Question

27. What actually shortens when a muscle fiber contracts?
        A)    thick and thin filaments
        B)    A bands, M lines, and Z discs
        C)    sarcomeres, H zones, and I bands
        D)    both b and c

28.Sarcoplasmic reticulum is the name given to which of the following?    
a.Rough endoplasmic reticulum in smooth muscle cells
b.Smooth endoplasmic reticulum in cells of the epimysium
c.Smooth endoplasmic reticulum in all muscle cells
d.Rough endoplasmic reticulum in cardiac muscle cells

29.Which of the following actions is caused by skeletal muscle?
a.Vasoconstriction
b.Vasodilation
c.Pupillary dilation
d.Eye movements
e.Heartbeat

30.Which of the following does NOT occur in a muscle during a contraction?
a.Thick and thin filaments interact
b.Muscle fibers stretch
c.Thick and thin filaments "slide" past one another
d.Muscle fibers shorten

31. A nerve impulse triggers the release of what chemical at a neuromuscular junction?
        A)    adenosine triphosphate (ATP)
        B)    acetylcholinesterase (AChE)
        C)    acetylcholine (ACh)
        D)    none of the above

32 .Rigor mortis demonstrates that skeletal muscle tissue
        A)    normally requires energy to end as well as to start a contraction
        B)    can survive and function for some time after the heart stops beating
        C)    maintains powerful contractions even with no ATP, until autolysis occurs
        D)    all of the above

Answer 1

27) Sarcomeres , H zone and I band actually shortens when a muscle fiber contracts.

M line cannot be shortened and thick and thin filament do not shorten.

28) Sarcoplasmic reticulum is the name given to smooth endoplasmic reticulum in all muscle cells .

29) Eye movement is voluntary movement and is controlled by skeletal muscles while heart beat is controlled by cardiac muscles and movement in blood vessels and ciliary body and iris of eye are controlled by smooth muscles.

30) Muscle fiber stretching is the process which does not occur in a muscle during a contraction.All the other 3 processes are part of sliding filament theory of muscle contraction.

31) A nerve impulse triggers the release of acetylcholine(ACh). Acetylcholinesterase is the enzyme which breaks the acetylcholine at neuromuscular junction.

32) Rigor mortis demonstrates that skeletal muscle tissue normally requires energy to end as well as to start a contraction  and can survive and function for some time after the heart stops beating and maintains powerful contractions even with no ATP, until autolysis occurs.