulci. Deeper grooves are called fissures The Corpus Callosum is located at the base of the longitudinal fissure network of myelinated fibers that join the L & R cerebral hemispheres

33. Frontal Parietal Temporal Occipital Speech Production General Interpretation Area Interpretation of Sensations Recognizing objects visually Concentration Understanding speech Remembering visually Vision Problem solving Ability to use words Remembering through sounds Combining images received visually Planning Exec. Fxns Sensations felt Hearing Voluntary muscle control Learning

34. Which deficit will the nurse expect to find in a client who has experienced an injury to the frontal lobe of the brain ? Choose the right answer to move to the next slide: a. Inability to interpret taste sensations b. Inability to interpret sound c. Impaired judgment d . Impaired learning

35. Yes, the answer is “C”: Impaired judgment The frontal lobe is responsible for many functions, including judgment, reasoning, voluntary eye movement, and motor functions.

36. Cerebellum Lies just below the cerebrum Divided by a fissure Gray on the outside Controls & coordinates skeletal muscle mvmts . [The cerebrum sends out the signal to the cerebellum for mvmt ] Maintains muscle tone (at all times)

37. The Brain Stem Comprised of 3 structures: Midbrain: “station” for info. passing b/w: SC & cerebrum SC & cerebellum Pons: “bridge” that joins the cerebellum with the cerebrum Filled w/ axonal bundles that integrate info. from eyes & ears Controls respirations Medulla Oblongata: HR; Resps ; B/P regulation Centers for coughing, vomiting, sneezing, swallowing & hiccups Becomes the SC after it passes through the foramen magnum

38. The Reticular Formation Collection of nerve cell bodies (nuclei) within the brainstem called the Reticular Formation Controls vital reflexes: Cardiovascular fxning Respiration Maintains wakefulness

39. Bypassing the Brain- The Reflex Arc Happen automatically (i.e. When you touch something very hot or sharp) Sensory neurons detect : Pain / Temp / Pressure If a sensory neuron detects something that could harm your body (i.e. Sharp object) An impulse passes from the receptor throughout the sensory neuron, to the SC & then to a motor neuron, which stimulates muscles to retract your finger from the sharp object.

40. Bypassing the Brain - The Reflex Arc Reflexes occur so fast - you don’t even think (cognitively) about how to react! The impulse does not make it to the brain in time to generate a rxn ! By the time the impulse gets to the brain, the SC has already taken care of the problem. Reflex Arcs: Save time & damaging consequences

41. The Ventricles 2 Lateral: one on each side of the brain 3 rd : in the center of the brain 4 th : lies on the top of the brainstem Cerebral Aqueduct connects the 3 rd & 4 th ventricles together & becomes the central canal of the SC

42. The ventricles & cerebral aqueduct serve as a system to circulate CSF CSF is a clear fluid that is made by the cells that line the ventricles CSF is contained in the 4 ventricle, the subarachnoid space & the central canal of the SC. Fxns to: Pick up wastes Cushions the CNS Keeps the ions in balance Stabilizes the membrane potentials.

43. Spinal Tap CSF is drawn through a needle for analysis from the subarachnoid space Can be tested for: presence of bacteria (which may cause meningitis) presence of proteins that can indicate other diseases (i.e. Alzheimer's)

44. Regulating Systems : The Diencephalon Made up of the Hypothalamus & Thalamus Hypothalamus regulates: Sleep Hunger & Thirst Body Temp B/P Fluid Levels Maintains Homeostasis Controls pituitary gland signaling to the Endocrine System, for secreting hormones

45. Regulating Systems : The Diencephalon Thalamus is the gateway to the cerebrum. Whenever an impulse travels from somewhere in your body, it passes through the Thalamus The Thalamus then relays the impulse to the proper location in the cerebral cortex, which then interprets the message

46. Click on right answer to move to next slide: During electroencephalography, the client is instructed to breathe deeply (hyperventilate). What is the nurse’s interpretation of this action? a. Seizure activity may be increased because of cerebral vasodilation associated with hyperventilation. b. Seizure activity may be increased because of cerebral vasoconstriction secondary to hyperventilation. c. Seizure threshold is lowered by acidosis associated with hyperventilation. d. Seizure threshold is lowered by hypoxemia associated with hyperventilation.

47. Correct Answer B Hyperventilation produces cerebral vasoconstriction and alkalosis, which increases the likelihood of seizure activity. The client is asked to breathe deeply 20 to 30 times for 3 minutes.

48. The Limbic System

49. The Limbic System

50. Disorders of the NS Multiple Sclerosis (MS) Affects the myelin sheath that covers the axon of a nerve The myelin sheath develops lesions that become inflamed & irritated. Leads to demyelination of the white matter of the brain & spinal cord After the myelin destruction, neuroglial tissue proliferates in the white matter of the CNS. When the lesion heals, hard yellow scar tissue (plaques) are left behind.

51. As the disease affects more nerves, the number of scleroses increases, leading to multiple damage sites The hard scar tissue interferes w/ the nerve’s ability to conduct an impulse through the axon If an impulse can’t be transmitted, a mvmt or response cannot occur As the dx progresses, mvmt becomes increasingly difficult & then impossible

52. Structures most commonly involved are the optic & occulomotor nerves & the spinal tract nerves. Does not affect the Peripheral NS Characterized by exacerbations & remissions Seen primarily in ages 18 – 40 y/o. [ F > M ] Exact cause is unknown: Slow acting viral infection? An autoimmune response? GENETICS? An allergic response? Trauma; anoxia; toxins; nutritional deficiencies; vascular lesions; anorexia?

53. Alzheimer’s Disease ‘mind’ slipping away Progressive degenerative disorder of the cerebral cortex {Cortical Degeneration} Accounts for >1/2 of all cases of Dementia Pt’s can’t care for themselves. They’ve forgotten how to perform ADLs. Bundles of a fibrous protein [ADAP: Alzheimer’s Dx Assoc. Protein] , are tangled around the nucleus of a neuron Amyloid plaques (globs of protein) also surround axonal branches. Plaques are thought to kill / destroy the neuron

54. Cause unknown: Neurochemical factors: Possible deficiencies: * ACh ; Somatostatin ; Substance-P; NEpi Slow-growing CNS virus?; Trauma ? Genetics (abnormal chromosome 21) Insidious Onset & Cannot be completely confirmed till after death Tests that can help diagnose possibility: PET (Positron Emission Tomography) CT ; MRI; EEG CSF analysis; Cerebral Angiogrophy

55. http://web.kamogawa.ne.jp/~miyake/ADunrabelingADEAR/ADEAR2003.htm