LESSON 3 - skeletal muscle & human movement 2

Question 1

what are muscles made up of ?

Answer 1

muscle fascicles

Question 2

what are fascicles ?

Answer 2

bundles of muscle fibers

Question 3

what are muscle fibers ?

Answer 3

individual muscle cells

Question 4

what are muscle fibers made up of ?

Answer 4

myofibrils

Question 5

what two things do myofibrils contain ?

Answer 5

actin and myosin

Question 6

what do actin and myosin filaments form?

Answer 6

sarcomere of the muscles

Question 7

what is the contractile unit of the muscle ?

Answer 7

sarcomere

Question 8

what type of motor neuron innervates the individual muscle ?

Answer 8

alpha motor neuron

Question 9

more motor units = ____ motor units

Answer 9

increased

Question 10

define motor units

Answer 10

a single alpha motor neuron + all the muscle fibers it innervates

Question 11

↑ operating motor units =

Answer 11

↑ contractile force

Question 12

around how many muscle fibres does each alpha motor unit innervate ?

Answer 12

20 - 2000 +

Question 13

if a motor unit innervates 300 muscle fibers how many branches will the axon have ?

Answer 13

300

Question 14

what is a motor neuron pool ?

Answer 14

the collection of all the alpha motor neurons that innervate one single muscle

Question 15

define the all-or none principal of motor units …

Answer 15

there is no “slight” vs “heavy” contraction; when a motor neuron fires and an AP is generated, all of the muscle is fibers associated will contact to its fullest potential

Question 16

force of muscle action carries from slight to max in how many ways ?

Answer 16

one of two ways

Question 17

what are the two ways that increase force

Answer 17

1. increasing NUMBER of recruited motor units
2. increasing FREQUENCY of motor unit discharge

Question 18

what is the formula for power ?

Answer 18

power = force x velocity

Question 19

what are the three main motor unit characteristics ?

Answer 19

1. size (# of muscle fibers innervated)
2. physiological properties of their muscle fibers
3. biochemical properties of their muscle fibers

Question 20

when talking about a muscles motor unit size and innervation ratio, which types of muscle will be bigger?

Answer 20

the ones that are being used more often

Question 21

how do we calculate innervation ratio ?

Answer 21

number of muscle fibers divided by alpha motor axons = innervation rate

Question 22

how do we calculate contraction time ?

Answer 22

as a function of each motor unit

Question 23

what are the two types of twitches ?

Answer 23

fast and slow twitch

Question 24

which type of twitch contraction time develop the greatest twitch force ?

Answer 24

fast twitch

Question 25

give the acronym for motor unit force x contraction time …

Answer 25

one slow red ox

Question 26

define the acronym “one slow red ox”

Answer 26

one = type 1 muscle
slow = slow muscle
red = red muscle
ox = oxidative (depends on oxygen)

Question 27

what are the three muscle fiber type classifications ?

Answer 27

• slow twitch (ST)
• fast twitch a (FTa)
• fast-twitch x (FTx)

Question 28

describe properties of fast fatiguable (FF : type 2x) :

Answer 28

• fast responding
• slowest contraction time
• highest peak
• not able to maintain the force (over time response falls)

Question 29

describe properties of fast fatigue-resistance (FR : type 2a) :

Answer 29

• show some fatigue

Question 30

describe properties of slow (S : type 1) :

Answer 30

• longest contraction times
• does not produce as much force r as quickly
• is highly fatigue resistant

Question 31

what type of muscle fiber is resistant to fatigue ? (ex. running marathon)

Answer 31

slow oxidative (SO) (ST)

Question 32

what type of muscle fiber is in the middle ? (ex. playing a sport)

Answer 32

fast oxidative/GLYCOLYTIC (FOG) (FTa)

Question 33

what type of muscle fiber is highly fatiguable? (sprinters)

Answer 33

fast-glycolytic (FG) (FTx)

Question 34

FILL IN THE BLANK :

if you want to be a highly aerobic athlete that’s capable of performing high levels of intensity for long periods of time; you must have a high percentage of _____ twitch fibers

Answer 34

slow

Question 35

what are the two method for altering force production?

Answer 35

• less force production
• more force production

Question 36

in regards to motor unit recruitment … “less force production =

Answer 36

fewer or smaller motor units”

Question 37

in regards to motor unit recruitment … “more force production =

Answer 37

more or larger motor units”

Question 38

what is the size principal ?

Answer 38

order of recruitment relates directly to size of alpha-motor neuron and their “excitability”

Question 39

define the most excitable (low force) to least excitable (high force) …

Answer 39

type 1, type 2a, type 2x

Question 40

how can measure the titanic maximal force of a muscle ?

Answer 40

by increasing / stimulating the nerve that innervates that muscle increasing the amplitude of the current

Question 41

what type of muscle contraction innervates all types of muscles ?

Answer 41

dynamic muscle contraction

Question 42

dynamic muscle contraction is the coordination of :

Answer 42

• nerve impulses
• calcium release and reuptake
• crossbrudge cycling
• ATP hydrolysis and resynthesis