Chapter 9 (Midterm 1)

Question 1

What are the differences between force generation and sacromere length?

Answer 1

larger fiber = greater force || more actin/myosin = more cross-bridges forming

Question 2

In length-tension relationship, what shape does the graph have?

Answer 2

active tension developed in the stimulated fiber = parabolic || passive tension in relaxed fiber = exponential

Question 3

What is the size principle in muscle?

Answer 3

small motor neurons = stimulated fast

Question 4

What is tetanus?

Answer 4

maintained contraction in response to repetitive stimulation

Question 5

What is summation?

Answer 5

increase in muscle tension from successive APs happening during the phase of mechanical activity

Question 6

What is a twitch?

Answer 6

a mechanical response of a muscle fiber to a single AP

Question 7

What are fast-oxidative-glycolytic fibers?

Answer 7

combine high myosin-ATPase activity with high oxidative capacity and intermediate glycolytic capacity?

Question 8

What are slow-oxidative fibers?

Answer 8

combine low myosin-ATPase activity with high oxidative capacity

Question 9

What are fast-glycolytic fibers?

Answer 9

combine high myosin ATPase activity with high glycolytic capacity

Question 10

What is isometric conctraction?

Answer 10

muscle develops tension but does not shorten/lengthen || constant length

Question 11

What is concentric contraction?

Answer 11

tension exceeds load = muscle fiber shortening occurs

Question 12

What are fast-twitch fibers?

Answer 12

reach peak tension faster than slow twitch

Question 13

What is cross-bridge cycling?

Answer 13

cycle between cross-bridge binds to thin filament, moves –> cycle repeats

Question 14

In the cross-bridge cycle, when is ATP needed?

Answer 14

Step 3 in order to cause cross-bridge to detach from actin

Question 15

How is cross-bridge cycling controlled?

Answer 15

myosin light chain phosphorylation / hydrolysis of ATP

Question 16

How is cross-bridge cycling stopped?

Answer 16

ATP must stay unhydrolyzed to prevent attachment of cross bridges to myosin

Question 17

What are cross-bridges

Answer 17

the two globular myosin heads attached (bridged) together by the myosin tails

Question 18

During the cross-bridge cycle, what happens to actin and myosin?

Answer 18

when myosin is energized via ATP hydrolysis, it binds to actin; ATP binding to myosin breaks this linkage

Question 19

What is the structure of skeletal muscle cell?

Answer 19

myofibrils, sarcoplasmic reticulum, terminal cisternae, transverse tubules, mitochondrion, cytosol/plasma membrane

Question 20

What is the form of skeletal muscle?

Answer 20

striated muscle due to the arrangement of the thick/thin filaments (myofibrils)

Question 21

What are the skeletal muscle’s functions?

Answer 21

support and movement

Question 22

What are myofibrils function?

Answer 22

contraction

Question 23

What is the sarcoplasmic reticulum and its function?

Answer 23

muscle endoplasmic reticulum that stores Ca2+ and is released after membrane excitation

Question 24

What are the characteristics of a skeletal muscle fiber?

Answer 24

multinucleated, many mitochondria, myofibrils/sarcomeres, and Transverse tubules

Question 25

What is a motor end-plate of a neuromuscular junction?

Answer 25

the highly folded post-synaptic side

Question 26

What is the muscle metabolic function under aerobic conditions?

Answer 26

production of ATP via ox-phos or glycolysis (less ATP, suitable for low O2)

Question 27

What size of muscle fibers are better suited for the GLYCOLYTIC pathway and what is the purpose?

Answer 27

larger fibers for strong contractions due to strenuous activity = low O2 conditions

Question 28

What size of muscle fibers are better suited for the OX-PHOS pathway and what is the purpose?

Answer 28

small fibers

Question 29

In length-tension relationship, where is the maximum force generated?

Answer 29

at the optimal length

Question 30

In length-tension relationship, what causes changes in the force generated?

Answer 30

the muscle length

Question 31

What is a neuromuscular junction?

Answer 31

synapse-like junction between an axon terminal of an efferent nerve fiber and a skeletal muscle fiber

Question 32

What is a synapse?

Answer 32

junctions between neurons

Question 33

Where are neuromuscular junctions located?

Answer 33

skeletal muscle

Question 34

Where are synapses located?

Answer 34

between neurons or between a neuron and an effector cell

Question 35

How is contraction stopped?

Answer 35

sarcoplasmic Ca2+ must be lowered by closing the ryanodine receptors and removing extracellular Ca2+ via ATPase and Na/Ca exchanger

Question 36

What is the structure of smooth muscle?

Answer 36

single nucleated, unstriated, actin/myosin in parallel arrangement and anchored to connective tissues at dense bodies

Question 37

What is the form of smooth muscle?

Answer 37

smooth not striated due to actin and myosin not arranged in sarcomeres, no myofibrils

Question 38

What are the functions of smooth muscle?

Answer 38

allows organ or blood vessel to undergo change in volume (stretching)

Question 39

What is a single unit smooth muscle?

Answer 39

less innervated and more gap junctions

Question 40

What is a multi-unit smooth muscle?

Answer 40

very innervated and few/no gap junctions,

Question 41

Where is smooth muscle found?

Answer 41

blood vessels and internal organs

Question 42

Define innervate?

Answer 42

to supply with nerves

Question 43

Which of the three muscles does it contract the slowest?

Answer 43

smooth muscle

Question 44

What effect do fast glycolytic fibers have on fatigue?

Answer 44

fatigue very rapidly, highly susceptible to fatigue

Question 45

What kind of force do fast glycolytic fibers generate?

Answer 45

fast and strong movements

Question 46

What effect do fast oxidative-glycolytic fibers have on fatigue?

Answer 46

have an intermediate capacity to resist fatigue

Question 47

What kind of force do fast oxidative-glycolytic fibers have on fatigue?

Answer 47

intermediate force-generating ability

Question 48

What effect do slow oxidative fibers have on fatigue?

Answer 48

very resistant to fatigue = maintain contractile activity for long periods & barely loss of tension

Question 49

What kind of force do slow oxidative fibers have on fatigue?

Answer 49

does not produce a lot of tension or contraction, used for maintaining posture and fine movements --- small non-rigorous things