6.5a: Homeostasis – Thermoregulation

22/10/2013 § 1 Comment

There’s an environment in every single one of us (ooh, so deep) and they are maintained through a control process called homeostasis, which is maintaining the internal environment of the body between limits. By limits, I think they mean the high and low points. Homeostasis controls body temperature, blood pH, carbon dioxide concentration, blood glucose concentration, and water balance. The nervous and endocrine system are responsible for sending messages to various glands in our bodies to release hormones that help maintain equilibrium in our bodies.

Okay, so negative feedback is a huge part of this topic. When some part of your internal environment is going haywire, or some levels are too high or too low, the body emits negative feedback in order to bring your body back to acceptable levels.

With body temperature, the hypothalamus (in ze brain) is responsible for maintaining a body temperature of 37°C, and if the temperature rises or falls below that, it sends messages to the body to respond so that negative feedback happens and the temperature can be brought back to 37°C. These messages are all transported via neurons. The body responds to overheating and chilling in different ways, e.g. our skeletal muscles relax and we sweat to cool ourselves down when we’re too hot, and by contrast, our skeletal muscles shiver and are active and our skin drives up to save heat when we’re too cold.

Blood glucose is also maintained in our bodies. Instead of the brain, the pancreas monitors the concentration of glucose and sends messages (via hormones) to also do negative feedback in order to lower or raise blood glucose levels accordingly. This is normally done by stimulating liver cells to absorb glucose (to lower levels) or break down glycogen (to raise levels).

Finally, there’s diabetes, which our body can’t do much about. Type I and Type II diabetes are different in a few ways (Type I / Type II):

  • Type I diabetes begins during childhood, Type II after
  • alpha cells produce insufficient insulin, the target cells become insensitive to insulin
  • insulin injections can control glucose levels, insulin injections are not necessary
  • a diet won’t help, a low carb diet can handle the situation



Page 260, wind-chill nomogram

1. Estimate, using Figure 22, the wind-chill for a wind speed of 5 m s-1 at a temperature of -30°C. = 7.0 MJ m-2 h-1

2. Identify how a person would feel if the wind speed is 0.2 m s-1 at a temperature of 10°C. = Cool.

3. Calculate the energy lost in one hour for a person with a surface area of 2 m2, when the air temperature is 20°C and the wind speed is 1 m s-1. = 1.8 ~ 2.0 MJ m-2 h-1

4. Compare the effects of air temperature with wind speed on the value of the wind-chill. As wind speed accelerates (not at all at a constant rate), wind chill increases. As air temperature decreases (at a far more constant rate than wind speed), wind chill increases.

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