At the onset of a muscle contraction, the presence of calcium triggers the opening of the Na-K channels in the membrane. Potassium is a calcium inhibitor, so as the potassium flows out of the cell, it eventually reduces the presence of calcium. This causes the closure of the Na-K channel (negative feedback mechanism). In a hypokalemic state, the lack of sufficient K doesn't inhibit the calcium channel, and in turn doesn't properly terminate the muscle contraction at the cellular level.
Answer:
An example of disease misconceptions is the belief that vaccines are not beneficial
Explanation:
Anti-vaccine groups have been identified by the World Health Organization (WHO) as one of the most important global threats against health security. Anti-vaccination is a movement that comes from a controversial belief based on a paper published in a top medical journal (The Lancet). This study suggested that the MMR vaccine (against measles, mumps, and rubella) might be associated with autism spectrum disorders in children. However, in other studies, it has been shown that there is no association between this vaccine and autism, thereby this controversial paper was retracted by the editors of the journal.
Answer:
Iron deficiency anemia is the most likely choice.
Explanation:
Iron deficiency anemia is characterized by scattered skin discoloration, bruising, easy fatiguing and can be developed with no prior medical issues.
Answer:
Physiological changes occur with aging in all organ systems. The cardiac output decreases, blood pressure increases and arteriosclerosis develops. The lungs show impaired gas exchange, a decrease in vital capacity and slower expiratory flow rates. The creatinine clearance decreases with age although the serum creatinine level remains relatively constant due to a proportionate age-related decrease in creatinine production. Functional changes, largely related to altered motility patterns, occur in the gastrointestinal system with senescence, and atrophic gastritis and altered hepatic drug metabolism are common in the elderly. Progressive elevation of blood glucose occurs with age on a multifactorial basis and osteoporosis is frequently seen due to a linear decline in bone mass after the fourth decade. The epidermis of the skin atrophies with age and due to changes in collagen and elastin the skin loses its tone and elasticity. Lean body mass declines with age and this is primarily due to loss and atrophy of muscle cells. Degenerative changes occur in many joints and this, combined with the loss of muscle mass, inhibits elderly patients' locomotion. These changes with age have important practical implications for the clinical management of elderly patients: metabolism is altered, changes in response to commonly used drugs make different drug dosages necessary and there is need for rational preventive programs of diet and exercise in an effort to delay or reverse some of these changes.
