Muscle structure and function

Question 1

THe ________ is located between muscle fibers.

Answer 1

edomysium

Question 2

_____ = thick filament, ______ = thin filament

Answer 2

myosin; actin

Question 3

Depolarization of the T-tubule system causes Ca2+ release from the sarcoplasmic reticulum’s ________ sacs.

Answer 3

lateral

Question 4

What does Ca2+ bind to in the actin filaments?

Answer 4

troponin-tropomyosin

Question 5

During muscle contraction, actin combines with myosin ________ to split ATP with energy release.

Answer 5

ATPase

Question 6

ATP binds to myosin _______, breaking actin-myosin bond.

Answer 6

crossbridge

Question 7

When muscle stimulation ceases, calcium moves back into the SR lateral sacs through ______ ______ requiring ATP hydrolysis.

Answer 7

active transport

Question 8

______ removal restores inhibitory action of troponin-tropomyosin.

Answer 8

calcium

Question 9

What is sarcomere length at rest?

Answer 9

4 micrometers (10^-6)

Question 10

What is sarcomere length during contraction ?

Answer 10

2.7 micrometers (10^-6)

Question 11

What is the optimal sarcomere length?

Answer 11

between 2-2.2 micrometers

Question 12

When the motor neuron signal arrives, where is Ash released?

Answer 12

NMJ

Question 13

With Ca++ influx, _____ moves aside which allows myosin to bind to actin.

Answer 13

troponin

Question 14

The crossbridge slides, then _______ is ejected, and ATP replaces ADP, causing crossbridge to release and spring back.

Answer 14

phosphate

Question 15

What type of muscle is the strongest? Why?

Answer 15

Pennate; fibers are packed more closely together

Question 16

With a ____ degree angle of clination, there is a corresponding 13% loss of strength, but you can pack more muscle into the area.

Answer 16

30

Question 17

The longer the muscle, the (more/less) force it can exert.

Answer 17

less

Question 18

The longer the muscle, the (slower/faster) it can exert a certain force.

Answer 18

faster

Question 19

_______ muscles have faster working velocity and longer working range.

Answer 19

fusiform

Question 20

_______ muscles have a higher peak force and shorter working range.

Answer 20

pennate

Question 21

At a whole body level, optimal joint angle is influenced by _____ ______.

Answer 21

muscle length

Question 22

Biomechanically, what is impacting optimal muscle length?

Answer 22

muscle moment arm

Question 23

Every muscle generates muscle force most optimally at 90 degrees. (T/F)

Answer 23

FALSE (every muscle has a joint angle at which muscle force generation is optimal)

Question 24

What two things influence the joint angle at which muscle force generation is optimal?

Answer 24

1. Actin-myosin overlap

2. Joint biomechanics

Question 25

When assessing muscle strength clinically with manual muscle tests, one must use the _________ ______ for that muscle.

Answer 25

standardized position

Question 26

Type __ fibers have high aerobic capacity, low force and slow contraction speed.

Answer 26

1

Question 27

Type __ fibers have fast contraction speed, high force and rapid cross bridge turnover, and high anaerobic capacity,

Answer 27

2

Question 28

The MN cell body is located in the ___ matter in the SC.

Answer 28

grey

Question 29

Voltage dependent Na+ channels open when initial depolarization reaches ____mV and this leads to an influx of Na+ leading to further depolarization until ____mV.

Answer 29

-50; +40

Question 30

Voltage-dependent K+ channels open when depolarization reaches ____mV, leading to efflux of K+ which leads to ________ of the cell membrane.

Answer 30

+40; repolarization

Question 31

Ratio of muscle fibers per MF is generally related to a muscles _______ _____.

Answer 31

movement function

Question 32

__________ ______ principle = the motor units are recruited in a graded manner, from small to large,.

Answer 32

henneman’s size

Question 33

Recruitment occurs ______ the motor units.

Answer 33

across

Question 34

_____ _____ = modulation of firing rate of a motor unit (frequency of motor unit discharge)

Answer 34

rate coding

Question 35

As firing rate increases, ________ occurs (initial small twitch like contraction will build to produce a constant higher force contraction)

Answer 35

summation

Question 36

How is force modulated?

Answer 36

input from sensory receptors

Question 37

How does the fore generate from a muscle meet the needs of a task?

Answer 37

Can increase the number of activated fibers of increase firing rate.