Muscle 5

Question 1

The force developed by a muscle fibre is increased by…

Answer 1

summation of multiple twitches

Question 2

motor unit

Answer 2

a single motor neuron and all the muscle fibres it innervates

Question 3

motor neuron pool

Answer 3

the group of all motor neurons innervating a single muscle

Question 4

Weak stimulus to motor neuron pool recruits…..first

Answer 4

smallest motor neurons

Question 5

small-diameter motor neuron

Answer 5

Rm is high and conduction velocity is low (slow-twitch, type I)

Question 6

large-diameter motor neuron

Answer 6

Rm is low and conduction velocity is high (fast-twitch type II)

Question 7

size principle

Answer 7

all muscle fibres within one motor unit are the same type

Question 8

small motors units

Answer 8

small motor neurons; slow-oxidative

Question 9

intermediate motor units

Answer 9

intermediate size motor neurons; fast-oxidative-glycolytic

Question 10

large motor units

Answer 10

large morot neurons; fast glycolytic

Question 11

Asynchronous recruitment

Answer 11

the CNS modulates firing rates of upper motor neurons to allow different motor units to maintain contraction in order to prevent fatigue

Question 12

tension

Answer 12

the force tending to pull the attachment points of a muscle toward one another

Question 13

isotonic contraction

Answer 13

the muscle contracts, shortens, and creates force to generate movement

Question 14

isometric contraction

Answer 14

muscle contracts but does not shorten; creates force without moving a load

Question 15

two kinds of isotonic contractions

Answer 15

concentric and eccentric

Question 16

concentric contraction

Answer 16

muscle shortens while generating force

Question 17

eccentric contraction

Answer 17

muscle lengthens with generating force

Question 18

eccentric contraction acts to….

Answer 18

decelerate the joint at the end of a movement

Question 19

How do the sarcomeres shorten during isometric contraction without the muscle changing length?

Answer 19

elastic elements in tendons and connective tissue around muscle fibres

Question 20

myosatellite cells

Answer 20

involved in muscle repair and may form new muscle fibres (occurs in development)

Question 21

satellite cells

Answer 21

in response to an injury, become activated and proliferate

Question 22

Two proposed mechanisms by which muscle mass may be increased

Answer 22

hypertrophy and hyperplasia

Question 23

hypertrophy

Answer 23

When skeletal muscle is subjected to an overload stimulus, it causes perturbations in muscle fibres and the related extracellular matrix

Question 24

hypertrophy leads to..

Answer 24

-increase in size and number contractile proteins, sarcomeres, sarcoplasmic storage

Question 25

sarcopenia

Answer 25

muscle loss due to age

Question 26

cachexia

Answer 26

weakness and/or wasting due to chronic disease