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Muscles

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Which of the following surrounds the individual muscle cell?

A) epimysium
B) endomysium
C) perimysium
D) fascicle
B) endomysium
Muscle tone is ________.

A) a state of sustained partial contraction
B) the ability of a muscle to efficiently cause skeletal movements
C) the condition of athletes after intensive training
D) the feeling of well-being following exercise
A) a state of sustained partial contraction
Although there are no sarcomeres, smooth muscle still possesses thick and thin filaments.
T/F
True
Creatine phosphate functions in the muscle cell by ________.

A) forming a chemical compound with actin
B) storing energy that will be transferred to ADP to resynthesize ATP
C) forming a temporary chemical compound with myosin
D) inducing a conformational change in the myofilaments
B) storing energy that will be transferred to ADP to resynthesize ATP
An increase in the calcium ion level in the sarcoplasm starts the sliding of the thin filaments. When the level of calcium ions declines, sliding stops.
T/F
True
The connective tissue sheaths of skeletal muscle, in order from internal to external, are the ________.

A) perimysium, endomysium, and epimysium
B) endomysium, epimysium, and perimysium
C) epimysium, endomysium, and perimysium
D) endomysium, perimysium, and epimysium
E) epimysium, perimysium, and endomysium
D) endomysium, perimysium, and epimysium
Which of the following is CORRECTLY paired?

A) smooth muscle: striated
B) cardiac muscle: voluntary control
C) skeletal muscle: voluntary control
D) cardiac muscle: nonstriated
C) skeletal muscle: voluntary control
The term aponeurosis refers to ________.

A) the tropomyosin-troponin complex
B) the bands of myofibrils
C) a sheetlike indirect attachment to a skeletal element
D) the rough endoplasmic reticulum
C) a sheetlike indirect attachment to a skeletal element
The oxygen-binding protein found in muscle cells is ________.

A) immunoglobin
B) myoglobin
C) hemoglobin
D) ATP
B) myoglobin
Most skeletal muscles contain ________.

A) muscle fibers of the same type
B) a mixture of fiber types
C) a predominance of fast oxidative fibers
D) a predominance of slow oxidative fibers
B) a mixture of fiber types
What is the functional unit of a skeletal muscle called?

A) a myofilament
B) the sarcoplasmic reticulum
C) a myofibril
D) a sarcomere
D) a sarcomere
Which muscle characteristic describes the ability of muscle to respond to a stimulus?

A) extensibility
B) contractility
C) elasticity
D) excitability
D) excitability
Thick myofilaments are made of ________.

A) tropomyosin
B) actin
C) troponin
D) myosin
D) myosin
Once a motor neuron has fired, all the muscle fibers in a muscle contract.
T/F
False
What is the role of calcium ions in muscle contraction?

A) increase levels of myoglobin
B) reestablish glycogen stores
C) form hydroxyapatite crystals
D) bind to regulatory sites on troponin to remove contraction inhibition
D) bind to regulatory sites on troponin to remove contraction inhibition
The contractile units of skeletal muscles are ________.

A) myofibrils
B) T tubules
C) mitochondria
D) microtubules
A) myofibrils
An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ________.

A) glycolysis
B) the electron transport chain
C) hydrolysis
D) the citric acid cycle
A) glycolysis
The major role of the sarcoplasmic reticulum is to regulate ________.

A) intracellular levels of Na+
B) intracellular levels of Ca2+
C) extracellular levels of Ca2+
D) extracellular levels of Na+
B) intracellular levels of Ca2+
The smallest contractile unit of a muscle fiber is ________.

A) the myofilament
B) troponin
C) the sarcomere
D) the elastic filament
C) the sarcomere
What produces the striations of a skeletal muscle cell?

A) the sarcoplasmic reticulum
B) a difference in the thickness of the sarcolemma
C) the arrangement of myofilaments
D) the T tubules
C) the arrangement of myofilaments
The sliding filament model of contraction involves ________.

A) the shortening of thick filaments so that thin filaments slide past
B) the Z discs sliding over the myofilaments
C) actin and myosin lengthening in order to slide past each other
D) actin and myosin sliding past each other and partially overlapping
D) actin and myosin sliding past each other and partially overlapping
Which protein inhibits interaction between actin and myosin to prevent skeletal muscle contraction; and which ions remove the inhibition?

A) troponin; sodium ions
B) actin; calcium ions
C) myosin; sodium ions
D) tropomyosin; calcium ions
D) tropomyosin; calcium ions?
Isometric contraction leads to movement of a load.
T/F
False
Muscle contraction will always promote movement of body parts regardless of how they are attached.
T/F
False
After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction?

A) the tropomyosin blocking the myosin once full contraction is achieved
B) calcium ions returning to the terminal cisternae
C) acetylcholinesterase destroying the ACh
D) the action potential stops going down the overloaded T tubules
C) acetylcholinesterase destroying the ACh
When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods?

A) refractory period
B) fatigue period
C) relaxation period
D) latent period
A) refractory period
Which organelle contains the contractile elements found in skeletal muscle?

A) myofibril
B) glycosome
C) sarcolemma
D) sarcoplasmic reticulum
A) myofibril
Which muscle cells have the greatest ability to regenerate?

A) skeletal
B) smooth
C) no muscle can regenerate
D) cardiac
B) smooth
The first step toward generating a skeletal muscle contraction is ________.

A) binding of ATP to the myosin heads
B) a rise in intracellular Ca2+ levels
C) stimulation of the muscle by a nerve ending
D) binding of the myosin heads to actin
C) stimulation of the muscle by a nerve ending
The force of a muscle contraction is NOT affected by __________.

A) the amount of ATP stored in the muscle cells
B) the frequency of the stimulation
C) the degree of muscle stretch
D) the number of muscle fibers stimulated
E) the size of the muscle fibers stimulated
A) the amount of ATP stored in the muscle cells
What part of the sarcolemma contains acetylcholine receptors?

A) part adjacent to another muscle cell
B) end of the muscle fiber
C) any part of the sarcolemma
D) motor end plate
D) motor end plate
Muscle tissue has all of the following properties except ________.
A) secretion
B) excitability
C) extensibility
D) contractility
A) secretion
What special feature of smooth muscle allows it to stretch without immediately resulting in a strong contraction?

A) low energy requirements
B) slow, prolonged contractile activity
C) smooth muscle tone
D) stress-relaxation response
D) stress-relaxation response
The distance between Z discs ________ during muscle contraction.

A) decreases
B) decreases and then increases
C) stays the same
D) increases
A) decreases
During vigorous exercise, there may be insufficient oxygen available to completely break down pyruvic acid for energy. As a result, the pyruvic acid is converted to ________.

A) stearic acid
B) a strong base
C) lactic acid
D) hydrochloric acid
C) lactic acid
What is the functional role of the T tubules?

A) synthesize ATP to provide energy for muscle contraction
B) enhance cellular communication during muscle contraction
C) stabilize the G and F actin
D) hold cross bridges in place in a resting muscle
B) enhance cellular communication during muscle contraction
Choose the FALSE statement.

A) Skeletal muscle cells contain myoglobin.
B) Skeletal muscle cells have glycosomes.
C) Skeletal muscle cells are multinucleated.
D) Skeletal muscle cells have T tubules.
E) Skeletal muscle cells use creatine phosphate instead of ATP to do work.
E) Skeletal muscle cells use creatine phosphate instead of ATP to do work.
One of the important functions of skeletal muscle contraction is production of heat.
T/F
True
A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate.
T/F
False