Protection Support, and Movement (936-947)
Myofribrils are long strands of protein divided into sarcomeres (section of myofibril that contains all filaments needed to make that section contract)
I. Answer these question.
1. What are the main functions of the skeletal system?
2. How do filaments work to cause the sarcomere to shorten?
3. What does myosin do?
4. What are actin and myosin filaments?
II. Say if the sentences are true (T) or false (F).
1. The pulling action of the actin shortens the sarcomere, causing the whole muscle to contract.
2. Gliding joint gives flexibility to the wrist and ankle.
3. Pivot joint allows the bones in the neck to move a short distance to the left or right.
4. Ball and socket joint holds the upper arm and leg to the trunk of the body and allows these bones to move in almost any direction.
5. Saddle joint gives bones in the fingers the ability to move in all directions but in a much more limited way than a ball and socket joint.
6. Hinge joint lets many different bones in the body move toward or away from one another.
II.
Multiple choice. Choose the letter of the best answer.
1.
It means long strands of protein divided
into sarcomeres.
a)
myofibril c) actin ( filaments are
thin protein fibers)
b)
Myosin (filaments are
protein fibers that pull actin) d)
tendons
2. a filament that grabs another filament to contact a muscle
a)
gliding c)
actin
b)
saddle d) myosin
3. Skeletal muscle is attached to bones by
a) actin fibers b)
tendons c) filaments d) myofibrils
4. Which characteristic describes smooth muscle?
a) Found in the intestines c)
under voluntary control
b) Has multi-nucleated cells d)
uses a great deal of ATP
5. What is the term that describes the unit of a muscle cell that
contains all of the structures necessary to cause contraction?
a) sarcomere
c) Ca2 + ion
b) filament d)
myofibril
6. What is the main function of Ca2 + ions during muscle contraction?
a) Enhancing (improve, increase in power) the
effect of neurotransmitters that trigger
movement.
b) Stimulating neurons to use ATP to break the
actin-myosin bond
c) Binding to regulatory proteins to expose actin
binding sites.
d) Allowing myosin filaments to move faster towards actin filaments.
7. Which best describes the role of myosin during muscle contraction ?
a. Loosens proteins b) binds Ca2+ions c) pulls the M line d) grabs the actin
8. Which muscle is an example of an involuntary myscle?
a. tongue b) thigh c) heart d) bicep
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