BSC 2346 A&P Case Study Module 4 Complete Solution
Jordan is now 19-years old. As an infant, Jordan reached many gross motor skill milestones,... [Show More] 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?
1. Multiple sclerosis
Amyotrophic lateral sclerosis
Duchenne muscular dystrophy
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.
The pathologist would note changes in the skeletal muscle fibers, a lack of dystrophin which is the protein that holds muscle cells together. The pathologist would also note the rapid growth of connective tissue around the decline of muscle fibers (Journal of Neurology, Neurosurgery, and Psychiatry, 1972).
Explain, in your own words, why Jordan’s brother appears to have the same disease and why his sisters are unaffected.
Duchenne muscular dystrophy (DMD) is most common in males due to males having only one X chromosome. If their only X chromosome has the DMD trait then they will have DMD because they do not have a backup X chromosome (National Human Genome Research Institute, 2013). For females DMD is not as common but females are normally the carriers for the DMD trait. DMD is not common in females due to them having two X chromosomes so if one X chromosome is affected by the DMD trait than the second X chromosome acts as a backup in releasing dystrophin protein (National Human Genome Research Institute, 2013).
Jordan’s calves appear enlarged. Which of the following statements explains this phenomenon?
As his muscles degenerate, the muscle tissue is replaced by collagen and adipose tissue.
As Jordan ages, the neuromuscular junction loses its neurotransmitters.
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.
Jordan displayed Gower’s sign at a young age. Which of the following statements explains why this this true?
The weakness of his proximal leg muscles and erector spinae muscles force Jordan to use his arms to push on the floor.
His neuromuscular junctions were interrupting the signals to contract his muscles.
Jordan’s quadriceps and gluteus maximus are in spasm, which causes him to fall to his knees when trying to stand.
The chronic contractures in Jordan’s lower legs cause him to be reliant on his upper body for strength.
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 has to take calcium supplements for the rest of his life because muscular dystrophy will cause him to lose bone mass over the years which in turn will put him at a great risk for bone fractures in his long bones as well as spine (Bonekey Rep, 2012).
Jordan is prone to respiratory infections, in part because of the weakness of which muscles?
Pectoralis major and pectoralis minor
Diaphragm and abdominal wall muscles
Serratus anterior and scalene 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.
Dystrophin is a protein that is needed to strengthen the muscle fibers in order to prevent injury when the muscles contract and relax. Dystrophin is found within the muscle cells, if there is not enough dystrophin this causes muscle tears.
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?
1. Biceps femoris
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 caused by excess calcium and ATP.
Cramps are caused by a sedentary lifestyle.
Cramps are thought to be caused by hyperexcitiability of the motor neuron.
Cramps are voluntary, continuous contractions of sarcomeres.
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 A-band shortens.
When a muscle contracts, the H-zone becomes narrower (shortens).
When a muscle contracts, the lighter I-band becomes wider.
When a muscle contracts, the sarcomere remains the same size.
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.
Fascia is sheets of muscle tissue that are located below the surface of the skin. The fascia connective tissue stabilizes and attaches to muscles and enclose organs. They are active and help reduce friction between tissues and organs. Fascia provides strength and stability because the collagen it is made with is wrapped tightly. It is flexible and can resist tension, fascia’s function is dependent on its location in the 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 blood flow to the muscle being stretched.
Stretching increases the risk of injury in adolescent and elderly patients.
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.
ATP binds with myosin releasing energy to allowing the head of myosin change position in order to bind with actin. Calcium stays in the sarcoplasm until it is stimulated to be released, once released calcium binds with troponin which causes the troponin to remove from the binding sites. Once calcium ions are put back into the sarcoplasm muscle contractions end which allows the muscle to relax. This is when motor neurons release acetylcholine (neurotransmitter) to bind to receptors in the motor end plates. This happens when action potential moves down the axon of the motor neurons which changed the permeability of the synaptic membrane and causes an increase of calcium.
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?
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.
Slow oxidative fibers have a low myoglobin content and are used for explosive muscle movements, like sprinting.
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.
False [Show Less]