A&P II: Ch. 24 The Urinary System Review

The thin descending limb of the nephron loop is permeable to __________.

water The thin descending limb plays an important role in water reabsorption.

Diagram of a nephron, collecting duct and the blood vessels associated with the nephron. The initial part of the tubule coming out of the renal corpuscle is labeled A. The descending part of the nephron loop is labeled B, the last part of the tubule after the nephron loop is labeled C and the collecting duct is labeled D. Secretion takes place at all of these locations, except _____.

B Only reabsorption of water happens in the thin descending limb of the nephron loop.

The amount of filtrate formed by both kidneys in 1 minute is defined as the __________.

GFR The glomerular filtration rate is about 125 ml/min.

Filtration takes place at _____.

A Filtration happens at the glomerulus and is responsible for the formation of filtrate, which collects in the glomerular capsule.

Which of the following is true about tubular reabsorption?

It involves carrier-mediated transport. Most of the substances that are reabsorbed via the transcellular route require the use of carrier proteins, for facilitated diffusion or active transport.

Calculate the NFP, if the GHP is 50 mm Hg, the GCOP is 30 mm Hg and the CHP is 15 mm Hg.

NFP = 5 mm Hg The positive net filtration pressure will drive filtration.

Which of the following will result in a decrease of GFR?

constriction of the afferent arteriole Constriction of the afferent arteriole and dilation of the efferent arteriole are the mechanisms of myogenic autoregulation, which will cause a decrease in GFR.

The hormone ANP causes an __________.

increase GFR ANP increases the GFR. High GFR leads to more fluid loss and therefore decreases blood volume and effectively lowers blood pressure.

A decrease in GFR will cause __________.

lower Na and Cl ion concentration in the distal tubule Because less filtrate moves slower through the tubule and allows for more reabsorption, fewer sodium and chloride ions are delivered to the macula densa cells of the distal tubule. This activates the tubuloglomerular feedback mechanism, resulting in an increased GFR

Aldosterone antagonist drugs prevent aldosterone from having an effect at its receptors. As a result __________.

more urine will be produced Aldosterone antagonists are diuretic drugs. Less Na+, and therefore less water reabsorption, results in increased diuresis.

Which of the following will NOT pass across the filtration membrane?

plasma proteins Plasma proteins, like albumin, are too large to pass through the filtration membrane.

Most nutrients, such as glucose, are reabsorbed in the __________.

proximal tubule The proximal tubule is responsible for the reabsorption of nearly 100% of nutrients such as glucose, amino acids, and other organic substances.

Which of the following is NOT one of the functions of the urinary system?

regulation of leukocyte production The urinary system is involved in the regulation of erythrocyte production, because the kidneys release the hormone erythropoietin, but it does not regulate production of leukocytes.

Which of the following is NOT part of the filtration membrane?

squamous epithelial cells of the glomerular capsule The parietal layer of the glomerular capsule is not part of the filtration membrane. Instead it forms the chamber in which filtrate is collected.

Consuming alcohol inhibits the release of ADH. As a result __________.

urine volume will increase If ADH is reduced, there will be less water reabsorption, therefore more water will remain in the filtrate, and therefore more urine will be produced.

Diagram of the medullary collecting duct in the renal medulla. The filtrate concentration is indicated with dots of solute. The number and density of dots increases down the collecting duct. Blue arrows labeled H2O are shown leaving the collecting duct. Urea is also shown leaving the duct. At the end of the duct urine with high density of solute dots is shown as a droplet. The question mark shows molecules that are at the collecting duct. The hormone identified with a question mark is __________.

ADH In the presence of ADH, water channels called aquaporins allow for water reabsorption in the collecting duct, and as a result, concentrated urine is produced.

Diagram of the internal structure of a renal corpuscle with the glomerulus and the capsular space. There is an arrow labeled A pointing from the glomerulus to the capsular space and indicating 50 mm Hg. There is an arrow labeled B pointing from the capsular space to the glomerulus and indicating 30 mm Hg. There is an arrow labeled C pointing from the capsular space to the glomerulus and indicating 10 mm Hg. There is an arrow labeled D pointing from the glomerulus and capsular space towards the beginning of the proximal tubule and indicating 10 mm Hg. The average GCOP is labeled _____.

B The glomerular colloid osmotic pressure (GCOP) is the osmotic gradient that pulls water back into the glomerular capillaries. The GCOP averages about 30 mm Hg, slightly higher than the osmotic pressure in a typical capillary bed.

The filtrate is most concentrated __________.

at the turn of the nephron loop The filtrate concentration at the turn of the nephron loop can reach 1200 mOsm.

Which of the following will cause an increase in GHP and GFR?

dilation of the afferent arteriole Vasodilation of the afferent arteriole will allow more blood to get into the glomerular capillaries, therefore increasing GHP and GFR.

Returning fluid and solutes from filtrate to blood happens via __________.

tubular reabsorption Tubular reabsorption transports nutrients back into the blood. The nutrients were filtered due to their small size, allowing them to go through the filtration membrane.