Renal physiology Flashcards
Two actions of ADH other than increasing water permeability in the collecting duct.
increase urea absorption in the collecting duct; increase NA/K2Cl activity in thick ascending limb
WHat is the mechanism stimulating renin release?
decrease in blood pressure in kidneys
What type of fluid disturbance is caused by drinking too much water (ex SIADH)? How does it effect osmolarity, Hct, and plasma protein concentration?
hyposmotic volume expansion
Increase ICF
Osmolarity: Decrease
Hct: NC
Plasma protein conc: Decrease
Class of drugs that can cause renal failure in high vasoconstrictive states due to inhibition of prostaglandin production?
NSAIDS. prostaglandins are keeping the afferent arterioles vasodilated to maintain GFR. Inhibition of prostaglandin production leads to acute renal failure.
What is the main source of anions in the ECF?
Chloride
Cells in this part of the nephron have well-developed apical brush border and extensive basolateral infoldings with a large number of mitochondrias.
proximal tubular cells
At what plasma glucose level does glucosuria begin?
200 mg/dL
What is the compensation for metabolic alkalosis?
increased CO2 by decreased respiration
What is the Henderson-Haselbach equation?
pH= pKa+Log (HCO3-)/(.03pCO2)
Angiotensin I is then cleaved by ___, primarily in the ___ to make ___?
angiotensin converting enzyme, lung capillaries, angiotensin II
How does nephrotic syndrome cause edema?
loss of proteins results in decreased oncotic pressure in the capillaries. Relative excess hydrostatic pressure then pushes water into ISF
ECF volume expansion____ (increases/decreases) reabsoprtion in proximal tubules.
decreases
Substances regulated by aldosterone in collecting tubules. (2)
Na+, K+
Which hormones are stimulated to be released by a decrease in blood volume?
ADH, aldosterone, angiotensin II (via renin)
What are the vasa recta of the kidney and what purpose do they serve?
they are branches of the peritublar capillaries that follow the loops of Henle and help with water conservation. Water and solutes excreted by the loop of Henle are absorbed here.
What percentage of HCO3-is reabsorbed?
over 90%
What percentage of the blood to the kidney goes to the cortex?
over 90%
Name four actions of angiotensin II.
- potent vasoconstriction
- release of aldosterone from adrenal cortex
- release of ADH from posterior pituitary
- stimulates hypothalamus to increase thirst
Name the hormone that inserts aquaporins in the principle cells of the late distal tubule and collecting ducts in response to water deprivation.
ADH
What does kallikrein do?
it activates bradykinin
What is the primary disturbance in metabolic alkalosis?
increased bicarbonate
What is the compensation for metabolic acidosis?
a drop in CO2 by hyperventilation
What type of fluid disturbance may be caused by dehydration, sweating, fever or diabetes insipidus? How does it effect osmolarity, Hct, and plasma protein concentration?
hyperosmotic volume contraction
reduce ICF
Osmolarity: increase
Hct: NC
Plasma protein conc: Increase
Class of drugs that inhibits production of angiotensin II?
ACE inhibitors
Endothelial cells of peritubular capillaries secrete which hormone in response to hypoxia?
erythropoietin
T/F: There is no active transport in thin loop of loops of Henle
true
High pH, high pCO2 (high HCO3-) causes which metabolic condition?
metabolic alkalosis
What are some actions of aldolsterone on distal tubules and collecting duct? (3)
- on principle cells:
- increases Na+ reabsorption
- increase K+ secretion - on intercalated cells
- increases H+ secretion
What is the primary disturbance in respiratory acidosis?
a build-up in CO2
How much of the tubular fluid is absorbed through the intercalated cells in the loop of Henle?
very little, there are no aquaporins here
What are some common causes of alkalosis?
hyperventilation, high altitude, pneumonia and pulmonary embolus (hypoxemia causes hyperventilation)
Where is glucose absorbed in the nephron?
proximal tubule (100%)
Of the 120ml per min filtered into the nephron, how much is returned to the plasma in the tubules?
119ml, meaning only about 1 ml per min of urine is produced by the kidney each minute
Compare the osmolarity in the different fluid compartments.
mostly the same between all compartments because most cells are very permeable to water.
Which juxtaglomerular apparatus cells are located in the walls of thick ascending LH and DST; wedged between the afferent and efferent arterioles. They can detect osmolarity and volume changes in the tubular fluid.
macula densa
Where is the juxtaglomerular apparatus located?
next to each glomerulus, it makes contact with the beginning of the distal tubule.
How does the kidney compensate for respiratory acidosis? (2)
increase in HCo3 absorption
Increase in H+ excretion
What are the seven physiological responses to high altitude?
- acute increase in ventilation
- chronic increase in ventilation
- increase in EPO leading to an increase in hematocrit and hemaglobin (chronic hypoxia)
- increase in 2,3-DPG,
- Cellular changes (increase in mitochondria)
- increase in excretion of bicarbonates to compensate for respiratory alkalosis, 7. Chronic hypoxic pumonary vasoconstriciton results in RVH
Substances reabsorbed in the early proximal tubule. (5)
all glucose and amino acids, most bicarbonate, sodium, and water
ECF volume contraction___ (increases/decreases) reabsorpiton in proximal tubules.
increases
Which cells secrete erytropoetitin?
juxtaglomerular cells
If a person presents with high plasma osmolarity with low plasma ADH what is the likely cause?
lack of ADH release cause by diabetes inipidus
Name three effects of PTH on the kidney
- increase Ca+2 reabsorption
- decrease phosphate reabsorption
- increase vitamin D production
How much of the filtrate is absorbed in the proximal tubule?
2/3
What is the function of renin?
cleaves angiotensinogen to angiotensin I
How much total body water in a 70kg individual?
42L
Low pH, low pCO2 (low HCO3-) causes which metabolic condition?
metabolic acidosis
What absorption/secretions occur at the proximal tubule? (5)
NaCl and water diffuse out of the tubule.
Na/K pumps pull Na back into the peritubular capillaries.
Amino acids and glucose are both contransported out with Na.
HCO3 active transport out
What are the effects of ADH (vasopressin) on the production of urine? (4)
- Increases apical membrane H2O permeability in late distal tubule and collecting duct
- Increases urea permeability for inner medullary collecting duct
- Stimulates NaCl absorption in TALH
- Increases blood flow to juxtamedullary glomeruli
High, pH, low pCO2 (low HCO3-) causes which metabolic condition?
acute respiratory alkalosis
What is the primary disturbance in respiratory alkalosis?
a drop in CO2, often due to hyperventilation
What is the function of secreted prostaglandins in the kidney?
vasodilation of the afferent arterioles to increase GFR
What hormone activates 1-alpha-hydroxylase?
PTH
What causes the production of ADH? (2)
- decrease ECF volume
2. Increased plasma K+ concentration
What is the effect of dding pure water to plasma? How does this water distribute to the ECF and ICF?
All fluid spaces will increase their volume in proportion to their original size (ECF will get 1/3 of water added and ICF gets 2/3)
What is the primary disturbance in metabolic acidosis?
a decrease in bicarbonate
Give the break down of the body weight for: total fluid, intracellular fluid, and extracellular fluid
60%=total fluid
40%=intracellular fluid
20%=extracellular fluid
What causes the macula densa to initiate an increase in blood pressure?
a decrease in sodium chloride levels.
The two determinants of filtration across the glomerular filtration barrier are ____ and ____.
size and charge
Which cells produce renin in the kidney?
cell in the jxta-glomerular apparatus
What stimulates water reabsorption in the principle cells of the late distal tubule?
vasopressin
Name three cell types in the late distal and collecting duct. What does each cell type transport?
- principle cells:
- Na+ reabsorption
- K+ secretion
- H2O reabsorption in the presence of ADH - Thype A intercalated cells
- apical H+ pump, K+ reabsorption during K+ depletion
- basalateral HCO3-/Cl-exchanger - Type B intercalated cells
- apical HCO3-/Cl-exchanger
- basalateral H+ pump
What are common causes of metabolic acidosis?
diabetic ketoacidosis (production of ketone acids), diarrhea (loss of GI bicarb), salisylate overdoes, acetazoleamide (diuretic) OD, lactic acidosis, renal failure (can excrete organic acids), ethylene glycol ingestion
Reabsorption of water is regulated by which hormone in the collecting tubules?
ADH
Name two stimuli for ADH secretion.
increased plasma osmolarity; decreased blood volume
Name the major segments of a nephron (5)
- renal corpuscle
- proximal tubule
- loop of Henle
- distal tubule
- collecting duct
Cells in this part of the nephron are flat with no membrane amplification and only a few mitochondria.
thin portiono floop of Henle
Name five conditions where the electrical charge barrier on the glomerulus is lost.
nephrotic syndrome, albuminauria, hypoproteinemia, generalized edema, hyperlipdemia
What are some common causes of respiratory acidosis?
COPD, airway obstruction, opiates and sedative, guillan-barr or ALS
What is the overall action of angiotensin II?
increase intravascular volume and blood pressure
In the kidneys, what substance is freely filtered and is neither reabsorbed nor secreted?
inulin
Which body compartment is considered the ‘sodium space”?
ECF
What is the compensation for respiratory alkalosis?
increased bicarb excretion from the kidney
Where in the kidney is Na+ reabsorbed? (3)
- 67% at proximal tubule
- 25% at thick ascending limb of loops of Henle
- 8% at distal tubule and collecting duct
Reabsorption of which ion is under the control of PTH in the early distal convoluted tubule?
Ca+2
If N+ levels are increased and there is volume expansion, which hormone is released and what is the result?
atrial natriuretic peptide is released causing decreased Na+ absorption in the distal tubule.
Name four causes of metabolic alkalosis.
vomiting, diuretic use, antacids, hyperaldosteronism
Describe three action of angiotensin II.
immediate vasoconstriction, followed by increases in ADH in the pituitary and aldosterone in the renal cortex.
What is the general formula for excretion in terms of amount filtered, amount reabsorbed and amount secreted?
The amount of material that is filtered-reabsorbed + secreted
What are some common causes of acidosis? (2)
vomiting, loop of thiazide diuretics (volume contraction)
Which hormone decreases sodium reabsorption?
ANP
Hormones that increase Na+ reabsorption are?
aldosterone (distal tubule); angiotensin II (proximal tubule)
Substance responsible for constricting efferent arteriole?
angiotensin II
What type of fluid disturbance can be caused by excess salt intake? How does it effect osmolarity, Hct and plasma protein concentration?
hyperosmotic volume expansion
reduce ICF
Osmolarity: increase
Hct: decrease
Plasma protein conc: decrease
Ammonia is secreted in the early proximal tubule, which acts as a buffer for ____.
H+
Where does HCO3- reabsorption occur?
proximal tubule
What is the enzyme responsible for converting 25-OH vitaminD to I, 25(OH)2?
1-alpha-hyroxylase
Where is Bowman’ capsule physically located in the kidney?
cortex
Which section of the nephron is impermeable to sodium?
thin descending loop of Henle
What are the two types of nephrons and what distinguishes them from each other?
- superficial nephrons-short loop of Henle, located upper/middle in cortex
- juxtamedullary nephrons-long loop of Henle, located in lower cortex and loop extends deep into medulla
Hyperkalemia stimulates the release of which hormone in order to increase K+ secretion from distal tubules?
aldosterone
Name three factors leading to renin secretion.
decreased renal blood pressure, decreased sodium in distal tubule, increased sympathetic tone
What accounts for most of the ICF anions?
fixed negative charges on proteins and nucleic acids
What comprises epithelial layer of the glomerulus?
podocyte foot processes
In cases like heart failure, which hormone is released from the atria that regulates the renin-angiotensin system.
ANP
Name the class of substances responsible for dilating afferent arteriole?
prostaglandins
What type of fluid disturbance is caused by adrenal insufficiency? How does it effect osmolarity, Hct, and plasma protein concentration?
hyposmotic volume contraction
Increase ICF
Osmolarity: decrease
Hct: increase
Plasma protein conc.: increase
How do you calculate anion gap?
Na-Cl-HCO3
Name four causes of acidosis.
acute lung disease, chronic lung disease, drugs (opioids, narcotics, sedatives), weakening of resp. muscles
Where is the proximal tubule physically located in the kidney?
medulla
What type of fluid disturbance is diarrhea? How does it effect osmolarity, Hct and plasma protein concentration?
osmolarity: NC
Hct: increase
Plasma protein conc: increase
Where is glucose absorbed in the nephron?
proximal tubule
Low pH, high pCO2 (high HCO3-) causes which metabolic condition?
chronic respiratory acidosis
