5.6 Flashcards
Metabolism refers to
Chemical reactions in the body
1 calorie= ___ J
4.2 Joules
How do we measure the amount of energy food provides?
Calorimeter- burns food
energy content of carbohydrates
17.2 kJ/gram
energy content of proteins
17.2 kJ/gram
respiratory quotient (RQ) is the ratio:
RQ = CO2 eliminated / O2 consumed
for each nutrient the metabolism is different
energy content of fat
39 KJ/gram
RQ for carbohydrates
1
RQ for proteins
0.82
RQ for fat
0.7
How can we measure TEE?
measuring a personws heat production (=rate of metabolism)
TEE=
heat production + external work
What is the indirect method of measuring TEE?
we measure oxygen consumption
Define BMR
minimal energy expenditure required to exist
awake, without physical activity
TEE=
BMR + DIT + EE in physcial activity
Diet Induced Thermogenesis
How do we measure BMR?
- usually in the morning
- no physical activity
- 20 C
- no food
- no stress
- no drugs
Normal BMR values
Men= 7,000 KJ/day Women= 6,000 KJ/day
BMR is influenced by
- body size
- sex
- age
- temparture
- climate
- pregnancy
- some hormones
- drugs, stress, injuries
BMR is how much of TEE?
usually 50-70%
DIT is how much of TEE?
10-15%
EE in physical activity is how much of TEE?
15-30%
Brown adipose structure?
less fat
a lot of mitochondria
What is the special feature of brown adipocyte?
their mitochondria contains Uncouplin Protein (UCP1)
UCP1 effect?
allows H+ to flow from intermembrane space to matrix
leading to less ATP synthesis and more heat production
What does stimulation of B3 R on brown adipocytes lead to?
Gs
Hormone sensitive Lipase activation
TAG cleavage
free FA activate UCP1
What will stimulate the baige adipose tissue?
exposure to cold and to catecholamines
feeding center and satiety center get info from
arcuate nucleus
POMC
Pro Opio Melano Cortin
Anorexigenic neurons release
POMC -> decreased appetite
Orexigenic neurons release
Neuropeptide Y -> increased appetite
effects of leptin
- decreased hunger (stimulate anorexigenic neurons)
- increased thermogenesis
- increased energy expenditure
so overall to restore adipose tissue mass to set point
Neuropeptides from GI that will decrease hunger?
- GLP1 (stimulates insulin secretion)
- Peptide YY (inhibits ghrelin)
- CCK (Chylocystokinin)
- CART (Cocaine-And-Amphetamine-Regulated-Transcript)
Neuropeptides from GI that will increase hunger?
- Ghrelin (GHRH)
- Orexins (fight against sleep)
