Nitrogen Economy 1 Flashcards
What does nitrogen enter the body as? (AAs / fats / carbs)
Mostly as amino acids in dietary protein!
Gluconeogenesis is fueled by 3 raw materials. What are they?
- glycerol (from lipolysis)
- lactate (from anaerobic metabolism)
- amino acids (alanine)
Degradation of proteins is determined by _____.
The half-life of proteins
P, E, S, T significance. regarding half-lives?
Proline, Glutamate, Serine and Threonine all have SHORT half-lives
Characteristics of Parietal cells
- Produce HCl, keeping stomach pH below 1
- Contain carbonic anhydrase
Role of secretin?
- Stimulates pancreatic bicarbonate secretion, which neutralizes gastric HCl
I cells secrete ____ which use (Gs/Gq) to activate IP3 and DAG to release enzymes
CCK, Gq
S cells secrete ____ which use (Gs/Gq) to activate CAMP
Secretin, Gs
Transport of amino acids into cells?
Secondary transport; Na+ linked co-transport. Very high oxygen demand is seen.
In Cystinuria, the apical transport system, ____, mediates influx of amino acids and ____
B-zero +, CSSC
If the B-zero + transporter is defective, what results?
Cystinuria, because of the accumulation and thus, precipitation, of CSSC. (kidney stones)
In cystinuria, which amino acid must be restricted, as a diet?
Methionine, bc it can break down and form cystine.
Cystinosis
- Cystine accumulates in the lysosomes and cannot be exported out to the cytosol
Hartnup disease
- Due to amino acid transporter deficiency (failing to absorb tryptophan)
- Pellagra-like sx are seen
With Hartnup dx, if Trp cannot be absorbed: what, then, cannot occur as a product?
Niacin! In Hartnup dx, niacin will be deficient bc there is no Trp to process into niacin
In patients with Niacin deficiency, what do they develop?
Pellagra (4 Ds: diarrhea, dermatitis, dementia, death)
Where is urea produced? Where is ammonia produced?
Urea is produced in the liver, and ammonia is produced in the kidney
In which state (fed/fasting) is the most urea produced?
During the first day or so, of the fasting period
Which “long term stress hormone” initiates the degradation of body protein?
Cortisol - it supports gluconeogenesis in the fasting state, thereby accelerating nitrogen loss
During a fasting state, as proteins are being degraded for fuel, which are the main two AAs?
Alanine and Glutamine
- Both go to the liver (used in gluconeogenesis).
- The nitrogen is disposed as urea
Exercise increases activity of the purine nucleotide cycle, which converts _____ to _____ plus ammonia
Converts aspartate to fumarate
An increase in the amount of fumarate increases the capacity of the TCA cycle
