If the GFR is too low, needed substances may pass so quickly through the renal tubules that they are not absorbed and instead are lost in the urine.
In the kidneys, the countercurrent mechanism involves the interaction between the flow of filtrate through the loop of Henle of the juxtamedullary nephrons (the countercurrent multiplier) and the flow of blood through the limbs of adjacent blood vessels (the countercurrent exchanger). This relationship establishes and maintains an osmotic gradient extending from the cortex through the depths of the medulla that allows the kidneys to vary urine concentration dramatically.
Water reabsorption through the proximal convoluted tubule is termed obligatory water reabsorption, whereas water reabsorption through the distal convoluted tubule is termed facultative water reabsorption.
The position of the kidneys behind the peritoneal lining of the abdominal cavity is described by the term retroperitoneal.
In the absence of hormones, the distal tubule and collecting ducts are relatively impermeable to water.
Aldosterone is a hormone that causes the renal tubules to reclaim sodium ions from the filtrate.
Blood pressure in the renal glomerulus is lower than in most parts of the body in order to conserve body water.
The proximal convoluted tubule is the portion of the nephron that attaches to the collecting duct.
The macula densa cells are chemoreceptors that respond to changes in the urea content of the filtrate.
The mechanism that establishes the medullary osmotic gradient depends most on the permeability properties of the
loop of Henle
An increase in the permeability of the cells of the collecting tubule to water is due to a (n)
increase in the production of ADH.
Which of the choices below is not a function of the urinary system?
eliminates solid, undigested wastes and excretes carbon dioxide, water, salts, and heat.
The glomerulus differs from other capillaries in the body in that it
is drained by an efferent arteriole.
The descending limb of the loop of Henle
contains fluid that becomes more concentrated as it moves down into the medulla
Select the correct statement about the ureters
The ureters are capable of peristalsis like that of the gastrointestinal tract.
The fatty tissue surrounding the kidneys is important because it
stabilizes the position of the kidneys by holding them in their normal position.
The juxtaglomerular apparatus is responsible for
regulating the rate of filtrate formation and controlling systemic blood pressure.
The chief force pushing water and solutes out of the blood across the filtration membrane is
glomerular hydrostatic pressure (glomerular blood pressure)
Which of the following statements describes the histology of the ureters?
They are trilayers (mucosa, muscularis, and adventitia)
Which of the following statements is a false or incorrect statement?
The male urethra serves both the urinary and reproductive systems at the same time.
Which of the following acts as the trigger for the initiation of micturion (voiding)?
the stretching of the bladder wall.
Most electrolyte reabsorption by the renal tubules is
hormonally controlled in the distal tubule segments.
The fluid in the glomerular (Bowman's) capsule is similar to plasma except that it does not contain a significant amount of
A disease caused by inadequate secretion of antidiuretic hormone (ADH) by the pituitary gland with symptoms of polyuria is
Place the following in correct sequence from the formation of a drop of urine to its elimination from the body.
Nephron, collecting duct, minor calyx, major calyx, ureter, to urethra
Select the correct statement about the nephrons
The parietal layer of the glomerular capsule is simple squamous epithelium.
What would happen if the capsular hydrostatic pressure were increased above normal?
Net filtration would decrease
by passive process requires ATP to move solutes from the interior of the tubule to the blood.
Which of the following is not a reason why substances are either not reabsorbed or are incompletely reabsorbed from the nephron?
They are extremely complex molecules.
Reabsorption of high levels of glucose and amino acids in the filtrate is accomplished by
secondary active transport
Which of the choices below is a function of the loop of Henle?
form a large volume of very dilute urine or small volume of very concentrated urine.
Fetal kidneys do not have to work very hard because
the placenta allows the mother's urinary system to clear the waste from fetal blood.
Which of the following best describes the kidney function in older adults (70 years or older)
Kidney function decreases due to kidney atrophy.
If the Tm for a particular amino acid is 120mg/100 ml and the concentration of that amino acid in the blood is 230 mg/100 ml, the amino acid will
appear in the urine.
If one says that the clearance value of glucose is zero, what does this mean?
Normally all glucose is reabsorped.
Which of the choices below is not a method by which the cells of the renal tubules can raise blood pH?
by secreting sodium ions
In the ascending limb of the loop of Henle the
thick segment moves ions out into interstitial spaces for reabsorption.
Select the correct statement about urinary system development?
kidneys develop from urogenital ridges.
Which of the choices below does not describe the importance of tubular secretion?
ridding the body of bicarbonate ions.
What is the function of the juxtaglomerular apparatus?
help regulate blood pressure and the rate of blood filtration by the kidneys.
Which of the choices below are the most important hormone regulators of electrolyte reapsorption and secretion?
Angiotensin II and aldosterone
Which of the cells of the kidney are chemoreceptors that respond to changes in solute content of the filtrate?
macula densa cells
The capillary bed that surrounds the descending and ascending loop of Henle of juxtamdelluary nephrons is called the
mechanism is the general tendency of vascular smooth muscle to contract when stretched.