Chapter 9 Muscle Tissue Application Questions

1. A nurse observes that a patient's skeletal muscles fatigue quickly during repetitive activity. Which cellular structure is most directly responsible for the energy supply that allows continued contraction?

Mitochondria

A patient receives a drug that blocks acetylcholine receptors on the sarcolemma. What immediate effect would this have on skeletal muscle contraction?

The muscle would fail to contract.

A patient with low blood calcium levels shows weak skeletal muscle contractions. Why?

Calcium binds to troponin to allow cross-bridge formation.

After a spinal cord injury, a patient experiences paralysis below the injury. Which aspect of muscle physiology explains this?

Loss of nervous system stimulation to skeletal muscle fibers

1. A patient with myasthenia gravis develops muscle weakness due to decreased numbers of functional acetylcholine receptors. Which event at the neuromuscular junction is most impaired?

ACh binding to the sarcolemma

1. A drug inhibits the release of calcium from the sarcoplasmic reticulum. Which process will be directly affected?

Cross-bridge cycling

1. A patient with botulism cannot contract skeletal muscles because the toxin prevents ACh release. Which step of muscle contraction is disrupted?

Activation at the neuromuscular junction

A patient with muscle cramps is given a supplement that enhances ATP production. Which stage of the cross-bridge cycle requires ATP?

Cross-bridge detachment

A nurse observes a patient's muscles remain contracted even after stimulation has ceased. Which enzyme is most likely inhibited?

Acetylcholinesterase

In a patient with damaged T-tubules, which process would be impaired?

Transmission of the action potential deep into the muscle fiber

1. A surgeon identifies an area where the epimysium is fused to the periosteum of bone. This is an example of:

Direct attachment

A newborn is diagnosed with a smooth muscle developmental defect affecting the gastrointestinal tract. What symptom would most likely be observed?

Difficulty moving food through the intestines

A nurse is caring for a patient with a genetic defect that decreases the sensitivity of voltage-gated calcium channels in skeletal muscle. Which step in excitation-contraction coupling would be most directly affected?

Calcium release from the sarcoplasmic reticulum

After a motor neuron fires, calcium is released from the sarcoplasmic reticulum. The nurse explains to the patient that this calcium release allows:

Exposure of binding sites on actin for cross-bridge formation

A patient receives a medication that enhances calcium reuptake into the sarcoplasmic reticulum. What is the likely result?

Faster muscle relaxation

In a laboratory setting, a muscle cell is stimulated by an action potential, but contraction does not occur. Microscopic examination reveals that the T-tubules are disrupted. What best explains this?

The action potential cannot reach the sarcoplasmic reticulum to trigger Ca²⁺ release.

A patient recovering from surgery is given a muscle relaxant that prevents calcium from binding to troponin. What will the nurse observe?

Flaccid muscles due to prevention of cross-bridge formation

A patient recovering from a stroke has difficulty performing fine motor tasks such as buttoning a shirt. The nurse explains that this difficulty may result from:

A decrease in small motor units responsible for fine contro

During physical therapy, a patient performs isometric exercises. The nurse understands that during isometric contraction:

Muscle tension increases without shortening

A patient lifts a light object, then a much heavier object. The nurse explains that the stronger contraction is due to:

Recruitment of additional motor units

A nurse observes that a patient's muscle twitches increase in strength as stimulation frequency rises. This best illustrates:

Wave (temporal) summation

A marathon runner has well-developed muscle tone even at rest. The nurse recognizes this results from:

Spinal reflexes that alternately activate motor units

A nurse explains to a patient with muscle fatigue that repeated stimulation without adequate rest can cause:

Inability to generate further tension due to depletion of resources

A patient's muscle fibers are overstretched during a sports injury. Which statement best describes why contraction is weakened?

The overlap between actin and myosin is reduced, decreasing cross-bridge formation.

During a lab experiment, a skeletal muscle sample is stimulated once and produces a single contraction. The instructor identifies this as:

A muscle twitch

A nurse assesses that a patient's muscle contractions are smooth and sustained during activity. This indicates:

Fused (complete) tetanus

A weightlifter develops larger muscle fibers over time. The nurse recognizes this as:

Hypertrophy

A nurse notes that smooth muscle cells in the stomach contract in waves to mix food. This coordinated movement is called:

Peristalsis

A patient's smooth muscle cells remain contracted even after stretching by a full stomach. This demonstrates:

The stress-relaxation response

A patient is given a drug that blocks gap junctions in smooth muscle. The nurse expects which effect?

Loss of synchronized contractions

In smooth muscle, calcium binds to which molecule to initiate contraction?

Calmodulin

During pregnancy, estrogen causes the uterine smooth muscle to enlarge and increase in number. This is an example of:

Hyperplasia

A patient with asthma is given a bronchodilator that relaxes airway smooth muscle. The nurse explains the drug acts by:

Reducing intracellular calcium levels