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86 Cards in this Set
- Front
- Back
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Body temperature is maintain at what degree's Celsius?
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37 C
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Body temperature is a balance between what 2 things?
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Heat production and heat loss
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What are some ways one can get heat loss?
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Radiation
Conduction Convection Vaporization |
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What is the formula for the rate of body heat storage (BHS)?
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BHS= TMR - useful physical work rate - (evaporative heat loss rate - (rate of heat lost or gained by radiative + convective + conductive process))
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Humans, birds, and other mammals are considered to be?
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homeothermic
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Reptiles, amphibia, and fish are considered to be?
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poikilothermic
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Which part of the body will give you the most accurate reflection of the internal temperature?
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Rectal Temp.
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By how much is the ORAL Temp different from the RECTAL Temp?
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0.5 Celsius higher
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Why is the oral temperature slightly warmer than the actual internal temperature?
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Because of the ingestion of hot and cold fluids, gum chewing, smoking, mouth breathing, etc.
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T or F: Core temperature does not undergo daytime fluctuations
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False, there is a total variation of 1 Celsius (at 6am: lowest temperature, at pm: highest)
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Before ovulation, is temperature (HIGHER/LOWER) by 1 Celsius?
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LOWER (probably due to progesterone)
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Why does temperature rise with exercise?
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Heat dissipation < Heat production
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T or F: Blood temperature is constant throughout the entire body.
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False, it changes in different areas. Depends on the metabolic activity at a specific region, amount of blood flow, steepness of the temperature gradient (to surrounding tissues)
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How different is the temperature of PERIPHERAL tissues compared to CORE temperature?
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Peripheral tissues are cooler
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Behavioral regulation vs. Physiological regulation
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Bl: voluntary, conscious response to affect BT.
P: involuntary to maintain Tk-fine balance |
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What is the mechanism with the largest involvement to cause a loss in temperature?
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60% radiation
(then evaporation) |
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On exposure to cold, what is your body's response?
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VASOCONSTRICTION to the skin and peripheral tissues -> diverting blood to VISCERAL organs
Skin and Fat = insulators |
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On exposure to heat, what is your body's response?
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VASODILATION to the skin and can be dissipated from the body faster.
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Since the environment is usually cooler than body temperature, where do we get most of our heat?
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FOOD
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What 3 parts of the body make up the body core?
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Trunk
Viscera Brain |
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What fraction of the body mass is from the BODY CORE?
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1/3
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If instead of eating, you are doing work, what's the source of heat production?
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MUSCLES
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What is work rate?
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The rate of performing useful work such as walking
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When the environment is warmer than one's core temperature, what is an efficient way of dissipating that heat?
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Evaporation
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How many kcal/gramH2Oevaporated of heat are lost?
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0.6 kcal
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What happens to the evaporative heat loss at the following environmental temperatures:
a- 30Celsius b- Above 30Celsius c- Above 35 or 36Celsius |
a- 25% of total heat lost
b- Increases linearly as T increases c- HEAT CAN BE LOST ONLY AT THIS TEMPERATURE |
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At what temperature can one ONLY lose heat?
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at 35 or 36 Celsius
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Can evaporation occur in COLD temperatures?
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Yes
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What systems participate in evaporation even in COLD temperatures?
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SKIN and RESPIRATORY TRACT
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Normally, humans lose how many milliLiters of water/ hour in COLD weather?
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50ml/hr
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How many controllable SWEAT GLANDS do humans have?
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2.5 million
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Under high environmental temperatures, how many ml H2O loss can reach to?
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1600ml/h
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What controls the secretion of sweat glands?
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CNS sympathetic innervations
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What is the neurotransmitter that it is released everywhere EXCEPT palms of hands and soles of feet for secretion of sweat?
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Acetylcholine
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What is the neurotransmitter that it is released in the palms of the hands and soles of feet for secretion of sweat?
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Epinephrine
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T or F: Adaptation to heat takes several weeks.
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True
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What Beta blocker (drug) it is usually used to prevent performance anxiety?
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Propranolol
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What affects loss of heat through sweating?
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rate of air movement
air temperature H2O vapor press at skin T relative humidity of the air H2O press saturated at air T Area of skin wet with sweat *evaporation of heat |
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Where does panting occur?
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mouth & respiratory tract
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What is panting?
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H2O vaporized in the mouth
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T or F: Thermal radiation is the transfer of heat from one object to another during contact.
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False, these objects are not in contact.
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Which color absorbs more heat through thermal radiation?
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Black
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Which color is a good reflector?
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White
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Which system in the body is a good reflector in visible light?
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Skin
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Are all areas of the body equally effective in radiative heat exchange?
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NO
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What are some surfaces the exchange energy with other skin areas?
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Between legs,
Under arms, & between fingers. |
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In the surfaces where some areas exchange with other skin areas, how can you increase thermal loss?
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Opening arms,
Opening legs |
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How can the body adjust to reduce the effective radiative area of the body to 50%?
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by curling up
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T or F: Conduction is the flow of heat from one object to another with which it is in CONTACT.
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True
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Conduction happens in what direction?
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From HEAT to COLD
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If there is little air movement, is heat lost in greater or lesser amounts by conduction?
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lesser
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What is the best insulator tissue in the body?
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FAT
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What is considered an even greater insulator than fat (outside of the human body)?
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AIR
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What is the scientific name for goose pimples?
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Horripilation
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In other animals, what are other good insulators besides fat?
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feathers and fur
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T or F: Convection is the movement of particles from a warmer location to a cooler location.
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True
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Natural convection is CONTROLLABLE/ UNCONTROLLABLE?
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uncontrollable
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Explain the "wind chill factor" and its relationship to skin temperature?
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skin has a 2-4mm layer of warm air when air is not blowing. As the wind increases, the loss of warmer air through forced convection increases.
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What controls the heat transfer from the blood stream to the skin?
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Sympathetic Nervous System
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How many Celsius are lost every time there is heat transfered from the BLOOD to the SKIN?
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1 Celsius (37 ->36)
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What is the reasoning behind pale skin during cold days?
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blood would not be as close to the surface as it is on sunny days
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How does one's body detect temperature?
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Cells in skin, deep viscera, spinal cord, mesencephalic reticular formation, hypothalamus, and preoptic region of the brainstem ALL have firing rates with changes in temperatures. (some increase their firing rates with LOW Temp. and others decrease their firing rates with HIGH Temp.)
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T or F: There are cold and warm sensors in the skin, viscera, and spinal cord.
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True
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Temperature requires what things in order to be regulated?
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- Needs to be Detected
- transmission of info into an integrating network - Deviation or error signal production - transmission of error signals -> effector mechanism for action |
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What are some of the actions that the effector transmits in order to regulate body temperature?
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Shivering
Sweating Vasomotor |
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Where is the integrating network that reads the Temp info?
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preoptic-anterior hypothalamic area
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T or F: the preoptic-anterior hypothalamic area never has any conflicting signal. (*hint: think viscera)
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False, the viscera has overriding forces because the visceral needs are more important. Example: in the cold, you exercise, skin T is low but muscle activity is highly generating enough heat so that internal heat load would be increased.
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Is there a set-point or a preferred T info?
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Yes,
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The anterior hypothalamus activates what kind of Temp?
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COLD
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The posterior hypothalamus activates what kind of Temp?
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WARM
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Warm Temp can cause what kind of response in the body's BVs and glands?
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VASODILATION and SWEATING
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Detecting temperature in the body is read as what in the hypothalamus?
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As a Transmission ERROR signal
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What is the effector's job when the error signal is received?
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Raise the Temp of a local region to INCREASE HEAT LOSS mechanisms in other skin regions.
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Name 5 pathological conditions and adaptations associated with regulation of Temperature?
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1- Fever (alteration of set point)
2- Acclimatization 3- Anesthetic Hyperthermia 4- Heat Stroke 5- Cooling |
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During fever, is the body T sensed as TOO LOW or TOO HIGH?
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Too LOW
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Consequences in response to fever:
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Heat generating and CONSERVING mechanisms are brought into play until the internal T reaches perceived by the POA (preoptic anterior hypothalamus) are corrected.
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What can cause fever, in other words, what DECREASES the SET POINT (to 97F w/o lowering body T) at which Temp is regulated?
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-pyrogens (endogenous)
-infection -antipyretic drugs -> Aspirin, Tylenol (acetaminophen) |
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What happens to the body temperature when Anesthesia causes a problem to a patient?
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RISE in body Temp
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What is the cause of Anesthetic hyperthermia?
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Mutation in the gene for Ca2+- release channel (RYANODINE RECEPTOR) in SR.
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How many degrees Celsius can the body temperature increase during Anesthetic hyperthermia?
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4.4 Celsius/ 1 hour
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T or F: Humans can withstand prolonged cold exposure by NONSHIVERING THERMOGENESIS (in other words, we can do acclimatization)
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False, some animals can but not human kind.
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During acclimatization, what is decreased and what stays the same (maintained)
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Shivering decreases
Heat production is maintained |
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Acclimatization is possible because of what type of tissue and metabolic cycles of animals?
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Brown Fat and Futile Cycles
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T or F: During Heat STROKE, one continues to sweat and Body T stays the drops.
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False, Body T is HIGH and Sweating STOPS
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What are the lowest temperatures humans can withstand ?
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21- 24 Celsius
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When is cooling useful (21- 24Celsius)?
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for certain surgeries
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