The average conduction velocity speed is approximately $20$-$80$ m/s. It takes approximately $1$ ms for a neurotransmitter to cross the synapses. Calculate the lower limit for your patella reflex vs. what you imagine for the patellar reflex of a giraffe. As a test, see if you can find a difference in reaction speed of people of differing heights.
I tried to come up with a formula $S(H)$, where $S$ is the lower limit on reflex time, and $H$ is the 'height,' which is actually the distance between the kneecap and the head.
The total distance that the signal would have to travel, excluding the synapses, is $2H$ inches. This is equal to $\frac{127H}{25}$ cm. This is then equal to $\frac{127H}{2500}$ m. The lower limit corresponds to an optimal speed of $80$ m/s, so this would take $\frac{127H}{200000}$ seconds. Then, we convert to milliseconds, so this takes $\frac{127H}{200}$ ms. We then add the time that the signal takes to cross the synapses, so $\boxed{S(H)=\frac{127}{200}H+1}$.
-Because $S'(H)>0$, the taller an animal is, the slower its reaction time.
-$\lim_{h \to 0}S(H)=1$, so theoretically, if microorganisms have similar synaptic behavior, they should take at least 1 millisecond to respond to their environment actively.
Is there any flaw in my reasoning or derivation of $S(h)$?