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.
loop of Henle
The mechanism that establishes the medullary osmotic gradient depends most on the permeability properties of the ________.
increase in the production of ADH
An increase in the permeability of the cells of the collecting tubule to water is due to a(n) ________.
eliminates solid, undigested wastes and excretes carbon dioxide, water, salts, and heat
Which of the choices below is not a function of the urinary system?
is drained by an efferent arteriole
The glomerulus differs from other capillaries in the body in that it ________.
contains fluid that becomes more concentrated as it moves down into the medulla
The descending limb of the loop of Henle ________.
The ureters are capable of peristalsis like that of the gastrointestinal tract.
Select the correct statement about the ureters.
stabilizes the position of the kidneys by holding them in their normal position
The fatty tissue surrounding the kidneys is important because it ________.
regulating the rate of filtrate formation and controlling systemic blood pressure
The juxtaglomerular apparatus is responsible for ________.
glomerular hydrostatic pressure (glomerular blood pressure)
The chief force pushing water and solutes out of the blood across the filtration membrane is ________.
They are trilayered (mucosa, muscularis, and adventitia).
Which of the following statements describes the histology of the ureters?
The male urethra serves both the urinary and reproductive systems at the same time.
Which of the following statements is a false or incorrect statement?
the stretching of the bladder wall
Which of the following acts as the trigger for the initiation of micturition (voiding)?
hormonally controlled in distal tubule segments
Most electrolyte reabsorption by the renal tubules is ________.
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 ________.
An important characteristic of urine is its specific gravity or density, which is ________.
nephron, collecting duct, minor calyx, major calyx, ureter, urethra
Place the following in correct sequence from the formation of a drop of urine to its elimination from the body.
The parietal layer of the glomerular capsule is simple squamous epithelium.
Select the correct statement about the nephrons.
Net filtration would decrease.
What would happen if the capsular hydrostatic pressure were increased above normal?
by active mechanisms usually involves movement against an electrical and/or chemical gradient
Tubular reabsorption ________.
They are extremely complex molecules.
Which of the following is not a reason why substances are either not reabsorbed or are incompletely reabsorbed from the nephron?
secondary active transport
Reabsorption of high levels of glucose and amino acids in the filtrate is accomplished by ________.
form a large volume of very dilute urine or a small volume of very concentrated urine
Which of the choices below is a function of the loop of Henle?
the placenta allows the mother's urinary system to clear the waste from fetal blood
Fetal kidneys do not have to work very hard because ________.
Kidney function decreases due to kidney atrophy.
Which of the following best describes kidney function in older adults (70 years or older)?
glomerular hydrostatic pressure
The factor favoring filtrate formation at the glomerulus is the ________.
appear in the urine
If the Tm for a particular amino acid is 120 mg/100 ml and the concentration of that amino acid in the blood is 230 mg/100 ml, the amino acid will ________.
Normally all the glucose is reabsorbed.
If one says that the clearance value of glucose is zero, what does this mean?