Muscle tissue 11-2

Question 1

How many millivolts (mV) are inside a resting muscle cell

Answer 1

-90 mv

Question 2

At how many mV open the voltage-gated sodium channels?

Answer 2

-55 mV

Question 3

How many mV are present when the sodium channels close and the potassium channels open

Answer 3

+30

Question 4

What is tension?

Answer 4

when muscles contract

Question 5

What happens during the lag phase before muscle contraction?

Answer 5

• calcium release
• thick/thin filament interaction
• muscle fiber contraction

Question 6

What are the factors that affect tension?

Answer 6

• stretch
• temperature
• hydration
• stimulus frequency
• fatigue

Question 7

What is a twitch?

Answer 7

Cycle of contraction and relaxation of a muscle fiber produced by a single stiumulus

Question 8

What is a treppe?

Answer 8

repeated stimulation after relaxation phase has been completed, causing higher tensions due to increased Calcium concentrations in the sarcoplasm

Question 9

Wave summation

Answer 9

stimulation of a muscle fiber is fast enough that one twitch is added to another (before complete relaxation)

Question 10

Incomplete tetanus

Answer 10

muscle fiber reaches maximal tension and partially relaxes

Question 11

complete tetanus

Answer 11

muscle fiber reaches maximal tension and stays contracted (no relaxation phase)

Question 12

motor unit

Answer 12

all muscle fibers innervated by one neuron

Question 13

What controls motor neuron movement?

Answer 13

number and size of motor unit

-small motor units go to thinner muscle fibers first

Question 14

What is muscle tone?

Answer 14

constant tension caused by changing activation of motor units
-stabilizes bones and joints

Question 15

isometric contraction

Answer 15

tension rises, length of muscle remains constant

Question 16

isotonic concentric contraction

Answer 16

tension rises, muscle shortens (bicep curl)

Question 17

isotonic eccentric contraction

Answer 17

muscle lengthens while maintaining tension

Question 18

What is the optimum resting length in muscle?

Answer 18

90-110%

Question 19

What type of energy is used by the cell?

Answer 19

ATP

Question 20

Aerobic metabolism

Answer 20

• provides most ATP needed for contraction
• Uses oxygen to generate large amounts of ATP from glucose or fatty acids
• slowest process

Question 21

Anaerobic metabolism (glycolysis)

Answer 21

• peak activity

- faster

Question 22

creatine phosphate

Answer 22

releases stored energy to convert ADP to ATP

-fastest

Question 23

muscle fatigue

Answer 23

muscles no longer contract or contracts weakly

Question 24

What are the contributing factors of muscle fatigue?

Answer 24

• exhaustion of energy resources (ATP & glycogen)
• ionic imbalances (mainly potassium)
• build up of lactic acid and ammonia
• exhaustion of ACh at the neuromuscular junction

Question 25

oxygen debt

Answer 25

excess post-exercise oxygen consumption (EPOC) - convert lactic acid back to ATP and glucose - amount of oxygen required during resting period to restore muscle to normal conditions

Question 26

what happens during the recovery period?

Answer 26

- begins immediately after activity ends - Oxygen debt - heat loss

Question 27

Slow muscle fibers

Answer 27

- slow oxidative fibers - slow twitch muscle - red muscle - type I

Question 28

fast muscle fibers

Answer 28

- fast glycolytic fibers - fast twitch muscle - white muscle - type IIB

Question 29

intermediate fibers

Answer 29

- fast oxidative fiber; type IIA - greater resistance to fatigue compared to fast fibers - increase in mitochondria and blood supply - endurance training can convert fast muscle to intermediate muscle

Question 30

White muscles

Answer 30

pale muscles dominated by fast fibers

Question 31

red muscles

Answer 31

dark muscles dominated by slow fibers and myoglobin

Question 32

hypertrophy

Answer 32

enlargement of muscles

Question 33

atrophy

Answer 33

reduction and loss of muscle mass

Question 34

anaerobic endurance

Answer 34

time over which muscular contractions are sustained by glycolysis and ATP/CP reserves

Question 35

aerobic endurance

Answer 35

time over which muscle can continue to contract while supported by mitochondrial activities

Question 36

what are the characteristics of cardiac muscle?

Answer 36

- only located in heart - only 1 nucleus - short, broad t-tubules - striated - involuntary - longer contractions - no wave summation or tetanic contractions

Question 37

intercalated discs

Answer 37

where membranes contact one another | -form gap junctions

Question 38

what are the characteristics of smooth muscle?

Answer 38

- thin, spindle shaped - nonstriated - lack t-tubules - involuntary - gap junctions

Question 39

What are the steps in the contraction of smooth muscle?

Answer 39

1. calcium ions enter from outside cell and are released from the SR 2. Calcium binds to calmodulin, which activates myosin light chain kinase

Question 40

Plasticity

Answer 40

actin myosin fibers are scattered in different directions

Question 41

Multi-unit smooth muscle

Answer 41

- cells are innervated by more than one motor neuron - rare - iris of eye, male reproductive system, arector pili muscle

Question 42

visceral smooth muscle

Answer 42

- cells that are not always innervated by motor neurons | - blood vessels, digestive tract

Question 43

TRUE or FALSE: | Neurons that innervate smooth muscle are under voluntary control

Answer 43

FALSE | they are NOT under voluntary control