The Urinary System - Chapter 26

Question 1

The basic functional unit of the kidney is the:

Answer 1

nephron

Question 2

The process of urine formation involves all of the following except:

Answer 2

secretion of excess lipoprotien and glucose molecules

Question 3

The glomerular filtration rate is regulated by all of the following except:

Answer 3

cardiac output

Question 4

The distal convoluted tubule is an important site for:

Answer 4

active secretion of ions, active secretion of acids and other materials, selective reabsorption of sodium ions from the tubular fluid

Question 5

Changing the diameters of the afferent and efferent artierioles to alter the GFR can be an example of __________ regulation.

Answer 5

Hormonal, Autonomic, and Autoregulation

Question 6

What is the primary function of the urinary system?

Answer 6

perform vital excretory functions and eliminates the organic wastes generated by cells throughout the body.. Regulate the volume and solute concentration of body fluids.

Question 7

What organs make up the urinary system?

Answer 7

1. Kidneys
2. Ureters
3. Urinary Bladder
4. Urethra

Question 8

Trace the pathway of the protein-free filtrate from where it is produced in the renal corpuscle until it drains into the renal pelvis in the form of urine.

Answer 8

Renal Corpuscle –> Proximal Convoluted tubule –> Nephron loop –> distal convoluted tubule –> collecting duct –> papillary duct –> renal pelvis

Question 9

Name the segments of the nephron distal to the renal corpuscle. State the functions of each.

Answer 9

1. Proximal Convoluted Tubule - reabsorbs all the useful organic substrates from the filtrate
2. Nephron Loop - reabsorbs over 90% of the water in the filtrate
3. Distal Convoluted Tubule - secretes wastes into the tubular fluid that were not filtered or reabsorbed

Question 10

What is the function of the juxtaglomerular complex?

Answer 10

The fuxtaglomerular complex secretes the enzyme RENIN and the hormone ERYTHROPOIETIN

Question 11

Using arrows, trace a drop of blood from its entry into the renal artery until its exit by a renal vein.

Answer 11

Renal artery –> segmental arteries –> interlobar arteries –> arcuate arteries –> cortical radiate arteries –> afferent arterioles –> glomerulus –> venules –> cortical radiate veins –> arcuate veins –> interlobular veins –> renal vein

Question 12

Name and define the three distinct processes involved in the production of urine.

Answer 12

1. Filtration - the selective removal of large solutes and suspended materials from a solution on the basis of size. Requires a filtration membrane and hydrostatic pressure, as provided by gravity or by blood pressure.
2. Reabsorption - the removal of water and solute molecules from the filtrate after it enters the renal tubules
3. Secretion - the transport of solutes from the peritubular fluid, across the tubular epithelium and into the tubular fluid.

Question 13

What are the primary effects of angiotensin II on kidney function and regulation?

Answer 13

Located in the peripheral capillary beds. Angiotensin causes powerful vasoconstriction of precapilary sphincters, increasing pressures in the renal arteries and their branches. At the nephron, angiotensin II causes the efferent arteries to constrict, causing increase glomerular pressures and filtration rates. At the PCT, it stimulates the reabsorption of sodium ions and water. In the CNS, angiotensin II triggers the release of ADH, stimulating the reabsorption of water in the distal portion of the DCT and the collecting system, and it causes the sensation of thirst. At the adrenal gland, angiotensin II stimulates the secreation of aldosterone by the cortez. Aldosterone accelerates sodium reabsorption in the DCT and the coritcal portion of the collecting system.

Question 14

Which structures of the urinary system are responsible for the transport, storage, and elimination of urine?

Answer 14

Transport - ureters
Storage - urninary bladder
Elimination - urethra

Question 15

When the renal threshold for a substance exceeds it’s tubular maximum:

Answer 15

the amount of the substance that exceeds the tubular maximum will be found in urine

Question 16

Sympathetic Activation of nerve fibers in the nephron causes

Answer 16

The regulation of glomerular blood flow and pressure, the stimulation of renin release from the juxtaglomerular complex, and the direct stimulation of water and Na+ reabsorption

Question 17

Sodium reabsorption in the DCT and in the cortical portion of the collecting system is accelerated by the secretion of:

Answer 17

Aldosterone

Question 18

When ADH levels rise,

Answer 18

the amount of water reabsorbed increases

Question 19

The control of blood pH by the kidneys during acidosis involves

Answer 19

The secretion of hydrogen ions and reabsorption of the bicarbonate ions from the tubular fluid.

Question 20

How are proteins excluded from filtrate? Why is this important?

Answer 20

They are too large to fit through the filtration slits between adjacent pedicels. Keeping proteins in the plasma ensures that blood colloid osmotic pressure with oppose filtration and return water to the plasma.

Question 21

What interacting controls stabilize the glomerular filtration rate (GFR)?

Answer 21

Controls on the GFR are auto-regulation at the local level, hormonal regulation initiated by the kidneys, and autonomic regulation (by the sympathetic ANS)

Auto-regulation
Hormonal Regulation
Autonomic Regulation

Question 22

What primary changes occur in the composition and concentration of filtrate as a result of activity in the proximal convoluted tubule?

Answer 22

As a result of facilitated diffusion and cotransport mechanisms in the PCT, 99 percent of the glucose amino acids, and other nutrients are reabsorbed before the filtrate leaves the PCT. A reduction of the solute concentration of the tubular fluid occurs due to the active ion reabsorption of sodium, potassium, calcium, magnesium, bicarbonate, phosphate, and sulfate ions. The passive diffusion of urea, chloride ions, and lipid-soluble materials further reduces the solute concention of the tubular fluid and promotes additional water reabsorption.

Question 23

Describe two functions of countercurrent multiplication in the kidney.

Answer 23

1. an efficient way to reabsorb solutes and water before the tubular fluid reaches the DCT and collecting system
2. establishes a concentration gradient that permits the passive reabsorption of water from urine in the collecting system.

Question 24

Describe the micturition reflex.

Answer 24

When the bladder contains about 200mL of urin, the reflex begins to function when the stretch receptors ahve provided adequate stimulation of the parasympathetic motor neurons. The activity in the motor neurons generates action potentials that reach the smooth muscle in the wall of the urinary bladder. These efferent impulses travel over the pelvic nerves, producing a sustained contraction of the urinary bladder.

Question 25

In a normal kidney, which of the following conditions would cause an increase of the glomerular filtration rate (GFR)?

Answer 25

A decrease in the concentration of plasma proteins in the blood.

Question 26

In response to excess water in the body…

Answer 26

the permeability of the distal convoluted tubules and collecting ducts to water is decreased

Question 27

Sylvia is suffering from sever edema in her arms and legs. Her physician prescribes a diuretic. Why might this help alleviate Sylvia’s problem?

Answer 27

Increasing the volume of urine produced decreases the blood volume, which in turn leads to a decreased blood hydrostatic pressure. Edema frequently results when the hydrostatic pressure of the blood exceeds the opposing forces at the capillaries in the affected area. Depending on the actual cause of the edema, decreasing the blood hydrostatic pressure would decrease edema formation and possible cause some of the fluid to move from the interstitial spaces back to the blood.

Question 28

David’s grandfather suffers from hypertension. His doctor tells him that part of his problem stems from renal arteriosclerosis. Why would this cause hypertension?

Answer 28

Renal Arteriosclerosis restricts blood flow to the kidneys and produces renal ischemia. Decreased blood flow and ischemia triggers the juxtaglomerular complex to produce more renin, which leads to elevated levels of angiotensin II and aldosterone. Angiotensin II causes vasoconstriction, increased peripheral resistance, and thus increased blood pressure. The aldosterone promotes sodium retation, which leasds to more water retained by the body and an increase in blood volume AND high blood pressure.

Question 29

Mannitol is a sugar that is filtered, but not reabsorbed, by the kidneys. What effect would drinking a solution of mannitol have on the volume of urine produced?

Answer 29

Because mannitol is filtered by not reabsorbed, drinking a mannitol solution would lead to an increase in the osmolarity of the filtrate. Less water would be reabsorbed and an increased volume of urine would be produced.

Question 30

The drug Diamox is sometimes used to treat mountain sickness. Diamox inhibits the action of carbonic anhydrase in proximal convoluted tubule. Polyuria is a side effect associated with the med. Why does polyuria occur?

Answer 30

Carbonic Anahydrase catalyzes the reaction that forms carbonic acid, a source of hydrogen ions that are excreted by the kidneys. Hydrogen ion excreation occurs by an antiport system in the which sodium ions are exchanged for hydrogen ions. Fewer hydrogen ions would be available so less sodium would be reabsorbed, causing an increased osmolarity of the filtrate. In turn, an increased volume of urine and more frequent urination would occur.