MasteringAandP The Urinary System Chapter 25 P Besaw
What region subdivides to form two or three major calyces and several minor calyces? Select from letters A-D.
c Renal pelvis
Which vessels supply the cortical tissue of the kidney with blood?
cortical radiate arteries
What two structures constitute the renal corpuscle?
glomerulus and glomerular (Bowman's) capsule
Which of the three parts of the renal tubule is formed by cuboidal epithelial cells bordered by dense microvilli?
proximal convoluted tubule
In which kidney region are all renal corpuscles located?
Where does the efferent arteriole of the juxtamedullary nephron carry blood to?
Which of the following is the most likely to cause pyelonephritis?
infection of the urinary bladder
Pyelonephritis is an infection and/or inflammation of the entire kidney usually caused by fecal bacteria that spread from the anal area to the urinary tract. The bladder is directly connected to the kidney via the ureters.
What is the juxtaglomerular apparatus?
a system that regulates the rate of filtrate formation and systemic blood pressure
The __________ collect(s) urine, which drains continuously from the papillae; the urine is then emptied into the __________.
calyces; renal pelvis
What vessel directly feeds into the glomerulus?
Which capillary bed produces filtrate?
What is the function of the macula densa cells of the juxtaglomerular complex (JGC)?
The macula densa cells monitor the NaCl content of the filtrate entering the distal convoluted tubule.
Where is filtrate produced in the nephron?
Which of the following statements 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.
The vasa recta act as a countercurrent exchanger by "exchanging" water and salt between the descending and ascending loops of the vasa recta and the medullary interstitial space. Which of the following statements about the vasa recta is correct?
The osmolality of blood plasma inside the vasa recta increases as it descends into the inner medulla.
Which of the following statements about aldosterone is NOT correct?
Aldosterone increases sodium reabsorption.
Aldosterone increases the number of passive sodium channels in the luminal membrane of the distal tubule and collecting duct, thus aiding sodium reabsorption.
Aldosterone is stimulated by decreased plasma sodium levels and increased plasma potassium levels.
xxx Aldosterone increases sodium reabsorption by increasing the number of Na+-K+ ATPase pumps in the luminal membrane of the proximal tubule.
Aldosterone is produced in the adrenal cortex.
In overhydration, what would be the levels of ADH (high, normal, or low) and what would be the osmolarity of the urine?
Think about drinking 1 liter of water. Would you need to retain all that water? Would your urine be concentrated or dilute?
ADH – low; 100 mOsm (urine)
Yes, in overhydration, ADH would be very low and the cells of the collecting duct would be relatively impermeable to water and urea. Thus, the final urine would be dilute, having an osmolarity of about 100 mOsm.
In severe dehydration or blood loss, what would be the levels of ADH and what would be the urine flow rate?
If you are dehydrated or have blood loss, you would need to retain water.
ADH – high; low urine flow rate (0.25 ml/min)
Yes, ADH would be high, causing a large percentage of the water to be reabsorbed. Therefore, the urine flow rate would be low.
Which of the following substances is not normally found in filtrate?
Think about how a coffee filter works.
blood cells and large particles
Yes, both blood cells and large particles, such as proteins, are not allowed to filter through a healthy glomerular membrane.
What is the primary driving force (pressure) that produces glomerular filtration?
What was the primary driving force for filtration from a capillary?
hydrostatic pressure of blood (blood pressure)
Yes, the hydrostatic pressure of blood forces fluid out of the glomerular capillaries.
Which of the following would only be found in the glomerular filtrate if the glomerular membrane were damaged?
If a filter is damaged, it would let particles through that it normally would not filter.
Yes, large proteins are not normally filtered by a healthy glomerular membrane.
If the osmotic pressure in the glomerular capillaries increased from 28 mm Hg to 35 mm Hg, would net filtration increase or decrease?
Proteins in the plasma would increase the osmotic pressure of the blood.
net filtration would decrease
Yes, because osmotic pressure opposes filtration, increasing osmotic pressure would decrease net filtration.
Calculate the net filtration pressure if capillary hydrostatic pressure is 60 mm Hg, capillary osmotic pressure is 25 mm Hg, and capsular hydrostatic pressure is 10 mm Hg.
Remember that hydrostatic pressure pushes water away and osmotic pressure draws water in.
25 mm Hg
Yes, 60 – (25 + 10) = 25 mm Hg. The two pressures that oppose filtration must be subtracted from the force favoring filtration.
Most solutes that are reabsorbed in the proximal convoluted tubule use which of the following pathways?
Hint 1. The paracellular and transcellular pathways
The transcellular pathway goes through the cell, and the paracellular pathway goes in between cells.
Yes, most substances are reabsorbed first through the luminal and then through the basolateral membranes of the proximal convoluted tubule.
During reabsorption of water in the proximal convoluted tubule, what causes water to diffuse from the lumen into the interstitial space?
Hint 1. Osmosis
Osmosis is a passive process. What sort of conditions favor passive transport?
an increase in the osmolarity of the interstitium
Yes, the increase in osmolarity causes the water to move into the interstitium.
The decreased intracellular concentration of sodium in tubular cells during active transport is caused by which of the following mechanisms?
Hint 1. Why might sodium levels decrease?
If sodium levels decrease, sodium is either not entering the cell or it is being transported out
the sodium-potassium ATPase pump in the basolateral membrane
Yes, this pump moves sodium out of the cell into the interstitium, thus decreasing intracellular sodium.
The active transport of which ion out of proximal convoluted tubule cells causes the reabsorption of both water and solutes?
Hint 1. Ion concentrations and active transport
Which ion would require moving against its concentration gradient ( low to high concentration) from within a cell to outside a cell
Yes, the active transport of sodium out of the cell, across the basolateral membrane into the interstitium, provides the driving force for reabsorption of both water and solutes.
Which of the following transporters in the luminal membrane results in secretion?
Hint 1. Secretion
Secretion is the movement of particles into the lumen of the nephron. Which solute could be secreted in paracellular transport?
Yes, because this is a countertransporter, Na+ is transported into the cell and H+ is transported out of the cell into the lumen.
What is the limiting factor for the reabsorption of most actively transported solutes in the proximal tubule?
Hint 1. Entry-point for actively transported solutes
Where does the bottle-neck in the movement of most solutes moving into a cell occur?
number of transport carriers in the luminal membrane
Yes, the number of carriers is the rate-limiting factor. For example, in Diabetes Mellitus, plasma glucose levels are very high, and the sodium-glucose transporter cannot transport (reabsorb) all the glucose passing through the proximal tubule. Glucose is therefore found in the urine.
Which of the following is the volume of filtrate formed each minute by all of the glomeruli of the kidneys?
glomerular filtration rate (GFR)
What hormone promotes active tubular secretion of potassium ions in the late distal convoluted tubule (DCT) and collecting ducts?
In what part of the renal tubule are aquaporins scarce or absent so that water CANNOT be reabsorbed?
proximal convoluted tubule (DCT)
xxx ascending limb of the nephron loop
descending limb of the nephron loop
In what part of the renal tubule does parathyroid hormone (PTH) promote the reabsorption of calcium ions?
distal convoluted tubule (DCT)
Which of the following promotes the formation of dilute urine?
decreased osmolality of extracellular fluids
Which statement best describes the effect diuretics have?
Diuretics increase urinary output.
Where does antidiuretic hormone (ADH) exert its effects to promote water reabsorption?
Where in the nephron does most solute reabsorption occur?
proximal convoluted tubule
Approximately 80% of the energy used for active transport is devoted to the reabsorption of __________.
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
The descending limb of the loop of Henle is permeable to both solutes and water.
Under normal conditions, the proximal convoluted tubule reabsorbs all of the glucose, lactate, and amino acids in the filtrate and 65% of the Na+ and water.
The leading cause of chronic renal disease is hypertension.
A nonfasting urine sample from an individual who has previously ingested donuts and a soft drink showed the presence of sugar (glucose). Which of the following statement explains the presence of the glucose in the urine?
The individual exceeded the transport maximum.
Which of the following is NOT a cause of anuria?
obstruction in the urethra
xxxxvasodilation of afferent arterioles
Vasodilation of the afferent arterioles occurs during times of low systemic blood pressure. This reflexive response raises glomerular blood pressure and helps maintain normal glomerular filtration rates. Anuria is an abnormally low urine output (<50 ml/day).
What type of epithelial tissue forms the mucosa layer of the urinary bladder?
Which of the following is NOT one of the things that must happen for micturition to occur?
The internal urethral sphincter must open.
The external urethral sphincter must open.
xxxThe extrusor muscle must relax.
The detrusor muscle must contract
There is no "extrusor" muscle; only the detrusor muscle.
Which part of the brain controls the micturition reflex?
When renal calculi obstruct a ureter, pain is perceived to radiate from the lower back to the anterior abdominal wall on the same side. This is an event that ______.
is called referred pain
Referred pain is pain perceived at a location other than the site of the painful stimulus.
Urinary incontinence may occur if a person has ______.
an overactive detrusor muscle
The detrusor muscle is composed of smooth muscle and surrounds the entire bladder. When it stimulated to contract by the parasympathetic nervous system, it squeezes urine out of the bladder into the urethra, causing urination.
Polycystic kidney disease always affects both kidneys instead of only the right or left kidney because ______.
it is a genetic disease