A person with diarrhoea loses excessive salt and water from the body. This loss results in Na⁺ depletion, dehydration, a decreased extracellular fluid volume, a reduction in plasma volume, and a decreased systemic arterial blood pressure.The following refer to the events that occur to compensate for this fluid loss. Match the effects, labelled a. through c., with the factors listed. (Options may be used more than once or not at all.)
-sympathetic activity to the afferent arterioles of the nephrons
A)exhibits no change
B)is increased
C)is decreased

Question

Quizplus · Accepted Answer

The sympathetic activity to the afferent arterioles of the nephrons is increased to maintain systemic arterial blood pressure by constricting those arterioles and, therefore, increasing the resistance to blood flow, which maintains the glomerular filtration rate (GFR).

Answer: C
 The decreased extracellular fluid volume stimulates the renin-angiotensin-aldosterone system (RAAS) and, consequently, angiotensin II production. Angiotensin II causes vasoconstriction of arterioles, which serves to increase systemic arterial blood pressure.

Answer: B
 The secretion of antidiuretic hormone (ADH) increases in response to dehydration, causing increased water reabsorption in the kidneys, resulting in less urine output and an increased blood volume, which leads to an increase in systemic arterial blood pressure.

A Person with Diarrhoea Loses Excessive Salt and Water from the Body