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Exercise Physiology
Ch. 7 NERVOUS SYSTEM
68
Physiology
Undergraduate 1
10/11/2013

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Term
Nervous System Functions
Definition
Control of the internal environment

Voluntary control of movement

programming spinal cord reflexes

records and stores experiences (memory)
Term
Organization of Nervous system
Definition
(CNS)-Brain/spinal cord

(PNS)-sensory/motor divisions
Term
PNS (sensory division)
Definition
Afferent fibers
-receptors to CNS
Term
PNS (motor division)
Definition
Efferent fibers
-CNS to effector organs
Term
Cell body
Definition
contains the nucleus
Term
Dendrites
Definition
send impulses to cell body
Term
Axon
Definition
sends impulses away from cell body
Term
synapse
Definition
contact points between axon of one neuron and dendrites of another
Term
Multiple Sclerosis
Definition
disease that makes myelin shealths breakdown

causes motor impairment
Term
Irritability
Definition
ability to respond to a stimulus and convert it to a neural impulse
Term
Conductivity
Definition
transmission of the impulse along the axon
Term
Resting Membrane Potential
Definition
the negative charge a cell has at rest

~-75 mV
Term
Factors of RMP
Definition
permeabillity of plasma membrane to ions

difference in ion conc. across membrane
(Na,K, Cl, Ca)
Term
sodium-potassium pump
Definition
maintains RMP

K tends to leak out of cell

2K in/3 Na out

powered by ATP
Term
Action potential
Definition
occurs when a strong enough stimulus depolarizes the cell

Na channels open, Na leaks into cell (causes inside of cell to become positive)
Term
Repolarization
Definition
Cell returning to RMP

K SHOOTS out of cell
Na channels shut
Term
All or none law
Definition
Once nerve shoots, its sends signal the length of the axon
Term
Vesicles
Definition
Transport neurotransmitters in packets
Term
Synapse
Definition
Small gap between presynaptic cleft and postsynaptic cleft
Term
Neurotransmitter
Definition
Chemical messenger released from presynaptic cleft

binds to receptor and causes depolarization of postsyaptic membrane
Term
EPSP
Definition
Excitatory post synaptic potentials

Causes depolarization

-Temporal and Spatial summation
Term
Temporal summation
Definition
summing several EPSP's from one presynaptic neuron
Term
Spatial summation
Definition
Summing from several different presynaptic neurons
Term
IPSP
Definition
Inhibitory PostSynaptic Potential

causes hyperpolarization (more negative, harder to fire)
Term
Proprioceptors
Definition
Receptors that provide CNS with information about body position

Located in joints and muscles
Term
Kinesthesia
Definition
Knowing where and how fast we are moving limbs
Term
3 types of joint proprioceptors
Definition
Free nerve endings

Golgi-type receptors

Pacinian corpuscles
Term
Free nerve endings
Definition
sensitive to touch and pressure

initially strongly stimulated, then adapt
Term
Golgi-type receptors
Definition
found in ligaments and around joints

similar to free nerve endings
Term
Pacinian corpuscles
Definition
in tissues around joints

detect rate of joint rotation
Term
Muscle Proprioreceptor's function
Definition
provide sensory feedback to nervous system
Term
types of muscle receptors
Definition
Muscle spindle
Golgi tendon organ
Term
Muscle spindle
Definition
Responds to muscle length changes
Term
Intrafusal fibers
Definition
Part of muscle spindle that runs parallel to muscle fibers
Term
Gamma motor neurons
Definition
part of muscle spindle that stimulates intrafusal fibers (alpha motor neuron)
Term
Stretch reflex
Definition
a stretch on a muscle causes a reflex contraction

Ex. Knee Jerk reflex
Term
Golgi Tendon Organ (GTO)
Definition
Monitors force/tension development, prevents damage during excessive force generation

Stimulation results in muscle reflex relaxation (IPSP's to muscles)

Ability to voluntarily oppose GTO inhibition may be related to strength gains (allows muscle to push limit further)
Term
Muscle Chemoreceptors
Definition
Sensitive to changes in the chemical environment (H, K ions, CO2)

Provides CNS with info about Metabolic rate of muscle activity (needed in cardiovascular regulation)
Term
Withdrawal reflex
Definition
does not require brain receptors

reflex of muscle in response to sensory input
Term
Crossed-extensor reflex
Definition
Opposite limb supports body during withdrawal of injured limb
Term
Somatic motor division (PNS)
Definition
carries neural messages from spinal cord to skeletal muscles
Term
Motor unit
Definition
A motor neuron and all the muscle fibers it innervates
Term
Innervation ratio
Definition
Number of muscle fibers per motor neuron

Low ratio= more control

High ratio= more strength
Term
Motor unit recruitment
Definition
Recruitment of more muscle fibers through motor unit activation
Term
Size principle
Definition
Smallest motor units recruited first
Term
3 types of motor units
Definition
Type S- Slow
Type FR- Fast Fatigue resistant
Type FF- Fast, Fatigable
Term
Type S fibers
Definition
Slow type, long duration
Term
Type FR fibers
Definition
Fast, fatigue resistant type
Term
Type FF fibers
Definition
Fast, fatigable type
Term
Vestibular Apparatus
Definition
Located in ear

Maintains general equillibrium and balance (head position

Sensitive to changes in linear and angular acceleration (stimulated by head movement)

eye movement during exercise
Term
Brain Stem
Definition
many metabolic functions

cardiorespiratory control

Complex reflexes
Term
Brain Stem Structures
Definition
Medulla
Pons
Midbrain
Term
Cerebrum
Definition
Cerebral cortex and motor cortex

storage center
Term
Cerebral cortex
Definition
Organ. of complex movement

Storage of learned experiences

Reception of sensory movement
Term
Motor cortex
Definition
Motor control and voluntary movement
Term
Cerebellum
Definition
Coordination of quick movements and posture

Feedback from proprioceptors
Term
What does the Cerebellum connect to?
Definition
Motor cortex

Brainstem

Spinal cord
Term
Central fatigue
Definition
depletion of excitatory neurotransmitters in motor cortex

reduced motor output to muscle
Term
Central governor theory
Definition
brain controls fatigue levels to prevent disruption to homeostasis
Term
Spinal Cord functions
Definition
Withdrawal reflex

spinal tuning
Term
Spinal tuning
Definition
voluntary movement translated into correct muscle action
Term
What controls motor function (3)
Definition
Subcortical and cortical motivation areas

Cerebellum and basal ganglia

Motor cortex through thalamus
Term
Subcortical and cortical motivation areas
Definition
send a rough draft into movement plan
Term
Cerebellum and basal ganglia
Definition
covert rough draft into movement plan

cerebellum: fast movements

Basal ganglia: Slow, deliberate movements
Term
Motor cortex through thalmus
Definition
sends message down spinal neurons for spinal tuning to muscles

fine tuning from muscle receptors and proprioceptors
Term
ANS (Autonomic Nervous System)
Definition
Responsible for maintaining body's internal environment

2 divisions (sympathetic, parasympathetic)
Term
Sympathetic nervous system
Definition
Norepinephrine

Excites an organ
Term
Parasympathetic nervous system
Definition
Acetylcholine

Inhibits an organ
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