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!
<span>Scientists agree that both genetic and environmental factors influence self-esteem.
The answer is true. Disorders affecting self-esteem could be genetic and environmental factors including bullying and being ignored could affect self-esteem.</span>
