Exam 2 - Module 6 - Lesson Answers

Question 1

three muscle tissue types

Answer 1

skeletal, cardiac, and smooth

Question 2

which of the muscle types is/are striated

Answer 2

skeletal and cardiac

Question 3

which of the muscle types is under strict voluntary control

Answer 3

skeletal muscle is under the control of the voluntary nervous system

Question 4

why is elasticity an important quality of muscle tissue

Answer 4

it allows muscle to return to its original length during relaxation after contraction

Question 5

perimysium

Answer 5

connective tissue later surrounding an individual fascicle

Question 6

largest unit of organization in skeletal muscle tissue

Answer 6

fascicle

Question 7

smallest unit of organization in skeletal muscle tissue

Answer 7

myofilament (or filament)

Question 8

muscle fiber vs muscle cell

Answer 8

they mean the same thing

Question 9

myofibril

Answer 9

contains many myofilaments

muscle fiber > myofibril

Question 10

how do tendons facilitate body movement

Answer 10

when a muscle contracts, the force of movement is transmitted through the tendon, which pulls on the bone to produce skeletal movement

Question 11

acetylcholine (ACh)

Answer 11

molecule released by a neuron at the neuromuscular junction (NMJ)

Question 12

what causes the depolarization of the muscle cell membrane

Answer 12

influx of positively charged sodium (Na+) ions into the muscle cell via voltage-gated channels on the muscle cell membrane

Question 13

at rest, what molecule blocks the myosin-binding sites on actin

Answer 13

tropomyosin

Question 14

what causes the exposure of the myosin-binding sites on actin

Answer 14

binding of calcium (Ca++) to troponin moves the tropomyosin such that the binding sites become exposed

Question 15

what must attach to the myosin heads in order for them to be able to detach from the actin (thus breaking the cross-bridges for the onset of muscle relaxation)

Answer 15

for muscle relaxation to occur, ATP must attach to the myosin head; a lack of ATP in the body, such as occurs upon death, leads to an extended contracted state called rigor mortis

Question 16

what causes the striated appearance of skeletal muscle tissue

Answer 16

dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell cause the entire cell to appear striated.

Question 17

how would muscle contractions be affected if ATP was completely depleted in a muscle fiber

Answer 17

without ATP, the myosin heads cannot detach from their binding sites on activ. all of the “stuck” cross-bridges result in muscle stiffness. in live people that is “writer’s cramps” - recently dead person it is rigo mortis

Question 18

name the three types of skeletal muscle fibers and abbreviations

Answer 18

slow oxidative (SO), slow glycolytic (SG), and fast glycolytic (FG)

Question 19

which skeletal muscle fiber fatigues the fastest

Answer 19

fast glycotic

Question 20

which skeletal muscle fiber fatigues the slowest

Answer 20

slow oxidative

Question 21

why do muscle cells use creatine phophate instead of glycolysis to supply ATP for the first few seconds of muscle contraction

Answer 21

creatine phosphate is used because that and ADP are converted very quickly into ATP by creatine kinase. glycolysis cannot generate ATP as quickly as creatine phosphate

Question 22

what changes occur at the cellular level in response to endurance training

Answer 22

endurance training modifies slow fibers to make them more efficient by producing more mitochondria to enable more aeroib metabolism and more ATP production. endurance exercise can also increase the amount of myoglobin in a cell and formation of more extensive capillary networks around the fiber

Question 23

what changes occur at the cellular level in response to resistance training

Answer 23

resistance exercises affect muscles by causing the formation of more actin and myosin, thus increasing the number of myofibrils and sarcomeres in the muscle fibers. this increases the thickness of the muscle fibers and the overall bulk of the muscle

Question 24

how many nuclei in each muscle type

Answer 24

skeletal = multinucleated / cardiac = uni or binucleate / smooth = uninucleate

Question 25

which of the muscle types is/are under involuntary control

Answer 25

cardiac and smooth

Question 26

which of the muscle types has/have gap junctions

Answer 26

cardiac and smooth

Question 27

which muscle type has/have intercalated discs

Answer 27

cardiac

Question 28

which muscle type does/do not contain myofibrils and T tubules?

Answer 28

smooth

Question 29

when a muscle contracts

Answer 29

it gets shorter

Question 30

when deltoid contracts

Answer 30

performs abduction of the arm (it moves the arm away from the body)

Question 31

movement of your arms when doing a chin up

Answer 31

adduction (moving the arms toward the midle of the body

Question 32

adductor longus

Answer 32

brings the legs together

Question 33

biceps brachii

Answer 33

performs flexion of the forearm

Question 34

triceps brachii

Answer 34

extends the forearm

Question 35

three muscles of the quadriceps femoris

Answer 35

rectus femoris, vastus medialis, vastus lateralis

Question 36

name two of the hamstring muscles

Answer 36

biceps femoris and semitendinosus

Question 37

quadriceps

Answer 37

extend the leg

Question 38

hamstrings

Answer 38

flex the leg

Question 39

dorsiflexion

Answer 39

flexion of the foot (pointing your toe toward your shin)

The tibialis anterior does dorsiflexion of the foot

Question 40

plantar flexion

Answer 40

pointing the toes away from the body

the gastrocnemius does plantar flexion of the foot