Chapter 7:
The Nervous System

EXERCISE PHYSIOLOGY

General Nervous System Functions

1. Control of the______________________ environment

–Nervous system works with _______________system

2. Voluntary control of movement

3. Programming spinal cord reflexes

4. Assimilation of experiences necessary for memory and learning

Organization of the Nervous System

•_______________ (CNS)

–_______________ and _______________ cord

______________________________ (PNS)

–Neurons _______________ the CNS

–Sensory division

_______________ fibers transmit impulses from receptors to CNS

–Motor division

_______________ fibers transmit impulses from CNS to _______________organs

Divisions of the Nervous System

Relationship Between PNS and CNS

Structure of a Neuron

•_______________

•_______________: Conduct impulses toward cell body

–_______________

–Carries electrical impulse _______________ from cell body

–May be covered by _______________ cells

•Forms discontinuous _______________ sheath along length of axon

•_______________: Contact points between axon of one neuron and dendrite of another neuron

Structure of a Neuron

Synaptic Transmission

Electrical Activity in Neurons

•Neurons are “_______________ Tissue”

–_______________: ability to respond to a stimulus and convert it to a neural impulse

–Conductivity: transmission of the impulse along the axon

Electrical Activity in Neurons

•Resting membrane potential

–At rest, the neurons are _______________ charged

–Determined by concentrations of ions (_______________) across membrane

•_______________ potential

–Occurs when depolarization reaches threshold

•_______________ of the membrane changes, allowing Na⁺ into the cell, making the interior positively charged

Repolarization

•_______________ in membrane _______________, restoring resting membrane potential

An Action Potential

Depolarization

Repolarization

Neurotransmitters and Synaptic Transmission

•Neurons communicate across _______________ using _______________

–Released from presynaptic membrane

–Binds to _______________on post_______________membrane

Basic Structure of a Chemical Synapse

Neurotransmitters and Synaptic Transmission

•Excitatory postsynaptic potentials (EPSP)

–Causes depolarization which may or may not reach threshold

–Temporal summation: summing several EPSPs from one presynaptic neuron

–Spatial summation: summing from several different presynaptic neurons

•Inhibitory postsynpatic potentials (IPSP)

–Causes hyperpolarization

Sensory Information

–_______________

–Proprioception: ability to determine _______________ of joint

–Kinesthesia: _______________ of _______________ motion or acceleration

•Muscle Chemoreceptors

–Sensitive to changes in the _______________ environment surrounding a muscle

Proprioceptors

•Provide CNS with information about _______________ _______________and joint angle

–Free nerve endings – _______________ & _______________

–Golgi-type receptors – in _______________ & _______________

–Pacinian corpuscles – in _______________ around joints

•Strongly stimulated then adapt

Muscle Chemoreceptors

•Provide _______________ with information regarding the metabolic rate of muscular activity

–Hydrogen ion concentration

–Carbon dioxide (CO₂)

–Potassium (K⁺)

Reflexes

•Rapid, _______________ means of reacting to stimuli

•Order of events:

1.Sensory nerve sends impulse to _______________

2.Interneurons activate _______________ neurons

3.Motor neurons control movement of _______________

•Reciprocal inhibition

–EPSPs to muscles to _______________ from stimulus

–IPSPs to _______________ muscles

A Reflex Arc Illustrating Reciprocal Inhibition

Somatic Motor Function

•Somatic motor neurons of _______________

–Responsible for carrying _______________ messages from _______________to skeletal muscles

•Motor unit

–Motor neuron and all the muscle fibers it innervates

•Innervation ratio

–Number of muscle fibers per motor neuron

Illustration of a Motor Unit

_______________ Apparatus and Equilibrium

•Located in the inner ear (Semi-circular canals)

•Responsible for maintaining general equilibrium and balance

•Sensitive to changes in linear and angular acceleration

Vestibular Apparatus in Maintaining Equilibrium

Motor Control Functions of the Brain

•Brain stem: responsible for

–Many _______________ functions

–_______________ control

Major structures

•_______________

•_______________

•_______________

•_______________– a series of complex neurons scattered throughout the brain stem

Motor Control Functions of the Brain

–_______________

–Cerebral cortex

•Organization of complex movement

•Storage of learned experiences

•Reception of sensory information

–Motor cortex

•Most concerned with _______________ movement

•Cerebellum

- Monitors _______________ movement

Motor Functions of
the Spinal Cord

•_______________ reflex

•Contains groups of neurons capable of controlling certain aspects of motor activity

•Spinal tuning

–Voluntary movement is translated into appropriate muscle action

Control of Motor Function

•Subcortical and cortical motivation areas

–Sends a “rough draft” of the movement

•_______________ and _______________

–Coverts “rough draft” into movement plan

–

–Cerebellum: _______________ movements

–Basal ganglia: _______________, _______________ movements

Motor cortex through Thalamus

–Forwards message sent down spinal neurons for “Spinal tuning” and onto muscles

–Feedback from muscle receptors and proprioceptors allows fine-tuning of motor program

Structures and Processes Leading to Voluntary Movement

Autonomic Nervous System

•Responsible for _______________ _______________ environment

–Effector organs not under voluntary control

•_______________, ______________________________, _______________

Sympathetic division

–Releases _______________ (NE)

–Excites an _______________organ

•Parasympathetic division

–Releases _______________ (ACh)

–Inhibits _______________ organ

Neurotransmitters of the Autonomic Nervous System

Exercise Enhance Brain Health

•A recent five-year study in humans has concluded that exercise improves _______________and reduces the risk of _______________ impairment associated with aging

•It is clear that regular exercise can protect the brain against disease (e.g. _______________) and certain types of brain injury (e.g. _______________)