4.4_2 Renal II Part II Flashcards
ECF Volume regulation is also known as…
Long term regulation of blood-pressure
Distribution of body water is between what three compartments?
1) Blood
2) Interstitial Fluid (IF)
3) Intracellular fluid or cytoplasm
Distribution of body water is determined by what?
Number of osmotically active particles in each
___ and ___ are the major “osmolyte” salts that draw water into compartments
Na+
Cl-
If Na+ is retained…
So is water
Changes to plasma volume drive changes to…
Interstitial fluid volume (since they are in equilibrium)
What changes the plasma volume?
Na+ content
Regulation of Na+ content is achieved through what two ways?
1) Atrial natriuretic peptide
2) Renin Angiotensin Aldosterone System
Each method of regulating Na+ content is ultimately influencing what?
Na+ reabsorption in distal convoluted tubule and collecting duct
Atrial Natriuretic Peptide responds to…
High blood pressure
High blood volume
Atrial Natriuretic Peptide leads to..
Increased salt emanation and hence increases water elimination (shuts down the recapturing of sodium)
Stimulus of ANP
Increased stretch of baroreceptors in atria
Control center of ANP
Atria release ANP into the blood
Net effect of ANP
Peripheral resistance decreases, blood volume decreases, decreasing blood pressure
RAAS
Renin-Angiotensin-Aldosterone-System
RAAS = Salt _____ = _____ plasma volume
Retention
Increased
What does RAAS begin with?
Renin
What is renin?
An enzyme produced by specialized smooth muscle cells within juxtaglomerular apparatus surrounding the afferent arterioles of the kidney
Why would renin be released from the juxtaglomerular apparatus?
Severe blood loss Low Blood pressure Low salt intake Low plasma & Filtrate sodium Stress, trauma, exercise
What is severe blood loss and low blood pressure sensed by in RAAS system?
Baroreceptors of the afferent arteriole
What is low salt intake and low plasma &filtrate sodium sensed by in the RAAS system?
Reduced delivery of Na+ to the macula densa cells (DCT)
What is increased stress, trauma and exercised sensed by i the RAAS system?
Increased sympathetic stimulation of the arterioles in the juxtaglomerular apparatus
Cells of the JGA
Granular cells
Macula densa
Granular cells
Specialized smooth muscle cells that produce renin in response to stimuli
Macula densa
Cells assess NaCl in DCT filtrate (If Na+ is low, it promotes renin secretion from the granular cells)
What does renin do? (cascade)
Activates Angiotensin (from liver) to Angiotensin I by taking off some amino acids
Is angiotensin I active?
No, it is inactive
What is ACE and what does it do?
Angiotensin converting enzyme
Converts Angiotensin I to Angiotensin II
Where is ACE located?
In the lungs
What are ACE inhibitors?
Very common medication for hypertension
Angiotensin II causes..
(a) A global vasoconstriction of arterioles
(b) Increases secretion of the adrenal cortical steroid hormone ALDOSTERONE
What does aldosterone do?
Increases the capacity of the distal tubule and collecting duct to reabsorb Na+
How does the distal tubule and collecting duct reabsorb Na+?
Via increased expression of transport proteins
Aldosterone: Na+ and H2O reabsorbed at the expense of….
K+ secretion
Receptor and control center for aldosterone secretion
Adrenal cortex
Kidneys regulate blood pH by altering plasma ____
HCO3-
Bicarbonate
Normally, is all HCO3- reabsorbed from the filtrate?
Yes
What cells express carbonic anhydrase to drive the CO2 + H2O to Bicarbonate reaction?
Type A and Type B Intercalated cells of the nephron PCT and collecting duct
Increase in [H+] in plasma (acidosis0 would lead to..
Type A cells move more H+ into filtrate in tubule lumen, increase HCO3- in the blood
Decrease in [H+] in plasma (alkalosis) would lead to…
Type B cells secrete less H+, excrete excess plasma HCO3- (into filtrate)
