REGULATION OF FOOD INTAKE& ENERGY STORAGE

Departemen Fisiologi Fakultas Kedokteran USU

Energi input Energi output

Food energy Metabolic pool in body

Internal work

External work

Thermal energy(heat)

Energy storage 25 %

75 %

Nearly all energy derived from food is eventually converted to heat

Cells cannot use this energy to do work, but the heat:Warms the tissues and bloodHelps maintain the homeostatic body

temperatureAllows metabolic reactions to occur efficiently

Balance of Energy in Our Body :

• Balanced energy intake: not losing or gaining weight

• Negative energy balance (weight loss): energy intake < energy expended

• Positive energy balance (weight gain): energy intake > energy expended

Neural Centers for Regulation of Food intake

Amygdala & Prefrontal cortex → control of appetiteHypothalamus → feeding center (lateral nuclei ) & satiety center ( ventromedial nuclei)Brain stem → mechanical act of the feeding process

Brain : human hypothalamus

Brain : cross sectional of hypothalamus

Lateral Hypothalamic Area

Dorsomedial Nucleus

Ventromedial nucleus

Paraventricular Nucleus

Pengaruh hormon terhadap aktivitas reseptor dan neurotransmitter di hipetalamus

• The hypothalamus releases peptides that influence feeding behavior

Feeding behavior and hunger depend on one or more of five factorsNeural signals from the digestive tractBloodborne signals related to the body

energy storesHormones, Body temperature, and Psychological factors

Regulation of Quantity of Food Intake

Energy regulation ( Long-term regulation) : long-term maintenance of normal quantities of energy stores in the body.

Alimentary regulation ( Short-term regulation):to preventing overeating at the time of each meal.

Leptin, secreted by fat tissue, appears to be the overall satiety signalActs on the ventromedial hypothalamusControls appetite and energy outputSuppresses the secretion of neuropeptide Y, a potent

appetite stimulant

Gastrointestinal distension• Stimulation of gastric stretch receptors suppress food intake.

The extent of glucose use & insulin secretion

• When more glucose is available for use (being absorbed from the digestive tract) → stimulate glucoreceptive neuron in hypothalamus → satiety.

• Increase insulin secretion → satiety signal.

The level of Cholecystokinin secretion

Chyme in duodenum, contain fat & CH

CCK release from mucosaStimulate secretion of bile &

exocrine pancreas

Signal by n.vagus, to NTS

Satiety signal

Stop eating

The level of ghrelin

• Produce by oxyntic gland in gastric mucosa

• Its level increase 1 hour before meals & drops after meal.

• Acts on hypothalamus to increase food intake by stimulating NPY neuron.

Hormones, Temperature, and Psychological Factors

Glucagon and epinephrine stimulate hungerIncreased body temperature may inhibit eating

behaviorPsychological factors that have little to do with caloric

balance can also influence eating behaviors

Ganong’s Review of Medical Physiology. 21rd Ed, McGraw-Hill.2004.pp

Guyton & Hall. Textbook of Medical Physiology. 11th ed. Elsevier Saunders.2006. pp 865-888.

Marieb EN. Human Anatomy and Physiology. 6th Ed. Pearson Educ.2004. chapter 24-Nutrition,Metabolism and Body Temp.Regulation.

Martini FH. Fundamentals of Anatomy and Physiology, 6th Ed. Pearson Educ.2004. chapter 25-Metabolism and Energetic.

Silverthorn DU. Human Physiology an Integrated Approach. 3rd Ed. Pearson Educ.2004. chapter 22-Metabolism and Energy Balance.