Muscular (E3)

Question 1

3 layers of skeletal muscle

Answer 1

1. Epimysium
2. Perimysium
3. Endomysium

Question 2

Components of myofibrils

Answer 2

Sarcomere composed of thin and thick filaments and Z & M lines or discs

Question 3

Thick filaments

Answer 3

Composed mainly of myosin which is made up of 2 heavy chains and 4 light chains

Question 4

Thin filaments

Answer 4

Composed of actin, nebulin, troponin, and tropomyosin

Question 5

Muscle tone

Answer 5

Resistance to stretch exhibited by a relaxed muscle
- due to baseline calcium in the cytosol

Question 6

Intrinsic muscle tone in smooth muscle

Answer 6

Due to baseline Ca+ levels in the cytosol causing low level tension activity

Question 7

Alpha motor neurons

Answer 7

-innervate skeletal muscle fibers
-cell bodies are located in the brainstem and spinal cord

Question 8

T/F: all neuromuscular junctions are excitatory.

Answer 8

True

Question 9

Botulinum toxin

Answer 9

Neurotoxin released from clostridium botulinum
-blocks Ach release

Question 10

Curare

Answer 10

-blocks Ach receptors
-similar in action to nondepolarizers

Question 11

T/F: a muscle cell has multiple nuclei

Answer 11

True

Question 12

Satellite cells

Answer 12

Undifferentiated stem cells that repair damaged or destroyed skeletal muscle fibers

Question 13

Skeletal muscle

Answer 13

-attached to bones by tendons

Question 14

Sarcomere

Answer 14

One unit of thin and thick filaments

Question 15

Wide dark bands in the middle

Answer 15

A band

Question 16

Light bands

Answer 16

I bands

Question 17

Narrow dark bands in middle

Answer 17

H zone (inside A band)
M line (inside H zone)

Question 18

Sarcoplasmic reticulum

Answer 18

-same as endoplasmic reticulum in most cells
-store large quantities of Ca+

Question 19

Sarcolemma

Answer 19

-plasma membrane of muscle cell
-propagates action potential

Question 20

Contraction

Answer 20

Activation of the force generating sites within muscle fibers (the cross bridges)

Question 21

Motor unit

Answer 21

A motor neurons and the muscle fibers it innervates

Question 22

How is the length of a skeletal muscle cell related to the force it can generate?

Answer 22

Skelta muscle cells generate the most force when the contraction occurs at an intermediate length

Question 23

Phases of muscle twitch

Answer 23

Latent period
Contraction phase
Relaxation phase

Question 24

Latent period

Answer 24

Time elapsed from the application of a stimulus to the beginning of the contraction

Question 25

Contraction period

Answer 25

Cross bridges are active in the muscle shortens if tension is great enough to overcome the load

Question 26

Relaxation period

Answer 26

Active transport of calcium back into the sarcoplasmic reticulum and degradation of acetylcholine

Question 27

Single twitch

Answer 27

Same size twitches if completely relaxed between

Question 28

Twitch summation

Answer 28

Muscle fiber restimulated before completely relaxed, second twitch added to first twitch

Question 29

Tetanus

Answer 29

Muscle fibers stimulated so rapidly. It does not relax, maximus is saying contraction occurs

Question 30

Train of four responses

Answer 30

Absent - 100 One twitch - 90 Two twitches - 80 Three twitches -75 Four twitches -0-75

Question 31

Central command fatigue

Answer 31

Appropriate regions of the cerebral cortex fail to send excitatory signals to them motor neurons

Question 32

Oxidative fibers

Answer 32

-more mitochondria -more blood flow -long term contractions (posture)

Question 33

Glycolytic fibers

Answer 33

-few mitochondria -large store of glycogen -quick activity bursts -lack myoglobin (white muscle fibers)