Answer:
i think its the last one im not sure tho
I think the answer is measles vaccine.
B. i asked my mom shes a surgeon
1. The cells of the SA node at the top of the heart are known as the pacemaker of the heart because the rate at which these cells send out electrical signals determines the rate at which the entire heart beats (heart rate).
2. septum : The septum is a thick wall of muscle that divides the heart. It separates the left and right sides of the heart.
3.The respiratory and circulatory systems work together to maintain homeostasis. The respiratory system moves gases into and out of the blood. The circulatory system moves blood to all parts of the body.
hope this helps! sorry I couldn't do all of them!
