Renal II Flashcards
(25 cards)
What is the juxtaglomerular apparatus composed of?
- Macula densa
- Granular cells (secrete renin)
- Extraglomerular mesangial cells (secrete erythropoietin)
Fxn of juxtaglomerular apparatus
Regulates:
- BP
- Blood cell production
- Rate at which kidneys filter fluid
Chemical transmitters
Have direct effects on VSM Ca2+ channels
Where does corticopapillary osmotic gradient take place?
Long loops of henle
What does the “single effect” result in?
- Increased osmolarity in interstitial fluid & descending limb
- Decreased osmolarity in ascending limb
What are the 3 steps to concentrate urine?
- Pump
- Equilibrate
- Shift
Tubular fluid
- Progressively concentrated as it flows down descending limb
- Progressively diluted as it flows up ascending limb
What kind of fluid leaves the loop of henle?
Dilute
Countercurrent
Flow in opposing directions through the 2 limbs
What is the essential component?
Active transport
Vasa recta as countercurrent exchangers
- In medulla
- Have hairpin loops
- Descending limb: NaCl & urea in & H2O out
- Ascending limb: NaCl & urea out & H2O in
- Passive process, protects ISF gradient
Fxn of vasa recta
- Deliver nutrients
- Remove excess Na+ & H2O
How are wide fluctuations in K+ of ECF prevented?
By shifts of K+ btwn ICF & ECF:
- Liver
- Skeletal muscle
- Adipose tissue
Hyperosmolarity
H2O flows from ICF to ECF
What does exercise cause?
- Shift of K+ out of cells
- Slight increase in blood K+
Acidosis vs alkalosis
Acidosis = K+ out of cells Alkalosis = K+ into cells
*Causes of K+ shift out of cells
Leads to hyperkalemia
- Insulin deficiency
- Beta2-Adrenergic antagonists
- Alpha-Adrenergic agonists
- Acidosis
- Hyper osmolarity
- Lysis
- Exercise
Causes of K+ shift into cells
Leads to hypokalemia
- Insulin
- Beta2-adrenergic agonists
- Alpha-adrenergic antagonists
- Alkalosis
- Hypo osmolarity
Where is K+ excretion & Ca2+ reabsorption regulated?
Distal nephron
What % of filtered K+ is reabsorbed in proximal tubule & loop of henle?
87%, regardless K+ status
Diuretics
- Increase flow rate
- Causes elimination of more K+ in urine –> hypokalemia
What predominates in the homeostatic response ?
Reabsorption
What promotes K+ secretion? How?
Aldosterone via stimulation of basolateral membrane Na, K, ATPase
Ca2+ balance depends on what?
- GI absorption
- Bone release & uptake (very dynamic!)
- Kidney excretion
