Renal part 2- Exam 3 Flashcards
What is the formula for urinary excretion?
Glomerular filtration - tubular reabsorption + tubular secretion
____ is the more important that secretion in determining the final urinary excretion rate.
Reabsorption
Glomerular filtration is relatively (selective/nonselective)
nonselective
Tubular reabsorption is (selective/nonselective)
highly selective
What three substances are highly reabsorbed?
Sodium
chloride
bicarb
What 2 things are poorly reabsorbed?
urea and creatinine and are excreted in large amounts
In order for reabsorption to occur, what must happen?
must be transported across the tubular epithelial into the renal interstitial fluid, then through the peritubular capillary membrane back to the blood
What are the two pathways tubular reabsorption can take?
transcellular route
paracellular route
How does the water and solutes get into the peritubular capillary?
by ultrafiltration (bulk flow)
What two forces mediate ultrafiltration?
hydrostatic and colloid osmotic forces
Somethings are pumped out of the lumen across the cell and into the peritubular capillary through ____
active transport using ATP
What is secondary active transport? Give an example
Glucose, if indirectly coupled to an energy source
Renal tubular cells are held together by ______
tight junctions
Name 4 kinds of kidney primary active transporters
Hydrogen ATPase
Hydrogen-potassium ATPase
Calcium ATPase
How many mv does the reabsorption of sodium ions across the proximal tubular membrane create?
-70mv charge
Secondary active transport of glucose and amino acids in the _____
proximal tubule
What are the 2 sodium glucose co transporters?
SGLT2 and SGL1
Why do you not see glucose or amino acids in your urine?
because they are reabsorbed via secondary active transport, all 100% of them
What drug class is Invokana? How does it work?
SGLT inhibitors
blocks the reabsorption of glucose into the blood resulting in increased levels of glucose in the urine
90% of the filtered glucose is reabsorbed by the ____ in the (early/late) proximal tubule
SGLT2
early
10% by the ____ in the (early/late) the proximal tubule
SGLT1
late
Why does the type I diabetic have glucose in the urine?
have a complete saturation and exceeded capacity of SGLT2 transporter, so glucose in the urine
What is counter transport?
energy liberated from the downhill movement of one of the substances (sodium ions) enables uphill movement of a second substance in the opposite direction (hydrogen ions)
What is counter transport mediated by?
specific protein in the brush border of the luminal membrane
SODIUM-HYDROGEN EXCHANGER (NHE)
What is the tubular load?
the amount of solute delivered to the tubule
what does the transport maximum limit?
rate at which the solute can be transported, activity reabsorbed or secreted
What is the threshold for glucose?
[plasma glucose] is 200 mg/dl – increases the filtered load to 250 mg/min,
When a small amount of glucose begins to appear in the urine
What is the overall glucose transport max
375 mg/min
What type of substances have a transport maximum?
substances that have a protein transporter
What types of substances do NOT have a transport maximum?
substances that are passively reabsorbed
substances that use an electrochemical gradient for diffusion
sodium
The rate of transport is determined by what three things?
-Electrochemical gradient for diffusion
-The permeability of the membrane for the substance
-The time that the fluid containing the substance remains within the tubule.
T/F: Sodium has a transport maximum
FALSE, because the ATPase pump activity is far greater than the actual rate of net sodium reabsorption
for sodium, the greater amount of sodium the ____ the reabsorption
greater
The slower the flow rate of tubular fluid, the _____ the % of sodium that can be reabsorbed
greater
Decreased macula densa sodium chloride causes _____ of afferent arterioles and _____ renin release
Dilation
Increased
What does the macula densa sense?
Sense a change in volume delivery to the distal tubule.
By sensing a reduction of sodium and chloride in the tubule
What a decrease in GFR cause?
an increase in sodium and chloride reabsorption
What end of the tubule is highly permeable to water? Due to ?
promixal tubule
tight junctions between the epithelial cells
water is (more/less) permeable in the loop of Henle and distal parts of the nephron
Less
______ can greatly increase water permeability in the distal and collecting tubules
Antidiuretic hormone
in the proximal tubular ____ of water and sodium are reabsorbed
65%
Proximal tubular reabsorption has _____ brush border for SA
extensive
proximal tubular reabsorption has (many/few) protein carriers
many
proximal tubule has (low/high) co transport and counter transport
high
Descending loop of Henle is (thick/thin)
thin
Descending loop of Henle is (highly/lowly) permeable to water
highly- 20% of filtered water
What is the main function of the descending loop of Henle?
Mainly allows simple diffusion of substances through its walls
Descending loop of Henle is (low/moderate/high) permeable to most solutes
moderately
The ascending LOH has two sections. Name them
Thin part and thick part
In the ascending LOH, the ___ section has LOWER reabsoptive capacity than _____
thin
thick
What is happening in the thick ascending section of LOH?
lots of metabolic activity- 25%
active reabsorption of sodium, chloride and potassium, calcium, bicarb and magnesium
The __ section of the ascending LOH has ???. What does it promote?
thick
sodium/potassium pump
Favorable gradient for moving of sodium from the tubular fluid into the cell.
In the thick ascending loop, movement of sodium across the luminal membrane is mediated by a ???
1-sodium,2-chloride,1-potassium co-transporter.
Uses the potential energy released by downhill diffusion of sodium into the cell to drive the reabsorption of potassium into the cell against a concentration gradient.
***Loop diuretics works on what part of the kidney? How does it work?
thick ascending LOH
blocks 1-sodium,2-chloride,1-potassium co-transporter which keeps the electrolytes in the filtrate, so more water stays in the tube and ends up in urine. Drys the patient out
Loop diuretics (increase/decrease) the ability of the kidneys to concentrate the urine
decrease
Memorize this chart
DO IT!!
The first portion of the distal tubule forms the ______
macula densa
The distal tubule, describe what is happening to water?
NOT permeable to water
lots of ions reabsorption
____ section dilutes the tubular fluid
thick section of the ascending LOH
the early distal tubule reabsorbs ____ of the filtered load of sodium-chloride
5%
How does the early distal tubule move sodium chloride?
through a sodium-chloride co-transporter that moves from the tubular lumen into the cell
_____ are widely used to treat disorders such as hypertension and heart failure. How do they work?
Thiazide diuretics
inhibit the sodium-chloride co-transporter
in the distal tubule
The late distal tubules and cortical collecting tubules are composed of what kind of cells
principal cells and intercalcated cells
What is the role of the principal cells?
Reabsorb sodium and water from the lumen and secret potassium ions into the lumen
How do potassium sparing diuretics work?
Compete with aldosterone for receptors sites in the principal cell
Name two potassium sparing diuretics
spironlactone and eplerenone
Name two sodium channel blockers
Amiloride
Triamterene (Dyrenium)
What is the role of intercalated cells?
Reabsorb potassium ions and secrete hydrogen ions into the lumen
Reabsorbs bicarbonate ions
Medullary collecting ducts reabsorb less than ____ of the filtered water and sodium
10%
What is the final site for processing the urine?
Medullary collecting duct
the _____ is extremely important role in determining the final urine output of water and solutes
Medullary collecting ducts
In the medullary collecting ducts, what is the permeability of water controlled by?
ADH levels
If the ADH level is high, water is _____. Urine volume _____
reabsorbed
decreases
Is the medullary collecting ducts permeable to urea?
yes, has special urea transporters
If more water gets reabsorbed than solute, what will the concentration do?
concentration rises to greater than 1
If the ratio becomes less than 1, what does this mean?
more solute than water has been reabsorbed
Glomerulotubular balance: when GFR increases, what happens to reabsorption
reabsorption increases
When GFR increases what does it prevent?
overload of the distal tubular segments
Aldosterone ____ sodium reabsorption and stimulates ____ secretion
increases
potassium
Where is the site of action for aldosterone?
principal cells of the cortical collecting tubule
aldosterone stimulate the ______ (pump) on what side of the cortical collecting tubule? What does it promote?
ATPase
basolateral
promotes potassium to be excrete and Na be reabsorbed
dehydration causes aldosterone to be (high/low)
high
What does the kidneys do with extra water?
pee it out
The urine becomes more (solute/dilute) as it passes along the tubule
dilute
everything get reabsorbed
The ____ loop is responsible for concentrating the urine
descending loop
____ loop is NOT permeable to water
thick segment of the ascending loop
Tubular fluid remains _____ in the proximal tubules
isosomotic
the fluid leaving the early distal tubular segment is _____. Does ADH have an effect?
hypo-osmotic
ADH does not have an effect
Water is continuously lost from the body by what four organ systems?
lungs
GI
Skin
Kidneys
Urine specific gravity tests what?
rapid estimate of urine solute concentration
If you are dehydrated, the urine specific gravity will increase/decrease?
increase
more solutes compared to water in the urine
concentrated urine will have a high/low ADH level
high
A hyperosmotic renal medulla interstitium will result in a (diluted/concentrated) urine
concentrated
add the chart with the the loop and what parts are permeable to what substances
What are the steps that cause hyperosmotic medullary
- assume loop is filled with fluid with a concentration of 300mOSM/L
- Ion pump of the thick ascending limb reduces the concentration inside the tubule and raises the interstitial concentration because the ions leave and water CANNOT follow
3.Descending limb of the loop and the interstitial fluid quickly reach equilibrium by osmosis of water out of the descending limb - Additional flow of fluid into the loop from the proximal tubule
- Additional ions are pumped into the interstitium with water remaining in the tubular fluid
- Steps repeated over and over
diagram of the steps of the hyperosmotic medullary
What is it called when the kidney can concentrate the urine
Counter current multiplier
What portion of the loop is critically dependent on ADH?
Cortical collecting tubule
In the cortical collecting tubule, in the absence of ADH the segment is (super permeable/ impermeable to water)
impermeable
When ADH is high in the distal tubule and collecting ducts, what happens?
cortical collecting tubule becomes highly permeable to water and the water leaves the tubules and the urines gets more concentrated (more water is retained by the body)
_____ accounts for 40% of the hyperosmotic renal medullary interstitium
urea
When ADH is high, what happens to urea?
large amounts of urea is REABSORBED
What does the recirculation of urea help with?
helps to trap the urea in the renal medulla and contributes to the hyperosmolarity of the renal medulla
The countercurrent exchange in the Vasa Recta leads to ?
preserves hyperosmolarity of the renal medulla
When the medullary blood flow is low, what 2 things happen?
minimizes solute loss from the medullary interstitium
the vasa recta serves as a countercurrent exchanger
What is happening in the descending loop of the vasa recta?
the plasma flowing down the descending limbs becomes more hyperosmotic because the diffusion of water out of the blood.
diffusion of solutes from the renal interstitial fluid into the blood
What is happening in the ascending limb of the vasa recta?
solutes diffuse back into the interstitial fluid and water diffuses back into the vasa recta
Diagram of the countercurrent exchange in the vasa recta
Know the flow chart of what happens when you are in a water deficit
_____ are proteins that up-regulate and form channels in medullary collecting ducts
aquaporins
Where does ADH comes from? What is other name for it?
posterior pituitary gland
vasopressin
What is the function of the loop of Henle?
to make sure the interstitium is concentrated
What is the function of the vasa recta?
to make sure the interstitium is salty aka not being diluted
Descending part of the loop is (permeable/impermeable) to water
very permeable, water travels very easily across
Thick ascending LOH is (permeable/impermeable) to water
impermeable to water
ions leave the loop and go into the interstitium
**What is the diluting segment?
the thick portion of the ascending LOH, ions leave aka the filtrate is being diluted
how are the ions transported across the membrane in the ascending LOH?
secondary messenger systems and ATPase pumps pump the ions out of the filtration
What is the transport max for glucose?
375
At 200 mg/dL of glucose present, what will you start to see?
glucose in the urine
Why would a diabetic be thirsty?
because the patient is dumping glucose into the urine and water follows the glucose aka dehydrating yourself
How does Invokana and similar type drugs work?
compete with and block the SGLT transport so that they becomes saturated much easier, so glucose is peed out
Chronic kidney disease is measured on a _____ scale
1-5 scale
______ renal failure results from decreased blood supply to the kidneys
Prerenal acute renal failure
________ results from any abnormality origination from outside the kidneys
prerenal acutre renal failure
______ is caused by any abnormalities within the kidney itself
intrarenal acute renal failure
______ occurs when their is an obstruction of the urinary collecting system
postrenal acute renal failure
Kidney stones are an example of what kind of acute kidney failure?
Postrenal acute kidney failure
What are some causes of prerenal acute renal failure?
hemorrhage, diarrhea/vomiting, burns, MI, valvular damage, anaphylactic shock, anesthesia, sepsis, severe infections, primary renal hemodynamic abnormalities, renal artery stenosis, embolism and thrombosis of renal artery/vein
T/F: Kidneys can not tolerate a lack of blood flow
FALSE, kidneys CAN tolerate a lack of blood flow to a certain degree, as long as blood flow does not fall below 25% the kidney is fine
What are the three categories within intrarenal acute renal failure?
conditions that damage: 1. glomerular capillaries or other small renal vessels
2. renal tubular epithelium
3. renal interstitium
What are some common causes of intrarenal acute renal failure?
vasculitis, cholesterol emboli, malignant hypertension, acute glomerulonephritis, acute tubular necrosis due to ischemia or toxins, acute pyelonephritis, acute allergic interstitial nephritis
What is glomerulonephritis?
abnormal immune reaction that damages the glomeruli, usually caused by a group A beta streptococci bacterial infection
Albumin in your urine is a sign of?
Glomerulonephritis
basement membrane is being destroyed
crush injury can lead to ?
rhabdomyalsis, when the products released from crush injuries can cause severe kidney problems
____ an irreversible decrease in the number of the functional nephrons
chronic renal failure
What are some causes of chronic renal failure?
DM, obesity, HTN, renal vascular disorder, immunologic disorders, infections, primary tubular disorders, urinary tract obstruction
_____ replacement of normal tissue with connective tissue
sclerosis
What are some common causes of End Stage Renal Disease
DM-45% - Obesity
HTN- 27%- Obesity
Glomerulonephritis- 8%
Polysystic kidney disease- 2%
Other -18%
_____ damage to the interstitium by bacterial infections
pyelonephritis
______ excretion of proteins in the urine because of increased glomerular permeability
nephrotic syndrome
What are some common causes of nephrotic syndome?
Chronic glomerulonephritis
amyloidosis
minimal charge nephrotic syndrome (loss of negative charges)
