Energy Expenditure And Temperature

Question 1

Caloric Theory

Answer 1

Heats consists of a self-repellent fluid (“caloric”) that can be transferred from one body to another, but cannot be created or destroyed.

Question 2

Caloric Theory was superseded by

Answer 2

the mechanical theory of heat

Question 3

Lavoisier and LaPlace Calorimeter (1780)

Answer 3

Placed animal in chamber with insulation all around it (insulated from outside environment). Air flow, packed with ice. Experiment evaluated amount of heat produced by the mouse (measured by amount of ice that melted into water). 80 kcal of heat melts 1 kg of ice. How do you measure thermal production Measure heat based on what it does to ice Body heat of guinea pig melts ice Ice into an isolated chamber it wont melt but if you add a guniea pig its body heat will melt. Air needs to be able to enter and exit. Heat only leaves the chamber because of ice melting and then you measure the amount of water collected and get heat.

Question 4

Heat according to caloric theory is similar too

Answer 4

phlogostin

Question 5

Joules work on heat

Answer 5

Theoretical experiment: Chamber mixed with water. Drop a 427 kg weight from height of one meter. Transfer of energy into spinner. When weight falls, will raise temperature by 1°C. 427 mkg work → 1 kcal heat. 427 mkg = 1 kcal heat mechanical energy → 0.56 g (mechanical) give 1 kcal chemical energy → 0.465 x 10-10g = 1 kcal nuclear energy 1 BTU = 1 lb water raised 1°F = 252 calories Calorie = energy it takes to increase the temperature of one gram of water by 1°C Conversion between Joules and calories: 1 calorie = 4.1833 Joule

Question 6

427 mkg

Answer 6

1 kcal heat mechanical energy

Question 7

0.56 g (mechanical) give

Answer 7

1 kcal chemical energy

Question 8

0.465 x 10^-10g

Answer 8

1 kcal nuclear energy

Question 9

Conversions

Answer 9

427 mkg = 1 kcal heat mechanical energy → 0.56 g (mechanical) give 1 kcal chemical energy → 0.465 x 10-10g = 1 kcal nuclear energy

Question 10

1 BTU

Answer 10

1 lb water raised 1°F = 252 calories A lb is half a liter but 1 degree farenheight is about half a degree centigrade 1 btu equals approx 1 kilojoule

Question 11

Calorie

Answer 11

energy it takes to increase the temperature of one gram of water by 1°C

Question 12

Conversion between Joules and calories:

Answer 12

1 calorie = 4.1833 Joule

Question 13

kcal

Answer 13

food calorie which equals 1000 small calories which equals 4186 joules

Question 14

Joules unit conversion

Answer 14

1 J = (kg x m^2)/s^2 = N x m = W x s = Pa x m^3 = C x V

Question 15

Specific heat of water:

Answer 15

1 calorie = 4.1855 J = “15° calorie” (14.5°C → 15.5°C, typical calorie) 4.184 J = “thermochemical calorie” (0°C → 1°C) - physiologist use this one 4.190 J = “mean calorie” (0°C - 100° C) (avg energy to move 1 g of water 1 C)

Question 16

Resting Metabolic Rate

Answer 16

70 kcal/hour 250 mlO2/min 85 Watts

Question 17

Exercise Increases the RMR

Answer 17

400-600 kcal/hr – 5x increase in calorie/heat production along with rr/circulatory rates and o2 consuption and is pretty constant across mid range mammals.

Question 18

Athletes and Thouroghbreads

Answer 18

Athletes and thoroughbread horses can go from 10-20x RMR during exercise They have a lower resting rate and a larger maximum rate

Question 19

Shivering increases energy production by

Answer 19

400%

Question 20

Q10

Answer 20

relationship btw enzymatc activity at 2 different temperatures in bio tissues q10 is 2 meaning for an increase of 10 degrees activity will double. We use it in the other direction to lower in kids we can go really low. A 20 degree drop in temperature reduces the rmr by 4

Question 21

Carbs and Protein

Answer 21

4 kcal/gram

Question 22

Alcohol

Answer 22

7 kcal/gram

Question 23

Fats

Answer 23

9 kcal/gram Fats are the most concentrated form

Question 24

To maintain body weight you need

Answer 24

15 cal/lb (RMR)

Question 25

A 200 lb person would need to eat how many calories per pound to maintain his weight

Answer 25

15 calories/lb so about 3000 calories to gain or lose weight

Question 26

3500 kcal/lb to

Answer 26

gain or lose weight - dependent on water balance

Question 27

Most of metabolism is set to

Answer 27

gain weight i.e. increase fat stores for leaner times

Question 28

Exercise increase skeletal muscle and rmr by

Answer 28

Exercise increase skeletal muscle and rmr by 5x so contribution decreases for these 5 and increases for skeletal muscle reduce for these 5 and increase

Question 29

Exercise increase skeletal muscle and rmr by

Answer 29

Exercise increase skeletal muscle and rmr by 5x so contribution decreases for these 5 and increases for skeletal muscle reduce for these 5 and increase

Question 30

Brain

Answer 30

2 percent body mass uses 20% energy, blood, O2

Question 31

Ratio of central nervous system to body metabolism in vertebrates

Answer 31

Mink et al Am J Physiol 241:R203-R212, 1981 most vertebrate species use 2-8% of their basal metabolism for the central nervous system (CNS). “of all animals, man has the largest brain in proportion to his size,”- Aristotle Domesticated animals use less (bred for size and dumbness?) \<2% Primates use more (\>10%); also mouse 8.5%; but shrew 1.5% Very large animals also low; ostrich 0.7%, elephant 2.0%, whale 0.5% Humans need to use less of their brain to take care of them selves percent is how much of their energy used to support CNS more energy used for your brain less function

Question 32

Mechanical Work is

Answer 32

easily defined physiologically using muscles

Question 33

Chemical Work

Answer 33

is difficult to define but is used in assumptions to quanitfy the work done by the brain Moving ions, neurotransmitters (nerve cells) Establishing “batteries” = energy stored in ion gradients Mitochondrial “fuel cell” to recharge batteries Work defined by energy expenditure by muscles Brain is hard to relate to the physics of work – most chemical work – use energy based on ATPase and pumps and how much work done to make the pumps work

Question 34

Brain O2 consumption

Answer 34

1.5 umol/g/min = 3.5 ml/100g/min

Question 35

70 Kg Man has ____ Kg brain

Answer 35

1.4 Kg brain

Question 36

Brain consumes ______ O2/day

Answer 36

Brain consumes 3 Moles O2/day 67L O2/day = about 15 balloons

Question 37

Brain makes ______ water per day

Answer 37

6 Moles of water per day (18 g/M, 18 mL/M = 108 mL H2O/day)

Question 38

The brain Makes ______ Moles of ATP

Answer 38

Makes 18.12 Moles of ATP (~9 Kg; 20 lb) / day 7mM/min = 10 M ATP a day;

Question 39

In an Normal Young Adult Male Cerebral Blood Flow is

Answer 39

57 ml/min/100g of brain tissue 798 ml/min/total brain (1400 grams) Brain about a liter a min bec 1/5 co and co 5 liters is led bulb about as efficient as mito

Question 40

In an Normal Young Adult Male Cerebral O2 consumption is

Answer 40

3.5 ml/min/100g of brain tissue 49 ml/min/total brain (1400 grams)

Question 41

In an Normal Young Adult Male Cerebral glucose utilization is

Answer 41

5.5 mg/min/100g of brain tissue 77 mg/min/total brain (1400 grams)

Question 42

brain uses energy

Answer 42

in small burst rather than one shot like most energy production

Question 43

The 10% Brain Myth

Answer 43

Humans only use 10% of their brain and if we use more of it at one time we can increase our mental abilities it is false

Question 44

Proof 10% Brain Myth is False: Energy

Answer 44

1. Look at the energy!!! Resting brain metabolism is 2 times that of brain with suppressed activity Maximum cerebral metabolic rate is about 2.5 times resting metabolism Metabolic scope is thus about 5. Thus, at rest the brain is using using about 20% of our useful energy capacity, Rmr – darkned room 50 ml/min Zero activity – 02 is half 25ml/min Comp activate – seizure – increse by 2 times ½ to 2 and a 1/2 gives the 1/5 ratio

Question 45

Proof 10% Brain Myth is False: Full Activation

Answer 45

2. Full activation, all nerve cells firing at once is non-functional (represented by status epilepticus. So, for best brain function focus narrows the number of nerve cells used at any one time. - Focal and Local

Question 46

Brain Use Facts: Truths

Answer 46

1. There is no part of the brain that is not used at some time or other. 2. There is some activity in every part of the brain at all times 3. The brain uses a lot of energy. If 90% were unnecessary there would a large survival value to smaller, more efficient brains. Brains. An inefficient brain would be unlikely to evolve. 4. Because of the constraints of the female pelvic opening and the difficulties of childbirth due to a large brain with large skull, evolutionary pressure would select against a brain where 90% of the mass is redundant.

Question 47

Metaphor

Answer 47

Brain as a piano 88 keys use all keys at some point but only use 10 keys at any one time

Question 48

Brain Energy Consumption

Answer 48

20% of cardiac output goes to the brain; 20% of O2 consumption of the body at rest comes from the brain. Flaming marshmallow analogy → oxidation of glucose (in brain, happens in steps as opposed to continuously)

Question 49

Temperature, RMR, Life Span

Answer 49

Low temperature environments - decrease RMR and increase life span

Question 50

Homeothermy vs Poikilothermy

Answer 50

Regulation of internal body temperature

Question 51

Homeothermy

Answer 51

Regulation of internal body temperature

Question 52

Poikilothermy

Answer 52

Internal body temperature varies

Question 53

Endothermy vs Ectothermy

Answer 53

Regulation by exchange with environment Endotherm: internal heat generation mechanisms Ectotherm: environment causes temperature changes

Question 54

Endothermy

Answer 54

produce heat to control body temperature - warm blooded

Question 55

Ectothermy

Answer 55

Use ambient temperature to control blood temperature with very little or neglibile heat production - cold blooded

Question 56

Warm Blooded vs Cold Blooded

Answer 56

Set point vs relative temperature Human enzymes optimized to work at body temperature Other enzymes can work at variable temperatures Dinosaurs have trouble cooling off due to size

Question 57

Average Temperature of Mammals

Answer 57

37-38ºC

Question 58

Average Temperature of Birds

Answer 58

39-40ºC

Question 59

Average Temperature of Marsupials

Answer 59

36ºC

Question 60

Average Temperature of Monotremes

Answer 60

31ºC They are homeotherms and endotherms

Question 61

Temperature Facts

Answer 61

Birds evolved from dinosaurs Advantage constant temp – effient enzymes at that range Higher temp – more efficient metabolism – need to eat more

Question 62

Modes of Heat Transfer

Answer 62

Conduction – needs something to carry it – occurs when objects are in direct contact Convection – via fluid from hot to cold needs contact Radiation - waves Evaporation – water changing state or Conduction: requires contact Convection: carries by another fluid i.e. air or water Radiation: electromagnetic energy Evaporation: water evaporating from skin, endothermic to cause cooling

Question 63

Heat Balance Equation

Answer 63

Question 64

Modes of Heat Transfer Equations

Answer 64

A lot of this is based on gradients all from ficks law of diff gradients are impt for energy

Question 65

Van’t Hoff relation & Physiological Q10

Answer 65

Question 66

Svante Arrhenius (1859 – 1927)

Answer 66

Arrhenius used absolute temp and co2 variations and climate changes

Question 67

Surface Law / Surface Rule

Answer 67

§Heat loss is from the surface, small animals have increased S / V and so have increased heat loss which must be balanced by increased metabolic heat production to keep warm Smaller u r the more heat u lose so smaller higher met rate Heat loss proportional to surface area – E C and R are directly proportional to surface area Heat production is a function of mito volume Animal smaller volume is bigger Larger animal produce more vol wise but smaller area to get rid of it Area to vol is 3 to 2

Question 68

Bergmann’s Rule

Answer 68

1847 Warm blooded animals in colder climates are larger in body size than relatives in warm climates Heat loss related to surface area Heat production is related to volume/mito Some wiggle room Small animal loses heat faster than a large animal, needs higher metabolic rate in order to keep warm Hypothesis: lose less heat because of the surface-to-volume ratio Easier to keep warm with larger body size Equatorial vs temperate

Question 69

Body Temp, RMR, and Life Span

Answer 69

Decrease body temp live longer bec lower met rate Lower met rate increase lifespan Increase body size increase life span but lower met rate Lower met rate increase life span

Question 70

The relation of body weight to metabolic weight and organ size

Answer 70

Question 71

Study in mice

Answer 71

Reduction of core body temperature resulted in an extended lifespan Lower metabolic rate = greater lifespan