Human Thermoregulation (Open System)

Question 1

2 methods of meauring metabolic rate in an organism

Answer 1

1) direct calorimetry: organism is enclosed in a thermally insulated chamber and the temp INSIDE the chamber is monitored. Directly measures rate of energy expenditure
2) indirect calorimetry: relies on O2 uptake. in aerobic respiration, the amount of hear released is proportional to the O2 consumed.

Question 2

VO2?

Answer 2

volume of O2 consumed per unit time

Question 3

how does oral temperature change in a human as it is exposed to different temperatures?

Answer 3

oral temperature (Tb) should stay the same throughout temperature increases.Overall body temp shouldn’t fluctuate w temp because we are endotherms and trying to maintain a constant CORE temperature.

Question 4

how does peripheral temperaure change in a human as it is exposed to different temperatuers?

Answer 4

may fluctuate more than core temperatures as a result of the CORE PRINCIPLE; vasoconstriction/dilation to keep a constant temperature at the core. We sacrifice our periphery to maintain our core and oral temperatures

Question 5

how does vasodilation and sweating affect our core temp?

Answer 5

Allows hot blood to flow out to periphery, away from core. Sweat cools the blood at the periphery THROUGH EVAPORATION and it is cooler when it flows back to the core.

Hot blood transfers heat energy to the sweat at the surface through radiation, and the sweat is then evaporated.

Question 6

Do the values for heart rate and respiration rate values follow the expected trends as temperature increases? Explain.

Answer 6

• When you have to actively dissipate or gain heat, heart rate and respiration rate may increase.
• Shivering = extra o2 consumption = increase heart rate to get more O2 to muscles by faster blood flow.
• May see increase in respiration rate in order to get more O2 at the same time.

when hot: body temp also increases 10 beats per minute per degree centigrade increase. Respiration rates also increase with fever.
- When blood vessels DILATE as a response to increased body temperatures (to cool off), the heart has to pump faster to maintain blood pressure.

Question 7

why does respiration rate increase with increasing temperature?

Answer 7

heat speeds up the reactions which means kinetic energy is higher.

This means reactions speed up (ENZYME KINETICS) and rate of cellular respiration increases. Channel speed also increases. With increased speeds of reaction, more ATP is needed, there for more O2 needed to fund the ATP synthesizing reactions (increase breathing rate)

Question 8

Metabolic
activity will increase or decrease dependent on the body’s need to ____ or ____ heat at
varying external temperatures.

Answer 8

Metabolic
activity will increase or decrease dependent on the body’s need to GENERATE or DISSIPATE heat at
varying external temperatures.