53 Urine concentration & Dilution

Question 1

Hypoxia induces production of this hormone in the kidneys. Induces RBC synthesis in the bone marrow

Answer 1

Erythropoietin

Question 2

Promotes Ca++ reabsorption. When Ca++ is low, PTH is released, stimulating the conversion this hormone into its active form

Answer 2

Vitamin D (active form)

Question 3

Vasodilator. Increases the GFR by dilating the afferent arterioles

Answer 3

Prostaglandins

Question 4

The kidney senses how much Na+ is being delivered to the kidney and secretes this hormone in response to this. The juxtaglomerular cells also secrete this hormone secondary to decrease in GFR (decrease in renal arterial pressure)

Answer 4

Renin

Question 5

T/F. Water levels (in grams) are the major determinant of ECF volume

Answer 5

False. Sodium levels (in grams) are the major determinant of ECF volume

Question 6

This system promotes sodium reabsorption (and water reabsorption) and regulates blood pressure

Answer 6

RAAS (renin angiotensin aldosterone system)

Question 7

What is the major determinant of ECF osmolatiry?

Answer 7

Water

Question 8

This hormone promotes water reabsorption (doesn’t promote Na+ reabsorption) and concentrates urine

Answer 8

ADH (vasopressin)

Question 9

T/F. ECF sodium levels must be kept constant b/c Na+ is the primary determinant of ECF volume (i.e. blood pressure)

Answer 9

True

Question 10

This hormone is responsible for acute excretion of sodium

Answer 10

Atrial natriuretic peptide (ANP)

Question 11

This hormone is the only one involved in chronic sodium conservation (in the kidneys)

Answer 11

Aldosterone. However, angiotensin II, aldosterone, and the Sympathetic NS are involved in acute conservation

Question 12

This hormone is responsible for chronic excretion of sodium by diluting the urine

Answer 12

Anti-diuretic hormone (ADH)

Question 13

In the PT, what percentage of sodium is reabsorbed?

Answer 13

~67%

Question 14

T/F. 67% of sodium is reabsorbed in the PT. 25% in the ascending thick limb of the loop of henle, and 5-7% in the DT. 2-3% in collecting ducts

Answer 14

True. ~0.6 % of filtered Na+ is excreted

Question 15

This system functions to promote sodium reabsorption. In addition, it stimulates K+ and H+ excretion

Answer 15

RAAS

Question 16

T/F. Low blood volume, low renal blood flow, low sodium delivery to the distal tubule, and increased sympathetic innervation all lead to release of renin from the kidneys and activation of the RAAS

Answer 16

True

Question 17

This hormone preferentially constricts the efferent arterioles (increasing the FF), increases Na+ reabsorption, and promotes aldosterone secretion

Answer 17

Angiotensin II

Question 18

Release of this hormone is stimulated by: angiotensin II, high K+, and ACTH

Answer 18

Aldosterone

Question 19

Release of this hormone is inhibited by Atrial natriuretic factor (ANF) and high [Na+]

Answer 19

Aldosterone

Question 20

This hormone functions to:

• Increase Na+ reabsorption (principal cells)
• Increase K+ secretion (principal cells)
• Increase H+ secretion (intercalated cells)

Answer 20

Aldosterone

Question 21

This hormone is secreted by the cardia atria in response to increased blood volume

Answer 21

Atrial natriuretic peptide

Question 22

This hormone inhibits Na+ reabsorption, renin release, and aldosterone formation (increasing GFR)

Answer 22

Atrial Natriuretic Peptide (ANP)

Question 23

Activates the alpha-1 (PT) and beta-1 receptors (juxtaglomerular cells)

Stimulates Na+ reabsorption in the PT and stimulates renin release (activating RAAS)

Also decreases GFR and renal blood flow

Answer 23

Sympathetic NS

Question 24

This hormone promotes an increase in ICF potassium by increasing transport of K+ into the cells (this occurs by stimulating the activity of Na/K ATPase)

Answer 24

Insulin

Question 25

What effect does hyperosmolarity of the ECF have on ICF K+ levels?

Answer 25

ICF K+ levels decrease b/c high ECF osmolarity causes water to diffuse from the cell. ICF K+ concentration increases, causing K+ to leave via K+ leak channels

Question 26

T/F. The H+/K+ antiporter functions such that if there is a high H+ concentration on one side of the cell membrane, the K+ concentration on that side is low

Answer 26

True

Question 27

T/F. The beta receptors promote K+ expulsion, while the alpha receptors promote K+ entry

Answer 27

False. The beta receptors promote K+ entry, while alpha receptors promote K+ expulsion

Question 28

These cells function in reabsorption of K+

Answer 28

Intercalated cells

Question 29

What are the two major factors in renal handling of K+?

Answer 29

Dietary K+ intake and aldosterone (increases K+ secretion) levels

Question 30

These cells are involved in K+ secretion (promoted by aldosterone)

Answer 30

Principal cells

Question 31

___ is released as the result of direct stimulation of K+ on the adrenal glands (functions to increase K+ secretion)

Answer 31

Aldosterone

Question 32

T/F. The TF/P for a freely filtered substance is >1 in the PT

Answer 32

False. The TF/P for a freely filtered substance is 1 in the PT

Question 33

T/F. The sympathetic NS stimulates release of renin, which activates the RAAS

Answer 33

True