PRELIM-renal function Flashcards by CHARLENE SAN JOSE

how many percent of blood that is pumped by the heart are being filtered by the kidney?

25%

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Plasma filtrate must pass through three glomerular filtration
barrier cellular layers: the , the ___, and the ___

capillary wall membrane,
basement membrane (basal lamina)
visceral epithelium of
Bowman’s capsule.

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The endothelial cells of the capillary wall differ from those in other capillaries by containing pores and
are referred to as ___.

fenestrated

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In addition to the structure of the glomerular filtration bar
rier that prohibits the filtration of large molecules, the barrier
contains a ____ positive charge even though they are small enough to pass
through the three layers of the barrier

shield of negativity that repels molecules with a

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example of a component being repelled by a shield of negativity

albumin

albumin (the primary protein associated with
renal disease) has a positive charge and would easily pass
through the barrier

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what are the Factors influence the actual filtration process

Cellular structure of the capillary walls and bowman’s capsule
Hydrostatic and oncotic pressures
Feedback mechanisms of the renin angiotensin-aldosterone system

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a part of glomerulus that is

o Containing pores and are referred to as fenestrated
o Pores increase capillary permeability but do not allow the passage of large molecules and blood cells

Capillary wall membrane

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a part of glomerulus that is

o Restriction of large molecules occurs as the filtrate passes

Basement membrane

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a part of glomerulus that is

o Thin membranes covering the filtration slits formed by the intertwining processes of the podocytes of the inner layer of bowman’s capsules

Visceral epithelium of bowman’s capsule

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Prevent a marked decrease in blood flowing through the kidney, thus preventing an increase in the blood level of toxic waste products

Dilation of the afferent arterioles and constriction of the efferent arterioles

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a mechanism of the arterioles managed by the juxtaglomerular apparatus
to prevent over-filtration or damage to the glomerulus

constriction of the afferent arterioles and the dilation of the efferent

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regulates the flow
of blood to and within the glomerulus. The system responds
to changes in blood pressure and plasma sodium content that
are monitored by the juxtaglomerular apparatus

The renin-angiotensin-aldosterone system

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what are the function of angiotensin II

: causing vasodilation of the afferent arterioles and constriction of the efferent arterioles
: stimulating reabsorption of sodium and water in the proximal convoluted tubules,
: triggering the release of the
sodium-retaining hormone aldosterone by the adrenal cortex
: Release of antidiuretic hormone from hypothalamus.

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the action of ___ is to produce a constant pressure within the
nephron

angiotensin II

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only difference between the compositions of the filtrate and the plasma is the __

absence of plasma protein, any protein-bound substances, and cells.

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the specific gravity of a fluid leaving the glomerulus and stating that it is really an ultrafiltrate of the plasma is __

specific gravity of 1.010

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what are the two/2 cellular mechanisms involved in tubular reabsorption

active transport and passive transport.

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a cellular mechanism involved in reabsorption that needs a carrier protein contained in the membrane of the renal tubular epithelial cells

active transport

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active transport is responsible in reabsorption of ____ in ____

glucose, amino acids, and salts in the proximal convoluted tubule,

chloride in the ascending loop of Henle,

sodium in the proximal and distal convoluted tubule.

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passive transport is responsible in reabsorption of ____ in ____

WATER in Proximal convoluted tubule
Descending loop of Henle
Collecting duct

urea in Proximal convoluted tubule
Ascending loop of Henle

sodium in Ascending loop of Henle

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the movement of molecules across a
membrane as a result of differences in their concentration or
electrical potential on opposite sides of the membrane

passive transport

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what is it called to a physical differences in the concentration or electric potential on opposite sides of the membrane; related to passive transport

gradient

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which part of the nephron is impermeable to water?

ascending loop of henle

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if the concentration of the substances needed to be reabsorved reached the ___ the substances will appear on the urin

maximal reabsorptive capacity

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The plasma concentration at which active transport stops is termed the ___.

renal threshold

renal threshold for glucose

160-180 mg/dl

Glucose appearing in the urine of a person with a normal blood glucose level is the result of tubular damage and not diabetes mellitus. true or false

true

A non fasting patient with high glucose intake would not have a normal blood glucose. true or false

true

Renal concentration begins in the ___, where the filtrate is exposed to the high osmotic gradient of the renal medulla

descending and ascending loops of Henle

Water is removed by osmosis in the descending loop of Henle, and sodium and chloride are reabsorbed in the ascending loop. Excessive reab sorption of water as the filtrate passes through the highly con centrated medulla is prevented by the water-impermeable walls of the ascending loop. This selective reabsorption process is called the ___ and serves to maintain the osmotic gradient of the medulla

countercurrent mechanism

The final concentration of the filtrate through the reabsorption of water begins in the ___ and -__

late distal convoluted tubule and continues in the collecting duct

in collecting duct, A high level of ADH will what the permeability and what will happen to the urine concentration

A high level of ADH increases permeability, resulting in increased reabsorption of water, and a low-volume concentrated urine

what is the actual final determinant of urine volume and concentration?

chemical balance in the body

2 purpose of tubular secretion

eliminating waste products not filtered by the glomerulus regulating the acid–base balance in the body through the secretion of hydrogen ions.

The major site for removal of these nonfiltered substances/ or for the secretion is the ___

proximal convoluted tubule

ammonia is produced from the breakdown of the __

amino acid glutamine.

explain how bicarbonate ions are kept in the plasma and prevented from getting secreted by the hydrogen ions

the secretion of hydrogen ions (H+) by the renal tubular cells into the filtrate prevents the filtered bicarbonate from being excreted in the urine and causes the return of a bicarbonate ion to the plasma.

where does the hydrogen ions are secreted?

in the proximal convoluted tubule

aside from the distal convoluted tubule, which part of the nephron is able to secret ammonium ion as well?

collecting duct

A disruption in these secretory functions can result in ___, the inability to produce an acid urine.

metabolic acidosis or renal tubular acidosis

The standard tests used to measure the filtering capacity of the glomeruli are termed ___

clearance tests

In clearance test, A test that requires an infused substance is termed an ___ and is seldom the method of choice if a suitable test substance is already present in the body (____).

exogenous procedure; endogenous procedure

* Standard method for Glomerular Filtration Rate

Urea Clearance test

The earliest glomerular filtration tests measured urea because of its presence in all urine specimens and the existence of routinely used methods of chemical analysis.

urea clearance test

urea clearance test has how many percent of urea as its indication?

40%

was the original refer ence method for clearance tests,

inulin clearance test

a polymer of fructose, is an extremely stable sub stance that is not reabsorbed or secreted by the tubules. It is not a normal body constituent, however, and must be infused by IV at a constant rate throughout the testing period.

inulin cleareance test

2 types of infusion for inulin clearance test

priming dose and continuous infusion

give the concentration of each type of infusion for inulin clearance test

o Priming Dose: 25 mL of 10% Inulin Solution o Continuous Infusion: 500 mL of 1.5% Inulin Solution

reference values for inulin clearance test

 127 mL/min → Male  118 mL/min → Female

is a waste product of muscle metabolism that is pro duced enzymatically by creatine phosphokinase from creatine,

creatinine

Because creatinine is normally found at a relatively constant level in the blood,, it provides the laboratory with an endogenous procedure for evaluating glomerular function.

creatinine clearance test

Some creatinine is secreted by the tubules, and secretion increases as blood levels ___. increase or decrease

increase / rise

true or false . Bacteria will break down urinary creatinine if specimens are kept at room temperature for extended periods

true

Medications, including gentamicin, cephalosporins, and cimetidine (Tagamet), inhibit tubular secretion of creati nine, thus causing falsely low serum levels. true or false

true

Measurement of creatinine clearance is not a reliable indicator in patients suffering from MUSCLE-WASTING DISEASES or persons involved in heavy exercise or athletes SUPPLEMENTING with creatine. true or false

true

for creatine clearance test, Accurate results depend on the accurate completeness of __

a 24-hour collection.

GFR is reported in what units?

milliliters per minute (ml/mn)

whatis the most frequently used formula for ESTIMATED GLOMERULAR FILTRATION RATE or eGFR

Modification of Diet in Renal Disease (MDRD) study

significance of creatinine clearance test or cct

o Determines the functional Capacity of Nephrons o Determines the extent of nephron damage in known cases of renal disease o Monitor the effectiveness of treatment o Determine the feasibility of administering medications

reference values for creatinine clearance test

 107-139 mL/min → Male  87-107 mL/min → Female * Normal reference of plasma creatinine is 0.5-1.5 mg/dL

Measurement of serum ___ has been shown to provide a good procedure for screening and monitoring GFR

cystatin C

is a small protein (molecular weight 13,359) produced at a constant rate by all nucleated cells.

cystatin C

An advantage of cystatin C is that it is independent of muscle mass. true or false

true

Recent studies also have shown that measuring both serum or plasma ____ and __-- can provide even more accurate information on a patient’s GFR.6

cystatin C and creatinine

do we need fasting for the cystatin?

nope

diseases we can identfy elevated cystatin C?

Acute & Chronic Renal Failure, Diabetic Nephropathy

* Indirect estimate of GFR

cystatin C

* Dissociates from human leukocyte antigens at constant rate and is rapidly removed from plasma by glomerular filtration

beta 2 microglobulin

* A rise has been to be more sensitive indicator of decrease in GFR than creatinine clearance

beta microgolobulin

* Not reliable in patient who have history of immunologic disorder or malignancy

beta 2 microglobulin

a methos for beta - 2 microglobulin

enzyme immunoassay

It would monitor the high risk for renal disease such as patients with uncontrolled hypertension, patients who are diabetic; the most common complication of DM is Kidney Failure

estimated glomerular filtration rate or the eGFR

the ___ is often the first function affected in renal disease.

loss of tubular reabsorption capability

Tests to determine the ability of the tubules to reabsorb the essential salts and water that have been nonselectively filtered by the glomerulus are called ___

concentration tests

the ultrafiltrate that enters the tubules has a specific gravity of 1.010; therefore, after reabsorption one would expect the final urine product to be more CONCENTRATED true or false

true

___ measures only the number of particles in a solution,

osmolality

specific gravity is influenced by the number and ___ of the particles.

density (molecular weight)

___ is performed for a more accurate evaluation of renal concentrating ability

osmolality

stage 1 of GFR rate

kidney damage with normal or elevated GFR > or -- to 90

stage 2 of GFR rate

kidney damage with mild decrease of GFR 60-89

stage 3 of GFR

moderate decrease of GFR 30-59

stage 4 of GFR rate

severe decrease of GFR 15-29

stage 5 of decrease GFR

kidney failure lower than 15 <15 or dialysis

2 test we can conduct for the specific gravty

fishberg test and mosenthal test

a test in SG in which the patients are deprived of fluids for 24 hours prior to measuring SG

fishberg test

a test for SG in which it Compares volume and specific gravity of urine of day and night urine samples

mosenthal test

o Renal concentration is concerned with small particles, primarily ___

sodium and chloride molecules

* Large molecular-weight molecules such as __- and _-_ do not contribute to the evaluation of renal concentration

glucose and urea

Principle: Measurement of Dew point

VAPOR PRESSURE OSMOMETERS

* Temperature at which water vapor condenses to a liquid * Standard reference: NaCl

VAPOR PRESSURE OSMOMETERS

Temperature at which water and ice are in equilibrium and is related to solute concentration Standard Reference: NaCl

FREEZING POINT OSMOMETERS

_____ are used primarily to analyze serum and sweat microsamples for disorders NOT RELATED to renal function, such as cystic fibro sis. They are used primarily in the chemistry department.

Vapor pressure osmometers

disease we can use vapor pressure osmometer

cystic fibrosis

total renal blood flow through the nephron must be measured by a substance that is ___ rather than filtered through the glomerulus

secreted

The test most commonly associated with tubular secretion and renal blood flow is the ____

p-aminohippuric acid (PAH) test.

To measure the exact amount of blood flowing through the kidney, it is necessary to use a substance that is completely removed from the blood (plasma) each time it comes in contact with functional renal tissue

PAH Test

if the PAH wasn't able to be in ocntact with the fnctional renal tissue, it will be secreted in the ___

proximal convoluted tube

The inability to produce an acid urine in the presence of metabolic acidosis is called _____

renal tubular acidosis.

__are the measurements can be used to determine the defective function of tubular secretion primarily the proximal or distal convoluted tube

Urine pH, titratable acidity, and urinary ammonia