Chapter 51 Flashcards
The action potential of skeletal muscle:
● a. Has a prolonged plateau phase
● b. Spreads inward to all parts of the muscle via the T tubules
● c. Causes the immediate uptake of Ca2+ into the lateral sacs of the sarcoplasmic reticulum
● d. Is longer than the action potential of cardiac muscle
B
The functions of tropomyosin in skeletal muscle include:
● A/ Sliding on actin to produce shortening
● b. Releasing Ca2+ after initiation of contraction
● C. Binding to myosin during contraction
● d. Acts as a “relaxing protein” at rest by covering up the sites where myosin binds to actin
D
The cross-bridges of the sarcomere in skeletal muscle are made up of:
● a. Actin
● b. Myosin
● C. Tropomyosin
● d. Myelin
B
The contractile response in skeletal muscle:
● Starts after the action potential is over
● b. Does not last as long as the action potential
● c. Produces more tension when the muscle contracts isometrically than when the muscle contracts isotonically
● d. Decreases in magnitude with repeated stimulation
C
Gap junctions:
● a. Are absent in cardiac muscle
● b. Are present but of little functional importance in cardiac muscle
● c. Are present and provide the pathway for rapid spread of excitation from one cardiac muscle fiber to another
● d. Are absent in smooth muscle
C
Where in a eukaryotic cell, can a microtubule NOT be found?
● a. Flagella
● b. Mitotic spindle
● c. Nucleus
● d. Cilia
D
Which type of macromolecules make up the wall of microtubules?
A.Globular proteins
B.Glycoproteins
C. Deoxyribonucleic acids
D.Carbohydrates
A
Which of the following is NOT a component of the cytoskeleton?
● a. Microfilaments
● b. Intermediate filaments
● c. Microtubules
● d. Ribosomes
D
Microfilaments are composed of which protein?
● a. Actin
● b. Tubulin
● c. Keratin
● d. Collagen
B
Which of the following is NOT a function of the cytoskeleton?
● a. Maintaining cell shape
● b. Cell division
● c. Cellular movement
● d. Regulating gene expression
D
Which type of filament is important for maintaining the shape of nerve cells and their axons?
● a. Microfilaments
● b. Intermediate filaments
● c. Microtubules
● d. All of the above
B
Which type of filament is important for maintaining the shape of red blood cells?
● a. Microfilaments
● b. Intermediate filaments
● c. Microtubules
● d. None of the above
B
Which type of filament is involved in cell crawling and amoeboid movement?
● a Microfilaments
● b Intermediate filaments
● c. Microtubules
● d. All of the above
A
The following are TRUE of the actin filament, EXCEPT:
● a. It is formed from the polymerization of F-actin monomers in physiologic conditions
● b. It has a double helical form
● c. it comprises 20% of the protein mass of muscle
● d. None of the above
A
The secondary messenger that plays a very important role in muscles:
a. CAMP
b. Calcium
c. АТР
d. cGMP
A
