Chapter 14 Integration of the nervous system functions Compared to animals we have large complex brains that have the same basic function of receiving and sending signals, but we are also capable to unique complex functions: recording history, reasoning, planning, to a degree unparalleled in the animal kingdom. AP1 Chapter 14 1
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Chapter 14 Integration of the nervous system functions Compared to animals we have large complex brains that have the same basic function of receiving.
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AP1 Chapter 14 1
Chapter 14Integration of the nervous system
functions
Compared to animals we have large complex brains that have the same basic function of receiving and sending signals, but we are also capable to unique complex functions: recording history, reasoning, planning, to a degree unparalleled in the animal kingdom.
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Chapter 14 Outline
I. Sensation
II. Control of skeletal muscle
III. Brain Stem Function
IV. Other Brain functions
V. FX of aging of the nervous system
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I. Sensation
A. Sensory receptors
B. Sensory tracts
C. Sensory areas of the cerebral cortex
D. Sensory processing
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I. Sensation• Sensation/perception
– Conscious awareness of FX of stimuli on sensory receptors– Sensation requires 3 steps:
Stimuli originating inside or outside of the body are
detected by sensory receptors & AP’s are
propagated to the CNS via the nerves
w/in the CNS AP’s to the cerebral cortex & to other
areas of the CNS
Many AP’s reaching the cerebral cortex are ignored others are
translated and person becomes aware of the stimuli
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• Senses: means by which the brain perceives information about the environment & the body
Divided into 2 groups
Provide sensory info about the body &
environment
•More specialized structure•Specialized nerve endings•Localized to specific organs
– Here auditory stimuli are processed by this part of the brain– Superior Temporal Lobe
• Visual Cortex– Portions of visual images are processed by this part of the brain (Color, shape & mvmt are
processed separately rather than a complete color motion picture)– Located in the occipital lobe
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D. S
enso
ry P
roce
ssin
g• Association Areas are involved in the process of
recognition (Process sensory input from the primary sensory areas)– They are normally adjacent to their 1o sensory area.– There are 3
a. Auditory Association Area
b. Somatic Sensory Association Area
c. Visual Association Area
Also interconnected w/other parts of the brain
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II. Control of Skeletal Muscles
A. Motor areas of the cerebral cortex
B. Motor Tracts
C. Modifying and refining motor activities
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II. Control of Skeletal Muscle• Reflexes (occur w/o
conscious thought)• Voluntary Mvmts:
– Mvmts consciously activated to achieve a specific goal (*)
– AP’s mv from upper motor neurons (UMN) to lower motor neurons (LMN)
a. UMN: cell bodies w/in cerebral cortex and connect directly or indirectly (internerons) to LMN
b. LMN: cell bodies synapse with UMN in the 1.anterior horns of the gray matter (SC) or 2. cranial nerve nuclei of brainstem then axons leave CNS & extend thru the PNS nerves to supply ske. muscle
• Motor Syst of brain & SC responsible for maintaining:a. Body’s posture & balance
b. Moving: trunk, head, limbs, & eyes
c. Communicating thru facial expressions & speech
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II. Control of Skeletal MusclesVoluntary Movements Depend on
Initiation of of most voluntary mvmts begin in the premotor area of
cerebral cortex & involve the stimulation
of the UMN’s
UMN form descending tracts
iStimulate LMN
iStimulate skeletal muscle
contraction
Cerebral cortex interacts with Basal nuclei & cerebellum to
plan, coordinate, & execute mvmts
A. Motor Areas- Cerebral Cortex1. *Primary Motor Cortex(PMC)
– Although only 30% of the UMN are located in the PMC, AP’s from PMC control many voluntary mvmts
– The higher the # of MU (that have few muscle fibers) the more precise the movement
2. Premotor Area:– Staging area where motor fxns are
organized b4 they are initiated in the (PMC)
– Which muscles must contract, in what order to contract, & to what degree do they contract
3. Prefrontal Area:– Involved in motivation & foresight to
plan and initiate mvts – Involved in motivation & regulation of
emotional behavior & mood 28AP1 Chapter 14
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B. Motor TractsDescending pathways w/axons carrying AP’s from regions of the cerebrum/cerebellum to
brainstem & SC
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2 divisions
Direct Pathways/Pyramidal System
Corticospinal TractCorticobulbar Tract
LateralCorticospinal Tract
AnteriorCorticospinal Tract
Indirect Pathways/Extrapyramidal System
Rubrospinal
Vestibulospinal Reticulospinal
Tectospinal
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Direct Pathway
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Maintenance of muscle tone & controlling the speed & precision of skilled mvmts, 1oly fine mvmts involved in dexterity*
nasal & oral cavities• CN 7 Taste• CN 8 Hearing and balance• CN 9 Taste and tactile
sensation in the throat• CN 10 Taste and tactile
sensation in the larynx; visceral sensation in the throat and abdomen
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B. RAS Fxns of the Bnsm• Reticular activating system
(RAS)– Can be stimulated by inputs
from the cerebral cortex (mental activities), & a variety of sensory inputs from stimuli such as visual (flashes of light), auditory (ringing alarm), olfactory (burning/coffee), & sematosensory (splashing cold H2O on/touching your face).
• CN’s 2,5,&8 stimulate wakefulness & consciousness• RAS is involved in sleep wake
– Maintain alertness & attention
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C. Motor Output & reflexes projecting thru the Bnsm
Somatic Motor Output & Reflexes
• Reflexes:– Eyes/neck mvmt in response
to visual & auditory stimuli or tactile stimulation
• Passin’ thru– Eyes: move & look toward on
object, tracking a moving object
– Chewing, how hard or soft something is and changing mvmt accordingly control of tongue for chewing & speech
– Facial muscles for expressions
– Pharynx & larynx associated with swallowing & speech.
Parasympathetic Output & Reflexes
• Reflexes controlled via the reticular formation:– Visual reflexes (pupil size)
1. Wernicke’s Area• Portion of the parietal lobe• Sensory speech area• Req’d for understanding &
formulating coherent speech
2. Broca’s Area• Inferior part of the frontal lobe• Motor speech area• Initiates the complex series
of mvmts necessary for speech
Connected to each other by a bundle of neurons
known as arcuate fasciculus
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B. Right & Left Cerebral cortex
Rt. CerebralHemisphere
Lt. CerebralHemisphere
•Motor Output goes to the left side•Sensory input comes from the left side•Spatial perception, facial recognition, & musical ability
•Motor Output goes to the right side•Sensory input comes from the right side• mathematics & speech
Commissure: band of tracts that connect the 2 hemisphere for info sharing
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C. B
rain
wav
es &
sle
ep• Electroencephalogram:
(EEG)– Can record
simultaneous Ap’s in large #’s of neurons & displays wave-like patterns known as brain waves.
– Most normal people don’t have a regular pattern but there are 4 regular patterns seen at specific times:
a) Alpha
b) Beta
c) Theta
d) Delta
• These waves can be used as a diagnostic tool to diagnose brain disorders
• Patterns also vary during the 4 stages of sleep.
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D. Memory: 3 types1. Sensory memory:
– Lasts less than a sec & involves transient D’s in membrane potential
– Retention of sensory input received by the brain while something is scanned, evaluated, & acted on
2. Short term memory– Lasts sec’s to min’s if
considered important enough to move from 1 to 2.
– Limited by the # of bits of info that can be stored at 1 time
– New info may cause loss of old– Physiology: short term D’s in
membrane potential (longer than 1) but can be eliminated by new info entering the cell
3. Long term memory– Lasts hours to years
to a lifetime– There are 2 types:
a. Declarative/ Explicit
b. Procedural/ Implicit/ Reflexive
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D. Memory: Long termDeclarative
• Retention of facts• Accessed via the
hippocampus, amygdala, or amygdaloid nuclear complex– H: involved in retrieving the
actual memory*– A: involved in the emotional
overtones of that memory *– Emotions may also serve as a
switch for storing or not storing a memory
• Memories appear to be compartmentalized* in the cerebrum– This also makes retrieval
complex (put a puzzle together)
Procedural• Involves the development
of skills like riding a bike or playing the piano.
• Primarily stored in cerebellum & premotor area of the cerebrum (only small amounts are lost thru time)#
• Conditioned/Pavlovian reflexes are implicit (but cerebellar lesions cause their loss)
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D. M
emor
y: L
ong
term
• Physiology of long term memory:– D’s in the neuron (long term potentiation) which
facilities future transmission of AP’s.– The neuron grows new axons to increase the
number of synapse. (especially seen in development of skills)
• Repetition of info association with new info with existing memories assist in the transfer from short to long term memory
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D. Limbic System• Influences emotions, innate responses to
emotions, motivation, mood & sensations of pain & pleasure
• Associated with basic survival (reproduction, food H2O)
• Damage:– Voracious appetite– Increased sexual activity (often inappropriate)– Docility (loss of fear and anger)– Temporal lobe damage (Loc of Limbic System)
• Can also result in loss of memory formation
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V. FX of Aging on the NS
• General decline in sensory & motor fxns • Short term memory is decreased• Thinking ability doesn’t D