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Lecture 26

BIOL 3070 Lecture Notes - Lecture 26: Heat Capacity, Electrical Equipment In Hazardous Areas, Ice Crystals

4 pages86 viewsWinter 2017

Course Code
BIOL 3070

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Lecture 26:
Temperature effects many processes and enzymes inside the body such as the rate of enzymatic
reactions and cell membrane fluidity (cholesterol).
o At low temperature the membrane is rigid and less permeable
o At high temperature the membrane is too fluid
There is a thermal limit for animal life and it changes between animals
o Tb is different between ectotherms and endotherms
o Etothers: are aials that at produe eergy iside their ody ad rely o
external sources of animals to maintain their internal energy.
o Endotherms: are animals that produce energy inside their body to maintain their
internal temperature compared to the environmental changes.
Body heat= heat produced + (heat gained heat lost)= metabolic heat + heat transferred with
Heat is transferred from the environment to the body by 5 ways:
1)conduction: direct contact between a cool object and warmer body would lead to the transfer
of energy from the warmer to the cooler
2) radiation: transfer of heat from a warmer object to a cooler object through electromagnetic
waves (light), no direct contact is needed
3) convention: transfer of heat from warmer to cooler objects by air currents where the warmer
air rises and is replaced by cooler air
4) evaporation: conversion of liquid to gas; sweat to vapor; the heat of vaporization is absorbed
from the skin
5) heat storage: has 3 factors:
o A) surface area: the saller the aial the faster its apale of loosig or gaiig
energy from the environment. Also the metabolic rate is higher in smaller animals
compared to the larger animals
o B) Temperature gradient: the larger the temperature difference between the organism
and its environment the greater the heat transfer due to a greater temperature
o C) specific heat conductance: the specific heat conductance is a constant value for
different types of objects that determines how much heat would be transferred. The
larger the specific heat the more energy would be transferred and thus lost. Animals
with high specific heat tend to have body temperatures that fluctuates with the ambient
environment. The lower the specific heat conductance constant the better the
organism is in insulating its body temperature and its known as insulation (fur and fat)
ΔHtotal= ΔHmetabolism + ΔHconduction/convention + ΔH radiation + ΔHevaporation+
Mechanisms for regulating heat transfer:
o 1) behavioral changes: moving into another environment that favors the optimal
o 2) internal physiological adjustments: changes in blood flow or sweating that is
controlled by the autonomic nervous system (sympathetic NS)
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