Which group of cells is responsible for the autoregulation of heart contraction?

Blood returning from the lungs enters into which chamber of the heart?

Which of the following accurately shows the electrical pathway through the heart?

Which nerve, as part of the parasympathetic nervous system, serves to decrease heart rate?

What specialized area of tissue delays the proliferation of electrical stimulation in the heart, allowing the heart chambers to fill with blood?

Which of the following is true about cardiac muscle?

Both the sympathetic and the parasympathetic nervous systems are essential for homeostasis and for survival. For example, when we are trying to run away from a threat, the sympathetic nervous system is in full effect to allow us to escape from danger. However, when there is no obvious threat, the parasympathetic nervous system tends to be more in control.

There are similarities and differences between the sympathetic and the parasympathetic nervous systems. In preganglionic nerve fibers, both the sympathetic and the parasympathetic nervous system utilize the neurotransmitter acetylcholine. Closer to the target organ, the parasympathetic nervous system remains dependent on acetylcholine whereas norepinephrine and epinephrine are the predominant neurotransmitters utilized by the sympathetic nervous system.

When norepinephrine and epinephrine bind to their receptors, different effects are carried out based on the type of receptor, affinity, and location of the receptor. For example, epinephrine has a higher affinity for the beta-2 receptor. When epinephrine binds to the beta-2 receptor, common effects include vasodilation and bronchodilation. Norepinephrine has a stronger affinity for the alpha-1, alpha-2 and beta-1 receptors. When norepinephrine binds to its receptor, common effects on the body include vasoconstriction (alpha-1), increased heart rate (beta-1) and uterine contraction (alpha-1).

In patients with heart failure, the physician might prescribe a beta blocker to help with the condition. How will a beta blocker be useful in patients with heart failure?

Which valve in the heart separates the right atrium from the right ventricle?

Which cardiac valve prevents backflow of blood from the left ventricle into the left atrium?

What are the valves between the right atrium and right ventricle, and between the left atrium and left ventricle, respectively?