NON-PROTEIN NITROGEN COMPOUNDS Flashcards
pair of grandular organs located at the retroperitoneal space
KIDNEYS
slightly lower than the other; adjacent to the liver
right kidney
FUNCTIONS OF THE KIDNEYS
- Excretory function
- Regulatory function
- Endocrine function
eliminates wastes and excess inorganic substances via urine formation
Excretory function
play a major role in homeostasis (balance)
Regulatory function
mechanism of differential reabsorption and secretion in the renal tubule
Regulatory function
Primary Endocrine function
:
production of hormones
Secondary Endocrine function:
degradation of insulin, glucagon and aldosterone
Urine formation
Glomerular filtration
Tubular reabsorption
Tubular secretion
substances are excreted out in the urine
Tubular secretion
substances are transferred from renal tubule to the circulation (ex. electrolytes: sodium - major extracellular cation)
Tubular reabsorption
- major extracellular cation
sodium
– absence of urine output; kidney failure
anuria
urine production diminishes – accumulation of [?]
metabolic waste
maintenance of which substances in the circulation
electrolytes
glucose
amino acids
water
maintenance of substances and pH in the circulation
homeostasis
the kidneys are capable of regulating these processes
mechanism of differential reabsorption and secretion in the renal tubule
– tuft of capillaries
glomerulus
– enclosing the glomerulus
bowman’s capsule
other parts:
renal tubules, ascending/descending loop of Henlee, PCT, DCT
– surrounding the tubules
peritubular capillaries
– hormone that regulates blood pressure
Renin
Renin-Angiotensin-Aldosterone System
Primary
– milk-curdling enzyme produced by neonates
Rennin
similar to pepsin in adults
Rennin
– hormone-like behavior; responsible for pain and muscle contraction (ex. tooth-ache)
Prostaglandin
– prevents production of prostaglandin, relieving pain
Analgesic
- hormone that regulates the production of rbc
Erythropoietin
– action of the hormone is targeted to a particular organ so that a specific process is stimulated and eventually degraded
Target organ
Not protein but has nitrogen in their structure
Most of them are used to evaluate renal function
Derived from the catabolism of proteins and nucleic acids
Clinically significant NPN cpds:
- urea – 45%
- amino acids – 20%
- uric acid – 20%
- creatinine – 5 %
- creatine – 1-2 %
- ammonia – 0.2%
important metabolytes; undergo reabsorption
- amino acids
- creatine
for protein production
amino acids
for energy metabolism
creatine
found in skeletal muscles
creatine
Nitrogen in a protein-free filtrate (a specimen) is converted to NH3 (ammonia) using hot H2SO4 (sulfuric acid)
KJELDAHL DIGESTION
Nessler’s reagent –
double iodide salt of potassium & mercury
– yellow to orange brown product
Dimercuric ammonium iodide
BERTHELOT METHOD
Reactant:
Reagent:
Catalyst:
Product:
NH3
phenol and alkaline hypochlorite
sodium nitroprusside (sodium ferricyanide)
indophenol blue
Modification by Searcy: using [?] (less toxic; used in the production of aspirin) instead of phenol
salicylic acid
MONITORING CONSUMPTION OF AMMONIA
Reaction:
Catalyst:
NH3
Glutamate dehydrogenase
Measure a decrease in the absorbance at 340 nm
MONITORING CONSUMPTION OF AMMONIA
Most abundant NPN compound
UREA
Major nitrogen-containing product of protein catabolism
UREA
Cycle
Krebs Henseleit Cycle
– removal of the amino group
Deamination
in retained in low conc in the circulation
Ammonia
~90% is excreted through the kidney
UREA
