ENERGY BALANCE & THERMOREGULATION

energy balance: intake = output

positive = intake > output, energy store as glycogen/fat

metabolic rate = energy use/time

factors

• hormone - thyroid, insulin
• exercise
• body temp
• age - child higher
• gender - male higher

basal metabolic rate (BMR) = minimum waking rate of internal energy output when rest

• thyroid hormone - calorigenic effect
• epinephrine increase BMR

food intake

• appetite center
• satiety center - fullness, suppress eating
• arcuate nucleus of hypothalamus 
• neuropeptide Y increase appetite
• melanocortin suppress
• adipocyte 
• leptin inhibit NPY neuron, stimulate melanocortin neuron
• pancreas
• insulin 
• stomach
• ghrelin = hunger hormone

thermoregulation: maintain body temp within normal homeostatic range by gain/loss heat in differ environment condition

• internal core 37.7
• >41 = convulsion
• 43 survival limit 
• menstrual
• increase when exercise
• extreme temp
• shell temp 1-6 lower 

site

• oral
• axillary
• rectal 
• eardrum

body temp 

• >37.3 denature enzyme, block metabolism
• <36.3 slow down metabolism, affect brain

heat production

• BMR
• skeletal muscle activity - shiver
• chemical thermogenesis - epinephrine, norepinephrine, thyroxine
• brown fat - 50g burn 500 calories/day - detect with PET

heat exchange rate

• vasodilation 
• increase blood flow
• transfer body heat to environment
• vasoconstriction
• reduce heat loss

heat transfer

• conduction
• radiation
• convection
• evaporation

hypothalamus

• central thermoreceptor
• monitor core temp 
• peripheral thermoreceptor 
• skin temp 
• posterior region - cold
• trigger reflex mediate heat produce & conserve
• anterior region - warm
• trigger reflex mediate heat loss

fever

• body temp elevate 
• infection/inflammation
• macrophage release pyrogen increase internal temp

hyperthermia

• high body temp
• cause
• exercise-induced
• pathological - infection

hypothermia

• overwhelming cold areas
• hypothyroidism - met ds