Investigation into Temperature Regulation in Animals

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Investigation into Temperature Regulation in Animals

Aim

My aim is to find out how insulation and body surface area affect how heat energy is lost in animals.

Introduction

The temperature of animals affects their life functions, which are all the chemical reactions, which take place in the animal’s body.  For every temperature rise of 10°C, these biochemical reactions, which account for most of the body’s functions, double in rate up to a point when proteins break down.

If an animal becomes too hot, proteins in the body break down, eventually leading to death.  If an animal becomes too cold, the bodily functions slow down.  Because of this, various animals have different ways of keeping their body temperature constant, so they work most efficiently.  Some animals rely on their own bodies to maintain their temperature.  These animals include mammals and birds, and are called endotherms because they make heat inside their bodies.  Others rely upon their environment to maintain body temperature, which are animals like reptiles and amphibians.  These animals are called ectotherms because they gain heat from outside their bodies.  The normal temperature for humans is just under 37°C (for the inside of the body i.e. organs), and the body is constantly kept at this temperature, unless we are ill (skin temperature may vary).  Inner temperature is kept constant at the expense of outer (skin) temperature.  If body temperature gets much above 40°, then we are likely to die.  If the body temperature falls much below 35°C, our body stops responding to temperature, and the body continually loses heat due to falling metabolic rates.  The person eventually goes into a coma.  This is called hypothermia.

The body is kept at this ‘optimum’ temperature of 37°C in different ways if it gets too hot or cold.  When it gets cold: -

  • The hairs are raised on the skin.  This is brought about by contracting erector muscles in the skin, which results in the hair standing up, and a layer of air is trapped between them.  Because air is a poor conductor of heat, this helps insulate the body and prevents heat loss.  This response is not much use to humans because of the small amount of body hair compared to other mammals.
  • Blood is held back from capillaries near the surface of the skin, and is diverted to blood vessels deeper down.  This prevents heat being lost through the blood as it flows through the skin.  This response is brought about by the blood vessels contracting near the surface of the skin, and is called vasoconstriction.
  • The body, by means of increasing the rate of metabolism, makes more heat.  The liver plays an important part in this.  We also shiver, and may run about to keep warm.  Shivering is caused by an involuntary contraction of our muscles, and also causes more heat to be made.
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When it’s hot: -

  • The hairs on the skin are lowered, brought about by the relaxing of erector muscles.  As a result, the hairs lie flat, and a layer of air is no longer held between them, so heat is more easily lost.
  • Blood flows closer to the surface of the skin, as the blood vessels near the surface widen so that more blood flows through them and the heat is lost through the skin.  This is called vasodilation.
  • Sweating occurs, and as the sweat evaporates, it cools the skin and the blood flowing near the surface.  Evaporation occurs ...

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