The main responsible for the delay among the atrial and
ventricular contractions is the action potential conduction velocity of the AV
node cells. If the atria and ventricles contract simultaneously, atria cannot
give any help in filling the ventricles, which is needed, especially in those
with stiff ventricles as in the elderly. Hence atria have to contract first and
then the ventricles.
1st image I think would be the answer
The answer is coevolution.
Coevolution is a change in <span>one species that results from a change in another species that it interacts with. For example, some species of orchid and African moth coevolved. That was a consequence of African moths' dependence on flower nectar and the orchids' dependence on moths' help in pollination. This two species coevolved, therefore the orchids have deep flowers while African moths have long proboscides.</span>
The correct answer is choice B, Tt. I hope this helps.
Is the flu vaccine a answer? If so I’m pretty sure that’s the answer.
