by galled » Fri Oct 13, 2017 4:57 pm
Heat can affect BP, but how/what it does varies depending on a number of factors. Generally heat will cause the body to go into cooling mode (sweating etc.), one of which is to cause blood vessels to expand to increase heat transfer/expel heat. (Blood vessels contract when it's cold for exact opposite reasons.)
However, if you get too hot (where your brain is being overheated), your circulatory system ramps up to try and cool your brain (like putting your cooling system on high). This in turn increases blood pressure--which is extremely dangerous--high BP with dilated blood vessels puts you in danger of stroke. Stay cool!