Weight Loss and Nitrogen Metabolism Flashcards
What happens to food energy
metabolic pool in body to internal/external work to thermal energy
and/or
energy stored
How is daily energy expenditure used
purposeful activity (25%)
non exercise activity (7%)
Thermic effect of food (8%)
Basal metabolic rate (60%)
what are the energy stores
Lipids (~85%)
Proteins (~15%)
Carbohydrates (~0.6%)
Where are the energy stores located
Liver - major glycogen reserve
Adipose tissue - stores lipids as triglycerides
Skeletal muscle - half of protein in the body and glycogen reserve
Neural tissue - reliable supply of glucose
Other peripheral tissue - metabolise substrates under endocrine control
What does low blood glucose cause
coma and death
What happens to energy stores during starvation
1) carbohydrates rapidly deplete
2) fat
3) protein
What is cachexia
muscle wasting with cancer
what is sarcopenia
muscle wasting with age
frailty
where is the major amino acid and nitrogen reserve in the body
muscle
Types of muscle wasting
-starvation
-injury/illness
-immobilisation (wasting of thigh muscle)
-nerve damage
-cancer
-AIDS
-sepsis
-renal failure
-sarcopenia
-spaceflight
What causes muscle wasting
difference between nitrogen input into the body (dietary) and nitrogen excretion mainly as urea
How are proteins degraded
Proteins converted to AA
AA turn into pyruvate
pyruvate enters TCA cycle/oxidative phosphorylation
What are the 2 proteins for proteolysis
1) lysosomes
2) proteasomes
proteases of degradation
aminopeptidases - dipeptidases
calpains - cleave contractile proteins
caspases - cell death regulatory e.g. apoptosis
Lysosome pathway
degrades extracellular and cell surface proteins via endosomes and most proteins via autophagosomes
(common in starvation)
