Energy & Metabolism 3 Flashcards
how many KJ = 1 calorie?
1 calorie = 4.18 KJ so..
calories x 4.18 = kilojoules
kilojoules / 4.18 = calories
define metabolism
all of the chemical reactions occurring in the body
how much energy does the brain & muscles use?
Brain uses 22% of energy
Muscles use 22% of energy
Define metabolic rate
rate of energy output by the body
Define resting metabolic rate (RMR)
- “energy cost at rest”
to keep you alive
What is the Basal metabolic rate (BMR)
- standardised measure of resting metabolic rate
- individual is fasted, rested & inactive but awake
What is the total metabolic rate (TMR)
BMR/RMR + energy output from physical activity
What is the basal metabolic rate determined by?
- weight
- height
- surface area
- age
- gender
- muscle mass
- hormones
- pregnancy
- lactation
how do you measure metabolism
- direct calorimetry - uses a calorimetric chamber, measures heat output.
- indirect calorimetry - measures oxygen use/ gas exchange
What is energy input?
- estimated energy requirement (EER)
- the body derives energy from breakdown of nutrients
- the potential energy value of foods is given in KJ or Cal
What are catabolic reactions?
- exothermic reactions
- energy transferred to an energy carrying molecule ATP & heat
What are anabolic reactions?
- endothermic reactions
- require energy in the body in the form of ATP
- builds small molecules into larger ones
What are catabolic pathways?
- breakdown complex molecules to simpler ones
- exothermic release energy as heat & ATP
eg: cellular respiration
What are anabolic pathways?
- build up complex molecules of life
- endothermic require energy input in the form of ATP
eg: biosynthetic reactions
How does ATP effect chemical reactions?
it is the only form of energy that can be used to power cell activity
Explain creatine phosphate
- like ATP - an energy rich molecule but cant be used directly
- used to quickly convert ADP to ATP by direct phosphate group
Glucose can be obtained from…
- Free blood glucose (after a meal)
- Glycogenolysis: breakdown of glycogen stores in muscle and liver
- Glucneogenesis: formation of glucose from other nutrients in the liver
Three linked metabolic pathways involved are:
- Glycolysis
- Krebs cycle
- Electron transport chain
Explain glycolysis
- Glucose is broken down to 2 pyruvic acid molecules in the cytoplasm
- net gain of 2 ATP
Explain Kreb’s cycle
- occurs in the mitochondria
For each Acetyl-CoA entering krebs cycle: - carbon atoms are removed as CO2 waste
- 1 ATP made by direct phosphorylation
- 3 NAD+ reduced to 3 NADH + H+
- another carrier FAD is reduced to 1 FADH2
What are NAD & FAD
- glycolysis and kreb’s cycle include ‘redox’ reactions
- oxidation = removal of hydrogen & high energy electrons
What is the electron transport chain
- NADH + H+ & FADH2 pass on their hydrogens & high energy electron to oxygen as the final ‘acceptor’
- linked to ATP production
Explain that catabolism of fat
- glycerol component converted to pyruvic acid & carries onto kreb’s cycle & ETC
- fragments are split off thru a series of enzymatic reactions called beta-ovidation in the mitochondria
Explain the catabolism of protein
- used when other source are unavailable eg: starvation or during prolonged exercise
- in the liver the amine group is removed
- remaining molecules are converted to pyruvic acid
