Chapter 16

what are the two divisions of the autonomic nervous system?

• sympathetic division

• parasympathetic division

what does the sympathetic division do?

increases alertness, metabolic rate, and muscular abilities

what does the parasympathetic division do?

reduces metabolic rate and promotes digestion

what division dominates?

parasympathetic division

when does the sympathetic division kick in?

during exertion, stress, or an emergency

• “fight or flight”

most often the sympathetic and parasympathetic divisions have ____ effects

opposing

true or false: can the two division work independently?

true

what are the seven responses to increased activation of the sympathetic division of the ANS

1. heightened mental alertness

2. increased metabolic rate

3. reduced digestive and urinary functions

4. energy reserves activated

5. increased respiratory rate and respiratory passageways dilate

6. increased heart rate and blood pressure

7. sweat glands activated

what are the five responses to increased activation of the parasympathetic division of the ANS

1. decreased metabolic rate

2. decreased heart rate and blood pressure

3. increased secretion by salivary and digestive glands

4. increased motility and blood flow in the digestive tract

5. urination and defecation stimulation

what are the neurotransmitters of the sympathetic division?

epinephrine and norepinephrine and acetylcholine

what are some changes caused by the sympathetic division due to epinephrine and norepinephrine?

• increased alertness

• feelings of energy and euphoria

• change in breathing, heart rate, and blood pressure

what are some changes caused by the sympathetic division due to acetylcholine?

• elevation in muscle tone

• mobilization of energy reserves

what effect does acetylcholine have?

causes vasodilation

what effect does norepinephrine have?

causes vasoconstriction

what are the major effects of the parasympathetic division?

• increase in smooth muscle activity along the digestive tract

• stimulation and coordination of defecation

• contraction of the urinary bladder during urination

• constriction of the respiratory passageways

• reduction in heart rate and in the force of contraction

the effect on post-synaptic cell depends on what?

the type of receptor; whether or not it’s excitatory vs. inhibitory

what is dual innervation?

when an organ or a tissue receives nerve connections from both the sympathetic and the parasympathetic divisions of the ANS

where is the sympathetic division located?

widespread impact, reaches organs and tissues throughout body

where is the parasympathetic division located?

innervates only specific visceral structures

what type of organs receive dual innervation?

the most vital organs

what is the role of the autonomic motor neurons?

to maintain resting level of activity in the absence of stimuli

what determines autonomic tone?

the background level of activation of autonomic motor neurons

why is autonomic tone an important aspect of ANS function?

• if the nerve is inactive under normal conditions, it can only increase activity

• if nerve maintains a background level of activity, can increase or decrease activity

• provides a high degree of control

when is autonomic tone significant?

where dual innervation occurs

what is an example of an organ that receives dual innervation?

the heart

how does the parasympathetic division maintain heart rate?

releases ACh to slow heart rate

how does the sympathetic division maintain heart rate?

releases NE to increase heart rate

how does autonomic tone apply to dual innervation?

there is a balance between the two divisions

• autonomic tone is present and there is a continual release of both neurotransmitters

how does sympathetic tone work?

it keeps smooth muscle partially contracted

what are higher-order functions?

1. require the cerebral cortex

2. involve conscious and unconscious information processing

3. are not a part of the programmed “wiring” of the brain

what are the different types of memories?

• fact memories

• skill memories

• short-term memories

• long-term memories

what are fact memories?

specific bits of information

what are skill memories?

learned motor behaviors; incorporated at unconscious level with repetition

what are short-term memories?

information that can be recalled immediately

what are long-term memories?

long-lasting, possible for life

what is memory consolidation?

conversion from short-term to long-term memories

what are the two types of long-term memories?

1. secondary memories

2. tertiary memories

what are secondary memories?

they fade and require effort to recall

what are tertiary memories?

they are with you for life

what is the role of the cerebral cortex in memory?

stores long-term memories

where are motor and sensory memories stored?

in the appropriate association areas

what are the cellular mechanisms of memory formation and storage?

1. increased neurotransmitter release

2. facilitation at synapses

3. formation of additional synaptic connections

what is a memory engram?

single circuit corresponds to single memory; forms as result of experience and repetition

how long does it take for the conversion of short-term memory into long-term memory?

one hour

what are some factors that affect conversion?

• nature, intensity, frequency of original stimulus

• strong, repeated, and exceedingly pleasant or unpleasant events are most likely to be converted

what is amnesia?

loss of memory as a result of disease or trauma

what is retrograde amnesia?

memory loss of past events

what is anterograde amnesia?

loss of ability to store new memories

what are the two general levels of sleep?

• deep sleep

• rapid eye movement (REM) sleep

what is deep sleep?

• entire body relaxes and cerebral cortex activity is minimal

• heart rate, blood pressure, respiratory rate, and energy utilization decline up to 30%

what is REM sleep?

• active dreaming occurs

• less receptive to outside stimuli than in deep sleep

• intense inhibition of somatic motor neurons

• eyes move more rapidly as dream events unfold

what is the nighttime sleep pattern?

• alternates between deep sleep and REM sleep

• begin in deep sleep (about 90 minutes)

• REM periods average 5 minutes in length; increase to 20 minutes over 8 hours

• spend less than 2 hours each night dreaming

why is sleep important?

• has an important impact on CNS function

• produces only minor changes in physiological activities of organs and systems

• protein synthesis in neurons increases during sleep

• extended periods without sleep lead to disturbances in mental function

• 25% of the U.S. population experiences sleep disorders

what is the reticular activating system (RAS)

an important brain stem component that is found in the medulla oblongata

what happens when RAS is inactive

the cerebral cortex is also inactive

what happens when RAS is active?

sleep ends, and the cerebral cortex is activated

what happens when RAS is stimulated with norepinephrine or epinephrine?

RAS becomes active and maintains awake and alert state

what happens when RAS is stimulated with serotonin?

it promotes a deep sleep by inactivating RAS

what are some effects of aging on the nervous system?

1. reduction in brain size and weight

2. reduction in the number of neurons

3. decrease in blood flow to the brain

4. changes in the synaptic organization of the brain

5. intracellular and extracellular changes in the CNS neurons

at what age can anatomical and physiological changes begin in the brain?

30 years old

how does the reduction in brain size and weight occur?

there is decrease in volume of the cerebral cortex

what does it mean for there to be a reduction in the number of neurons?

loss of cortical neurons but there is not loss of neurons in the medulla oblongata

what is arteriosclerosis?

• fatty deposits in the walls of blood vessels

• reduces blood flow through arteries

• increases chances of reupture

how is there a change in synaptic organization of the brain?

the number of dendritic branches and interconnections decreases

what are neurofibrillary tangles?

form inside the cell body and axon

what are plaques?

extracellular accumulations of protein

what do plaques and tangles contain?

amyloid beta protein

where is the amyloid beta protein found?

appears in brain regions associated with memory and processing

what are some other effects of aging on the nervous system?

• anatomical changes

• sensory systems

• motor control

• incapacitation

  • senility (senile dementia)