Topic 6.6 Flashcards
What are the 3 sources of energy in the body?
- carbs
- fat
- proteins
How do we measure energy content?
joules or calories
Relationship bw calories and joules
1 calorie = 4.2 joules
How do we measure the energy content of molecules?
with a calorimeter
Energy content of carbohydrates + RQ
17,24 kJ/g
RQ = 1
Energy content of fats + RQ
39 kJ/g
RQ = 0,7
Energy content of proteins + RQ
17 kJ/g
RQ = 0,82
What is the respiratory quotient and its value in humans?
VCO2 / VO2 (ratio of produced CO2 to consummed 02)
RQ = 0,85
What is the total energy expenditure?
the total energy content of food intake when in neutral energy balance
Direct method of measuring TEE
measuring a person’s heat production (rate of metabolism)
TEE = ? (2)
TEE = Heat production + external work TEE = BMR + DIT + Energy expenditure in physical activity
What principle does the indirect method for TEE rely on?
It relies on the principle that nearly all E released in our body is derived from reactions in which O2 participate
Relationship bw O2 consumed and kJ of E released
1L of O2 consumed = 21 kJ of E released
What is the BMR?
The minimal energy expenditure required to exist
Requirements for measurement of BMR (6)
- usually measured in the morning
- no physical activity
- neutral temperature (20)
- no food 8-12 hours before
- No emotional stress / stimuli
- no drugs
BMR value based on surface area
170 kJ/ square meter / hour
BMR women
6000 kJ / day
BMR men
7000 kJ / day
Which hormones can increase BMR?
thyroid hormones and catecholamines
How much of the TEE do BMR, DIT , and E in physical activity represent?
- BMR : 50 - 70%
- DIT : 8-15%
- E in phys ac : 15-30%
Which tissue specializes in heat production?
Brown adipose tissue
How are brown adipocytes better at heat production?
Because they have UCP1 protein, which allows H+ ions to flow from the intermembrane space to the matrix and thus decreases the proton gdt necessary for ATP synthase
What type of adipose tissue do aadult humans have?
beige adipose tissue (also with UCP 1)
What factor increase cell differentication to beige adipose tissue? (2)
- cold
- catecholamines (beta)
What is the role of the satiety center?
inhibit apetite even in the presence of food
What is the role of the feeding center?
Increase apetite
What are the 2 centers that regulate feeding?
Satiety and feeding center
where are the regulatory centers located?
in the hypothalamus
Where do the regulatory centers recieve information from?
from the arcuate nucleus
What are the 2 types of neurons that project from the arcuate nucleus to the regulatory centers?
Anorexigenic neurons and orexigenic neurons
What do anorexigenic neurons do?
they release POMC, which decreases apetite
What do orexigenic neurons do?
They release neuropeptide Y, which leads to increased apetite
What 3 factors affect the arcuate nucleus and regulate hunger and feeding?
- Increasing adipose tissue mass, release of leptin
- Insulin
- Neuropeptides from the GI
What does Leptin do? (4)
- Decreases hunger by stimulating anorexigenic neurons
- Increases thermogenesis
- Increases energy expenditure
- Restore the adipose tissue to an appropriate set point
What does insulin do? (3)
- Stimulates anorexigenic neurons
- Inhibits orexigenic neurons
- Indirectly supports leptin secretion
Which neuropeptides from the GI decrease hunger? (4)
- GLP-1 (glucagon-like peptide 1)
- Peptide YY
- CCK
- CART (cocaine and amphetamine related transcript)
Which neuropeptides from GI increase hunger? (2)
- Ghrelin
- Orexins
What is the function of GLP-1?
stimulates insulin secretion
Function of peptide YY? (2)
- decrease ghrelin production
- directly acts on hypothalamus
Role of orexins (2)
stimulate hunger and awakeness
