An individual has just ingested a chemical that binds irreversibly to the ACh receptors in the sarcolemma. By itself it does not alter membrane potential, yet prevents normal neurotransmitter binding. Ignoring the effects on any other system, the consequence to skeletal muscle would be ________.

An individual has just ingested a chemical that binds irreversibly to the ACh receptors in the sarcolemma. By itself it does not alter membrane potential, yet prevents normal neurotransmitter binding. Ignoring the effects on any other system, the consequence to skeletal muscle would be ________. 

A) irreversible contraction as soon as the first nervous stimulation reached the sarcolemma
B) no contraction at all by nervous mechanisms
C) contraction if stimulated by an external electrode
D) no contraction at all by nervous mechanisms, but contraction if stimulated by an external electrode

Answer: D

Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped ________.

Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped ________. 

A) cross bridge attachment would be optimum because of all the free binding sites on actin
B) no muscle tension could be generated
C) maximum force production would result since the muscle has a maximum range of travel
D) ATP consumption would increase since the sarcomere is "trying" to contract

Answer: B

Of the following muscle types, which has only one nucleus, no sarcomeres, and rare gap junctions?

Of the following muscle types, which has only one nucleus, no sarcomeres, and rare gap junctions? 

A) visceral smooth muscle
B) multiunit smooth muscle
C) cardiac muscle
D) skeletal muscle

Answer: B

Three discrete types of muscle fibers are identified on the basis of their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers?

Three discrete types of muscle fibers are identified on the basis of their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers? 

A) a sprint by an Olympic runner
B) a long, relaxing swim
C) playing baseball or basketball
D) mountain climbing

Answer: B

The most distinguishing characteristic of muscle tissue is ________.

The most distinguishing characteristic of muscle tissue is ________. 

A) the design of the fibers
B) the sarcoplasmic reticulum
C) the diversity of activity of muscle tissue
D) the ability to transform chemical energy into mechanical energy

Answer: D

Which of the following is most accurate?

Which of the following is most accurate? 

A) Muscle tension remains relatively constant during isotonic contraction.
B) T-tubles may be sliding during isotonic contraction.
C) The I band lenghtens during isotonic contraction.
D) Myofilaments slide during isometric contractions.

Answer: A

After nervous stimulation stops, ACh in the synaptic cleft is prevented from continuing stimulation of contraction by ________.

After nervous stimulation stops, ACh in the synaptic cleft is prevented from continuing stimulation of contraction by ________. 

A) calcium ions returning to the terminal cisternae
B) the tropomyosin blocking the myosin once full contraction is achieved
C) acetylcholinesterase destroying the ACh
D) the action potential stopped going down the overloaded T tubules

Answer: C

The sliding filament model of contraction involves ________.

The sliding filament model of contraction involves ________. 

A) actin and myosin sliding past each other and partially overlap
B) the shortening of thick filaments so that thin filaments slide past
C) actin and myosin shortening but not sliding past each other
D) the Z discs sliding over the myofilaments

Answer: A

Muscle tone is ________.

Muscle tone is ________. 

A) the ability of a muscle to efficiently cause skeletal movements
B) the feeling of well-being following exercise
C) a state of sustained partial contraction
D) the condition of athletes after intensive training

Answer: C

An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ________.

An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ________. 

A) the citric acid cycle
B) glycolysis
C) hydrolysis
D) the electron transport chain

Answer: B

Which of the following statements is true?

Which of the following statements is true? 

A) Cardiac muscle cells have many nuclei.
B) Smooth muscle cells have T tubules.
C) Striated muscle cells are long and cylindrical with many nuclei.
D) Cardiac muscle cells are found in the heart and large blood vessels.

Answer: C

The giant protein titin maintains the organization of the ________ assisting in muscle stretching.

The giant protein titin maintains the organization of the ________ assisting in muscle stretching. 

A) A band
B) I band
C) Z disc
D) M line

Answer: A

Muscle tissue has all of the following properties except ________.

Muscle tissue has all of the following properties except ________.

A) secretion
B) contractility
C) extensibility
D) excitability

Answer: A

Smooth muscle is characterized by all of the following except ________.

Smooth muscle is characterized by all of the following except ________. 

A) it appears to lack troponin
B) there are more thick filaments than thin filaments
C) there are no sarcomeres
D) there are noncontractile intermediate filaments that attach to dense bodies within the cell

Answer: B

Which of the following is true about smooth muscle contraction?

Which of the following is true about smooth muscle contraction? 

A) Certain smooth muscle cells can actually divide to increase their numbers.
B) Smooth muscle, in contrast to skeletal muscle, cannot synthesize or secrete any connective tissue elements.
C) Smooth muscle cannot stretch as much as skeletal muscle.
D) Smooth muscle has well-developed T tubules at the site of invagination.

Answer: A

Which of the following statements is not true concerning developmental aspects of muscle?

Which of the following statements is not true concerning developmental aspects of muscle? 

A) There is no biological basis for the difference in strength between women and men.
B) Skeletal muscle is derived from mesoderm.
C) Skeletal muscle develops from somites.
D) Most muscle tissues develop from myoblasts.

Answer: A

The cells of single-unit visceral muscle ________.

The cells of single-unit visceral muscle ________. 

A) contract all at once
B) are chemically coupled to one another by gap junctions
C) exhibit spontaneous action potentials
D) consist of muscle fibers that are structurally independent of each other

Answer: C

The mechanism of contraction in smooth muscle is different from skeletal muscle in that ________.

The mechanism of contraction in smooth muscle is different from skeletal muscle in that ________. 

A) actin and myosin interact by the sliding filament mechanism
B) the trigger for contraction is a rise in intracellular calcium
C) the site of calcium regulation differs
D) ATP energizes the sliding process

Answer: C

Smooth muscle is significantly different from striated muscle in several ways. Which of the following is true?

Smooth muscle is significantly different from striated muscle in several ways. Which of the following is true? 

A) Smooth muscle has transverse tubules.
B) Smooth muscle is larger and more powerful than striated muscle.
C) The fibers of smooth muscle are arranged quadrangularly.
D) Smooth muscle contracts in a twisting way.

Answer: D

The muscle cell membrane is called the ________.

The muscle cell membrane is called the ________. 

A) endomysium
B) sarcolemma
C) perimysium
D) epimysium

Answer: B