Renal Part II Flashcards
Changes in what ion correspond to extra cellular volume changes?
Na+
Low Na+ indicates what about plasma volume?
Low plasma volume
How does the cardiac system compensate for decreased Na+?
Decreased firing of baroreceptors and activation of sympathetic nervous system
Decreased plasma volume and venous return
Decreased Na+
How do the kidneys compensate for decreased Na+?
Constricting afferent arterioles, decreasing Na+ and H2O excretion
What does aldosterone do to the distal convoluted tubule and cortical collecting duct?
Increased Na+ reabsorption
Where does aldosterone act?
Distal tubule and cortical collecting duct
How does aldosterone increase Na+ reabsorption?
Increased synthesis of Na/K pumps
What is the main goal of RAAS?
Raise blood pressure
What does RAAS stand for?
Renin-Angiotensin-Aldosterone System
Where does renin come from?
Made by the JG cells in the kidney
What is the rate limiting step of RAAS?
Renin production
What does renin do?
Catalyzes angiotensinogen to angiotensin i
What catalyzes angiotensin i to angiotensin ii?
ACE
What does ACE stand for?
Angiotensin converting enzyme
What produces ACE?
Capillary endothelium
What does angiotensin ii promote?
Increased aldosterone secretion and systemic vasoconstriction of arteries
Which member of the RAAS is produced in excess?
Angiosinogen
How do the renal sympathetic nerves stimulate renin production?
they directly innervate the JG cells, increased sympathetic activity —> increased activity of JG cells
Which cells are referred to as the intrarenal barorecptors?
JG cells
What do JG cells respond to?
Arteriole stretching - less stretched afferent arteriole = more renin secretion
What is the purpose of the macula densa cells?
Sense Na+ content in tubular fluid and communicate with JG cells
What does the atrial natriuretic peptide (ANP) do?
Decreases blood pressure by increasing Na+ secretion
How does ANP decrease blood pressure?
Inhibits Na+ reabsorption and increases GFR
What stimulates ANP?
Atrial distension from increased plasma volume
What step of RAAS do ACE inhibitors (such as lisinopril) act on?
angiotensin i doesn’t get converted to angiotensin ii
What step of RAAS do angiotensin i receptor blockers act on? (ex: losartan)
doesn’t allow angiotensin i to convert to angiotensin ii
Which medications are an example of an aldosterone receptor blocker?
epleronone and spironolactone
What does furasamide (Lasix) do?
Inhibits the N/KCC transporter in the loop of Henle, decreases blood pressure (loop diuretic)
What happens when the N/KCC transporter is blocked?
Ions can’t get across, the medullary interstitial fluid is blocked and water can’t get properly reabsorbed
Where are osmoreceptors located?
hypothalamus
What stimulates a decrease in osmoreceptor firing?
Increased H2O concentration in body (decreased osmolarity)
How do osmoreceptors stimulate decreased ADH secretion?
decreased firing
What does hyperkalemia promote?
Aldosterone release
How does aldosterone regulate potassium?
Increased aldosterone results in increased potassium secretion and na+ reabsorption
What happens to aldosterone during hypokalemia?
Decreased activity
HCO3- reabsorption is paired with what?
H+ secretion
What is the difference between metabolic and respiratory acidosis?
Metabolic is a decrease in blood pH, respiratory is an increase in CO2
What causes metabolic acidosis?
Untreated diabetes or excess lactic acid
How is metabolic acidosis compensated for?
Hyperventilation, increased renal secretion and excretion of H+, HCO3- reabsorption
How is metabolic alkalosis caused?
Persistent vomiting - note that this is rare
How is metabolic alkalosis compensated for?
Hypoventilation, increased renal secretion and excretion of HCO3-, decreased H+ secretion
How is respiratory acidosis caused?
COPD, sleep apnea, airflow obstruction
What compensates for respiratory acidosis
Increased renal H+ secretion and excretion, increased HCO3- reabsorption
When would respiratory alkalosis be seen?
During a panic attack or when hyperventilating
How is respiratory alkalosis compensated for?
Increased renal secretion and excretion of HCO3-, decreased H+ secretion
