Effects of Temperature on Human Biology

How do human adapt to the effects of temperature behaviourally?

To adapt to temperature as an environmental stressor humans will react behaviourally in order to create more favourable conditions for themself. For example, turning up central heating, wearing warmer clothes, drinking a hot drink

What are the physiological effects of high temperature?

• Vasodilation: blood vessels dilate to direct blood flow to the skin's surface which facilitates heat loss

• Increased heart rate: vasodilation causes blood vessels to dilate thus lowering blood pressure so the heart has to work harder (there is a low stroke volume to maintain cardiac output)

• More fatigue

• Increased metabolism (depends)

• Hyperthermia

• Heat exhaustion: can cause loss of electrolytes and water which causes dizziness, muscle cramps, and fainting

What are the physiological effects of low temperature?

• Vasoconstriction: blood vessels constrict to reduce blood flow to the skin and minimise heat loss through the skin's surface

• Increased heart rate: vasoconstriction causing blood pressure to increase in the rest of the circulatory system causing the heart to pump more forcefully (heart rate increases in response to stress so increases in both and high and low temperatures)

• Shivering: muscles contract to produce heat

• Hair erection: follicles stand trapping a layer of air

• Increased bladder activity

• Hypothermia: body's core temperature drops

How do humans adapt to temperature genetically?

In an extreme case where humans are forced to adapt to temperature. Genetically there will be a strong diversion from usual human genotype and only certain phenotypes will be able to survive and breed in those conditions decreasing the gene pool. On a larger scale this is implied within society where in hotter climates humans are taller and generally skinnier for higher surface area : volume compared to colder temperature climates