BSC2346 Human Anatomy and Physiology I
Module 04 Case Study
Jordan is now 19-years old. As an infant, Jordan reached many gross motor skill milestones, such as holding his head up, rolling over, sitting, and standing, at normal times. However, he was considered a “late walker” because he took his first steps at 17 months. By 2 years old, his parents noticed a hyperlordotic posture while he was standing. A Gower’s sign and Trendelenberg gait were noted by age four. Throughout his childhood, he suffered progressive muscle weakness, especially in the proximal musculature of the arms, pelvis, and legs. He required orthotic braces to assist his walking and was confined to wheelchair ambulation by age 13.
At 16, he was hospitalized with bronchitis requiring antibiotic treatment, but recovered. Jordan has a history of progressive muscle weakness, but no history of muscle pain or spasm, chest pain, or irregular heartbeat. The only medications that he normally takes are calcium and fluoride supplements. Jordan has three siblings. His older and younger sisters have never had any major medical issues. Jordan’s older brother is also to a wheelchair with problems similar to Jordan’s. No other immediate or distant family members have musculoskeletal issues.
Jordan’s history aligns most closely with which diagnosis?
Duchenne muscular dystrophy
Amyotrophic lateral sclerosis
Jordan had a biopsy of the left gastrocnemius muscle when he was 5 years old. Based on your answer for his diagnosis, describe the microscopic pathological changes that the pathologist would have noted in her report.
Explain, in your own words, why Jordan’s brother appears to have the same disease and why his sisters are unaffected.
Jordan’s calves appear enlarged. Which of the following statements explains this phenomenon?
Jordan’s muscle cells are experiencing calcification because the actin and myosin filaments are no longer able to release from each other.
As his muscle degenerate, calcium replaces the water in the muscle cells.
As his muscles degenerate, the muscle tissue is replaced by collagen and adipose tissue.
As Jordan ages, the neuromuscular junction loses its neurotransmitters.
Jordan displayed Gower’s sign at a young age. Which of the following statements explains why this this true?
The chronic contractures in Jordan’s lower legs cause him to be reliant on his upper body for strength.
Jordan’s quadriceps and gluteus maximus are in spasm, which causes him to fall to his knees when trying to stand.
His neuromuscular junctions were interrupting the signals to contract his muscles.
The weakness of his proximal leg muscles and erector spinae muscles force Jordan to use his arms to push on the floor.
Weakness in his erector spinae muscles forces Jordan to assume which exaggerated position when standing?
In your own words, please explain why Jordan must take calcium supplements for the rest of his life. (Hint: Think about your prior material and Wolff’s law.)
Jordan is prone to respiratory infections, in part because of the weakness of which muscles?
Pectoralis major and pectoralis minor
Serratus anterior and scalene muscles
Diaphragm and abdominal wall muscles
Genetic testing would reveal that Jordan has a y-linked disorder.
In your own words, briefly describe the role of dystrophin within the motor unit.
Colette has been experiencing some muscle pain and soreness after workouts this last week. She decides to research how muscles work because she wants to find ways to help alleviate her pain. She is hoping to find out the names of the muscles that are aching and find ways to stretch and strengthen them. Answer the following questions to help her find the answers she is looking for.
Colette has been sore “all over,” but her primary area of concern is the posterior right thigh. Which of the following muscles could be causing the soreness in this region?
Colette has played softball for over 20 years and has been told in the past that she may have a rotator cuff injury. Which of the following rotator cuff muscles is on the anterior aspect of the scapula?
Colette is trying to understand what causes her occasional calf muscle cramps. Which of the following statements is true regarding cramps?
Cramps are voluntary, continuous contractions of sarcomeres.
Cramps are thought to be caused by hyperexcitiability of the motor neuron.
Cramps are caused by a sedentary lifestyle.
Cramps are caused by excess calcium and ATP.
According to the sliding filament theory, myosin filaments slide past actin filaments during contraction of a muscle because the myosin heads bind to the sarcolemma.
Which of the following statements is true regarding muscle contraction?
When a muscle contracts, the sarcomere remains the same size.
When a muscle contracts, the H-zone becomes narrower (shortens).
When a muscle contracts, the A-band shortens.
When a muscle contracts, the lighter I-band becomes wider.
Colette is having trouble understanding the role of fascia within the musculoskeletal system. Explain, in your own words, how fascia is related to the muscles of the human body.
Colette is finding that studies about the benefits of stretching have mixed results. However, stretching can improve flexibility, which is a priority for her. Which of the following statements is true?
Stretching increases the risk of injury in adolescent and elderly patients.
Stretching increases blood flow to the muscle being stretched.
Static stretching has been shown to reduce soreness and increase athletic performance.
Stretching weakens the ability of actin and myosin binding process.
In your own words, describe how acetylcholine, calcium, and ATP are involved in the process of muscle contraction.
While Colette is researching weight lifting techniques, she finds contradictory information about the “best” way to build muscle. Which of the following statements is true of skeletal muscle?.
Slow oxidative fibers have a low myoglobin content and are used for explosive muscle movements, like sprinting.
Fast glycolytic fibers are used for actions like weightlifting, fatigue very quickly, and have very little myoglobin content.
The speed of muscle contraction is not dependent on how fast the myosin heads split ATP.
Anaerobic exercise depends on oxygen.
Muscle relaxation occurs when acetylcholine is cleaved from its receptors, calcium is pulled back inot the sarcoplasmic reticulum, the myosin is released from its binding site, and the muscle fiber returns to its resting length.
BSC2346 Human Anatomy and Physiology I