E1- Random Flashcards
What type of cells secrete renin?
Granular/Juxtaglomerular cells
What type of cells contract in response to AT II?
Mesangial cells
What are the two main barrier to proteins?
Basal lamina and filtration slits
What is the effect of NSAIDs?
Inhibit synthesis of prostaglandins so there is no vasodilation to oppose alpha 1 (loss of protective affect on RBF)
What 5 types of transports occur in the PT?
Primary active Na+, K+ pump Secondary active Na+, glucose, AA symport Tertiary active alpha-KG, PAH OAT Na+, H+ antiport Cl- paracellular transport
What hormone increases the activity of the Na+, H+ transporter?
AT II
In what part of the nephron does Mannitol work? (osmotic diuretic)
Proximal tubule
How does Mannitol work? (osmotic diuretic)
Blocks the reabsorption of H20, trapping it in the nephron lumen to then be excreted with Na+
What is the thin descending limb permeable to?
H20
What is the thick ascending limb permeable to?
NaCl
What is pattern of flow in the descending vasa recta?
H2O flows out
NaCl flows in
What is pattern of flow in the ascending vasa recta?
H2O flows in
NaCl flows out
What types of transports are in the LOH? (3)
Primary active Na+, K+ pump
NKCC2 transporter
Back flow of K+ –> paracellular Ca2+ reabsorption
In what part of the nephron does Furosemide work? (loop diuretic)
LOH
How does Furosemide work? (loop diuretic)
Inhibits the NKCC2 transporter and Ca2+ reabsorption
What hormone increases the activity of the NKCC2 transporter?
ADH/vasopressin
Is the early distal tubule permeable to H2O?
No
What determines the permeability of the late distal tubule and collecting duct to H2O?
ADH/vasopressin
What portion of the nephron is considered the diluting segment?
Early distal tubule
What type of transporter is in the early distal tubule?
NCC symport (Na+, Cl-)
In what part of the nephron does Chlorothiazide work? (thiazide diuretic)
Early distal tubule
How does Chlorothiazide work? (thiazide diuretic)
Inhibits the NCC symporter
Increases Calcium reabsorption in the distal tubule
What types of transporter are in the late distal tubule? (5)
Primary active Na+, K+ pump ENaC antiport H+ uniport H+, K+ pump Ca2+, Na+ pump
What hormone increases the activity of the Na+, K+ pump?
Aldosterone
What hormone increases the activity of the ENaC transporter?
Aldosterone
What hormone increases the activity of the H+ uniport?
Aldosterone
In what part of the nephron do Amiloride and Spironolactone work? (K+-sparing diuretics)
Collecting ducts
How do Amiloride and Spironolactone work? (K+-sparing diuretics)
Amiloride- Inhibits the ENaC antiport
Spiromolactone- Inhibits aldosterone
What part of the tubule adjusts the final concentration of urine?
Collecting duct
What porin inserts into the nephron cell when ADH levels are high to allow for the passage of H2O?
AQP2
What porins are always present that allow water to be reabsorbed?
AQP3
AQP4
What is the driving force for filtration?
P(GC)
If total urine flow is greater than 1100, is the subject in a positive or negative water balance?
negative
If total urine flow is less than 1100, is the subject in a positive or negative water balance?
positive
How are nephrons arranged?
In parallel
What two capillary beds are arranged in parallel?
Glomerular
Peritubular (cortical, vasa recta)
What autoregulation mechanism responds to changes in BP?
Myogenic
What autoregulation mechanism responds to changes in salt load?
Tubuloglomerular feedback
What are the characteristics of the perfect GFR marker>
Freely filtered, but neither reabsorbed nor secreted
What two things can be used to measure GFR?
Inulin clearance and creatine clearance
What can be used to measure RPF?
PAH
If the clearance of a substance is greater than the clearance of creatine, thus greater than GFR, was the substance secreted or reabsorbed?
Secreted
If the clearance of a substance is less than the clearance of creatine, thus less than GFR, was the substance secreted or reabsorbed?
Reabsorbed
If the clearance ratio of a substance to the clearance of inulin is zero, then what must also be true?
The substance must also be a GFR marker
If the clearance ratio of a substance to the clearance of inulin is less than 1.0, then what must also be true?
The substance is not filtered, or is filtered and reabsorbed
If the clearance ratio of a substance to the clearance of inulin is more than 1.0, then what must also be true?
The substance is filtered and secreted
What does it mean if the transport rate is positive?
Some material was removed from the filtrate by reabsorption
What does it mean if the transport rate is negative?
Some material was added to the filtrate by secretion
What does it mean if the tubular fluid to plasma ratio equals zero?
The substance has been exactly proportional to the reabsorption of water
What does it mean if the tubular fluid to plasma ratio is less than 1?
The reabsorption of the substance has occurred to a greater extent than water
What does it mean if the tubular fluid to plasma ratio is greater than 1?
The reabsorption of the substance has occurred to a lesser extent than water OR there has been a net secretion of the substance
If you increase GFR, will the /Tm be reached at higher or lower plasma concentrations?
Lower
What can cause hyperosmotic volume contraction?
Very low levels of ADH
Ineffective ADH
(dehydration, DM insipidus)
Is plasma osmolality high/low in hyperosmotic volume contraction?
Is urine osmolality high/low in hyperosmotic volume contraction?
Plasma = high Urine = low
What is the cause of low ADH in neurogenic diabetes insipidus?
Hypothalamic-pituitary injury
will respond to exogenous ADH agonist- desmopressin
What is the cause of low ADH in nephrogenic diabetes insipidus?
Renal origin, kidney is unable to respond to ADH or desmopressin
Plasma ADH is high since Hypothalamic-pituitary are functioning normally
What can cause hyposmotic volume expansion?
SIADH
Acute water load
What electrolyte imbalance is seen with SIADH?
Hyponatremia (euvolemia)
Is K+ higher inside/outside the cell?
Is Na+ higher inside/outside the cell?
K+ = inside Na+ = outside
Alpha1 activation has what effect on K+?
Shift of K+ out of cells
Hyperkalemia
Beta2 activation has what effect on K+?
Shift of K+ into cells
Hypokalemia
Insulin activation has what effect on K+?
Dietary shift of K+ into cells after a meal
Hypokalemia
Aldosterone activation has what effect on K+?
Shift of K+ into tubule cells for excretion
Hypokalemia
Besides alpha1 activation, what else can cause a K+ shift out of cells?
Hyperosmolarity and exercise
What is is effect of a hyperkalemic state on pH?
Acidosis
Hyperkalemic state, K+ moves into the cells, this stimulates the movement of H+ out of the cells
What is is effect of a hypokalemic state on pH?
Alkalosis
Hypokalemic state, K+ moves into the cells, this stimulates the movement of H+ out of the cells
What is an example of a volatile acid?
Respiratory CO2
What is the fist line of defense against pH change?
Buffers
What determines the effectiveness of a buffer?
Concentration
pK (most effective within +/- one unit
What is the most important buffering system in the ECF.
Bicarbonate
What is normal ratio of HCO3- to dissolved CO2?
20:1
What causes metabolic disturbances?
Changes in HCO3-
What causes respiratory disturbances?
Changes in CO2 (must be compensated for by kidneys)
What are causes of Metabolic acidosis?
Ingestion of acid Formation of non-volatile acids (lactic acids) Diabetic ketoacidosis Loss of HCO3- (diarrhea) Renal HCO3- recovery reduced Excretion of NH4+ reduced
What are causes of Metabolic alkalosis?
Antacid abuse
ECF volume contraction (vomiting, diuretics)
Hyperaldosteronism
What can cause of Respiratory alkalosis?
Hyperventilation
- high altitude
- anxiety
- hypoxemia
What can cause of Respiratory acidosis?
COPD
Asthma
Airway obstruction
What is the Mass Action Rule?
Every 10 increase in CO2 results in a 1 increase in HCO3-
Every 10 decrease in CO2 results in a 2 decrease in HCO3-
What parts of the nephron do not change transport on the face of increased or decreased total body K+?
PT and LOH
Why is metabolic alkalosis maintained even when vomiting has stopped?
ECF volume contraction increases H+ loss via RAAS
critical factor is elevated aldosterone
What is the treatment of metabolic alkalosis?
Saline
Corrects fluid volume deficit and then adjusts RAAS, leading to the excretion of HCO3-
Why will saline not work to treat metabolic alkalosis caused by aldosterone excess? (Conn syndrome)
What is the appropriate treatment?
ECF volume is already expanded
Remove tumor or aldosterone antagonist- Spirolactone
What type of acidoses have a normal anion gap?
Simple HCO3- loss: Diarrhea or Renal Tubular Acidosis
Cl- increases to meet the drop in HCO3-
What type of acidoses have an increased anion gap?
Excess of non-volatile acids
(fixed acids liberate H+ which is buffered by HCO3- w/o changing the Cl- levels)
Lactic acidosis Ketoacidosis Renal failure- phosphoric sulphuric Salicylate poisoning- aspirin Ethylene glycol poisoning Methanol poisoning
What type of RTA is due to impaired H+ secretion by H+-ATPase in the distal nephron?
Type 1 (distal)
What are the characteristics of Type I (distal) RTA?
Hyperkalemia/Hypokalemia
Normal anion gap/Increased anion gap
Hypokalemia
Normal anion gap
What type of RTA is due to a defect in the Na+-H+ exchanger in the proximal tubule, leading to the imparement of H+ secretion and HCO3- reabsorption?
Type II (proximal)
What are the characteristics of Type II (proximal) RTA?
Gain or loss of HCO3-
Normal anion gap/Increased anion gap
Loss of HCO3-
Normal anion gap
(in severe cases may also lead to hypokalemia)
What type of RTA is due to a defect in urinary acidification due to inhibition of renal glutaminase, which impairs formation of NH4+?
Type IV
What are the characteristics of Type IV RTA?
Hyperkalemia/Hypokalemia
Gain or loss of HCO3-
Normal anion gap/Increased anion gap
Hyperkalemia
Impaired HCO3- generation
Normal anion gap
What RTA is associated with a aldosterone deficiency?
Type IV
How does diabetic ketoacidosis cause volume depletion?
Ketoacids acidify blood, deplete HCO3-
Plasma glucose increases
Glucose acts as an osmotic diuretic and increases urine flow
Would you expect to see hyperkalemia or hypokalemia in a diabetic ketacidosis pt?
Hyperkalemia
What hormone will be elevated in a pt with diabetic ketacidosis?
What hormone will be decreased?
Elevated plasma glucose makes the blood hyerposmotic leading to increased ADH
ANP
Although vomiting can initiate metabolic alkalosis, what can maintain it?
Volume contraction and hypokalemia
Volume contraction stimulates aldosterone which increases alkalosis and K+ loss