MT3 - Energy and Temperature

Energy input partway

(( ADD IMAGE FROM SLIDES))

What is metabolic rate

energy expended over time

energy in food consumed equation

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If E balance in food is neutral…

no weight change

if E balance is possitive

weight INCREASE

if E balance is negative

weight loss

for energy in food consumed, INPUT ___ OUTPUT

Input = output

What is external work

energy expended when skeletal contracts (ex: exercise)

Internal work

all other forms that do not accomplish work outside the body (ex: pumping blood and shivering)

LEPTIN

hormone secreted from adipose (fat) cells ((ADIPOSE))

binding to hypothalamic receptors leads to suppression of
appetite, thereby reducing food intake (negative feedback)

Neuropeptide Y (NPY)

hormone produced by hypothalamus
that strongly stimulates appetite and feeding behavior

production is inhibited by leptin →
leptin’s influence on NPY results in appetite suppression by causing APPETITE SUPRESSION

Melanocortins (POMC: Pro-opiomelanocortin)

hormone produced by hypothalamus and decrease food intake

production is stimulated by leptin. Thus leptin’s influence
on melanocortins results in decreased appetite
→ makes you hungry

Ob/Ob (( obesity ))

Mutation in Leptin

overeating
gain fat because they can store it.
Fat mass: excessive (obesity)

lipodystrophy (low leptin level)

overeating but can't store fat → loses weight

(( Fat mass: deficient (fat loss) ))

Ghrelin

hunger hormone
-produced by the stomach
-promote food intake by activating NPY

Insulin Secretion

- Insulin is released from pancreas in response to increased
blood glucose levels (stimulates cellular uptake of glucose)

- Increased levels of insulin signal satiety

Normal body temperature

98.6 F (oral)

Temp thresh hold for cell fxn

110

Heat input

occurs via 1) heat gain from external environment, and
2) internal heat production

Heat Output

occurs via heat loss from exposed body surfaces to
external environment

If core temperature falls

heat production is increased
heat loss is decreased

If core temperature rises

heat production is decreased
heat loss is increased

other ways to regulate temperature

behavior and clothing
shivering / sweating