chapter 50 renal system

A student asks the pathophysiology instructor what the function of renin is in the body. What is the instructor's best response to the student's question?

"Renin is directly involved in the control of arterial blood pressure and it is essential for proper functioning of the glomerulus." Feedback: Renin is a hormone directly involved in the control of arterial blood pressure. It is essential for proper functioning of the glomerulus.

A patient who has just been told that he or she needs to go on dialysis asks the nurse what the normal output of urine is per day. What would be the nurse's best response

2,000 mL Feedback: Approximately 125 mL of fluid is filtered out of the glomerulus each minute. About 99% is returned to the blood stream as the filtrate progresses through the renal tubule. Approximately 1% or 2,000 mL of fluid is excreted each day in the form of urine.

The students are discussing the electrolytes in the body. What should the students know has the greatest influence on potassium loss from the body?

Aldosterone Feedback: Potassium concentration is regulated throughout the tubules with aldosterone being the strongest influence for loss. Renin activates angiotensinogen, which becomes angiotensin I. Antidiuretic hormone is produced by the hypothalamus and stored in the posterior pituitary gland and is important in maintaining fluid balance. Carbonic anhydrase causes sodium ions to be reabsorbed and allows carbon dioxide and water to combine to form carbonic acid. This leads to the formation of sodium bicarbonate, which is stored in the renal tubules as the body's reserve for use when the body needs a buffer against acid.

The nurse is caring for a patient suspected of having renal dysfunction. When reviewing laboratory results for this patient, the nurse recalls that several substances are filtered from the blood by the glomerulus and these substances are then excreted in the urine. The nurse identifies the presence of which substances in the urine as abnormal findings?

Blood cells and protein Feedback: The various substances normally filtered by the glomerulus, reabsorbed by the tubules, and excreted in the urine include sodium, chloride, bicarbonate, potassium, glucose, urea, creatinine, and uric acid. Within the tubule, some of these substances are selectively reabsorbed into the blood. Glucose scarring or swelling of or damage to the semipermeable membrane leads to the escape of larger plasma components such as blood cells or protein into the filtrate. A clinical sign of renal damage is the presence of blood cells or protein in the urine.

The anatomy class is learning about the countercurrent mechanism in the medullary nephrons. What would the students learn about this mechanism and what it acts to do?

Concentrate or dilute the urine Feedback: The countercurrent mechanism in the medullary nephrons acts to concentrate or dilute urine.

The nurse, who works in the emergency department, is aware that the renin-angiotensin-aldosterone system works to maintain blood flow in the kidneys. What vital sign would signify the initiation of this system in a trauma patient?

Decreased blood pressure Feedback: The renin-angiotensin-aldosterone system is initiated in response to changes in blood volume, so that a decrease in blood pressure would be most likely to initiate this system.

The nurse is caring for a patient who is in renal failure. When reviewing the patient's laboratory values, what would the nurse expect to find?

Decreased hemoglobin Feedback: Erythropoietin is the only known factor that can regulate the rate of red blood cell production. When a patient develops renal failure and the production of erythropoietin drops, the production of red blood cells also falls and the patient becomes anemic.

The students are learning about maintaining electrolytes in the body by actions within the kidney. Where do the students learn the fine-tuning of potassium levels occurs?

Distal convoluted tubule Feedback: The fine-tuning of potassium levels occurs in the distal convoluted tubule, where aldosterone activates the sodium-potassium exchange, leading to a loss of potassium.

The nurse is aware that which area of the kidney provides a quick response to any damage or injury to the kidney cells?

Macula densa Feedback: The macula densa consists of immune system cells and chemicals that can respond quickly to any cellular damage or injury. The juxtaglomerular apparatus produces erythropoietin and renin. The Renin-angiotensin-aldosterone system works to maintain blood flow to the kidneys. The countercurrent mechanism works to concentrate and dilute the urine.

The pathophysiology instructor is talking to the pre-nursing students about hypovolemia and the kidneys. The instructor points out that when the blood pressure is low due to dehydration, the body will compensate by secreting what?

Renin Feedback: Regulation of blood pressure is also a function of the kidney. Specialized vessels of the kidney called the vasa recta constantly monitor blood pressure as blood begins its passage into the kidney. When the vasa recta detects a decrease in blood pressure, specialized juxtaglomerular cells near the afferent arteriole, distal tubule, and efferent arteriole secrete the hormone renin. Renin converts angiotensinogen to angiotensin I, which is then converted to angiotensin II, the most powerful vasoconstrictor known. The vasoconstriction causes the blood pressure to increase. The cortex of the suprarenal gland secretes aldosterone in response to stimulation by the pituitary gland, which in turn is in response to poor perfusion or increasing serum osmolality. The result is an increase in blood pressure. When the vasa recta recognizes the increase in blood pressure, renin secretion stops. Failure of this feedback mechanism is one of the primary causes of hypertension.

What function does the kidney perform to assist in maintaining acid-base balance within the necessary normal range?

Return bicarbonate to the body's circulation Feedback: The kidney performs two major functions to assist in this balance. The first is to reabsorb and return to the body's circulation any bicarbonate from the urinary filtrate; the second is to excrete acid in the urine.

A student asks the physiology instructor what regulates the flow of fluid into the glomerulus by increasing or decreasing pressure on either side of the glomerulus. What should the instructor respond?

The arterioles Feedback: The two arterioles around the glomerulus work together to closely regulate the flow of fluid into the glomerulus, increasing or decreasing pressure on either side of the glomerulus as needed. The loop of Henle is part of the nephron.

A young woman presents with signs and symptoms of a urinary tract infection (UTI). What factor that has the most influence on this situation does the nurse know?

The woman has a short urethra. Feedback: In the female, the urethra is a very short tube that leads from the bladder to an area populated by normal bacterial flora including Escherichia coli, which can cause frequent bladder infections or cystitis.

As the physiology instructor explains to the students, the kidneys regulate calcium levels within a very tight range by the activity of the parathyroid hormone (PTH) and calcitonin. Where does the fine-tuning of the calcium level occur?

the distal convoluted tubule Feedback: PTH acts at the distal convoluted tubule to stimulate the reabsorption of calcium to increase serum calcium levels; if it is not present, the calcium is lost. Calcium is filtered at the glomerulus and mostly reabsorbed in the proximal convoluted tubule and the ascending loop of Henle. Bowman's capsule is part of the renal corpuscle that acts as a sieve or a strainer to allow fluid to flow through, but also keeps large particles from entering.

A student asks the physiology instructor how the kidneys control body fluid composition. The instructor explains that the kidneys, by actively removing solutes from the capillary system for excretion in the urine, perform a process called what?

tubular secretion Feedback: Tubular secretion is the movement of solutes from the capillary bed into the renal tubule. Glomerular filtration is the passing of fluid from the capillary system into the renal tubule in Bowman's capsule. Tubular reabsorption is the movement of solutes from the tubule into the capillary system.

The nursing instructor is talking with students about the renal system. What would the instructor tell the students about the renal system, especially how it helps maintain calcium levels in the body by regulating the activation of what?

vitamin D Feedback: The renal system has four major functions in the body. One is regulating vitamin D activation, which helps maintain and regulate calcium levels

The nurse admits a patient with a high potassium level. The nurse recognizes this activates the body's sodium-potassium exchange leading to which physical symptom?

water retention Feedback: If potassium levels are very high, the retention of sodium in exchange for potassium also leads to retention of water and a dilution of blood volume, which decreases potassium concentration. Dehydration is a lack of volume in the blood vessels, which can lead to dizziness. Fatigue is a symptom of anemia, which is associated with renal failure.