Renal Physiology

Question 1

what is the normal range of Na+?

Answer 1

135-145

Question 2

what is the normal range of K-?
what is the major concern of high potassium levels?

Answer 2

3.5-5
increases risk of arrhythmia

Question 3

what is the normal range of Cl-?

Answer 3

96-106

Question 4

what is the normal range of HCO3-?

Answer 4

23-30

Question 5

what is the normal range of Ca2+?

Answer 5

8.5-11

Question 6

what is the normal range of Mg2+?

Answer 6

around 2

Question 7

what is normal SCr level?

Answer 7

around 1

Question 8

what is the normal range of BUN?

Answer 8

8-20

Question 9

what is the approximate level of glucose that would be considered too high?

Answer 9

over 200

Question 10

what is the normal range of hemoglobin A1C?

Answer 10

below 5.7%

Question 11

what A1C level would indicate diabetes?

Answer 11

6.5% or more

Question 12

A 45-year-old patient comes to the emergency department
because 5-days history of worsening swelling in his legs and
numbness in his hands and feet. He first noticed the
symptoms 5 years ago, and they have continued to gradually
worsen.
His temperature is 37°C (98.7°F), blood pressure is 165/105
mmHg, pulse is 60/min, respirations are 16/min.
He has smoked 20 cigarettes daily for the past 20 years. A
repeat blood pressure reading 5 minutes later shows 170/105
mmHg. The patient appears to be alert and responsive to
questioning. Physical examination shows 2+ pitting edema in
his lower extremities and 1+ pitting edema in the upper
extremities. Neurologic examination shows decreased
sensation to touch in both hands and forearms, and feet and
ankles. Laboratory studies show normal values except for Cr of 4, urea nitrogen 50, glucose 350, and A1C 9%

Based on this information, the patient is likely suffering from? what diagnosis would you give this patient? is their condition reversible? what is the treatment plan?

Answer 12

neuropathy due to type 2 diabetes which is irreversible. Treatment is to slow progression and reduce edema

Question 13

A 55-year-old patient comes to the emergency department because of a 2-day
history of decreased urinary frequency. He was hospitalized for an episode of acute
pyelonephritis 2 weeks ago and was treated empirically with ceftriaxone and
gentamicin. His symptoms and laboratory abnormalities were completely resolved
by day 5 of treatment and he was discharged from the hospital 10 days ago. He says
that since his discharge he has been drinking lots of water but has not yet urinated.
He has no other known medical history and does not take any medications. His
temperature is 37°C (98.7°F), blood pressure is 152/98 mmHg, pulse is 60/min, and
respirations are 19/min. Physical examination shows 3+ pitting edema in both lower
extremities and bibasilar crackles in the lungs. There is no flank pain or abdominal
tenderness. A basal metabolic panel and complete blood count, urinalysis, and
glomerular filtration rate on his day of hospital discharge were within normal limits.
***pts potassium level is 6

What is acute pyelonephritis? what adverse reactions from gentamicin may be causing the pts inability to urinate? What could explain the pts extremely high BP if he has no known medical history? what is the diagnosis/treatment plan?

Answer 13

bacterial kidney infection causing inflammation.
Gentamicin is renal and ototoxic, so it may be damaging the pts kidney function.
kidney function affects BP, so if kidney is damaged it will impact the bodies BP.
Acute nephrotoxicity due to gentamicin. pt needs dialysis STAT to decrease potassium levels. patient needs to start a diuretic to reduce edema, but it won’t work effectively if kidney is damaged.

Question 14

T/F patients with AKI are more likely to die prematurely after hospitalization unless their renal function returns to baseline within 7 days

Answer 14

False, mortality increases even if renal function returns to baseline

Question 15

*slide 11-15 know anatomy

Answer 15

.

Question 16

A 65-year-old man goes to his primary care physician because of trouble initiating
urination, a problem that has slowly progressed over the last 6 months. A digital
rectal examination reveals a uniformly large, rubbery mass. This patient’s urinary
problems are likely due to which of these?
A. Compression of the bladder
B. Compression of the external urethral sphincter
C. Compression of the membranous urethra
D. Compression of the penile urethra
E. Compression of the prostatic urethra

Answer 16

E

Question 17

kidneys receive what percentage of cardiac output at rest?

Answer 17

25%

Question 18

where does most reabsorption occur in the kidney?

Answer 18

at the proximal convoluted tubule

Question 19

the afferent arteriole ______ blood whereas the efferent arteriole ______ blood

Answer 19

brings, takes

Question 20

what vitamin does the kidney help produce which helps with calcium absorption?

Answer 20

vitamin D

Question 21

if the kidney is damaged and produces less vitamin D, what is the main risk factor?

Answer 21

increases risk of bone disease

Question 22

what hormone does the kidney produce which has the primary role of increasing RBCs?

Answer 22

erythropoietin

Question 23

what does high glucose in the urine indicate?

Answer 23

high glucose plasma concentrations (insulin impairment)

Question 24

if a patient is admitted with edema and foamy urine, what is likely occurring?

Answer 24

more protein than normal is in the urine which leads to decreased plasma protein causing liquid to leak (edema)

Question 25

What is the term used to describe a substance moving from a peritubular capillary into the renal tubule? A. Reabsorption B. Excretion C. Filtration D. Secretion

Answer 25

D

Question 26

Which of the following components of a nephron perform the function of filtration? A. Glomerulus B. Proximal convoluted tubule C. Medulla D. Thin ascending limb E. Thin descending limb

Answer 26

A

Question 27

sodium reabsorption occurs in the ____ limb of the loop of henle

Answer 27

ascending

Question 28

water reabsorption occurs in the ____ limb of the loop of henle

Answer 28

descending

Question 29

A patient presents to his physician with a 3-week history of frothy urine as well as edema. He also has a history of chronic hepatitis B. A urine dipstick is positive for protein, and a 24-hour urine shows 4 g of protein per day. A renal biopsy demonstrates subepithelial deposits with a spike and dome appearance. The positive urine dipstick for protein is most likely due to damage to what part of the glomerulus? A. Bowman capsule B. Capillary endothelial cells C. Glomerular basement membrane D. Juxtaglomerular cells E. Macula densa

Answer 29

C

Question 30

the first layer of the glomerulus is also called ___________ and prevents what from passing through?

Answer 30

endothelium, blood...albumin

Question 31

the second layer of the glomerulus is called ___________ and prevents what from passing through?

Answer 31

Glomerular basement membrane protein

Question 32

the third layer of the glomerulus is called ___________ and prevents what from passing through?

Answer 32

Epithelium almost everything but water

Question 33

An otherwise healthy 27-year-old patient presents to the emergency department with dark urine and left flank pain. He has had a fever, sore throat, and malaise for the last 2 days. The vital signs include: temperature 38.1°C (100.5°F), blood pressure 120/82 mm Hg, and pulse 95/min. His family history is noncontributory. Physical examination reveals enlarged tonsils with tender anterior cervical lymphadenopathy. Urinalysis shows pink urine with 20–25 red blood cells/high power field (RBCs/HPF) and 2+ protein. This patient’s condition is most likely due to which of the following? A. Inherited abnormalities in type IV collagen B. Autoantibodies against alpha-3 chain of type IV collagen C. C3 nephritic factor D. Immune complex deposition E. Diffuse mesangial IgA deposition

Answer 33

D

Question 34

The final components of urine do NOT include? Select-ALL-that apply:* A. Glucose B. Urea C. Creatinine D. Lipids E. Proteins

Answer 34

A,D,E

Question 35

what is the autoregulatory range of mean arterial blood pressure for maintaining normal renal blood flow?

Answer 35

80-180

Question 36

what effect does angiotensin 2 have one renal circulation? what effect does angiotensin 2 have on RBF and GFR?

Answer 36

causes vasoconstriction of efferent > afferent arteriole decreases RBF and increases GFR

Question 37

what effect does norepi and epi have on renal circulation? what effect does norepi and epi have on RBF and FGR?

Answer 37

vasoconstriction of afferent and efferent arterioles decreases both

Question 38

what effect does natriuretic peptides (ANP, BNP) have on renal circulation? what effect does natriuretic peptides (ANP, BNP) have on RBF and GFR?

Answer 38

vasodilates afferent arteriole and constricts efferent arteriole no change to RBF, increases GFR

Question 39

what effect do prostaglandins have on renal circulation? what effect do prostaglandins have on RBF and GFR?

Answer 39

vasodilation of afferent > efferent arteriole increases both

Question 40

what is the myogenic response for autoregulating GFR and RBF?

Answer 40

if RBF increases, then pressure against the walls of the afferent arteriole increases. the response causes stretch receptors in smooth muscle to initiate vasoconstriction. this response decreases RBF which will decrease the pressure and decrease GFR

Question 41

when tubule flow increases, what is the autoregulation process that causes it to decrease?

Answer 41

with increased tubule flow, more NaCl will enter. Adenosine senses high sodium to cause afferent constriction and efferent dilation to decrease pressure and GFR which decreases tubule flow. the increase of NaCl also reduces renin release which blocks angiotensin 2 (the hormone which prevents efferent constriction)

Question 42

when tubule flow decreases, what is the autoregulation process that causes it to increase?

Answer 42

with decreased tubule flow, less NaCl will enter. this blocks adenosine and increases renin release to produce more angiotensin 2 to cause efferent constriction. this then increases pressure and increases GFR to increase tubule flow

Question 43

overall, the net result of autoregulation keeps GFR and tubule flow constant at all times, what are the simultaneous processes that keep GFR constant?

Answer 43

when afferent pressure decreases due to constriction, GFR falls. however, efferent pressure also decreases due to constriction, and GFR increases. on the opposite, when afferent pressure increases due to dilation, GFR increases. however, efferent pressure also increases due to dilation, and GFR falls

Question 44

Which of the following best describes the relationship between renal flow rate and mean arterial blood pressure within the autoregulatory zone? A. Increased flow, when mean arterial blood pressure increases B. Increased flow, when mean arterial blood pressure decreases C. Decreased flow, when mean arterial blood pressure decreases D. Constant flow, regardless of changes in mean arterial blood pressure E. Decreased flow, when mean arterial blood pressure increases

Answer 44

D

Question 45

Which of the following will be released after a high concentration of NaCl is sensed by the macula densa? A. Renin B. Adenosine C. Angiotensin II D. Angiotensin I E. Aldosterone

Answer 45

B

Question 46

A research study investigates the effects of various medications on the renal vasculature, focusing on the afferent and efferent arteriole. Which of the following most accurately describes the effect of lisinopril [ACE-I] on the renal vasculature? A. Constricts afferent and efferent arteriole B. Constricts afferent arteriole and dilates efferent arteriole C. Constricts afferent arteriole and no change in efferent arteriole D. Dilates afferent arteriole and constricts efferent arteriole E. Dilates both the afferent and efferent arteriole, with preferential dilation of the efferent arteriole F. No change in afferent arteriole, constricts efferent arteriole **explain the answer

Answer 46

E An ACE inhibitor such as lisinopril prevents the conversion of angiotensin 1 to angiotensin 2. since angiotensin 2 causes constriction of both the efferent and afferent arterioles, they will dilate if it is not being produced.

Question 47

Which of the following hormones is a vasoconstrictor? A. Nitric oxide B. Natriuretic hormone C. Bradykinin D. Angiotensin II

Answer 47

D

Question 48

What signal causes the heart to secrete atrial natriuretic hormone? A. Increased blood pressure B. Decreased blood pressure C. Increased Na+ levels D. Decreased Na+ levels

Answer 48

D

Question 49

blood pressure is primarily maintained by the balanced function of what 3 systems?

Answer 49

The Renin-Angiotensin-Aldosterone (RAA) cycle Production of Atrial Natriuretic Peptides Anti-Diuretic Hormone/Vasopressin (ADH/VP)

Question 50

what does the Renin-Angiotensin-Aldosterone (RAA) cycle regulate?

Answer 50

the amount of sodium lost and eliminated in urine

Question 51

what does Anti-Diuretic Hormone/Vasopressin (ADH/VP) do?

Answer 51

controls water balance by regulating the loss and elimination of water into urine

Question 52

describe the renin-angiotensin system which regulates the production of aldosterone

Answer 52

the afferent vessel is stimulated if there is decreased perfusion, low serum sodium, reduced total blood volume, or reduced blood pressure. this triggers the production of renin which is converted to angiotensin 2 to stimulate the adrenal cortex and release aldosterone

Question 53

what is the function of aldosterone?

Answer 53

control the balance of water and salts in the kidney by keeping sodium in and releasing potassium from the body

Question 54

what three things trigger an increased production of aldosterone?

Answer 54

decreased blood pressure decreased renal flow hyperkalemia

Question 55

what is an important adverse reaction of an aldosterone antagonist that should be monitored?

Answer 55

hyperkalemia

Question 56

what drug is an aldosterone antagonist? how does it work?

Answer 56

spironolactone it is a potassium sparing diuretic that can decrease blood pressure, treat edema, and treat heart failure

Question 57

Which hormone plays a role in water reabsorption in the collecting duct/tubule? A. Aldosterone B. Thyroxine C. Anti-diuretic hormone D. Corticotropin-releasing hormone

Answer 57

C

Question 58

what drugs are SGLT-2 inhibitors and what is their mechanism of action?

Answer 58

gliflozins or flozins they block reabsorption of sodium and glucose to decrease blood glucose, reduce blood pressure, and prevent CVD

Question 59

where are SGLT-2s located?

Answer 59

at the renal proximal tubule

Question 60

what is the mechanism of action of ADH?

Answer 60

it binds to the V2 receptor and increases the number of aquaporins which increases water reabsorption

Question 61

what do aquaretics block and why are they not typically used?

Answer 61

they block V2 receptors. they are too potent and cause too much uncontrolled water loss

Question 62

what are the names of 2 two V2 selective antagonist drugs?

Answer 62

conivaptan and tolvaptan

Question 63

A patient with chronic kidney disease [CKD] was admitted for Hgb of 7 gm/dl and HCT of 21%. What is the cause of anemia seen in patients with CKD? A. Decreased erythropoietin production B. Excessive sequestration of red blood cells in the spleen C. Vitamin deficiency D. Red cell membranopathy E. Deficient globin synthesis

Answer 63

A

Question 64

what is approximately normal hematocrit levels?

Answer 64

40%

Question 65

how does the sympathetic nervous system respond to decline in systolic function?

Answer 65

epi and norepi is released via adrenergic receptors to cause: vasoconstriction, increased heart rate, and increased contractility

Question 66

how does the renin angiotensin aldosterone system respond to decline in systolic function?

Answer 66

angiotensin 2 is released to cause: vasoconstriction, increased BP, increased aldosterone, and increased fibrosis (thickening/scarring of heart tissue)

Question 67

how does the natriuretic peptide system respond to decline in systolic function?

Answer 67

NPs released to cause: vasodilation, decreased BP, decreased vasopressin, decreased aldosterone, and decreased fibrosis

Question 68

what drug classes do we use to treat heart failure?

Answer 68

Beta blockers (reduce heart rate and contractility), ACE-Is (block vasoconstriction), and enhancing the natriuretic peptide system

Question 69

what is the mechanism of action of entresto? (sacubitril/valsartan)

Answer 69

blocks conversion of angio 1 to angio 2 and blocks neprilysin from breaking down natriuretic peptides

Question 70

A marathon runner drinks a large quantity of electrolyte solution (sports drink) with expectations to improve performance during races. Elevation of what electrolyte in his urine is responsible for changes in tubuloglomerular feedback? A. Chloride B. Glucose C. Magnesium D. Potassium E. Urea

Answer 70

The correct answer is (A), chloride. In tubuloglomerular feedback, if there is increased sodium and chloride sensed by the macula densa cells at the distal convoluted tubule, this will cause a reflexive constriction of the afferent arteriole, decreasing renal blood flow and thus the glomerular filtration rate. The other answers—glucose (B), magnesium (C), potassium (D) and urea (E)—are not involved in tubuloglomerular feedback.

Question 71

A 48-year-old man comes in to your clinic with lightheadedness. He says he just finished a week-long hike and ran out of water yesterday. His blood pressure is 80/60 mmHg. Recalling the renal physiology you learned, you remember the kidney has a cell that responds to low blood pressure by secreting renin. Which of the following best describes the origin of the cell responsible for secreting renin? A. Endothelium B. Epithelium C. Modified smooth muscle D. Neuron E. Skeletal muscle

Answer 71

The correct answer is (C), modified smooth muscle. The juxtaglomerular (JG) cells are of smooth muscle origin and they reside in the juxtaglomerular apparatus, a section of the nephrons where the ascending limb of the loop of Henle meets with the afferent and efferent arterioles. It is these JG cells that respond to low blood pressure by secreting renin. Endothelial cells (A) can secrete nitric oxide, a vasodilator, or they can secrete endothelin, a vasoconstrictor. JG cells are not epithelial cells (B), neuronal cells (D), or skeletal muscle cells (E).

Question 72

A 70-year-old woman with chronic osteoarthritis is being seen in the hospital. She has had trouble urinating, she is dehydrated, and her glomerular filtration rate (GFR) is very low. She takes an ACE (angiotensin converting enzyme) inhibitor for hypertension. Given her history, what is most likely cause of her low GFR? A. Constriction of the afferent arteriole B. Constriction of the afferent and efferent arterioles C. Constriction of the efferent arteriole D. Dilation of the afferent arteriole E. Dilation of the efferent arteriole

Answer 72

The correct answer is (E), dilation of the efferent arteriole. ACE inhibitors preferentially dilate the efferent arteriole. This is good when we are trying to avoid high glomerular pressures in chronic kidney disease but can lead to a reduced GFR when patients get dehydrated and need the high efferent tone to maintain GFR. ACE inhibitors do not act significantly on the afferent arterioles (A, B, D). They dilate, not constrict, the efferent arteriole (C).

Question 73

While working in a renal physiology lab, you decide to evaluate the effects of physiologic doses of angiotensin 2 by injecting it into subject lab rats and measuring renal blood flow (RBF). Which of the following is true regarding the effects of angiotensin 2 on renal vasculature? A. At low doses, it is a vasodilator of afferent and efferent arterioles. At high doses, it is a vasoconstrictor. B. No change C. Vasoconstriction, preferential vasoconstriction of efferent arteriole with increased filtration fraction D. Vasodilates afferent arteriole, constricts efferent arteriole, increasing filtration fraction E. Vasodilation, preferential vasodilation of afferent arteriole with no increase in filtration fraction

Answer 73

The correct answer is (C), preferential vasoconstriction of the efferent arteriole with increased filtration fraction. Angiotensin 2 will preferentially constrict the efferent arteriole, which will cause a decrease in RBF but an increase in GFR. This combination will lead to an increased filtration fraction. Option (A) describes dopamine. Angiotensin 2 will change RBF and GFR, making choice (B), no change, incorrect. Option (D) describes ANP. Option (E) describes prostaglandins.