Chapter 6
 Nervous System - Notes  (Changes and Suggestions in blue and green - 3/6/06)
Return to Chapter Index  

Return to Main Index   

 1.   Name and explain the importance of the six ways that the nervous system contributes to homeostasis and quality of life.

- monitoring - detect changes, obtain information, pleasure
    - communicating - informing parts of situations
    - stimulating - controlling actions
    - coordinating - promote cooperation, reduce antagonism
    - remembering - faster and more accurate responses in the same situation
    - thinking - faster and more accurate responses in different situations, problem-solving, creativity, variability in responses, ethics, politics, etc.

 2.   Name and briefly explain the purposes of the three main functions of neurons (i.e., reception, conduction, transmission). (p. 119)

    - reception = picking up information about changes = detecting stimuli
    - conduction = carrying information to another location in the body using action potentials
    - transmission = passing information or signal or stimulus or inhibitory message to another cell (neuron, muscle, gland)
        - uses synapses, neuromuscular junctions, neuroglandular junctions
        - note different transmitter substances
        - note one-way conduction, modulation, convergence, divergence, memory

 3.   Briefly describe the purposes (not the parts) of sensory neurons, somatic motor neurons, autonomic motor neurons, reflexes, conscious sensation, and voluntary motor pathways. (pp. 122-124)
    - sensory neurons - to detect and communicate about conditions
    - somatic motor neurons - control skeletal muscles (reflex and voluntary motions)
    - autonomic motor neurons - control involuntary muscles and glands
    - reflexes - negative (or sometimes positive) feedback loops for fast, accurate, predictable responses
    - conscious sensation - for conscious remembering, thinking, pleasure, learning, communication
    - voluntary motor pathways - for voluntary movements

 4.   Name two age changes in the functioning (not structure) of skin receptors and skin sensory neurons  and describe how they affect the nervous system's abilities to contribute to homeostasis and quality of life. (p. 51)

sensitivity to touch and pressure
two-point discrimination
ability to identify objects by touch
speed of response to touch -> sensation of vibration
    - these age changes in functioning result in;
negative feedback regulation
precise control of voluntary movements
        - affect social, psychological, economic realms

 5.   Name and describe two effects of aging on the ability to smell, and describe two outcomes from these age changes.

    - effects; (1)
detection of aromas and (2) identification of aromas
    - outcomes; altered eating,
detection of "toxins", detection of undesirable aromas (embarrassment)

 6.   Describe the overall effects of aging on taste sensations.

    - very  variable decline in detection of salt but thresholds remain so low that there is little, if any, practical effect (except with diet {salt} restrictions)

 7.   Name two age changes in sensory function other than changes in skin sensations, sense of smell, or sense of taste, and describe an outcome from each age change you select.

detection of (1) BP, (2) thirst, (3) bladder fullness, (4) bowel fullness, (5) proprioceptors -> (1) BP, (2) dehydration, (3 & 4) incontinence, (5) muscle coordination

 8.   Describe two functional (not structural) outcomes in muscles from age changes in somatic motor neurons, and give an example of how these outcomes might affect a person's homeostasis or quality of life.

# motor neurons, variability in speed of APs in motor neurons, slower neuromuscular junctions
    - outcomes: 
precision of control (fewer but stronger motor units), peak strength, speed to achieve peak strength, prolonged contraction (delayed relaxation) -> difficulty with very fast movements (e.g., sports, games, jobs)

 9.   Choose two age changes in autonomic motor functions and briefly describe their effects on homeostasis or quality of life.

BP reflex to maintain BP -> orthostatic hypotension -> dizziness, fainting, falls
BP reflexes ( parasympathetic heart inhibition, adjustments of heart to inspiration and expiration, adjustments when exercise ends) -> BP
regulation of vessels in skin - temp. regulation
parasympathetic reflex control of vessels for erection -> slower and reduced erection
pupillary reflexes (photopupil and ciliospinal)
# of neurons in esophagus (Auerbach's plexus) -> slower, weaker, less coordinated, less complete swallowing
sensitivity to norepinephrine (heart {  c-AMP}, lungs {  receptor affinity}, other organs {  # of receptors}) -> blood norepinephrine (partial compensation)

10.   Describe the overall effects of age changes in autonomic motor functioning.

    - little if any overall effects in most autonomic functions (unless body is put in extreme conditions; then note exception in previous objective)

11.   Describe the basic operation and overall purposes of reflexes. (p. 122)

    - sensory neurons -> CNS synapses and neurons -> motor neuron -> response
    - usually negative feedback mechanisms -> homeostasis
    - occasionally positive feedback (e.g., erection)

12.   Name four age changes in the functioning of reflexes, describe the effects of these changes on homeostasis and quality of life, and list four specific reflexes that show normal age changes.

    - (1) need stronger stimulus to initiate reflex (
# and sensitivity of receptors)
    - (2) slower response (slower reception and weaker and slower APs)
    - (3) weaker and prolonged responses (
# motor neurons, less synchronous motor APs, less effective neuromuscular junctions)
    - (4) great
in coordination in complex reflexes (e.g., balance) (result largely from CNS changes)

    - also affected by (1) stiffer tissues, which
receptor sensitivity, (2) weaker muscle and gland functioning
    - overall
negative feedback responses -> homeostasis
        - (e.g., swallow, gag, cough, balance, sweating, withdrawal reflexes)
    - overall
positive feedback responses - pleasure (erection)
    - partial compensation by altered/improved strategies to decrease need for fast strong reflexes (e.g., change in gait)

13.   Describe three overall results of nervous system aging on conscious sensation, and explain the effects from these changes on homeostasis and quality of life. (p. 123)

detection of stimulus
identification of stimulus
evaluation of strength of stimulus
    - effects =
learning, pleasure, control of movement
    - compensation by strengthening stimulus, allowing more time

14.   Describe the overall effects of nervous system aging on voluntary movement, and explain the effects from these changes on homeostasis and quality of life. (p. 124)

    - weaker
    - slower
    - prolonged movement
    - less accurate movement
    - less coordinated movement
    - effects diminish all strength, fast, and skilled activities
    - compensation by choosing other activities, use of more efficient motion strategies, "youth vs. experience", use of assistance devices (e.g., canes)

15.   Describe the age changes in the numbers of CNS neurons and CNS synapses, the overall effects from these changes, and the reasons for these effects. (p. 131)

neurons and synapse numbers in different regions
neuron and synapse numbers seem to have little effect
neurons and synapse numbers may have beneficial effects
    - overall effects = small effects because of (1) neuron plasticity, (2) loss of "reserve" neurons and synapses, (3) loss of "error" neurons and synapses

16.   Describe or define the meaning of the following aspects of mental activity. (pp. 132-135)

    -  short-term memory (1)
    -  long term memory (1)
    -  incidental memory (1)
    -  procedural memory (1)
    -  explicit memory (1)
    -  implicit memory (1)
    -  episodic memory (1)
    -  working memory (1)
    -  thinking (1)
    -  crystallized intelligence (1)
    -  fluid intelligence (1)
    -  personality (1)

17.   Describe the effects of aging on three different types or aspects of memory or thinking (any combination of three changes), personality, and one change in sleep. Types of memory include short term, long term, incidental, procedural, explicit, implicit, episodic, working. Types of thinking (intelligence) include crystallized intelligence and fluid intelligence.

    -  all show very variable changes between individuals and at different ages for each individuals
       -  short term memory - very variable among individuals but slight average decline(difficult to detect), especially after age 60-70, and especially for quick, verbal, unfamiliar, irrelevant information
          - recall improved by slow presentation, association, organization, relevance, reference to concrete concepts, mnemonic, more time to respond, relaxed atmosphere for response
       - long term memory - usually no significant change
       - incidental memory - usually little change except under time constraints
       - procedural memory - usually little change except under time constraints
       - explicit memory - usually decreases, especially with short time constraints
       - implicit memory - usually little change, but declines when attempting to consciously remember specific information
       - episodic memory - usually decreases, resulting in confusing times and places of passed events
       - working memory - usually decreases, resulting in decreases in complex mental processes
    - thinking - very variable among individuals with slight average decline (difficult to detect) especially after age 60-70, and especially with very rapid thinking processes
          - approx. 10% show improvement in thinking and "wisdom" (experience)
   - crystallized intelligence - usually little change or improvement, resulting in increasing speed and accuracy of intelligent mental activities in familiar situations
   - fluid intelligence - usually decreases, resulting in slower and less accurate intelligent mental activities in novel situations
   - personality - usually stable
        - different personalities are better for coping with difficult situations
    - sleep - very variable among individuals, with gradual decline in quality (more awakenings, less Stage 4 and REM)
        - NOTE - daytime sleepiness that is serious enough to interfere with normal activities is pathological, not normal

18.   List methods for improving memory functions.

    - written notes, repetition, organizing information, mnemonic devices, mental imaging, relating information to familiar experiences, memory training programs, increasing self-confidence

19.   Describe the importance of biorhythms and average age changes in biorhythms.

    - important for stabilizing and regulating regular activities (e.g., sleep:wakefulness periods and cycles, body temperature, blood pressure, hormone levels)
    - average decreases in amplitudes and lengths of circadian rhythms result in decreases in regularity of normal rhythmicity of body activities and decreases in synchrony among body activities, especially sleep patterns and quality of sleep.

20.   Describe the overall effects of nervous system age changes on the system's ability to maintain homeostasis and quality of life.

    - highly variable changes
    - average gradual decline
    - affects processes requiring high coordination most
    - compensatory strategies can negate effects of many age changes

21.   For strokes, indicate that strokes are diseases (not age changes), and give the following information. (p. 139)

    - rank as cause of death among elderly (3rd)
    - effects other than death (disability, social, psychological, economic)
    - trend in incidence (
especially after age 65)
    - two main causes (atherosclerosis, heart failure)
    - reasons that the two main causes produce stroke (block vessel, brain hemorrhage)
    - three main types of stroke based on time factors (TIA with recovery within 24 hours, RIND with partial gradual recovery, completed with little or no recovery)
    - methods of preventing strokes (prevent atherosclerosis)

22.   For dementia, indicate that dementias are abnormal (not age changes) and give the following information.

    - four criteria for dementia = (1) great
memory plus other high level function, (2) seriously affects activities, (3) chronic, (4) has physical basis
    - trend in incidence = increase, especially after age 60, incidence doubles each 5 years after age 65 to reach 30%+ at age 85
    - distinction between reversible dementia and irreversible dementia
    - note different incidences for moderate vs. severe forms
    - % caused by atherosclerosis = 10%-20%
    - % caused by Alzheimer's disease = 55%+
    - other causes = parkinsonism, head trauma, medications, malnutrition, etc.

23.   Explain how multi-infarct dementia develops.

    - continuous accumulation of small dead spots in the brain from inadequate blood flow causes gradual decline in many brain functions, finally resulting in dementia

24.   For Alzheimer's disease, provide the following information.

    - trend in incidence =
with age, especially after age 65
        - rare before age 40
        - one percent of people under age 65
        - rate doubles every five years in people over age 60, reaching 20 percent of people over age 80
    - two overall effects = disability, death
    - any three specific effects in victims =
short term memory, ability to perform activities of daily living (ADLs), disorientation, learning, language functions, variations in personality, confusion, long term memory, self-care, motor function, death
    - three effects on non-victims = expense, social upheaval, care-giver burden
    - types = (1) early onset AD, typically before age 40 (i.e., familial AD= FAD), (2) late onset AD, typically after age 60 (i.e., senile dementia of the Alzheimer's type = SDAT)
    - suspected causes = (1) genes, normal aging processes, head trauma, aluminum
    - time course = steady decline with 2-20 years to death after diagnosis
    - strategy for diagnosis = process of elimination, autopsy
    - effects on the brain = great
amyloid plaques (i.e., senile plaques), great neurofibrillar tangles, free radicals, inflammation, great acetylcholine, number of neurons, amyloid in vessels -> vessel stiffness -> decreased blood flow
    - treatment strategies = prevention in postmenopausal women using estrogen supplements; relieve symptoms, treat complications, provide support services for victim and family

25.   Describe or explain how factors found in Alzheimer's disease are believed to cause decreased brain functioning.

    - beta-amyloid -> senile plaque formation, free radical damage, inflammation, glycation, neuron death
    - tau protein -> increases in neurofibrillar tangles
    - apolipoprotein-epsilon - disruption of neuron membranes, increases formation of free radicals and plaques and tangles
    - presinilins - unknown effects

26.   List and describe genes influential in the development of AD.

    - genes on chromosome 21 -> increases in harmful beta-amyloid -> FAD
    - genes on chromosome 19 -> increases in harmful form of apolipoprotein epsilon -> SDAT
    - genes on chromosome 14 and on chromosome 1 -> increases in presinilins -> FAD

27.   For Parkinson disease, provide the following information.

    - trend in incidence = rare before age 50, increases to two percent of people over age 50
    - types and causes = primary Parkinson's disease (cause unknown), secondary Parkinson's diseases (cause by other CNS abnormalities)
    - any three effects = irregular control of muscle movements resulting in tremors, rhythmic uncontrolled contractions, inability to complete movements, slower movements, constipation, loss of balance, insomnia, memory loss, personality and psychological abnormalities, dementia
    - nervous system changes causing effects = imbalance in neurotransmitters controlling muscle movements (e.g., Dopamine)  For video clips, go to the following Internet site (
For videoclips showing the effects of Parkinson’s disease on muscles and movements, go to and Search and to see more Parkinson's disease video clips.)
    - time course = steady progress but variable in rate between individuals; death some time after five years from onset
    - diagnosis = measuring amount of brain dopamine, evaluating types and progress of signs and symptoms
    - treatments = supplements to increase dopamine; surgical implantation of dopamine- producing tissues; relieve symptoms, treat complications, provide support services for victim and family

28.   Describe dementia with Lewy bodies.
    - dementia associated with increases in clumps of microfilaments (Lewy bodies) in brain neurons

Return to Top of Page

Return to Chapter Index

Return to Main Index

© Copyright 2004 - Augustine G. DiGiovanna - All rights reserved.
This material MAY be reproduced or distributed in any form or by any means, or stored in any data base or retrieval system ONLY under one of the following two conditions: (1) If no individual, group, organization, institution, company, corporation or other entity is charged for its use and only for use by instructors and students in courses where students are required to purchase the book HUMAN AGING: BIOLOGICAL PERSPECTIVES by Augustine G. DiGiovanna, The McGraw-Hill Companies, New York, 1994 or 2000; (2) If prior written permission is obtained from Augustine G. DiGiovanna.