The function of the sinoatrial node is to
a. filter lymph.
b. prevent blood from backing up into the atrium.
c. keep the heart beating.
d. divide the right and left sides of the heart.

Based on the results of this study, what questions remain unanswered? how can these questions guide future research

Identify the type of energy used in each action. the flexing of an arm muscle: a signal transduction process by a neuron: a ball at the top of a hill: 1. electrical energy 2. mechanical energy 3. gravitational potential energy

How many major plates cover the earth