Chapter 50- Introduction to the Renal System

A student asks the physiology instructor where chloride is primarily reabsorbed. What would be the instructor's best answer? A) The loop of Henle B) The nephron C) The kidney D) The distal convolute tubule

A student asks the physiology instructor where chloride is primarily reabsorbed. What would be the instructor's best answer? A) The loop of Henle B) The nephron C) The kidney D) The distal convolute tubule

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? A) 2,000 mL B) 3,000 mL C) 4,000 mL D) 5,000 mL

Ans: A 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 other options are not correct.

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? A) The woman has a short urethra. B) The woman has multiple sexual partners. C) The woman takes too many bubble baths. D) The woman does not clean herself as she should.

Ans: A 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. Recurrent UTIs do not indicate the woman has multiple sexual partners, takes too many bubble baths, or does not clean herself adequately.

The students are discussing the electrolytes in the body. What should the students know has the greatest influence on potassium loss from the body? A) Aldosterone B) Antidiuretic hormone C) Renin D) Carbonic anhydrase

Ans: A 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.

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? A) "Renin is directly involved in the control of arterial blood pressure and it is essential for proper functioning of the glomerulus." B) "Renin is involved in venous blood pressure and controls the flow of blood through the tubules." C) "Renin is directly involved in the control of arterial blood pressure and the flow of blood through the pyramids of the kidney." D) "Renin is involved in venous blood pressure and it is essential for proper functioning of the glomerulus."

Ans: A Feedback: Renin is a hormone directly involved in the control of arterial blood pressure. It is essential for proper functioning of the glomerulus. The other options are not correct.

Where do the collecting ducts meet? A) Renal pelves B) Loop of Henle C) Bowman's capsule D) Distal convoluted tubule

Ans: A Feedback: The nephron widens at the distal convoluted tubule, then flows into the collecting ducts, which meet at the renal pelves. The collecting ducts do not meet in the loop of Henle, Bowman's capsule, or distal convoluted tubule.

The physiology instructor explains that the nephrons are fragile and require a constant supply of blood and oxygen. What compensatory mechanisms work to maintain this supply? A) The renin-angiotensin system, causing vasoconstriction B) Baroreceptor monitoring of the renal artery C) Increased sweating when total water volume becomes too great D) Antidiuretic hormone (ADH) release in response to increased blood volume or decreased osmolarity

Ans: A Feedback: The renin-angiotensin system causes vasoconstriction to improve blood flow to the fragile nephrons. Baroreceptors are not found in the renal artery. Increased sweating is not a reflex reaction to increased total body water. ADH is released in response to decreased blood volume and increased osmolarity.

A 78-year-old patient presents at the clinic complaining of urinary problems. The patient tells the nurse that he experiences frequency, urgency, and has problems initiating and maintaining a urinary stream. Based on the patient's age, what would the nurse suspect? A) Enlarged prostate B) Decreased bladder function C) Increased kidney function D) Partially obstructed ureter

Ans: A Feedback: The ureters, urinary bladder, and urethra make up the rest of the urinary tract. The longer male urethra passes through the prostate gland, which may enlarge or become infected, a problem often associated with advancing age. The patient's advancing age does not increase the risk of decreased bladder function, increased kidney function, or partially obstructed ureter.

Ans: A Feedback: The renin-angiotensin system causes vasoconstriction to improve blood flow to the fragile nephrons. Baroreceptors are not found in the renal artery. Increased sweating is not a reflex reaction to increased total body water. ADH is released in response to decreased blood volume and increased osmolarity.

Ans: A Feedback: When nephrons are lost, as in renal failure, the juxtaglomerular cells that produce erythropoietin are also lost leading to a decrease in red blood cell production and anemia. Urea, renin, and hydrogen do not affect red blood cell production and are not associated with anemia.

A student is giving a presentation about the function of antidiuretic hormone and reports that it is released in response to what stimuli? (Select all that apply.) A) Falling blood volume B) Parasympathetic stimulation C) Rising sodium levels D) Rising calcium levels E) Rising parathyroid hormone levels

Ans: A, C Feedback: Antidiuretic hormone (ADH) is released in response to falling blood volume, sympathetic stimulation, or rising sodium levels. It is not affected by rising calcium or parathyroid levels. Option B is not correct.

A patient is being treated for dehydration and asks the nurse how the body maintains proper fluid composition and volume. The nurse correctly includes which regulatory mechanisms? (Select all that apply.) A) Concentration of urine B) Increased production of erythropoietin C) Secretion of electrolytes D) Dilution of urine E) Increased blood pressure

Ans: A, C, D Feedback: The kidneys regulate the composition of body fluids by balancing the levels of the key electrolytes, secreting or absorbing these electrolytes to maintain the desired levels. Body fluid volume is controlled by diluting or concentrating urine. Erythropoietin helps to increase red blood cell production, which helps increase oxygen to the organs. Increased blood pressure does not change the volume or composition of body fluids.

A nursing instructor is quizzing a group of students about the function of the nephron. The student must choose which processes that control the function of the nephron to answer the question correctly? (Select all that apply.) A) Filtration B) Dilution C) Secretion D) Reabsorption E) Concentration

Ans: A, C, D Feedback: The nephrons function by using three basic processes: filtration, secretion, and reabsorption. Dilution and concentration are functions of sodium regulation.

A daughter is talking with the urologist who is caring for the woman's 78-year-old mother. The mother has multiple sclerosis and has lost control of her bladder. The daughter asks the urologist what made her mother become incontinent. What would be the urologist's best answer? A) "I don't know, but there are lots of medicines we can try to fix it." B) "After control of the bladder is learned, you must have a functioning nervous system to maintain it." C) "Your mother's age has a lot to do with it." D) "This happens sometimes and no one is quite sure why."

Ans: B Feedback: Control of bladder emptying is learned control over the urethral sphincter. Once it is established, a functioning nervous system is necessary to maintain control.

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? A) Dehydration B) Water retention C) Fatigue D) Dizziness

Ans: B 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.

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? A) Promote sodium excretion B) Concentrate or dilute the urine C) Block the effects of aldosterone D) Stimulate antidiuretic hormone (ADH) release

Ans: B Feedback: The countercurrent mechanism in the medullary nephrons acts to concentrate or dilute urine. It does not promote sodium excretion nor does it block the effects of aldosterone. This mechanism does not stimulate ADH release.

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? A) Proximal convoluted tubule B) Distal convoluted tubule C) Loop of Henle D) Glomerulus

Ans: B 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. Therefore, options A, C, and D are not correct.

What function does the kidney perform to assist in maintaining acid-base balance within the necessary normal range? A) Excrete acid in the lungs B) Return bicarbonate to the body's circulation C) Return acid to the body's circulation D) Excrete bicarbonate in the urine

Ans: B 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. Therefore, options A, C, and D are incorrect.

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? A) The ascending and descending parts of the loop of Henle B) The arterioles C) The nephron D) The venules

Ans: B 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. The nephron does not regulate blood flow to the glomerulus, and option D is a distracter for this question.

The nursing instructor is explaining the function of natriuretic hormone in relation to urine composition. The instructor shares that this hormone is released in response to which conditions? (Select all that apply.) A) Fluid depletion B) Fluid overload C) Hemodilution D) Hemoconcentration E) Decreased red blood cell production

Ans: B, C Feedback: Natriuretic hormone is released in response to fluid overload, not fluid depletion and hemodilution, and not hemoconcentration. Erythropoietin is released in response to decreased red blood cell production.

The renal system has several major functions in the body. What are they? (Select all that apply.) A) Acting as a diuretic for the body B) Clearing nitrogenous wastes from protein metabolism C) Regulating red blood cell production D) Regulating blood pressure E) Concentrating urine

Ans: B, C, D, E Feedback: Maintaining the volume and composition of body fluids within normal ranges includes clearing nitrogenous wastes from protein metabolism; maintaining acid-base balance and electrolyte levels; excreting various drugs and drug metabolites; regulating vitamin D activation, which helps to maintain and regulate calcium levels; regulating blood pressure through the renin-angiotensin-aldosterone system; and regulating red blood cell production through the production and secretion of erythropoietin. The renal system does not act as a diuretic.

Much of the sodium in the filtrate is reabsorbed in the proximal convoluted tubule to the peritubular capillaries. As the sodium is moved out of the filtrate, what does it take with it? A) Calcium B) Magnesium C) Chloride ions D) Potassium ions

Ans: C Feedback: As sodium is actively moved out of the filtrate, it takes chloride ions and water with it. Sodium does not take calcium, magnesium, or potassium ions with it.

The students are studying the male reproductive system. The instructor tells the students that in the male, the urethra leaves the urinary bladder and passes through what? A) Vas deferens B) Renal calyx C) Prostate gland D) Renal cortex

Ans: C Feedback: In the male, the urethra leaves the urinary bladder and passes through the prostate gland. The renal calyx and cortex are located in the kidney and the urethra does not pass through the kidney. The vas deferens delivers the sperm from the testicles to the urethra.

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? A) Bowman's capsule B) The proximal convoluted tubule C) The distal convoluted tubule D) The loop of Henle

Ans: C 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 patient who has signs and symptoms of kidney failure has experienced what percentage of loss of the nephrons in the kidneys? A) 10% B) 25% C) 50% D) 75%

Ans: D Feedback: Only 25% of the total number of nephrons is necessary to maintain healthy renal function so most patients must have experienced nephron loss of at least 75% to have signs and symptoms of kidney failure. The other options are not correct.

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? A) Vitamin A B) Vitamin B C) Vitamin C D) Vitamin D

Ans: 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. Vitamins A, B, and C are not associated with this function.

The pathophysiology instructor is talking to the prenursing 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? A) Antidiuretic hormone B) Aldosterone C) Renin D) Angiotensin

Ans: C 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 detect 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 recognize the increase in blood pressure, renin secretion stops. Failure of this feedback mechanism is one of the primary causes of hypertension. Therefore, options A, B, and D are incorrect.

The patient has just been diagnosed with acute renal failure. The patient asks the nurse what part of his or her kidneys is involved. What would the nurse reply? A) Glomerulus B) Renal pelves C) Nephron D) Renal capsule

Ans: C Feedback: The functional unit of the kidney is the nephron. There are about 2.4 million nephrons in an adult. These structures filter fluid and make urine. The glomerulus is a tuft of blood vessels with a capillary-like endothelium that allows easy passage of fluid and waste products. The renal pelves are in a region of the kidney that drains urine into the ureters. The renal capsule is a protective layer, which is made up of the fiber layer, a perirenal or brown fat layer, and the renal parietal layer.

The nurse is aware that which area of the kidney provides quick response to any damage or injury to the kidney cells? A) Juxtaglomerular apparatus B) Renin-angiotensin-aldosterone system C) Macula densa D) Countercurrent mechanism

Ans: C Feedback: The macula densa consists of immune system cells and chemicals that can respond quickly to any cellular damage or injury. The juxtaglomerular apparatus produce 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 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? A) Increased temperature B) Decreased pulse C) Decreased blood pressure D) Pain level of 3 on a scale of 1 to 10

Ans: C 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. An increase in temperature, a decrease in pulse, and a pain level of 3 would not affect blood volume.

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? A) Potassium and sodium B) Bicarbonate and urea C) Blood cells and protein D) Creatinine and chloride

Ans: C 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.

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? A) Glomerular filtration B) Tubular reabsorption C) Tubular secretion D) Tubular metabolism

Ans: C 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.

What releases erythropoietin when blood flow or oxygenation to the nephron is decreased? A) The countercurrent mechanism B) The nephron C) The juxtaglomerular cells D) The glomerulus

Ans: C Feedback: Whenever blood flow or oxygenation to the nephron is decreased (due to hemorrhage, shock, heart failure, or hypotension), the hormone erythropoietin is also released from the juxtaglomerular cells. Therefore, options A, B, and D are not correct.

Sodium ions are reabsorbed into the body by the aid of what catalyst? A) Aldosterone B) Sodium bicarbonate C) Angiotensin D) Carbonic anhydrase

Ans: D Feedback: Carbonic anhydrase, an enzyme, speeds the process of carbon dioxide and water combining to form carbonic acid. The carbonic acid immediately dissociates to form sodium bicarbonate, using a sodium ion from the renal tubule and a free hydrogen ion (an acid). The other options are not correct.

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? A) Increased hematocrit B) Increased white blood cell count C) Increased platelet count D) Decreased hemoglobin

Ans: D 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. Options A, B, and C are not correct.

A student asks the physiology instructor how bicarbonate is replaced by the body when a patient loses it from the body. What should the instructor answer? A) The renal tubules secrete new bicarbonate into the urine. B) The juxtaglomerular cells secrete new bicarbonate into the blood. C) The juxtaglomerular cells generate new bicarbonate. D) Renal tubular cells generate new bicarbonate.

Ans: D Feedback: To replace any lost bicarbonate, the renal tubular cells generate new bicarbonate through a variety of chemical reactions. This newly generated bicarbonate is then reabsorbed by the tubules and returned to the body. This makes options A, B, and C incorrect.