Final answer:
Contractures are an example of a skeletal hazard of immobility, due to the permanent shortening of tissues from a lack of movement. Calcium loss from bones during immobility is related to the body s response to reduce mechanical stress on the skeleton, while maintaining calcium homeostasis is important for overall physiological function.
Step-by-step explanation:
An example of a skeletal hazard of immobility is contractures. Contractures are the permanent shortening of muscles, tendons, or ligaments that can occur when mobility is limited and can restrict range of motion. When a person is immobile, the lack of movement can lead to decreased stimulation to the muscles and joints, risking the development of contractures. On the other hand, loss of bone mass is associated with calcium loss from bones, which can occur during prolonged immobility as the body may reabsorb calcium from the bone into the bloodstream because of reduced mechanical stress on the skeleton.
Conditions such as hypercalcemia can also interplay with skeletal health. Hypercalcemia is typically marked by increased urinary excretion of calcium by the kidneys and a reduction in calcium absorption from the intestines. Notably, these processes are distinct from the mechanical effects on the bones and muscles caused by immobility, such as contractures.
Finally, maintaining calcium homeostasis, a blood calcium level of about 10 mg/dL, is crucial for normal physiological functions, including bone health. Hormones like parathyroid hormone (PTH), vitamin D, and calcitonin regulate calcium homeostasis through interactions within the skeletal, endocrine, digestive, and urinary systems.