external work

internal work

all other forms not involved in mechanical work outside the body, which includes:

-skeletal muscle activity used besides external work

-energy expended just to sustain life (breathing, reactions in growth)

rate at which energy is expended during work (external and internal combined)

=energy expenditure/ unit of time(kcals/hr.)

-thyroid hormone

-physical activity (can get up to 15-20 fold)

energy in food consumed = external work + internal work + heat produced + stored energy

-alter body weight by changing caloric input and/ or output

first appetite controlling hormone identified, acts to decrease food intake and increase metabolic rate

produced and released by adipocytes

released into bloodstream by pancreas when blood levels of glucose and other nutrients are increased to store them

high insulin levels also inhibit release of neuropeptide (decreases appetite)

hunger hormone

produced by stomach and released into blood before meals

causes production of neuropeptide in hypothalamus

released by small intestine when filled with food

acts as a satiety signal in hypothalamus

identified when body weight is 20% (or more) than desirable body weight as suggested by USDA

BMI is greater than or equal to 30

men more at risk

1. fautly leptin signaling pathway ("leptin resistance")

2.  decreased physical activity

3.  differences in non-exercise activity thermogenesis (fidget factor)

4.  diferences in extracting energy from food (lean store less cals because they lose more energy in chemical bonds of food)

5.  hereditary influences

6. overeating during critical periods in life (infancy, early adolescence, pregnancies), fat cells become permanent

7. endocrine disorders

8. availability of cheap, energy dense food

9. stress

gastroplasty

gastric bypass

gastric banding

"stomach stapling"

reduces size of stomach so that you feel full easier

remaining part of stomach can enlarge if eating behavior is not changed

glycolysis

krebs cycle

oxidative phosphorylation

converts 6 carbon glucose molecules to two 3 carbon pyruvate molecules, resulting in 2 STP molecules, 2 reduced electron carriers

-oldest and simplest form of energy production by living cells, produces ATP quickly but limited amount produced

-if adequate oxygen in cell, mitochondria comes into play

acetyl Co A is intial substrate (occurs in mitochondria matrix)

-each full cycle yields one ATP molecule, 2 CO2 molecules, 3 NADH + H+ molecules and 1 FADH2 molecule

during full metabolism of glucose, most ATP produced here by way of the electron transport chain

chemiosmotic mechanism of ATP production

radiation

conduction

convection

evaporation

related to electromagnetic waves generated by the sun and absorbed by objects

-body can both emit and absorb

-fire, radiator, warm air also are sources

-50% of heat we produce metabolically lost via radiation

transfer of heat between body and objects it comes in physical contact with

-can either gain or lose heat depending on temp

-rate of heat temp depends on temp gradient, surface contact area, thermal conductivity of object (solid> liquid> gas)

transfer of heat via air or water currents

-currents remove thin layer of warm air surrounding body allowing more effective conduction

when water on skin evaporates into air, heat required to convert liquid to gas is absorbed from skin, thus cooling body

-happens continuously

-only way to lose heat when ambient air warmer than body

heat cramps

heat exhaustion

heat stroke

frostbite

hypothermia

least dangerous, painful cramping of large muscles used during exercise

-hot humid conditions

-dehydration and loss of sodium cause unabated muscle contraction

-treat with hydration, cooler environment, electrolytes

state of collapse, fainting results from decrease in blood pressure

-blood volume inadequate following profuse sweating

extremely dangerous, medical emergency

-results from breakdown of thermoregulatory systems

-sharp increase in body temp, no sweating because thermoregulatory center in hypothalamus has been damaged by heat

-heat loss mechanisms are shut down

particular part of body to point where damage actually occurs

-formation of ice crystals disrupt normal structure and function of cells

cooling of whole body exceeds capacity of heat producing/ conserving mechanisms

-decrease in blood flow to extremities, core temp decreases affecting cerebral functions (judgment)

-next, depression of brain's respiratory and cardio centers, results in weak, shallow breathing, disturbed cardiac rhythm which leads to death

physiological adaptations to constant exposure to new environmental conditions

- sweat-greater volume of sweat-more dilute sweat

-early adjustments occur 1-5 days but full acclimization takes 14 days

-cold less likely, body adapts better