SERUM CREATININE TEST Flashcards
Quantitation of overall function of the kicneys is based on the assumption that all functioning nephrons are performing normally and that a decline in renal function is due to loss of functioning_____ quantitatively related to the loss.
nephrons
in nearly all types of diffuse renal disease, impaired function of the kidneys is attributed to a diminished number of functioning_____rather than to compromised function of individual nephrons.
nephrons
Because _____is the initiating phase of all nephron functions, quantitative or qualitative assessment of______-or some variable that bears a constant relationship to it-generally provides the most useful indices for physicians to assess the severity and progress of kidney damage.
glomerular filtration
filtration
Kidney
The most prominent functions are removal of______(both waste and surplus),
______(maintenance of equilibrium) of the body’s water,
________ status, and
participation in______ regulation.
unwanted substances from plasma
homeostasis
electrolyte and acid-base
hormonal
In the clinical laboratory,_________ are used in assessment of
renal disease,
water balance,
acid acid-base disorders and in situations of trauma,
head injury,
surgery,
infectious disease.
kidney function tests
The______ are paired, bean-shaped organs located retroperitoneally on either sicle of the spinal column.
Macroscopically, a fibrous capsule of connective tissue encloses each kidney.
kidneys
When dissected longitudinally, two regions can be clearly discerned -an outer region called the_____ and an inner region called the_____.
The____ can also be seen.
cortex
medulla
pelvis
It is a basin-like cavity at the upper end of the ureter into which newly formed urine passes.
Pelvis
The bilateral_____ are thick-walled canals, cornecting the kidneys to the urinary bladder.
ureters
Urine is temporarily stored in the_____ until voided from the body by way of the urethra.
Urinary bladder
The______ is the first part of the nephron and functions filter incoming blood.
glomerulus
Several factors facilitate filtration.
One factor is the unusually_____ in the glomerular capillaries, which is a result of their position between two_____.
This sets up a steep pressure difference across the walls.
high pressure
arterioles
Another factor is the_________, which has a molecular size cutoff value of approximately ______ about the molecular size of albumin.
semipermeable glomerular basement membrane
65,000 Da,
This means that (5) pass freely through the basement membrane and enter the proximal convoluted tubule.
WEAGUC
water
electrolytes
glucose
amino acids
urea
creatinine
Other blood constituents, such as(4), are too large to be filtered.
albumin;
many plasma proteins;
cellular elements;
protein-bound substances, such as lipids and bilirubin
the basement membrane is negatively charged, negatively charged molecules, such as____, are repelled.
proteins
Of the ________ of blood that the kidneys receive each minute (approximately one quarter of the total cardiac output), the glomerulus filters out_______ of an essentially protein-free, cell-free fluid, called_____
1200-1500 mL
125-130 mL
glomerular filtrate
Glomerular filtrate
125-130 mL
The _____is the next part of the nephron to receive the now cell-free and essentially protein-free blood.
This filtrate contains waste products, which are toxic to the body above a certain concentration, and substances that are valuable to the body.
proximal tubule
One function of the proximal tubule is to return the bulk of each valuable substance back to the blood circulation.
Thus,____% of the water, sodium, and chloride;
___% of the glucose (up to the renal threshold);
______of the amino acids, vitamins, and proteins;
and_____ of urea, uric acid, and ions, such as magnesium, calcium, potassium, and bicarbonate, are reabsorbed.
75%
100
almost all
varying amounts
Almost all (_____) of uric acid, a waste product, is actively reabsorbed, only to be secreted at the distal end of the proximal tubule.
98%-100%
When the substances move from the tubular lumen to the peritubular capillary plasma, the process is called_______.
tubular reabsorption
With the exception of_____ and ____ ions, the process is active; that is, the tubular epithelial cells use energy to bind and transport the substances across the plasma membrane to the blood.
The transport processes that are involved normally have sufficient reserve for efficient reabsorption, but they are saturable.
water and chloride ions
When the concentration of the filtered substance exceeds the capacity of the transport system, the substance is then excreted in the_____.
The plasma concentration above which the substance appears in urine is known as the________, and its determination is useful in assessing both tubular function and nonrenal disease states.
urine
renal threshold
A second function of the proximal tubule is to secrete products of kidney tubular cell metabolism, such as_____ and _____ such as penicillin.
hydrogen ions and drugs
1) tubular secretion describes the movement of substances from_____ to _____, and
2) tubular secretion also describes when tubule cells secrete products of their own cellular metabolism into the filtrate in the tubular lumen.
peritubular capillary plasma to the tubular lumen
The osmolality in the medulla in this portion of the nephron increases steadily from the corticomedullary junction inward and facilitates the reabsorption of (3)
SCW
water
sodium
chloride
The hyperosmolality that develops in the medulla is continuously maintained by the_______, a hairpin-like loop between the proximal tubule and the distal convoluted tubule.
The opposing flows in the loop, the downward flow in the descending limb, and the upward flow in the ascending limb, is termed a_______
loop of Henle
countercurrent flow
To understand how the hyperosmolality is maintained in the medulla, it is best to look first at what happens in the ascending limb.
Sodium and chloride are actively and passively reabsorbed into the medulla interstitial fluid along the entire length of the ascending limb.
Because the ascending limb is relatively_________ to water, little water follows and the medulla interstitial fluid becomes______ compared with the fluid in the ascending limb.
impermeable
hyperosmotic
The fluid in the ascending limb becomes _____ or ____ as sodium and chloride ions are reabsorbed without the loss of water, so the ascending limb is often called the______ segment.
hypotonic or dilute
diluting segment
The descending limb, in contrast to the ascending limb, is______ to water and does not reabsorb_____ and ____
The high osmolality of the surrounding interstitial medulla fluid is the physical force that accelerates the reabsorption of water from the filtrate in the descending limb.
highly permeable
sodium and chloride
Interstitial hyperosmolality is maintained because the ascending limb continues to pump sodium and chloride ions into it.
This interaction of water leaving the descending loop and sodium and chloride leaving the ascending loop to maintain a high osmolality within the kidney medulla produces ______ urine as it leaves the loop.
This process is called the__________.
hypo-osmolal urine
countercurrent multiplier system
T or F
The distal convoluted tubule is much shorter than the proximal tubule, with two or three coils that connect to a collecting duct.
TRUE
The filtrate entering this section of the nephron is close to its final composition.
DCT
In the DCT
About____% of the sodium and chloride ions and____% of water have already been reabsorbed from the original glomerular filtrate.
95
90
The function of the______ is to effect small adjustments to achieve electrolyte and acid-base homeostasis.
These adjustrents occur under the hormonal control of both (2)
distal tubule
antidiuretic hormone (ADH) aldosterone
is a peptide hormone secreted by the posterior pituitary gland, mainly in response to increased blood osmolality;
ADH
ADH is a peptide hormone secreted by the________ mainly in response to increased blood osmolality;
posterior pituitary gland
ADH is also released when blood volume decreases by more than_____
Large decreases of blood volume will stimulate ADH secretion even when plasma osmolality is decreased.
5%-10%
ADH stimulates water_____.
The watts of the distal collecting tubules are normally_____ to water (like the ascending loop of Henle), but they become______ to water in ADH.
Water diffuses passively from the lumen of the tubules, resulting in more concentrated urine and decreased plasma osmolality.
reabsorption
impermeable-permeable
Aldosterone is produced by the_____ under the influence of the renin-angiotensin mechanism.
Its secretion is triggered by_____ blood flow or blood pressure in the afferent renal arteriole and by decreased plasma sodium.
adrenal cortex
decreased
Aldosterone stimulates_____ reabsorption in the distal tubules and potassium and hydrogen ion secretion.
Hydrogen ion secretion is linked to bicarbonate regeneration and ammonia secretion, which also occur here.
In addition to these ions, small amounts of chloride ions are reabsorbed.
sodium
stimulates sodium reabsorption in the distal tubules and potassium and hydrogen ion secretion.
Aldosterone
The____ are the final site for either concentrating or diluting urine.
collecting ducts
The hormones ADH and aldosterone act on this segment of the nephron to control reabsorption of water and sodium.
Collecting ducts
Chloride and urea are also reabsorbed here.
______plays an important role in maintaining the hyperosmolality of the renal medulla.
Collecting ducts
Urea
Because the collecting ducts in the medulla are highly permeable to____, it diffuses down its concentration gradient out of the tubule and into the medulla interstitium, increasing its osmolality.
urea
The determination of______ substances in the blood has traditionally been used to monitor renal function.
The term ______ originated in the early days of clinical chemistry when analytic methodology required removal of protein from the sample before analysis.
nonprotein nitrogenous substances
nonprotein nitrogen (NPN)
Although measurement of total urinary nitrogen is of value in the assessment of nitrogen balance for nutritional management, more useful clinical information is obtained by analyzing a patient’s specimen for individual components of the______
NPN fraction
(3) are nonprotein nitrogenous metabolites that are cleared from the body by the kidney following glomerular filtration.
Creatinine
urea
uric acid
Measurements of plasma or serum concentrations of these metabolites are commonly used as indicators of kidney function and other conclitions.
Creatinine, urea, and uric acid (nonprotein nitrogenous metabolites)
