BAI GIANG CO CHE DIEU HOA CUA CO THE

Whole body metabolismEnergy metabolism: the way the body stores and utilizes energy... Driving concepts for energy metabolism • Intermittent food intake • Blood glucose level must be ma

Whole body metabolism

Energy metabolism: the way the body

stores and utilizes energy

Driving concepts for energy

metabolism

• Intermittent food intake

• Blood glucose level must be maintained at all time for activity of the brain

Metabolic processes

• Anabolism

• Catabolism

Energy Intake, Utilization and Storage

1 To be used for energy.

2 To be used to synthesize

other molecules for function,

growth and repair.

3 To be used to synthesize larger molecules

for storage (e.g glycogen and

triglycerides).

Possible fates of small molecules from

digestion:

Energy balance

• Energy input = energy utilization + energy output

• Energy input = work performed + heat released

Metabolic Rate

• Metabolic rate is the amount of energy expended per unit time.

• Basal metabolic rate (BMR) is the metabolic rate when both the metabolic

rate and the work performed are minimal.

• BMR is estimated by measuring oxygen consumption.

• BMR is expressed as the rate of energy expenditure per unit of body

weight

• Average BMR in adults; 20-25 Kcal/ Kg/day Most of the BMR is due to the nervous system (40%) and skeletal muscles (20-30%).

Negative and positive energy balance

• Energy balance is maintained when the energy input equals the energy output

• An imbalance occurs when energy input does not equal energy output ->

a positive or negative energy balance.

• Positive energy balance: energy (nutrients) is taken in at a greater rate than what is expended as heat and work Weight gain occurs.

• Negative energy balance: energy intake is less than the rate at which the energy is expended. Weight loss occurs.

Metabolic reactions of the absorptive state

• Anabolic processes to synthesize macromolecules (glycogen, triglycerid, protein)

• Body’s energy needs are supplied mainly by absorbed glucose

• If the meal is reach in fats and protein, absorbed fatty acids and amino acids can also be catabolized for energy (oxidation of fatty acids –> acetyl CoA-> Krebs cycles; amino acids ->keto acids -> Kreb cycles)

• Synthesized proteins are mainly for structural and functional roles, do not for energy storage

Energy reserves

• The body has limited ability to store energy in the form of protein and

glycogen but unlimited ability to store energy as fats

• Triglyceride synthesis is common pathway for all excess absorbed nutrients

• Fats: 30% (normal person); 80% in obese person

• Triglycerides: Kcal/gr (70-80% of total body energy reserves- 2 months); Carbohydrates: 4KCal/gr (1% -few hours); protein: 5-6 Kcal/gr

(20-25%-unavailable for use)

• 2-3 hours after meal

glycogen, proteins, fats to energy

levels

nervous tissue and supplied from from glycogen (short supply-few hours) and gluconeogenesis

sourses (fatty acids) to conserve glucose for nervous

Metabolic reactions of the postabsorptive state

Insulin and Glucagon regulate absoptive and postabsortive metabolism