Question

1. (3pts) How would you describe the condition of respiratory acidosis? What would be the response within the respiratory system to this condition? What would be the response of the urinary system to this condition?

2. (2pts) What are the major buffer systems in the body?

3. (3pts) As you’re probably aware the human body is approximately 60% (with large individual variation) water. How is water distributed within the body? Be sure to address where it is found, what differences exist between location, and what forces act on water within the body to cause it to change location.

4. (4pts) What are the sources of water gain and loss in the body? What are they for sodium? How are they connected?

5. (3pts) A person has a tumor in the adrenal cortex that continuously secretes large amounts of aldosterone. What effects does this have on the total amount of sodium and potassium in her body?

6. (3pts) Describe the detection of and response to low blood pressure in the body. Be sure to place this scenario into the context of a homeostatic mechanism, and clearly identify the structures that act as receptors, integrating center and effectors. You should identify specific mechanisms of reaction and the systems involved.

Answer 1

respiratory acidosis is a state in which there is usually a failure of ventilation and an accumulation of carbon dioxide. The primary disturbance of elevated arterial PCO2 is the decreased ratio of arterial bicarbonate to arterial PCO2, which leads to a lowering of the pH. In the presence of alveolar hypoventilation, 2 features commonly are seen are respiratory acidosis and hypercapnia. To compensate for the disturbance in the balance between carbon dioxide and bicarbonate (HCO3-), the kidneys begin to excrete more acid in the forms of hydrogen and ammonium and reabsorb more base in the form of bicarbonate. This compensation helps to normalize the pH.
Etiology -
the respiratory centers in the pons and medulla control alveolar ventilation. Chemoreceptors for PCO2, PO2, and pH regulate ventilation. Central chemoreceptors in the medulla are sensitive to changes in the pH level. A decreased pH level influences the mechanics of ventilation and maintains proper levels of carbon dioxide and oxygen. When ventilation is disrupted, arterial PCO2 increases and an acid-base disorder develop. Another pathophysiological mechanism may be due to ventilation/perfusion mismatch of dead space.
Respiratory acidosis can be subcategorized as acute, chronic, or acute and chronic. In acute respiratory acidosis, there is a sudden elevation of PCO2 because of failure of ventilation. This may be due to cerebrovascular accidents, use of central nervous system (CNS) depressants such as opioids, or inability to use muscles of respiration because of disorders like myasthenia gravis, muscular dystrophy or Guillain-Barre Syndrome. Because of its acute nature, there is a slight compensation occurring minutes after the incidence. On the contrary, chronic respiratory acidosis may be caused by COPD where there is a decreased responsiveness of the reflexes to states of hypoxia and hypercapnia. Other individuals who develop chronic respiratory acidosis may have fatigue of the diaphragm resulting from a muscular disorder. Chronic respiratory acidosis can also be seen in obesity hypoventilation syndrome, also known as Pickwickian syndrome, amyotrophic lateral sclerosis, and in patients with severe thoracic skeletal defects. In patients with chronic compensated respiratory disease and acidosis, an acute insult such as pneumonia or disease exacerbation can lead to ventilation/perfusion mismatch.
pathophysiology-
carbon dioxide plays a remarkable role in the human body mainly through pH regulation of the blood. The pH is the primary stimulus to initiate ventilation. In its normal state, the body maintains CO2 in a well-controlled range from 38 to 42 mm Hg by balancing its production and elimination. In a state of hypoventilation, the body produces more CO2 than it can eliminate, causing a net retention of CO2. The increased CO2 is what leads to an increase in hydrogen ions and a slight increase in bicarbonate, as seen by a right shift in the following equilibrium reaction of carbon dioxide.