Ch. 26 Mastering A&P Part 2 Quiz

Questions and Answers

Which of the following statements about aldosterone is NOT correct?

Aldosterone promotes potassium excretion.

Aldosterone increases sodium reabsorption by increasing the number of Na+-K+ ATPase pumps in the luminal membrane of the proximal tubule.

Aldosterone helps regulate blood pressure.

Aldosterone decreases sodium reabsorption. (correct)

ADH (antidiuretic hormone) is released by the posterior pituitary gland.

True

What is the osmolarity of the filtrate at the end of the proximal tubule?

isotonic - 300 mOsm

In overhydration, what would be the levels of ADH and the osmolarity of the urine?

ADH - low; 100 mOsm (urine) Signup and view all the answers

In severe dehydration or blood loss, what would be the levels of ADH and the urine flow rate?

ADH - high; low urine flow rate (0.25 ml/min) Signup and view all the answers

Most solutes that are reabsorbed in the proximal convoluted tubule use which pathway?

transcellular Signup and view all the answers

During reabsorption of water in the proximal convoluted tubule, what causes water to osmose from the lumen into the interstitial space?

an increase in the osmolarity of the interstitium Signup and view all the answers

The decreased intracellular concentration of sodium in tubular cells during active transport is caused by which mechanism?

the sodium-potassium ATPase pump in the basolateral membrane Signup and view all the answers

The active transport of which ion out of proximal convoluted tubule cells causes the reabsorption of both water and solutes?

sodium Signup and view all the answers

Which transporters in the luminal membrane result in secretion?

Na+-H+ countertransport Signup and view all the answers

What is the limiting factor for the reabsorption of most actively transported solutes in the proximal tubule?

number of transport carriers in the luminal membrane Signup and view all the answers

What triggers the movement of water out of the descending limb?

Ions are transported out of the ascending limb, and the resulting concentration gradient in the peritubular fluid pulls water out of the descending limb. Signup and view all the answers

What would be the effect of blocking the hormone that works at the points indicated by the red arrows?

Increased production of dilute urine Signup and view all the answers

Which hormones cause the kidney to increase the body's content of sodium?

aldosterone Signup and view all the answers

Antidiuretic hormone (ADH) causes __________.

a decrease in urine volume but an increase in solute concentration Signup and view all the answers

The ability to form concentrated urine depends on the functions of?

the loop of Henle and the collecting duct Signup and view all the answers

The mechanism for producing concentrated urine involves which of the following?

a high concentration of NaCl in the interstitial fluid that surrounds the collecting ducts Signup and view all the answers

Antidiuretic hormone increases the permeability of the collecting ducts to water.

True Signup and view all the answers

A drug that inhibits angiotensin converting enzyme (ACE) may lead to which of the following?

decreased sodium reabsorption Signup and view all the answers

Which substances are not normally found in the filtrate?

protein Signup and view all the answers

Filtrate in the proximal convoluted tubule normally contains:

All of the answers are correct Signup and view all the answers

When the level of ADH decreases, what happens to the osmolarity of the urine?

the osmolarity of the urine decreases Signup and view all the answers

Which area is sensitive to the hormone ADH?

5 and 6 Signup and view all the answers

Where does most nutrient reabsorption occur?

3 Signup and view all the answers

Which area is sensitive to aldosterone?

5 Signup and view all the answers

The ureters extend from the __________.

renal pelvis to the urinary bladder Signup and view all the answers

Study Notes

Hormones and Regulation

Aldosterone increases sodium reabsorption by raising Na+-K+ ATPase pumps in the proximal tubule.
Antidiuretic hormone (ADH) is released from the posterior pituitary gland and acts on the kidneys.
Aldosterone causes the kidneys to increase sodium content in the body.
ADH decreases urine volume while increasing the concentration of solutes in the urine.

Urine Concentration and Filtration

The osmolarity of the filtrate at the end of the proximal tubule is isotonic at 300 mOsm.
Overhydration results in low ADH levels and urine osmolarity of 100 mOsm, leading to dilute urine.
Severe dehydration produces high ADH levels and a low urine flow rate of 0.25 ml/min.
The ability to form concentrated urine depends on the loop of Henle and the collecting duct's function.

Transport Mechanisms

Most solutes in the proximal convoluted tubule are reabsorbed via transcellular pathways.
Water reabsorption in the proximal convoluted tubule occurs due to increased osmolarity in the interstitial fluid.
The active transport of sodium out of proximal tubular cells aids solute and water reabsorption, with sodium-potassium ATPase responsible for maintaining low intracellular sodium.
Na+-H+ countertransport in the luminal membrane leads to the secretion of hydrogen ions.

Limitations and Effects

The limiting factor for the reabsorption of actively transported solutes is the number of transport carriers in the luminal membrane.
Inhibition of hormones acting at specific points in tubule function can lead to increased dilute urine production.
Blocking ADH results in decreased urine osmolarity as water reabsorption is lessened.

Filtrate Composition

Normal filtrate in the proximal convoluted tubule contains nutrients, urea, hydrogen ions, and water.
Proteins are not normally present in the filtrate.

Drug Effects

Inhibitors of angiotensin converting enzyme (ACE) can lead to less aldosterone secretion, increased sodium loss through urine, and reduced blood pressure.

Sensitivity and Reabsorption Sites

Areas sensitive to ADH are located in specified parts of the nephron.
The primary site for nutrient reabsorption is located in the proximal convoluted tubule.
The area sensitive to aldosterone is also specific to certain nephron segments.

Ureter Facts

The ureters transport urine from the renal pelvis to the urinary bladder.

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Description

Test your knowledge on Chapter 26 of Mastering Anatomy and Physiology with this quiz. The questions focus on key concepts such as aldosterone, ADH, and osmolarity. Perfect for students preparing for exams in anatomy and physiology.