Energy, Metabolism, Control Of Food Intake & Food Saftey Flashcards
(29 cards)
What is the first law of thermodynamics?
Energy cannot be created or destroyed, but transmitted from one form into another
Energy balance =
Energy intake + energy stores - energy expenditure
If I take and expenditure of energy is not equal we either get a negative or positive energy balance, what do these mean?
Negative = utilisation of the bodies energy stores
Positive = increase in body energy stores
What is the second law of thermodynamics?
When food is utilised in the body, there is always a loss of some energy on the form of heat (the energy lost as heat is called entropy)
What is a calorie?
The amount of heat required to raise the temperature of 1g of water by 1 degrees
Nutritionally we refer to kilocalories, how many kilocalories make up one calorie?
1kcal = 1000cal
How many kcal in 1g of carbohydrate?
4
How many kcal in 1g fat?
9
How many kcal in 1g of protein?
4
How many kcal in 1g of alcohol?
7
Energy consumed from food can be stored as 3 things, name these?
Fat - major energy stores
Glycogen - short term energy/carbohydrate reserve
Protein - rarely used by the body unless starvation
Metabolic rate depends on what 3 factors?
Basal metabolic rate 70-75%
Physical activity 20%
Thermic effect of food 10%
The body uses the largest amount of its energy to fuel what?
Basal metabolic rate
What is fat free mass (FFM)?
Total amount of non-fat/lean parts of the body
What is the glucostatic theory?
Food consumption is triggered by decreased glucose availability to the tissues
What is lipostatic theory?
Body fat is the key substance that regulated eating behaviour - after a meal blood glucose levels gradually fall and free fatty acids in the blood are increased, raised FFA signals hypothalamus to stimulate hunger
What is the aminostatic theory?
The fewer amino acids in the blood the stronger the feeling aid hunger
What is the thermostatic theory?
Heat generated during digestion leads to a rise in body temp which inhibits eating behaviours
Explain appetite, hunger and satiety?
Appetite = psychological desire to eat
Hunger = subjective feelings that determines when food is consumed
Satiety = a state that inhibits overeating and leads to the termination of a meal
What is sensory specific satiety?
Foods that are similar in taste and appearance to those recently consumed are rated less pleasant that new foods
Explain the role of serotonin in relation to food intake?
Suppresses appetite and carbohydrate cravings
Explain the role of dopamine in relation to food intake?
Mediates food rewards, potentially involved in cravings
Explain the role of CCK in relation to food intake?
Hormone produced in the duodenum which promotes satiety - acts by delaying gastric emptying thus increasing gastric distension
What is ghrelin and its effect on food intake?
A peptide, it increases with food deprivation and may trigger a meal
