Joseph P. is an 82-year-old male living at home. He is in overall ...

[javeds]

Joseph P. is an 82-year-old male living at home. He is in overall good health and enjoys taking long walks as often as possible.
 
  During his walks, he likes to stop for a cold glass of fruit juice at the local cafeteria. On cold or rainy days, he rides a stationary bicycle at home for 30 minutes to stay in good shape.
 
  What physiological factors would typically increase Joseph's risk of falling while walking outdoors?
 
  What are the common changes in blood pressure regulation that occurs with aging?
 
  Joseph enjoys fruit juice when he walks. Considering the renal system in the older adult, why would dehydration be a particular concern?

Question 2

Garrin is a 7-year-old boy with cystic fibrosis. The disease is caused by a genetic defect on chromosome 7. As a result, there is a defective production of protein chloride channels in epithelial cell membranes.
 
  One effect of the disease is the production of thick mucous that accumulates in Garrin's bronchial passages. As a result, he attends a physiotherapy clinic regularly for chest percussion treatments to loosen the respiratory mucous.
 
  Garrin's disease is hereditary. What does it mean to have a genetic defect on chromosome 7 in terms of DNA, genes, and chromosomes?
 
  In cystic fibrosis, cellular chloride channels are defective. Anatomically what type of channel is this, and what is its importance in cell function?
 
  In the mucus-secreting cells of the lungs, chloride and sodium remain in the cell. How does this result in the production of thick, viscous mucus in the bronchial passages?

[ebonylittles]

Answer to Question 1

Age-related risk factors for falling are as follows:
Decreased muscle strength
Overall slowing of movement and reaction time
Decreased joint proprioception
Decreased reflexes, particularly the righting reflexes
Increased postural sway
Altered gait, decreased joint mobility and flexibility
Impaired visual and vestibulocochlear function

The relationship between blood pressure and risk of cardiovascular disease is continuous, consistent, and independent of other risk factors. Numerous studies have shown that systolic blood pressure progressively increases with age, whereas increases in diastolic blood pressure tend to plateau and even decline after age 50. As a result, there is a sharp increase in what is known as systolic hypertension among older adults, which occurs as a consequence of increased arterial stiffness. An elevation in systolic blood pressure accompanied by a normotensive diastolic pressure causes a dramatic increase in pulse pressure. This is a known prognostic indicator for future coronary events.

The elderly kidney is less able to concentrate urine and is less responsive to ADH. Coupled with decreased thirst cues, older adults are prone to fluid shifts and dehydration.

Answer to Question 2

Genes are the individual units of inheritance that transmit information from one generation to another. They are contained in DNA, which are in turn coupled with DNA-associated proteins to form chromatin. When chromatin condenses, chromosomes are formed, and it is on the seventh chromosome that the defective gene rests.

Chloride channels are integral, or transmembrane, ion channels. Ion channels function to
move ions that would otherwise be unable to cross the lipid bilayer.
create an electrical gradient for the function of excitable cells (i.e., nerve cells and muscle fibers) and for the function of secretory cells.
assist in the regulation of cellular osmotic pressure.
provide electrical gradients to speed the movement of ions across the membrane.

The retention of ions increases intracellular osmotic pressure as there are more ions in the cell in relation to the extracellular environment. As a result, water moves into the cell, leaving mucous secretions thick and viscous.