53 Urine concentration & Dilution Flashcards
Hypoxia induces production of this hormone in the kidneys. Induces RBC synthesis in the bone marrow
Erythropoietin
Promotes Ca++ reabsorption. When Ca++ is low, PTH is released, stimulating the conversion this hormone into its active form
Vitamin D (active form)
Vasodilator. Increases the GFR by dilating the afferent arterioles
Prostaglandins
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)
Renin
T/F. Water levels (in grams) are the major determinant of ECF volume
False. Sodium levels (in grams) are the major determinant of ECF volume
This system promotes sodium reabsorption (and water reabsorption) and regulates blood pressure
RAAS (renin angiotensin aldosterone system)
What is the major determinant of ECF osmolatiry?
Water
This hormone promotes water reabsorption (doesn’t promote Na+ reabsorption) and concentrates urine
ADH (vasopressin)
T/F. ECF sodium levels must be kept constant b/c Na+ is the primary determinant of ECF volume (i.e. blood pressure)
True
This hormone is responsible for acute excretion of sodium
Atrial natriuretic peptide (ANP)
This hormone is the only one involved in chronic sodium conservation (in the kidneys)
Aldosterone. However, angiotensin II, aldosterone, and the Sympathetic NS are involved in acute conservation
This hormone is responsible for chronic excretion of sodium by diluting the urine
Anti-diuretic hormone (ADH)
In the PT, what percentage of sodium is reabsorbed?
~67%
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
True. ~0.6 % of filtered Na+ is excreted
This system functions to promote sodium reabsorption. In addition, it stimulates K+ and H+ excretion
RAAS
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
True
This hormone preferentially constricts the efferent arterioles (increasing the FF), increases Na+ reabsorption, and promotes aldosterone secretion
Angiotensin II
Release of this hormone is stimulated by: angiotensin II, high K+, and ACTH
Aldosterone
Release of this hormone is inhibited by Atrial natriuretic factor (ANF) and high [Na+]
Aldosterone
This hormone functions to:
- Increase Na+ reabsorption (principal cells)
- Increase K+ secretion (principal cells)
- Increase H+ secretion (intercalated cells)
Aldosterone
This hormone is secreted by the cardia atria in response to increased blood volume
Atrial natriuretic peptide
This hormone inhibits Na+ reabsorption, renin release, and aldosterone formation (increasing GFR)
Atrial Natriuretic Peptide (ANP)
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
Sympathetic NS
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)
Insulin
What effect does hyperosmolarity of the ECF have on ICF K+ levels?
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
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
True
T/F. The beta receptors promote K+ expulsion, while the alpha receptors promote K+ entry
False. The beta receptors promote K+ entry, while alpha receptors promote K+ expulsion
These cells function in reabsorption of K+
Intercalated cells
What are the two major factors in renal handling of K+?
Dietary K+ intake and aldosterone (increases K+ secretion) levels
These cells are involved in K+ secretion (promoted by aldosterone)
Principal cells
___ is released as the result of direct stimulation of K+ on the adrenal glands (functions to increase K+ secretion)
Aldosterone
T/F. The TF/P for a freely filtered substance is >1 in the PT
False. The TF/P for a freely filtered substance is 1 in the PT
T/F. The sympathetic NS stimulates release of renin, which activates the RAAS
True
