Nitrogen Metabolism

During growth periods during childhood and adolescence, pregnancy 11

• Positive nitrogen balance

• Negative nitrogen balance

In a healthy, well-fed adult, input of amino acids = _____ of amino acids. The amino acid pool is in a steady state / equilibrium. 6

____ is the site where most of the amino acids release their amino groups as ammonia 16

Seen in starvation, chronic illness (infections), cancer, uncontrolled diabetes mellitus 12

• Positive nitrogen balance

• Negative nitrogen balance

Degrades plasma proteins and proteins taken up by endocytosis 8

• Ubiquitin-proteasome pathway

• Lysosomal pathway

____ is the major end product of nitrogen metabolism 16

Positive nitrogen balance: Intake of dietary nitrogen is ___ the output of nitrogen 11

• Less than

• Greater than

Urea formed in the liver is transported to the kidneys, where it is excreted in the urine.  The kidneys also excrete ammonia as ammonium ions.  The other non-protein nitrogenous substances that are excreted by the kidney are creatinine and _____ acid. 17

Amino acids are used in amino acid catabolism and in the _______ of nitrogen containing compounds.slide 4

Non-energy dependent degradative pathway 8

• Ubiquitin-proteasome pathway

• Lysosomal pathway

Increase in urinary excretion of urea 12

• Positive nitrogen balance

• Negative nitrogen balance

ATP dependent 8

• Ubiquitin-proteasome pathway

• Lysosomal pathway

Increased tissue protein synthesis

• Positive nitrogen balance

• Negative nitrogen balance

Which of the following statements is true? 13

• All amino acids are glucogenic

• All amino acids are essential amino acids

• Amino acid catabolism is increased during starvation

• The major excretory end product of amino acid catabolism is ammonia

• Tissue protein synthesis is decreased during periods of growth

In a patient with renal disease, which of the following parameters would be the best indicators of renal function? 19

• Serum ammonia

• Serum albumin

• Blood glucose

• Serum free fatty acids

• Blood urea nitrogen

Niacin deficiency's 3 d's: dermatitis, diarrhea, and ______. 23

In infection, the liver synthesizes a group of proteins known as the ____-phase proteins.  C-reactive protein, serum amyloid A protein, haptoglobin, ceruloplasmin levels are increased in circulation in any type of inflammation. 15

The rate of tissue protein synthesis is equal to the rate of protein ________. slide 5

Damaged or unneeded proteins are degraded by two mechanisms: the lysosomal pathway that degrades extracellular proteins and the ubiquitin-______ pathway that degrades proteins synthesized by the cell 7

Tubular reabsorption of cystine is decreased due to an inherited deficiency of the cystine transporter.  Cystine is excreted in urine and tends to precipitate in the renal tubules in the renal tract - one of the causes of renal ____ in children 21.

_____ supplements can be used as treatment for pellagra 22

Compounds that contain nitrogen: proteins, derivatives of amino acids: creatine, ________, purines and pyrimidines, hemeslide 2

Hartnup's disease - inherited defect in the transport of the ___ amino acids like tryptophan 22

A 12 year old child is suspected of having pellagra because of chronic symptoms including diarrhea, a red scaly rash, and mild cerebellar ataxia.  However, his diet is not deficient in protein and he appears to be ingesting adequate amounts of niacin.  A sister has a similar problem.  Chemical analysis of his urine demonstrates large amounts of free amino acids.  Which amino acid do you expect to find in the urine? 23

• Cystine

• Phenylalanine

• Tyrosine

• Tryptophan

• Branched chain amino acids

The carbon skeletons of the amino acids are used for __________. 16