Lab #8: Renal Physiology Flashcards
How do the kidneys achieve homeostasis?
They achieve this homeostasis by
regulating the pH and concentration of ions and water in the various body fluids and they also provide for the elimination of the waste products of metabolism
How many nephrons are in the kidneys?
1 million
What 2 structures do nephrons contain?
renal corpuscle and renal tubule
what, where, and how fast is blood first filtered through?
a tuft of capillaries in the glomerulus at a rate of 120 ml/min
What is the renal tubule made up of?
- Proximal convoluted tubule (PCT)
- Nephron loop (Loop of Henle)
- Distal convoluted tubule (DCT)
Tubular filtrate
similar to blood plasma in composition except that large molecules over 70,000 MW are excluded (e.g., plasma proteins)
What is retained in the filtrate?
Toxic by-products of metabolism and excess substances, such as salt, are retained in the filtrate and are finally excreted in the urine (approximately 1 ml of urine formed per minute)
what does the final composition of urine reflect?
the final composition of urine is quite different from that of the glomerular filtrate and reflects the integrity of kidney function and changes in blood composition.
an analysis of urine
urinalysis
phenylketonuria (PKU)
genetically unable to metabolize the amino acid phenylalanine
if accumulated in the body, phenylalanine is converted into what?
phenylpyruvic acid
An accumulation of phenylalanine in individuals with PKU can result in
developmental delays, seizures, and intellectual impairments
Individuals with _________ _________ , have either an imbalance or a deficit in the amount of insulin produced by the pancreas
diabetes mellitus (commonly referred to simply as diabetes)
fatty acid metabolites
ketones
an increase in ketones causes the pH to _______
decrease
what is indicative of diabetes mellitus?
The presence of both glucose and ketones in the urine combined with a low urine pH
a combined test of urinary pH, protein, glucose, ketones, and occult blood
Labstix Test
The normal pH value of urine
~ 6 (can range from 4.5-8.0)
The normal protein value of urine
none or trace
The normal glucose, ketone, and occult blood level of urine
none
What makes the pH of urine more acidic?
a diet rich in proteins or can result from respiratory disorders, dehydration, or starvation
Alkaline urine
can result from a diet rich in citrus fruits and dairy, vomiting, urinary tract infections
Cystitis
urine decomposes in the bladder with the production of ammonia
the presence of protein in the urine
proteinuria or albuminuria
high glucose levels in the urine
glycosuria
Abnormally large amounts of ketone excretion
ketonuria
ketonuria suggest that the body is using fat as an energy source as opposed to glucose and can…
indicate either diabetes mellitus or starvation
blood not visible to the naked eye
Occult blood
Blood present in the urine can indicate that an individual has
a urinary tract infection, kidney stones, or cancerous cells
a disease in which the glomeruli are damaged and plasma proteins and erythrocytes leak into the nephrons
nephritis
individuals with nephritis will have….
blood present in their urine as well as high levels of protein
One of the kidney’s main functions is to
regulate the osmolarity of the body fluids at around 300 milliosmoles per liter to ensure the cells, particularly those in the brain, do not shrink or swell
if an individual is dehydrated,
they will produce a small amount of highly concentrated urine
If an individual is overhydrated,
they will produce a large amount of minimally concentrated (dilute) urine
Specific Gravity
The ratio of the density of a substance compared to the density of distilled water
The urinometer is calibrated to give a correct reading only if the urine is at
15 degrees celcius
If your urine is at a different temperature, you will need to correct the specific gravity value by
adding 0.001 for every 3 degrees celcius above, or by
subtracting 0.001 for every 3 degrees celcius below the calibration temperature (15 degrees celcius)
The normal range of urine specific gravity is
1.0015 to 1.035
low specific gravity reading
found in individuals with chronic nephritis (slow, onset kidney disease)
high specific gravity
is observed in acute nephritis (sudden, onset kidney disease)
Mohr Method (NaCl Concentration)
The process of titrating silver nitrate to analyze the presence of chloride ions in a substance using potassium chromate as an indicator
In the Mohr Method, you add first
one drop of 20% potassium chromate to the test tube
In the Mohr method, you add second
2.9% silver nitrate solution drop by drop to the test tube
Each drop of 2.9% silver nitrate added to produce the
reddish-brown colored solution represents
1 g/liter of NaCl present in the urine
