Renal Physiology: Guyton Chapter 29 - 32

Question 1

[27-minute video]: Guyton and Hall Medical Physiology (Chapter 29) - Urine Concentration and Dilution

Answer 1

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Question 2

[35-minute video]: Guyton and Hall Medical Physiology (Chapter 30) - Renal handling of K, Ca, P, Mg and ECF

Answer 2

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Question 3

[6-minute video]: Vasa Recta Counter Current Exchange

Answer 3

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Question 4

Define renal clearance.

Answer 4

This is the volume of plasma that is cleared of a substance per unit time through the kidney.

Question 5

Explain how diabetes insipidus causes increased urinary volume.

Answer 5

✔ Diabetes insipidus is characterized by a deficiency of antidiuretic hormone (ADH) or a failure of the kidneys to respond to ADH.
✔ ADH stimulates reabsorption of water, so when it is lacking or ineffective, the kidneys release large amounts of dilute urine.

Question 6

Explain how diabetes mellitus causes increased urinary volume.

Answer 6

In diabetes mellitus, high blood glucose levels exceed the kidney’s ability to reabsorb glucose. The excess glucose in the urine draws more water into the urine through osmosis, resulting in increased urinary volume.

Question 7

Explain how infusion of mannitol causes increased urinary volume.

Answer 7

✔ Mannitol is an osmotic diuretic.
✔ It is poorly reabsorbed in the renal tubules.
✔ Because of this, it remains in the tubular fluid, increasing its osmolarity and preventing water reabsorption.
✔ This leads to an increase in urine production and volume.

Question 8

Atrial natriuretic peptide decreases formation of all the following except:
(a) aldosterone
(b) angiotensin III
(c) vasopressin
(d) cyclic GMP
(e) renin

Answer 8

(d) cyclic GMP

Question 9

Urinary volume is increased by all the following except ________.
(a) diabetes insipidus
(b) increased renal arterial pressure
(c) sympathetic stimulation
(d) infusion of mannitol
(e) diabetes mellitus

Answer 9

(c) sympathetic stimulation

Question 10

If fluid is lost from the intravascular compartment ________.
(a) there is a gradual movement of fluid from other compartments as a compensation, which is usually complete
(b) there is limited compensation of movement of fluid from other compartments
(c) the volumes of the other compartments do not change
(d) the fluid moves from other compartments to the intravascular compartment within seconds
(e) none of the above

Answer 10

(a) there is a gradual movement of fluid from other compartments as a compensation, which is usually complete

Question 11

The volume of plasma needed each minute to supply a substance at the rate at which it is excreted in the urine is known as the ________.
(a) filtration rate of the substance
(b) extraction ratio of the substance
(c) diffusion constant of the substance
(d) clearance of the substance
(e) tubular mass of the substance

Answer 11

(d) clearance of the substance

Question 12

With respect to the counter current system
(a) the loops of Henle act as counter current exchangers
(b) solutes diffuse out of vessels conducting blood toward the cortex
(c) water diffuses out of ascending vessels
(d) water diffuses into the collecting ducts
(e) counter current exchange is passive and can operate even if counter current multiplication ceases

Answer 12

(e) counter current exchange is passive and can operate even if counter current multiplication ceases

Question 13

The vasa recta ________.
(a) are the straight portions of the proximal tubules found just proximal to the loops of Henle
(b) extend from the efferent arterioles of the superficial cortical nephrons
(c) are the microvilli found on the cells of the macula densa
(d) comprise the capillary network found in the medulla of the kidney
(e) are the small straight segments of afferent arterioles found directly next to the macula densa

Answer 13

(d) comprise the capillary network found in the medulla of the kidney