chapter 25 Urinary

What are aquaporins?

Aquaporins are water-filled pores in water permeable portions of the convoluted tubules such as the PCT.

Explain what is meant by the terms cotransport process and transport maximum.

Cotransport process refers to the active transport of one solute "uphill" (against a concentration gradient) coupled to the "downhill" (with a concentration gradient) movement of another during tubular reabsorption. Transport maximum reflects the number of carriers in the renal tubules available to "ferry" a particular substance.

Humans can survive for a period of time without water thanks to the ability of the kidneys to produce concentrated urine. Briefly explain the factors that allow this to happen.

Facultative water reabsorption depends on the presence of antidiuretic hormone. In the presence of ADH, the pores of the collecting tubule enlarge and the filtrate loses water by osmosis as it passes through the medullary regions of increasing osmolarity. Consequently, water is conserved and urine becomes concentrated. The water that passes through these regions is reabsorbed by the body in order to prevent dehydration.

Major calyces are large branches of the renal column.

False

The collecting duct is impermeable to water in the presence of ADH.

False

The proximal convoluted tubule is the portion of the nephron that attaches to the collecting duct.

False

The trigone is so named because of the shape of the urinary bladder.

False

reshly voided urine has very little smell, but shortly after voiding it can give off a very strong smell. Why?

Freshly voided urine is relatively sterile but if it is allowed to stand, bacteria begin to metabolize the urea solutes to release ammonia and other smells depending on the person's diet. A fruity smell generally means there is a diabetes problem

37) Reabsorption of high levels of glucose and amino acids in the filtrate is accomplished by ________.

secondary active transport

1) The mechanism that establishes the medullary osmotic gradient depends most on the permeability properties of the ________.

Loop of henle

45) As the renal artery approaches the kidney, it branches to supply the renal tissue. Place the following in correct sequence starting from the renal artery. 1. segmental 2. cortical radiate 3. arcuate 4. interlobar

segmental,interlobar,arcuate,cortical radiate

41) The factor favoring filtrate formation at the glomerulus is ________.

the glomerular hydrostatic pressure

39) Fetal kidneys do not have to work very hard because ________.

the placenta allows the motherʹs urinary system to clear the waste from fetal blood

46) In the ascending limb of the loop of Henle ________.

the thick segment moves ions out into interstitial spaces for reabsorption

5) The urinary bladder is composed of ________ epithelium.

transitional

42) 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 appear in the urine

In addition to the renin-angiotensin mechanism, the renal cells produce other chemicals. Name four, and briefly give the main function of each.

Renal cells also produce chemicals, some of which act locally as signaling molecules. These chemicals include prostaglandins (vasodilators and vasoconstrictors), which probably regulate GFR; nitric oxide, a potent vasodilator produced by the vascular endothelium; adenosine, which constricts renal vasculature; and endothelin, a vasoconstrictor that inhibits renin release.

12) Select the correct statement about the ureters.

The ureters are capable of peristalsis like that of the gastrointestinal tract.

What clinical effects would high blood pressure have on the kidneys of a bedridden patient?

This patient would have a much higher glomerular hydrostatic pressure and would therefore lose more fluids than normal. Because of the threat of dehydration, the staff should make sure the patient drinks plenty of water.

36) Which statement is true about urine

Urine has nitrogenous waste such as urea and uric acid.

3) A Bowmanʹs capsule does not contain ________.

a vasa recta

8) Which gland sits atop each kidney

adrenal

4) An increase in the permeability of the cells of the collecting tubule to water is due to ________.

an increase in the production of ADH

6) The kidneys are stimulated to produce renin ________.

by a decrease in the blood pressure

35) Tubular reabsorption ________.

by active mechanisms usually involves movement against an electrical and/or chemical gradient

24) The macula densa cells respond to ________.

changes in solute content of the filtrate

28) The function of angiotensin II is to ________.

constrict arterioles and increase blood pressure

Which of the choices below is not a glomerular filtration rate control method?

electrolyte levels

31) Place the following in correct sequence from the formation of a drop of urine to its elimination from the body. 1. major calyx 2. minor calyx 3. nephron 4. urethra 5. ureter 6. collecting duct

nephron,collecting duct,minor calyx,ureter,urethra

21) The filtration membrane includes all except ________.

renal fascia

Sodium-linked water flow across a membrane is called ________ water reabsorption.

obligatory

38) While the kidneys process about 180 L of blood-derived fluids daily, the amount that actually leaves the body is ________.

1%, or 1.8 L

List three substances that are abnormal urinary constituents and provide the proper clinical term for such abnormalities.

Abnormal urinary constituents include the following (the clinical term for each is listed in parentheses): glucose (glycosuria), proteins (proteinuria or albuminuria), ketone bodies (ketonuria), hemoglobin (hemoglobinuria), bile pigments (bilirubinuria), erythrocytes (hematuria), and leukocytes (pyuria).

Explain how an angiotensin converting enzyme inhibitor (ACE inhibitor) such as captopril would be effective as an antihypertensive.

Angiotensin II is a potent vasoconstrictor activating smooth muscle of arterioles throughout the body, causing mean arterial blood pressure to rise. ACE inhibitors reduce blood pressure by interrupting the renin-angiotensin-aldosterone system.

An excessive urine output is called anuria.

False

Angiotensin II is a substance made by the body to lower blood pressure during stress.

False

Blood pressure in the renal glomerulus is lower than in most parts of the body in order to conserve body water.

False

Glomerular filtration is an ATP-driven process.

False

Having a kinked ureter is called renal ptosis.

False

The functional unit of the kidney is the renal column.

False

The glomerular filtration rate is approximately 350 ml/min.

False

The kidney consumes about 15% of all oxygen used by the body at rest.

False

The macula densa cells are chemoreceptors that respond to changes in the urea content of the filtrate.

False

The myogenic mechanism reflects the tendency of vascular smooth muscle to stretch.

False

Urea is reabsorbed in the loop of Henle.

False

Ureters, like the urethra, are lined only with transitional epithelium.

False

40) Which of the following best describes kidney function in older adults (70 years or older)?

Kidney function decreases due to kidney atrophy.

47) Select the correct statement about urinary system development.

Kidneys develop from urogenital ridges.

33) What would happen if the capsular hydrostatic pressure were increased above normal?

Net filtration would decrease.

43) If one says that the clearance value of glucose is zero, what does this mean?

Normally all the glucose is reabsorbed

Blood supply that directly receives substances from the tubular cells.

Peritubular capillaries.

Site at which most of the tubular reabsorption occurs.

Proximal convoluted tubule.

49) Which statement is correct?

Reabsorption of water is hormonally controlled.

18) Which of the following statements describes the histology of the ureters?

They are trilayered mucosa, muscularis, and adventitia

Aldosterone is a hormone that causes the renal tubules to reclaim sodium ions from the filtrate.

True

Atrial naturetic factor inhibits sodium reabsorption.

True

Blood in the urine may be a symptom of bladder cancer.

True

In the absence of hormones, the distal tubule and collecting ducts are relatively impermeable to water.

True

Incontinence is the inability to control voluntary micturition.

True

Obligatory water reabsorption involves the movement of water along an osmotic gradient.

True

Particles smaller than 3 nanometers are passed into the filtrate.

True

The act of emptying the bladder is called voiding.

True

The entire responsibility for urine formation lies with the nephron.

True

The position of the kidneys behind the peritoneal lining of the abdominal cavity is described by the term retroperitoneal.

True

The terminal portion of the urinary system is the urethra.

True

The ureter transports urine from the kidney to the urinary bladder.

True

The urethra contains an internal sphincter of smooth muscle.

True

Tubular secretion is effective in controlling blood pH.

True

Urine is 95% water by volume.

True

48) The disruption in homeostasis known as pyelitis is ________.

an infection of the renal pelvis and calyces

Which of the choices below are the most important hormone regulators of electrolyte reabsorption and secretion?

angiotensin II and aldosterone

9) The ________ artery lies on the boundary between the cortex and medulla of the kidney.

arcuate

11) The descending limb of the loop of Henle ________

contains fluid that becomes more concentrated as it moves down into the medulla

25) Which of the following is not reabsorbed by the proximal convoluted tubule

creatinine

29) A disease caused by inadequate secretion of antidiuretic hormone (ADH) by the pituitary gland with symptoms of polyuria is ________.

diabetes insipidus

17) The chief force pushing water and solutes out of the blood across the filtration membrane is ________.

glomerular hydrostatic pressure (glomerular blood pressure)

List and describe three pressures operating at the filtration membrane, and explain how each influences net filtration pressure.

Glomerular hydrostatic pressure is the chief force pushing water and solutes across the filtration membrane. The higher the glomerular hydrostatic pressure, the more filtrate is pushed across the membrane. Colloid osmotic pressure of plasma proteins in the glomerular blood, and capsular hydrostatic pressure exerted by fluids in the glomerular capsule, drive fluids back into the glomerular capillaries. The net filtration pressure equals glomerular hydrostatic pressure minus the sum of colloid osmotic pressure of glomerular blood and capsular hydrostatic pressure.

2) Urine passes through the ___

pelvis of the kidney to ureter to bladder to urethra

26) The fluid in the glomerular (Bowmanʹs) capsule is similar to plasma except that it does not contain a significant amount of ________.

plasma protein

34) Which of the following is not a part of the juxtaglomerular apparatus?

podocyte cells

The presence of pus in the urine is a condition called ________.

pyuria

16) The juxtaglomerular apparatus is responsible for ________.

regulating the rate of filtrate formation and controlling systemic blood pressure

Urine crystals in the renal pelvis are called ________.

renal calculi

19) The first major branch of the renal artery is ________.

segmental

15) The functional and structural unit of the kidneys is ________.

the nephron

The area between the ureters and urethra is called the ________ in a bladder.

trigone

The capillary bed that surrounds the descending and ascending loop of Henle of juxtamedullary nephrons is called the ________.

vasa recta

30) An important characteristic of urine is its specific gravity or density, which is ________.

1.001-1.035

Which of the hormones below is responsible for facultative water reabsorption

ADH

Explain the role of aldosterone in sodium and water balance.

Aldosterone targets the distal tubule and collecting duct and enhances sodium ion reabsorption so that very little leaves the body in urine. Aldosterone also causes increased water reabsorption because, as sodium is reabsorbed, water follows it back into the blood.

14) The renal corpuscle is made up of ________.

Bowmanʹs capsule and glomerulus

Site of filtrate formation.

Glomerulus.

Collecting duct

Site that drains the distal convoluted tubule.

32) Select the correct statement about the nephrons.

The parietal layer of the glomerular capsule is simple squamous epithelium.

20) Which of the following acts as the trigger for the initiation of micturition (voiding)?

The stretching of the bladder wall serves as the trigger.

22) The mechanism of water reabsorption by the renal tubules is ________.

osmosis

) Explain how filtration works in the glomerular capillaries.

he glomerular capillaries are fenestrated, allowing fairly large molecules to pass through. The substances must pass through the basement membrane, where they are further selected for size by the filtration slits of the podocytes.

What is the function of the juxtaglomerular apparatus?

help regulate blood pressure and the rate of blood filtration by the kidneys

44) Excretion of dilute urine requires _______

impermeability of the collecting tubule to water

27) Alcohol acts as a diuretic because it ________.

inhibits the release of ADH

7) Blood vessels of the renal columns are called ______

interlobar

10) The glomerulus differs from other capillaries in the body in that it ________.

is drained by an efferent arteriole

23) Most electrolyte reabsorption by the renal tubules ________.

is hormonally controlled in distal tubule segments

13) The fatty tissue surrounding the kidneys is important because _______

it stabilizes the position of the kidneys by holding them in their normal position

Which of the choices below is the salt level-monitoring part of the nephron?

macula densa

Which cells of the kidney are chemoreceptors that respond to changes in solute content of the filtrate?

macula densa cells

The ________ mechanism is the general tendency of vascular smooth muscle to contract when stretched.

myogenic

The need to get up in the middle of the night to urinate is called ________.

nocturia