Chapter 25 Renal Quiz

Which of the following processes would be considered as a secretory rather than an excretory activity?

Aldosterone release by the adrenal glands

Which hormone(s) is/are required for facultative water reabsorption in the collecting ducts? aldosterone antidiuretic hormone renin parathyroid hormone

Antidiuretic hormone (ADH) stimulates an increase in the number of aquaporins used by the collecting duct to reabsorb water.

Why do you have to carefully monitor certain patients who are on "loop diuretics" to lower their blood pressure?

Certain diuretics are not specific and in addition to getting rid of excess water, additional ions like potassium will be secreted. If the diuretic is not potassium sparing, you must be careful to instruct patients that they may need to adjust their diet or take a potassium supplement while on this medicine.

Upon reaching what point in the nephron is reabsorption (1) dependent upon the body's needs at the time and (2) regulated by hormones?

Distal convoluted tubule (DCT) reabsorption only occurs under the influence of hormonal regulation.

Which of these should not normally appear in urine? urea glucose sodium creatine

Glucose: Glucose would normally be completely reabsorbed during urine formation and should not be in a urine sample.

Which of the following is NOT a major urine formation process? micturition glomerular filtration tubular reabsorption tubular secretion

Micturition is the process of urinating, releasing stored urine after it is formed.

Which of the following is the site where we would find the majority of the nephron loops?

Renal Pyramids; The loops of all nephrons travel into the medulla and renal pyramids where urine is concentrated.

drop the labels onto the figure in the correct order of events to complete the positive feedback loop:

Start: 1. Osmolality of interstitial fluid 2. Water leave descending limb 3. Osmolality of filtrate leaving descending limb 4. Osmolality of filtrate entering ascending limb 5. Salt pumped out of ascending limb

The lab results of a newly admitted patient indicate renal impairment. How might this affect the dosing regimen of drugs that are excreted by the kidney?

The dosage or the dosage interval may need to be reduced. If the renal clearance of the drug is reduced by kidney disease, then drugs eliminated by the kidney may need to be given less often, in smaller amounts, or both. This appropriate regimen is often found in information provided by the drug manufacturer.

Long Nephron Loops: Creation of the Medullary Osmotic Gradient feedback

The long nephron loops of juxtamedullary nephrons first concentrate and then dilute the filtrate. In the descending limb, water is reabsorbed as it moves down its osmotic gradient and concentrates the filtrate. In the ascending limb, solutes (Na+ and Cl−) are actively pumped out and reabsorbed. Since the ascending limb is impermeable to water, this dilutes the filtrate. The solutes left behind in the surrounding interstitial tissue fluid create a vertical osmotic gradient.

Key Players in the Medulla Osmotic Gradient

These countercurrent mechanisms establish and maintain an osmotic gradient extending from the cortex through the depths of the medulla. This gradient—the medullary osmotic gradient—allows the kidneys to vary urine concentration dramatically.

Which urinary structure serves as the transporter for urine toward the bladder? kidney ureter urethra renal pelvis

Ureter The ureters are continuously active in moving urine by peristalsis toward the bladder.

The myogenic mechanism of renal autoregulation primarily involves smooth muscle in which blood vessels?

afferent arterioles By regulating afferent arteriole diameter, the myogenic mechanism affects HPg and therefore GFR. Under normal physiological conditions, this intrinsic control works to maintain GFR despite moderate changes in systemic blood pressure.

The ________ use the medullary osmotic gradient to concentrate urine.

collecting ducts

In what part of the renal tubule does parathyroid hormone (PTH) promote the reabsorption of calcium ions?

distal convoluted tubule (DCT) Parathyroid hormone (PTH) promotes the reabsorption of calcium ions in the distal convoluted tubule (DCT).

The prefix _____ means glomerulus of the kidney.

glomerul(o)-

GFR regulation mechanisms primarily affect which of the following?

glomerular hydrostatic pressure (HPg) Much like other capillaries in the body, hydrostatic pressure within the glomerular capillaries produces net outward movement of fluid. Unique to glomerular capillaries, HPg is consistently higher than other capillaries (~55 mm Hg), which ensures the one-way movement of fluid and solutes out of the glomerulus under normal conditions.

The specialized capillary bed responsible for the pressure that drives filtration is the ______.

glomerulus

Your patient's urinalysis shows a large amount of protein in the urine. This suggests a problem in the ____________

glomerulus

What does a high concentration of NaCl in the renal tubule at the juxtaglomerular apparatus (JGA) most likely indicate?

insufficient NaCl reabsorption due to high GFR

The prefix _____ means situated near.

juxta-

Renin is released by cells of the _____ apparatus in response to afferent arteriole pressure and the degree of stretch of the arteriole wall.

juxtaglomerular

The long nephron loops of the _____ nephrons are located in the renal _____.

juxtamedullary ; medulla

The __________ create the medullary osmotic gradient and act as countercurrent _____ .

long nephron loops ; multipliers

Which of the following are mechanisms of intrinsic control of glomerular filtration (renal autoregulation)?

myogenic mechanism and tubuloglomerular feedback Both of these mechanisms occur strictly within kidney (i.e., intrinsic controls). The myogenic mechanism is mediated by smooth muscle within the afferent arteriole. In contrast, tubuloglomerular feedback is mediated by macula densa cells of the juxtaglomerular apparatus (JGA).

The prefix ____ means kidney.

nephr-

The structural and functional unit of the kidney is a ____.

nephron

Which pressure accounts for the other three? glomerular hydrostatic pressure net filtration pressure blood colloid osmotic pressure capsular hydrostatic pressure

net filtration pressure; Net filtration pressure is a combination of glomerular hydrostatic pressure minus capsular hydrostatic pressure and colloidal osmotic pressure.

Which part of the brain controls the micturition (urination) reflex? pons cerebrum medulla oblongata hypothalamus

pons The pons is the brain region where the micturition reflex originates.

What area of the nephron is responsible for the reabsorption of most of the water from the filtrate as well as most nutrients?

proximal convoluted tubule Most of the water from the filtrate as well as most nutrients are reabsorbed in the proximal convoluted tubule.

Which of the following is the primary function of the juxtaglomerular complex?

releases chemical signals that regulate the rate of filtrate formation; The macula densa cells and granular cells of the juxtaglomerular complex (JGC) release, respectively, vasoactive chemicals and renin. These chemical messengers lead to changes in vasomotor activity and Na+ reabsorption that affect the rate of filtrate formation and systemic blood pressure.

Approximately 80% of the energy used for active transport is devoted to the reabsorption of __________.

sodium

Which of the following is NOT a property used to establish the medullary osmotic gradient?

the blood flow through the ascending and descending portions of the vasa recta The flow of blood through the ascending and descending portions of the vasa recta does not establish the osmotic gradient. The vasa recta act as countercurrent exchangers to preserve the osmotic gradient.

Which of the following best describes glomerular filtration rate (GFR)?

the volume of filtrate created by the kidneys per minute; Fluid and small solutes that leave the glomerulus are collectively termed filtrate. Glomerular filtration is driven by glomerular hydrostatic pressure (HPg) and produces ~125 ml of filtrate per minute.

Macula densa cells of the juxtaglomerular apparatus (JGA) regulate GFR through which intrinsic mechanism?

tubuloglomerular feedback The JGA is a region of the nephron where the afferent arteriole and its associated tubule are closely apposed. This anatomical arrangement allows macula densa cells to adjust GFR according to the NaCl concentration in filtrate. This is called tubuloglomerular feedback because it allows the contents of the tubules (tubulo-) to affect the glomerular filtration rate.

The prefix ____ means urine, urinary tract, or urea.

ur-

An elevated level of urea in the blood is _____.

uremia

The _______ preserve the medullary osmotic gradient and act as countercurrent _____ .

vasa recta ; exchangers