nervous system

Question 1

functions

Answer 1

1. control internal environment
   »> coordinated with the endocrine system
2. voluntary control of movement
3. spinal cord reflexes
4. assimilation of experiences necessary for memory and learning

Question 2

central nervous system

Answer 2

• brain & spinal cord

Question 3

peripheral nervous system

Answer 3

• neurons outside CNS
• sensory division
• motor division

Question 4

sensory division

Answer 4

afferent fibers transfer impulses from receptors to CNS

Question 5

motor division

Answer 5

efferent fibers transmit impulses from CNS to effector organs

Question 6

neurons

Answer 6

• body (soma)
• dendrites
• axons: at the ends are axon terminals
  » these have synaptic knobss which house neurotransmitters
  communicate via electrical impulses

Question 7

multiple sclerosis patients (MS)

Answer 7

neurological disease that destroys myelin sheaths of axons
- occurs due to immune attack in myelin
- exact cause not known - defects in several genes
- results in progressive loss of nervous system function
- fatigue, muscle weakness, poor motor control, loss of balance, mental depression
exercise training improves both functional capacity and quality of life

Question 8

electrical activity in neurons

Answer 8

neurons are excitable cells
» irritability: ability to respond to a stimulus and trigger a neural impulse
» conductivity: transmission of the impulse along the axon

Question 9

resting membrane potential

Answer 9

negative charge inside cells at rest
> -5 to -100 mv across all cell types
> -40 to -75 mv in neurons
charge determined by:
Permeability: of plasma membrane to ions
> diff in ion concentrations across membrane
- Na+, K+, & Cl- play most important role
maintained by sodium-potassium pump
> potassium tends to diffuse out of the cell
- Na+/K+ pump moves 2 K+ in and 3 Na+ out

Question 10

neurons transmit messages via action potential

Answer 10

• occurs when a stimulus of sufficient strength depolarizes the neuron
  > opens Na+ channels, and Na+ diffuses into cell
  > inside becomes more positive

Question 11

repolarization

Answer 11

return to resting membrane potential
> K+ leaves the cell rapidly
> Na+ channels close

Question 12

all-or-none law

Answer 12

once a nerve impulse is initiated, it will travel the length of the neuron

Question 13

synapse

Answer 13

small gap between presynaptic neuron and postsynaptic neuron

Question 14

neurotransmitter

Answer 14

• chemical messenger released from presynaptic membrane
• binds to receptor on postsynaptic membrane
• causes depolarization of postsynaptic membrane

Question 15

excitatory postsynaptic potentials (EPSP)

Answer 15

can promote neural depolarization in two ways:
1.) temporal summation: summing several EPSPs from one presynaptic neuron
2.) spatial summation: summing EPSPs from several different presynaptic neurons

Question 16

inhibitory postsynaptic potentials (IPSP)

Answer 16

causes hyperpolarization (more negative resting membrane potential)
neurons with a more negative membrane potential resist depolarization

Question 17

neurotransmitters of interest for PA & exercise

Answer 17

1.) epinephrine & norepinephrine
2.) dopamine
3.) serotonin
4.) acetylcholine (AcH)

Question 18

nociceptors

Answer 18

pain receptors

Question 19

thermoreceptors

Answer 19

temperature receptors

Question 20

chemoreceptors

Answer 20

respond to water-soluble and lipid-soluble substances dissolved in body fluids

Question 21

mechanoreceptors

Answer 21

sensitive to stimuli that distort their plasma membranes

Question 22

proprioceptors

Answer 22

-receptors that provide CNS with info about body position
- located in joints and muscles

Question 23

kinesthesia

Answer 23

• conscious recognition of the position of body parts
• recognition of speed of limb movement

Question 24

free nerve endings

Answer 24

• most abundant type of joint proprioceptors
• sensitive to touch and pressure
• initially strong stimulated, then adapt
  (JP)

Question 25

golgi-type receptors

Answer 25

- found in ligaments and around joints - functionally similar to free nerve endings (JP)

Question 26

pacinian corpuscles

Answer 26

- located in tissues around joints - detect rate of joint rotation (JP)

Question 27

muscle proprioceptors

Answer 27

provide sensory feedback to nervous system - changes in muscle length - force development by muscle fibers

Question 28

muscle spindles

Answer 28

provides info about muscle length and rate of shortening Responsible for stretch reflex - stretch on muscle stimulates muscle spindles and promotes a reflex contraction > knee-jerk reflex

Question 29

golgi tendon organ

Answer 29

provides info about muscle force production- can prevent muscle injury during excessive force generation - stimulation results in reflex relaxation of muscle > inhibitory neurons send ipsps to muscle alpha motor neurons

Question 30

intrafusal fibers

Answer 30

run parallel to normal muscle fibers (extrafusal)

Question 31

gamma motor neurons

Answer 31

stimulate intrafusal fibers to contract in concert with extrafusal fibers

Question 32

skeletal muscle chemoreceptors

Answer 32

sensitive to changes in the chemical environment surrounding muscle fibers > H+ ions, CO2, K+ Provide CNS with info about muscle metabolism during exercise > important control of cardiovascular and pulmonary responses to exercise

Question 33

somatic motor function

Answer 33

motor neurons are located within spinal cord > responsible for carrying neural messages from spinal cord to skeletal muscles

Question 34

motor unit

Answer 34

motor neuron and all muscle fibers it innervates

Question 35

innervation ratio

Answer 35

number of muscle fibers per motor neuron > low ratio involved in fine motor control > high ratio in muscles that do not require fine motor control

Question 36

motor unit recruitment

Answer 36

recruitment of additional muscle fibers by activating more motor units

Question 37

size principle

Answer 37

orderly recruitment of motor units during exercise - smallest recruited first during exercise Type S or type 1 fibers (smallest) Type FR or type IIa (intermediate) Type FF or type IIx (largest)

Question 38

vestibular apparatus

Answer 38

-located within inner ear - responsible for maintaining general equilibrium and balance (maintain head position) - sensitive to changes in linear and angular acceleration (stimulated by head movement) - also controls head and eye movement during exercise

Question 39

spinal tuning

Answer 39

refers to neural networks within spinal cord that refine voluntary movement after receiving messages from higher brain centers

Question 40

withdrawal reflex

Answer 40

means of removing limb from source of pain

Question 41

motor cortex

Answer 41

receives inputs from variety of brain areas including basal nuclei, cerebellum, thalamus

Question 42

motor control

Answer 42

spinal mechanisms result in refinement of this - feedback from proprioceptors allows for further modification in motor control