Human Bio_Renal
______ of potassium is regulated by aldosterone in the ________. ________ is reabsorbed in the ascending loop of Henle by co-transport with Na+ and Cl-
10% of potassium is regulated by aldosterone in the DCT and collecting tubule. 20% is reabsorbed in the ascending loop of Henle by co-transport with Na+ and Cl-. This is of the ECF portion of K+ or 2% of total K+
filtered fraction = GFR/RPF - what are the actual numbers?
125 ml/min / 625 ml/min which equals 20%
what are the two mechanisms of K+ homeostasis? what percentage of K+ may be regulated in this way what hormones promote uptake of K+ into cells after rise in plasma
2% regulated by this represents the amount found in ECF: immediate regulation of K+ in ECF (hormones such as insulin, and epinephrine and cellular buffering) long-term regulation of renal excretion to match dietary intake thru aldosterone all three - insulin, epinephrine and aldosterone (renal regulation) promote uptake of K+
this bicarbonate/carbon dioxide ratio must be maintained in the bicarbonate buffer system what pH does this result in? what pK is that?
20/1 pH=6.1 + log 20/1 =7.4 pK = 6.1
what is the minimum amount of urine produced and its osmolarity?
500 ml/day with 600 mOsm eliminated per day
one of six signs of chronic kidney disease is GFR less than
60 mL/min
GANONG Question: A 53-year-old man comes to the clinic to participate in a clinical trial to evaluate a new epilepsy drug. Prior to the study laboratory work is done and a 24-h urine collection is made. The man's serum creatinine is 2.3 mg/dL, urine creatinine is 89.2 mg/dL, and his urine output volume per day is 2250 mL/day. What is his approximate GFR?
60 mL/min U/P × UV: ((89.2 mg/dL/2.3 mg/dL) × (2250 mL/day))/1440 min/day
what percentage of plasma enters and leaves through the efferent arteriole without being filtered
80% GFR only reflects 20% of plasma that has been filtered
where is water reabsorbed, what percentage and are there special conditions
80% of water is reabsorbed in an uncontrolled manner; 65% - reabsorbed in proximal tubule and 15% - reabsorbed in loop of Henle the other 20% is reabsorbed under control of vasopressin (ADH) which binds to the basolateral membrane of a principal cell in the distal or collecting tubule and is NOT linked to solute reabsorption
kidneys autoregulate GFR within what MAP range
80-180 mmHg
normal urine pH is 6-7.4 but may range from 4.5-8.0. The extremes may reflect what
< may indicate fever, acidosis and > may reflect UTI, kidney stones
what concentration of K+ represents hyper/hypokalemia in ECF/ what is the result of both?
>5.0 mEq/L is hyperkalemia causes RMP to be less negative (insulin may be infused to correct; used with glucose to prevent hypoglycemia; epinephrine may correct after exercise) <3.5 mEq/L is hypokalemia which leads to hyperpolarization
A positive test for glucose indicates _________. Without enough insulin, the body breaks down fat leading to the build up of ______ and a positive test for _________.
A positive test for glucose indicates diabetes mellitus. Without enough insulin, the body breaks down fat leading to the build up of ketones and a positive test for diabetes ketosis.
Antihypertensive drugs impact each aspect of the RAAS pathway below in what ways? ARB, aldosterone receptor blocker, and ACE inhibitor
ARB - preventing arteriolar vasoconstriction aldosterone receptor blocker - prevents Na+ reabsorption ACE inhibitor - prevent conversion of Angiotensin I to Angiotensin II
Which statements are T/F, if any? The renal cortex is the most superficial region that extends to the renal columns. The renal cortex light color is due to the glomeruli and convoluted tubules. This portion of the kidney despite comprising the least amount of space contains the majority of nephrons.
All statements are true.
Which statements are true? An active Na+ K+ ATPase pump in the tubular lumen is essential for Na+ reabsorption A small percentage of Na+ is reabsorbed in the DCT and collecting tubules under hormonal control and is linked to K+ excretion Na+ is reabsorbed in the descending limb of the loop of Henle
An active Na+ K+ ATPase pump in the basolateral membrane is essential for Na+ reabsorption A small percentage of Na+ is reabsorbed in the DCT and collecting tubules under hormonal control and is linked to K+ excretion - true only ~8% Na+ is reabsorbed in the ascending limb of the loop of Henle - ~25%
causes of respiratory alkalosis and compensations
An excessive loss of CO2 as a result of hyperventilation caused by fever, anxiety, aspirin poisoning and high altitude chemical buffers that liberate H+ and kidneys may compensate by conserving H+ and excrete more bicarbonate
Which statements are true/false Autoregulation aims to prevent spontaneous changes within hours. There are two major control mechanisms: myoglomerular mechanism which involves the constriction of the efferent arteriole and tubuloglomerular feedback
Autoregulation aims to prevent spontaneous changes within seconds/minutes. There are two major control mechanisms: myogenic mechanism which involves the constriction of the afferent arteriole and tubuloglomerular feedback
When a woman who has been on a low-sodium diet for 8 days is given an intravenous injection of captopril, a drug that inhibits ACE, which of the following would be expected
Blood pressure to fall because peripheral resistance would fall
causes of respiratory acidosis and compensations
CO2 retention is caused by hypoventilation causes by lung disease, depression of respiratory center, nerve/muscle disorders, and holding your breathe chemical buffers that immediately take up additional H+ and kidneys may excrete more H+ and reabsorb more HCO3-
Circulatory shock, reduction in plasma volume, sunken eyeballs is caused by ________ which describes ________osmolarity change.
Circulatory shock, reduction in plasma volume, sunken eyeballs is caused by insufficient water intake, excessive water loss, diabetes insipidus which describes hypertonicity osmolarity change.
Co2 is the major source of _______ the breakdown of dietary proteins produces this inorganic acid ________ this organic acid results from intermediary metabolism
Co2 is the major source of carbonic acid (respiratory) the breakdown of nutrients produces this inorganic acid S, P (renal) this organic acid results from intermediary metabolism lactic acid, fatty acids (renal)
In which area of the kidneys does aldosterone exert its greatest effect?
Cortical collecting duct Cortical collecting duct where aldosterone is responsible for sodium reabsorption via ENaC transporters.
Which portion of the nephron does secretion of K+ and H+ occur, and controlled reabsorption of Na+ and H2O occur
DCT and Collecting duct
Which of the following is least likely to contribute to the beneficial effects of ACE inhibitors in the treatment of heart failure? - NEED TO EVALUATE WHERE INFO IS FROM
Decreased plasma aldosterone Aldosterone causes volume loss that would be beneficial for heart failure
The efferent arterioles of cortical nephrons supplies what? Juxtamedullary nephrons?
Efferent arterioles of cortical nephrons supplies peritubular capillaries, and efferent arterioles of juxtamedullary nephrons supplies vasa recta
T/F AQP-2, AQP-3, and AQP-4 water channels are always present and open
False - AQP-3 and AQP-4 are always present and open, but AQP-2 are inserted into the luminal membrane by its promotion by Cyclic AMP. This membrane is impermeable in the absence of vasopressin. this is where water enters the tubular cell from the tubular lumen
T/F Adrenal gland tumors damages the adrenal cortex which produces hypovolemia, decreased Na+ and increased K+
False - Addison's disease does adrenal gland tumors results in increased plasma Na+ and decreased K+
T/F 80% of total energy spent by kidneys is used for K+ transport
False - Na+
T/F - Insensible loss output would include sweat, feces and urine excretion.
False - Sensible loss output would include sweat, feces and urine excretion (1800 ml/day). Insensible loss would include lungs and non-sweating skin (900 ml/day)
T/F - The ureters descend behind the peritoneum to the base of the bladder and pass posterior to the common iliac arteries as they enter the pelvis.
False - The ureters descend behind the peritoneum to the base of the bladder and pass anterior to the common iliac arteries as they enter the pelvis.
T/F - Up to 90% of kidney tissue can be destroyed before loss of kidney function is noticeable
False - Up to 75% of kidney tissue can be destroyed before loss of kidney function is noticeable
T/F - the Tmax for sodium is 375 mg/min
False - all actively absorbed substances have Tmax except Na+
T/F Hypophosphatemia results from inadequate phosphate urinary excretion in patients with chronic renal failure
False - hyperphosphatemia results
T/F - inappropriate secretion of vasopressin can cause hypertonicity which results in swelling if brain cells, weakness, circulatory disturbances and water intoxication
False - inappropriate secretion of vasopressin can cause hypotonicity which results in swelling if brain cells, weakness, circulatory disturbances and water intoxication
T/F the plasma clearance is the amount of substance removed from the plasma per minute
False - it is the volume of plasma cleared of a particular substance only and NOT the amount
T/F - the majority of nephrons have peritubular capillaries that form hairpin loops in close association with loops of Henle
False - the majority are cortical nephrons whose peritubular capillaries entwine around the nephrons
T/F - There are about 2K nephrons in the kidneys
False - there are about 2 million nephrons per kidney
T/F - no filtered water is absorbed from Henle's loop
False - there is additionally 15% of filtered water that is absorbed from Henle's loop
T/F controlled reabsorption and secretion of selected substances occur in the proximal tubule
False - uncontrolled reabsorption and secretion of selected substances occur in the proximal tubule
T/F Autoregulation is aimed at long-term regulation, and extrinsic sympathetic control is aimed at spontaneous changes in GFR
False- Autoregulation is aimed at spontaneous changes in GFR , and extrinsic sympathetic control is aimed at long-term regulation
T/F - there are two major mechanism that can control glomerular blood flow by regulating the radius of the efferent arteriole which includes autoregulation and tubuloglomerular feedback.
False- there are two major mechanism that can control glomerular blood flow by regulating the radius of the afferent arteriole which includes autoregulation and extrinsic sympathetic control
A new PhD student in a diabetes laboratory is working on a novel animal model for diabetes. The student is required to collect urine from control and diabetic mice and perform pH measurements on the urine. As expected, urine pH for the diabetic mice is quite low compared with controls. Prior to developing a project in the laboratory, the student presents the results at laboratory meeting and is required to discuss normal filtration in the kidney. How would she correctly describe the fate of filtered bicarbonate ions in an individual with normal renal function under normal acid-base conditions?
Filtered bicarbonate is mostly reabsorbed in the proximal tubule. Greater than 90% of filtered bicarbonate is reabsorbed by the proximal tubule, preventing loss of bicarbonate to the urine. Bicarbonate reabsorption is dependent on HCO3− concentration. When the plasma HCO3− concentration is low, all the filtered HCO3− is reabsorbed; but when the plasma HCO3− concentration is high, HCO3− appears in the urine and the urine becomes alkaline.
Glomerular filtrate is ___________through the ______ layers of glomerular membrane which includes:
Glomerular filtrate is passively forced through the three layers of glomerular membrane which includes: glomerular capillary wall (single layer of endothelial cells permeable to H20), basement membrane (comprised of negatively charged glycoproteins) and the inner layer of Bowman's capsule which consist of podocytes
Granular cells are the smooth muscle portion of the _________ portion of juxtaglomerular apparatus and detects changes in ______ and is innervated by ______
Granular cells are the smooth muscle portion of the afferent arteriole portion of juxtaglomerular apparatus and detects changes in renal perfusion, blood pressure and NaCl concentration and is innervated by sympathetic fibers
H+ may be secreted where and by use of what mechanisms?
H+ may be secreted in proximal thru H+ ATPase pumps and Na+ H+ antiporters, and distal, and collecting tubules thru Type A and B intercalated cells interspersed among principal cells
during acute metabolic acidosis the Na+ K+ H+ cotransporter would prioritize secretion of which?
H+ secretion and accompanying K+ retention or hyperkalemia would result
______directly reflects the concentration of dissolved CO2 in plasma
H2CO3
this is the most powerful buffer of blood
Hemoglobin: hemoglobin Hb=7.93 HbO2 pK=6.68 proteins are close to 7.4 bicarbonate buffer pK=6.1 phosphate pK=6.8 (but only has 1/6 concentration of bicarbonate system in ECF)
A medical student is required to present a case study as part of his matriculation. While the student has excellent bedside manner and performs admirably in small groups, the idea of speaking to an audience is frightening to him. Just prior to the presentation, the student begins to hyperventilate, causing an immediate increase in blood pH. Why did the increase in blood pH occur
Hyperventilation decreases the Pco2 in the alveoli.
A 35-year-old woman had a sudden onset of hypertension. Previously her blood pressure was 110/70 mm Hg, but upon visiting the physician's office with complaints of headache, her blood pressure was increased to 150/90 mm Hg. Her laboratory workup came back showing elevated levels of aldosterone and reductions in renin. What serum electrolyte or acid-base abnormality would you expect to find?
Hypokalemia Hypertension caused by Na+ retention is a direct result of primary hyperaldosteronism. Aldosterone causes K+ loss in the urine, resulting in the observed hypokalemia and drives renal H+ secretion, causing metabolic alkalosis
In Type A cells, H+ ______ is coupled with bicarbonate ______ and is active in______. H+ ATPase and H+ K+ ATPase pump is present _______
In Type A cells, H+ secretion is coupled with bicarbonate reabsorption (and potassium reabsorption) and is active in normal conditions and acidosis. H+ ATPase and H+ K+ ATPase pump is present in the luminal membrane.
In Type B cells, H+ ______ is coupled with bicarbonate ______ and is more active in______. H+ ATPase and H+ K+ ATPase pump is present _______
In Type B cells, H+ reabsorption is coupled with bicarbonate secretion (and potassium secretion) and is more active in alkalosis. H+ ATPase and H+ K+ ATPase pump is present in the basolateral membrane.
In the distal tubule and collecting duct reabsorption of _______, and secretion of _____is controlled by aldosterone, and _____ is controlled by vasopressin.
In the distal tubule and collecting duct reabsorption of sodium, and secretion of potassium is controlled by aldosterone, and water is controlled by vasopressin.
GANONG Question: A 50-year-old man comes to see his primary care physician complaining of back pain and fatigue. His physician diagnoses him with multiple myeloma. He also has secondary light chain nephropathy that causes him to have chronic metabolic acidosis due to a reduction in proximal tubular reabsorption of bicarbonate. Assuming the man has no other renal disease and that his lung function is normal, which of the following responses is most likely seen in the patient?
Increase in NH4+ in urine
A scientist is performing studies on runners after a 10,000-m race. She finds that the urine of runners after the race is more concentrated and has reduced volume than before the race. What mechanism contributes to the change in urine concentration and output?
Increase in water permeability in the collecting duct
A physiologist is studying the effect of food additives on GFR in order to determine what additives should be avoided in individuals with CKD. A caffeine was found to affect urine output through an effect on GFR. What is the effect and the mechanism involved
Increase urine output; afferent arteriole vasodilation
during acute metabolic alkalosis the Na+ K+ H+ cotransporter would prioritize secretion of which?
K+ secretion and accompanying H+ retention or hypokalemia would result
the most important substances secreted by tubules
K+, H+, hormones and drugs
Lacis cells lie ________ and modulate _______
Lacis cells lie outside the glomerulus and modulate GFR thru the use of actin like contractile elements
A 1-month-old boy is brought to the pediatric emergency department with persistent vomiting. The mother said the baby started vomiting after feeding and the emesis is whitish-yellow with no blood. The baby is otherwise healthy and had an uncomplicated vaginal birth. The physician palpates an olive-sized mass in the epigastric area and suspects pyloric stenosis. What would the physician expect the baby's acid-base balance to be
Metabolic alkalosis loss of stomach acids and net loss of H+, resulting in increased pH and metabolic alkalosis
GANONG Question (need to discuss): A 22-year-old woman arrives at the urgent care clinic complaining of lethargy and weakness. Upon examination, her blood pressure was 100/55 mm Hg, and her body mass index was 17 kg/m2. She was taking no medications, had no significant medical history and denied any recent illness. She mentioned to the physician that she was afraid of gaining weight and had been taking diuretics to limit weight gain. The physician diagnosed diuretic abuse. What lab finding would be consistent with loop or thiazide diuretic abuse?
Metabolic alkalosis Loop and thiazide diuretics can cause metabolic alkalosis due to their ability to increase Na+ delivery to the collecting ducts and the resulting increase cellular uptake of Na+ from the lumen by apical epithelial Na+ channels (ENaCs). Increased intracellular Na+ causes the basolateral Na/K exchanger to more actively exchange Na+ for K+, which is then passively secreted into the lumen through apical channels, resulting in K+ loss. The increased delivery of K+ to the collecting ducts facilitates the exchange of K+ for H+ by the H/K exchanger on the intercalated alpha cells, resulting in loss of H+ in urine and metabolic alkalosis.
RAAS is the most important and best known hormonal system is involved in regulating what?
Na+
What performs filtering functions of kidneys?
Nephrons
Are there treatments for kidney failure which would return the normal function to the kidneys?
No - an individual on dialysis would need medication to supplement for loss of other functions of kidneys and in case of transplantation they would need immunosupressant medications
which statements are true Patients with congestive heart failure have decreased ECF volume. Sensors in the granular cells respond as if there is a decreased ECF and results in NaCl and water secretion by the kidneys. ECF increases but fluid is not in the vascular system
Patients with congestive heart failure have increased ECF volume. Sensors in the granular cells respond as if there is a decreased ECF and results in NaCl and water reabsorption by the kidneys. ECF increases but fluid is not in the vascular system
_____buffer system is important in tubular fluid of the kidneys. this is important for these three reasons:
Phosphate buffer system is important in tubular fluid of the kidneys. this is important because it is more concentrated there, the pH of tubular fluid is closer to its pK, and none of the other body fluid buffer systems are present.
The greatest fraction of filtered sodium is reabsorbed in what portion of the nephron
Proximal tubule
Researchers propose that ________ is responsible for athletic pseudonephritis. ________also increases during strenuous exercise
Researchers propose that decreased glomerular blood flow is responsible for athletic pseudonephritis. Plasma renin activity also increases during strenuous exercise
Specific gravity of urine ranges from 1.002 to 1.03 Which statements are true Specific gravity is proportional to urine volume Specific gravity decreases with conditions such as diabetes insipidus and nephritis Specific gravity increases with dehydration, congestive heart failure inappropriate ADH secretion, and proteinuria
Specific gravity is inversely proportional to urine volume Specific gravity decreases with conditions such as diabetes insipidus and nephritis Specific gravity increases with dehydration, inappropriate ADH secretion, and proteinuria
T/F kidney tubules can selectively add some substances to filtered substances to hasten elimination
T - tubular secretion
which statements are true? 20% of the water in our body have the presence of cell proteins that cannot permeate the cell membrane to leave the cells. Unequal distribution of Na+ and K+ and their attendant ions are as result of membrane bound Na+ K+ pump present in some cells.
The ICF which makes up 80% of the water in our body have the presence of cell proteins that cannot permeate the cell membrane to leave the cells. Unequal distribution of Na+ and K+ and their attendant ions are as result of membrane bound Na+ K+ pump present in all cells.
This empties into the area cribosa which then carries into the next space which is?
The collecting tubules empties into the area cribosa which then carries into the minor calyx
The cortex is made up of?
The cortical labyrinth (glomeruli and convoluted tubules) and medullary rays (straight segments of loop Henle and collecting tubules).
What does sympathetic innervation of the bladder responsible for?
The relaxation of the detrusor muscle and contraction of the internal urethral sphincter muscle contracting the urethra closed for bladder filling
This vessel comes directly off of the abdominal aorta at right angles between L1-L2 vertebrae. What does this then branch into within the kidneys?
The renal artery branches off of the abdominal aorta which then branch into segmental arteries into lobar into interlobar arteries (between pyramids) into arcuate arteries (base of pyramids) into interlobular arteries (short arteries going into cortex) into afferent arterioles into glomerulus Renal veins follow this pathway in reverse
which statements are true? There are no proteins in interstitial fluid. The largest amount of cations is K+ and largest anion is PO43- in plasma. Bicarbonate may only be found in ECF (plasma and interstitial fluid)
There are no proteins in interstitial fluid. The largest amount of cations is K+ (98%)and largest anion is PO43- in ICF; Na+ is the largest cation component and Cl- in plasma Bicarbonate may only be found in ECF (plasma and interstitial fluid)
T/F - Plasma is the only fluid that can be acted on directly to regulate its volume and composition. Any changes in plasma are reflected in interstitial fluid as well. Any short term mechanisms of maintaining blood pressure (increasing CO, TPR etc.) won't work sufficiently without adequate plasma volume.
These are all true
ANP and BNP are produced in response to what, and results in?
They are produced in response to high NaCl, high ECF volume, high arterial blood pressure. This inhibits renin, aldosterone, and vasopressin and results in decreased Na+ reabsorption in the distal portion, and increased sodium and water excretion. A decrease in smooth muscle arterioles causing vasodilation of afferent arterioles and increased GFR. The sympathetic impact would result in decreased cardiac output, total peripheral resistance and arterial blood pressure
What part of this statement is false - The inner space of the kidney is the cortex which is dark red in color. It may have 7/14 pyramids that are striated due to the straight tubular structures.
This describes the medulla The inner space of the kidney is the medulla which is dark red in color. It may have 7/14 pyramids that are striated due to the straight tubular structures
T/F CPAH = Renal Plasma Flow as this substance is filtered and secreted but not reabsorbed Renal Blood flow = RPF CPAH/(1-hematocrit)
True
T/F - 2/3 of the body's water is ICF and the 1/3 is ECF which may be further broken down into 20% is plasma, and 80% interstitial fluid. Other minor components of the ECF includes lymph, and transcellular fluids like cerebrospinal fluid, intraocular fluid, synovial fluid and digestive fluids
True
T/F - plasma calcium concentration may be increased by Vitamin D3
True
T/F H+ and PAH would move from the peritubular capillaries into the tubular lumen
True
T/F Tmax for phosphate is similar to normal plasma concentration
True
T/F acid/base can alter plasma levels
True
T/F stimulated stretch receptors signal smooth muscle in bladder wall to contract by parasympathetic neurons
True
T/F - a long term adjustment to low arterial bp would involve a decrease in GFR which ultimately would lead to an increase in arterial BP?
True - a decrease in GFR would decrease urine output which would conserve fluid and salt and increase arterial blood pressure
T/F - one of the causes of stone formation is high blood calcium
True - as well as alkaline urine, bacterial infections and retention of urine
T/F - concentration of K+ remains constant in ECF despite fluctuations in dietary intake
True - intake is balanced by renal excretion plus losses from sweat, feces (sensible loss)
T/F a hemorrhage does not result in osmotic loss of water from cells
True - isotonic fluid loss does not result in change in osmolarity
T/F - an increase in NaCl would ultimately lead to a passive increase in Cl= reabsorption (initially said decrease, why?)
True - the RAAS system would result in increase Na+ reabsorption and Cl- reabsorption follows passively
which statements are true? Luminal K+ leak channels that are only in the principal cells of distal/collecting tubules actively secrete K+ under the control of aldosterone
True per lecture 5 slide 5 - should this be basolateral membrane?
The constriction sites are potential sites of obstruction -what and where are they?
Uretopelvic junction - near hilus pelvic brim - where they cross the iliac vessels uretovesical junction - where they join the bladder
When the body is exercising this pushes the bicarbonate buffer system to the formation of ______ A loss of plasma (vomiting) would result in this form
When the body is exercising this pushes the bicarbonate buffer system to the formation of water and carbon dioxide A loss of plasma (vomiting) would result in H+ and bicarbonate
Which statements are true? Osmotic diuresis may be caused by diabetes mellitus. Urine retention can increase 25 ml/min in the absence of vasopressin The medullary osmotic gradient has a great influence in the absence of vasopressin
Which statements are true? Osmotic diuresis may be caused by untreated diabetes mellitus. Urine flow can increase 25 ml/min in the absence of vasopressin The medullary osmotic gradient has NO influence as late tubule is impermeable to water in the absence of vasopressin
In what situations would renin be secreted?
a fall in NaCl, ECF volume and arterial blood pressure also renal sympathetic nerve activity stimulates renin secretion (need to discuss renal sympathetic nerve activity)
a plasma pH less than _______represents acidosis a plasma pH greater than _____ represents alkalosis Which is responsible for depression of the CNS, and which causes excitability of nervous systems
a pH less than 7.35 represents acidosis a pH greater than 7.45 represents alkalosis Acidosis is responsible for depression of the CNS, and alkalosis causes excitability of nervous systems
This is a group of H+ containing substances that dissociate in solution to release free H+ and anions
acid
what other factors have some impact on vasopressin or thirst but not both
acute infection, pain or trauma increase vasopressin secretion, alcohol/caffeine decrease vasopressin, and dry mouth only has an effect on thirst ECF osmolarity, ECF volume, angiotensin II levels are factors that effect both
This hormone is responsible for proper plasma volume
aldosterone
this hormone promotes uptake into cells and also stimulates K+ excretion by the kidneys
aldosterone
renin triggers a series of events leading to
aldosterone secretion which results in Na+ reabsorption from the distal portions of the tubule by promoting the insertion of Na+ leak channels in luminal membranes, and Na+/K+ pumps into the basolateral membranes
As urine flow increases during osmotic diuresis the osmolality of urine
approaches that of plasma because an increasingly large fraction of the excreted urine is isotonic proximal tubular fluid. When urine output increases, the amount of the solutes in the urine increase and the osmolality of urine approaches that of plasma. The majority of solute in the urine makes it isotonic since the majority is isotonic proximal tubular fluid
In the renal papilla this perforated region that has holes at the end of the papillary ducts is called what
area cribosa
arterial pH less than _____ or greater than _____ is not compatible with life
arterial pH less than 6.8 or greater than 8.0 is not compatible with life
The plasma concentration of this hormone would be decreased by dehydration
atrial natriuretic peptide
extrinsic sympathetic control leads to
auto-regulatory responses being overridden and long term regulation of arterial blood pressure
because of its negative charge, fluoride has an affinity to calcium which is why ________ of it is found in bones and teeth. Although ______is excreted in urine each day
because of its negative charge, fluoride has an affinity to calcium which is why 99% of it is found in bones and teeth. Although 60% is excreted in urine each day
a patient on beta blockers may be at greater risk of hyperkalemia after a potassium rich meal, why?
beta 2 adrenergic stimulation promotes uptake of K+ into cells (ICF storage) - this mechanism is blocked (discuss)
a large vertical osmotic gradient is established here
between the tubular lumen in the interstitial fluid of the medulla and follows the hairpin loop of Henle deep into the medulla
what is the relationship between HCO3 and H+
bicarbonate reabsorption is coupled with H+ secretion, and secretion of bicarbonate and is coupled with H+ absorption
carbonic acid/bicarbonate is the primary ECF buffer against noncarbonic acid changes; however it is tightly regulated. _____is regulated by the kidneys and ____ is regulated by the respiratory system
carbonic acid/bicarbonate is the primary ECF buffer against noncarbonic acid changes; however it is tightly regulated. HCO3 is regulated by the kidneys and H2CO3 is regulated by the respiratory system
this enzyme is abundant in RBCs, stomach, the pancreas and kidney tubular cells
carbonic anhydrase
Causes and compensation of metabolic acidosis
causes include severe diarrhea, diabetes mellitus, strenuous exercise, and uremic acidosis (kidneys cannot get rid of acids via urine) compensations include buffers that take up extra H+, lungs blowing off additional H+ and generating CO2 and kidneys excrete more H+ and conserve more HCO3-
Causes and compensation of metabolic akalosis
causes include vomiting and ingestion of alkaline drugs compensations include chemical buffer systems that liberate H+ and ventilation which reduces retaining CO2, and kidneys conserve H+ and excrete excess HCO3- in the urine
Erythropoietin is secreted by
cells in the peritubular capillary bed
changes in H+ influences _________ levels as the kidney changes rate of its elimination
changes in H+ influences K+ levels as the kidney changes rate of its elimination
______suppress changes in pH and is the first line of defense - acting within fractions of a second; however ______ mechanism eliminates acid from the body
chemical buffer system suppress changes in pH; however respiratory and kidneys (renal) mechanism eliminates acid from the body
what response during alkalosis would the intercalated type a cells have?
decreased H+ secretion by intercalated type a cells and proximal tubule
GANONG Question (need to discuss) A 48-year-old woman visited her physician complaining of constant thirst and frequent urination. She was admitted to the hospital to determine the cause of her polydipsia and polyuria. She was not given fluids for 6 h, and no change in her urine osmolarity was measured during this time. When given an infusion of a nonpressor dose of an antidiuretic hormone (ADH) agonist, she experienced a rapid increase in urine osmolarity. What diagnosis is most likely to account for the woman's polydipsia and polyuria
diabetes insipidus Restoration of urine concentrating ability with exogenous ADH infusion is consistent with a failure of endogenous ADH secretion and thus the diagnosis of central diabetes insipidus. The lack of response to ADH in the kidney is the hallmark of nephrogenic diabetes insipidus; thus addition of ADH would not be expected to change urine osmolarity had that been her diagnosis. Lack of water consumption for 6 h should increase urine osmolarity in cases of compulsive water drinking or in individuals with diabetes mellitus.
diluted urine would have high/low volume and high/low osmolarity? concentrated urine would have high/low volume and high/low osmolarity?
diluted urine would have high volume and low osmolarity? concentrated urine would have low volume and high osmolarity?
uremia is the presence of what
excess urea and nitrogenous waste in the blood
the result of glomerular filtration, tubular reabsorption, and tubular secretion is?
excretion - the final filtrate
T/F kidneys regulate plasma glucose
false
T/F - the osmolarity of a cell does not maintain cell size nor water balance
false - the osmolarity of a cell does maintain cell size which is controlled by water balance
what two mechanisms are used by the kidneys during acidosis to buffer excreted H+
filtered phosphate acts as a urinary buffer with secreted H+ to form phosphoric acid which is excreted tubular cells secrete NH3 into tubular fluid once urinary phosphate buffers are saturated and is fully excreted as ammonium
what is responsible for short term shifts that occur to maintain blood pressure? what is responsible for long-term regulation of blood pressure
fluid shift between plasma and interstitial fluid alters cardiac output and peripheral resistance in the short term while kidneys and the thirst mechanism control urinary output and fluid intake that regulation bp in the long-term.
the podocytes and their foot processes encircle this
glomerular capillaries
the filtration coefficient takes into account
glomerular surface area and permeability GFR=Kf * net filtration pressure
Where does the filtration process begin?
glomeruli - blood flow through the renal columns to get to the cortical regions where the glomeruli are
Normal GFR
greater than 90 mL/min
High BP results in secretion of this vs low BP
high blood pressure - ANP and BNP, and low blood pressure - renin
this opening is where things enter and exit the kidneys
hilum (found on medial concave surface of kidneys)
This responsible for pushing fluid out of Bowman's capsule
hydrostatic pressure which opposes filtration
by what mechanism is K+ excretion regulated by aldosterone
hyperkalemia stimulates the adrenal cortex to secrete aldosterone, this stimulates the Na+K+ pump in principal cells and causes K+ to leak into urine
what other factors would lead to decrease in aldosterone secretion
hypokalemia (need to discuss), or ANP/BNP, high BP
hypokalemia results in ____ and this condition_____ hyperkalemia results in ____ and this condition_____
hypokalemia produces H+ secretion and alkalosis hyperkalemia produces K+ secretion and this condition acidosis
what stimulates aldosterone secretion?
hyponatremia or hypovolemia or low BP via RAAS
what are the three adh/vasopressin trigger mechanisms
hypothalamic osmoreceptors when there is a 1-2% change in osmolarity (this dominates) left atrial receptors which monitor blood pressure >7% change in ECF volume angiotensin II when RAAS is activated to conserve Na+
RAAS initiation would result in what effect?
increase Na+ reabsorption by kidney tubules, passive increase in Cl-, fluid retention which would increase stroke volume and BP
Causes of renal failure include?
infectious organisms, pesticides, lead, high doses of aspirin, inappropriate immune responses, obstruction of urine flow. and insufficient renal blood supply ( 2nd to heart failure, hemorrhage, shock, atherosclerosis of renal arteries)
this hormone is most important in shifting intake of K+ to tissue stores after a meal
insulin
what is the relationship between aldosterone, Na+, K+ and H+
irrespective of the stimulus increased aldosterone result in sodium reabsorption and potassium and H+ secretion
what effect does alcohol have on vasopressin?
it inhibits it causing water diuresis
where is H+ secreted
it is secreted in the proximal, distal and collecting tubules
what type of nephron is responsible for highly concentrated urine? What differences are seen within the structure of their nephron?
juxtamedullary nephron which has a longer nephron loop deep into the medulla and glomerulus closer to the cortex-medullary junction
to identify a specific disease process ________test is needed
kidney biopsy
what is ithotripsy used to treat?
kidney stones
less water is _____when the secretion of vasopressin _____
less water is reabsorbed when the secretion of vasopressin decreases
How does loop diuretics, thiazide diuretics, and potassium sparing diuretics inhibit sodium reabsorption
loop diuretics - inhibit sodium potassium-chloride transporter in ascending limbs (25% of sodium load ) thiazide diuretics - inhibit sodium-chloride transporter in distal tubule (5% filtered sodium) potassium sparing diuretics - inhibit aldosterone sensitive sodium reabsorption in distal tubule and collecting ducts (5% filtered sodium) - DO NOT cause hypokalemia like the other two drug types
this portion of juxtamedullary nephrons establishes an osmotic gradient in the renal medulla
loop of Henle
_____ is the distal tubule portion of the juxtaglomerular apparatus and responds to changes in ______
macula densa is the distal tubule portion of the juxtaglomerular apparatus and responds to changes in NaCl
metabolic acidosis results in ____,_____,and _____. metabolic alkalosis results in ____,_____,and _____.
metabolic acidosis results in increase ventilation, increase rate of CO2 removal, and decrease rate of H+ generation from CO2. metabolic alkalosis results in decrease ventilation, decrease rate of CO2 removal, and increase rate of H+ generation from CO2.
Urine drips out at the end of the apex of the pyramids and follows what path?
minor calyx to major calyx to renal pelvis to ureter to bladder
most plasma proteins including albumin are _____charged
most plasma proteins including albumin are negatively charged
GANONG Question: A 56-year-old African American man has had consistent hemodialysis treatment for 2 years due to renal disease associated with sickle cell anemia. He has not had a sickle cell crisis in the past 3 years since he was compliant with his therapy; however, he recently missed his scheduled treatment. What would you expect his laboratory results to show when he came in for dialysis days later
negative base excess Because the patient has renal insufficiency, he will be in metabolic acidosis. Base excess is negative in metabolic acidosis.
This structure is responsible for urine formation
nephron
A positive test for _________indicates bacterial infection
nitrite produced from nitrate
What comprises a renal lobe?
one medullary pyramid and cortical tissue surrounding it (overlying renal cortex and adjacent renal columns)
organic ions including food additives, pollutants, drugs, prostanglandins, epinephrine may only be secreted ________using distinct ________
organic ions including food additives, pollutants, drugs, prostanglandins, epinephrine may only be secreted in the proximal tubule using distinct organic anion and cation secretory carriers
what tissues surrounds the kidneys from superficial to deep
pararenal fat, renal fascia, perirenal fat, and the renal capsule directly adheres
what substance is reabsorbed thru passive diffusion? what is reabsorbed by active transport?
passive - H20, 50% of urea in the proximal tubule active - glucose, amino acids reabsorbed by Na+ dependent secondary active transport. They also passively diffuse down their concentration gradients across the basolateral membrane into plasma. Symport carriers, like sodium and glucose co-transporter, SGLT in the proximal tubule and PO43-
What provides parasympathetic motor innervation to the smooth muscle of the bladder wall (detrusor muscle)? where is it located?
pelvic splanchnic nerves (S2-4)
This vascular component of the nephron nourishes renal tissue and participates in exchange between the efferent tubular fluid and plasma
peritubular capillaries
(urine concentration * urine flow rate) / plasma concentration equals
plasma clearance rate
how do you compute filtered load of glucose
plasma concentration * GFR
what do principals do?
principal cells reabsorb NA from DCT and respond to aldosterone; play an important role in sodium/fluid balance
this is the primary ICF buffer but will also buffer ECF this is the primary buffer against carbonic changes this is the primary ECF buffer against noncarbonic acid changes this buffers urine and ICF
protein buffer system is the primary ICF buffer but will also buffer ECF hemoglobin buffer system is the primary buffer against carbonic changes in metabolically produced CO2 in transit between tissues and the lungs carbonic acid/bicarbonate is the primary ECF buffer against noncarbonic acid changes the phosphate buffer system buffers urine and ICF
this is the most plentiful buffer of the body fluids
protein buffer system; primarily important intracellularly
what is the cause of renal ptosis?
rapid decline of renal adipose tissue (i.e. anorexia)
which tissue adheres to the kidneys but do not contribute to them being held in place on the posterior abdominal wall
renal (fibrous) capsule
These are the inward extensions of cortical tissues are?
renal columns of Bertin
This consists of nephrons drained by a single collecting duct
renal lobule
Hydronephrosis is a result of what?
renal ptosis where kidneys fall to lower position which causes urine to back up into kidneys
This structure has a broad base that faces the cortex
renal pyramids
GANONG Question (Need to discuss): A 56-year-old man is admitted to the ED with an acute myocardial infarction. The man was transferred to the CCU and was placed on 24 h intake and output. A few days later his 24 h urinary output was decreased lower than normal. An increase in which of the following contributes to the reduced urine flow in a patient with congestive heart failure and reduced effective circulating volume?
renal sympathetic nerve activity An increase in renal sympathetic nerve activity promotes a decrease in sodium and water excretion by decreasing GFR, increasing renin secretin, and increasing tubular sodium reabsorption. All the other factors would cause an increase in sodium and water excretion
this mechanism is the second line of defense acting in minutes against pH changes, and can return the pH 50-75% of the way toward normal alone
respiratory system
every unit change in pH represents a _________fold change in H+
tenfold
glomerular capillary blood pressure which favors filtration depends on
the contraction of the heart and resistance to blood flow from afferent and efferent arterioles
the ____is highly permeable to water and ______actively transports NaCl out of the _______ into the ______
the descending limb is highly permeable to water and ascending limb actively transports NaCl out of the tubular lumen into the interstitial fluid
which muscle of the bladder is under voluntary control? where is it located?
the external urethral sphincter which is located at the pelvic floor
Urinary incontinence is
the inability to prevent discharge of urine - voluntary control is disrupted
what portion of the nephron produces substances involved in the control of kidney function and is a combined vascular/tubular component? what is its function?
the juxtaglomerular apparatus; it functions in regulating glomerular filtration and blood pressure
this system is the third line of defense taking _____to______ to compensate for pH changes. In acidosis _______ in urine and _______to plasma, during alkalosis ______ in urine and _______in plasma
the kidneys are the third line of defense taking hours to days to compensate for pH changes. In acidosis excess H+ is secreted in urine and new bicarbonate is added to plasma, during alkalosis H+ secretions is reduced in urine and excess bicarbonate is eliminated in plasma
what are the five barriers involved in transepithelial transport?
the luminal cell membrane of tubular cell the cytosol the basolateral membrane the interstitial fluid the peritubular capillary
when sodium is high, how does the macula densa respond?
the macula densa triggers contraction of the afferent arterioles reducing blood flow.
tubuloglomerular feedback mechanism sense changes in salt level within the filtrate - what portion of the juxtaglomerular apparatus is responsible and where is it located?
the macula densa which is part of the DCT
The renal papilla and area cribosa may be found in what portion of the kidneys
the medullary pyramids of the medulla
Nephrons are comprised of renal corpuscle and renal tubule. What comprises the renal corpuscle?
the renal corpuscle is comprised of the glomerular (bowman's) capsule and glomerulus
the plasma clearance rate equals GFR when
the substance is filtered and not secreted nor reabsorbed
the plasma clearance rate is less than GFR when
the substance is filtered and reabsorbed
the plasma clearance rate is greater than GFR when
the substance is filtered and secreted
this vessel preserves the vertical osmotic gradient, allows the blood to leave the medulla and enter the renal vein isotonic to incoming arterial blood, and prevents dissolution of the medullary osmotic gradient while providing blood to the renal medulla
the vasa recta
with regard to autoregulation of GFR, the myogenic mechanism responds to changes in pressure in the vascular or tubular component of the nephron?
the vascular component
this is responsible for the more concentrated urine (relative to body fluids) that the kidneys are able to produce
the vertical osmotic gradient
If the clearance of a substance that is freely filtered is less than that of inulin
there is net reabsorption of the substance in the tubules
this is a measure of GFR this is a ~10% overestimation of GFR These are two substance that will have a plasma clearance rate less than GFR - These are two substance that will have a plasma clearance rate greater than GFR
this is a measure of GFR - inulin C=125 ml/mim this is a ~10% overestimation of GFR - creatinine C=137.5 ml/min These are two substance that will have a plasma clearance rate less than GFR - glucose C=0, and urea These are two substance that will have a plasma clearance rate greater than GFR - H+, PAH
what is the tubular maximum for glucose, and the renal threshold?
tmax is 375 g/min plasma glucose concentration at which tmax is reached is 300 mg/100mL. This is when glucose first appears in urine
T/F - Na+ reabsorption is matched by either K+ or H+ secretion in the distal tubule
true
T/F - there is a separation of solute and water excretion
true - this is due to dilution and concentration of urine which is the body's result of overhydration and dehydration
this highly selective and variable process involves transfer of substances by trans-epithelial transport?
tubular reabsorption from tubular lumen into peritubular capillaries
this speeds up clearance from plasma into nephron tubule from peritubular capillaries
tubular secretion
this is the only passively absorbed waste product
urea which is also the smallest of the waste products
potential ramifications of renal failure include which? uremic toxicity, metabolic aklalosis, potassium secretion, sodium imbalances, loss of plasma proteins, hypotension, anemia, depression of immune system
uremic toxicity, metabolic acidosis, potassium retention, sodium imbalances, loss of plasma proteins, hypertension, anemia, depression of immune system
afferent arteriole vasoconstriction results in what vs its vasodilation
vasoconstriction decreases GFR vasodilation increases GFR
When H+ secretion is coupled with the addition of new HCO3-, in what form is the H+ secreted and what is the source of bicarbonate?
water and CO2 produced in cellular metabolism. the water is split into hydroxide and hydrogen. the CO2 and hydroxide form new bicarbonate and the hydrogen reacts with filtered HPO42- in the tubular lumen to form H2PO4- which is excreted in urine
what is the relationship between BP, NaCl, adenosine and nitric oxide
when there is an increase in BP, there will be more NaCl which causes constriction of afferent arteriole to absorb the salt - this requires alot of energy (ATP) which produces adenosine as a byproduct when there is a decrease in NaCl, there is nitric oxide which causes vasodilation of afferent arteriole
Where are the kidneys located?
•T12-L3 in a retroperitoneal position in the superior lumbar region directly enveloped in a cushioning layer of perirenal fat
Exhaling would affect which kidney more?
•The left kidney, the right kidney sits lower than the left and its superior pole reaches the 12th rib, where the left reaches as high as the 11th rib
The upper end of the ureter is what?
•The renal pelvis which collects urine
