The heart rate speeds up or slows down because the
A) AV node detects lower levels of oxygen and sends faster signals to the SA node.
B) brain consciously detects the need for more oxygen and intentionally stimulates the heart.
C) medulla oblongata, through the autonomic system, stimulates or depresses heart rate based on activity and stress.
D) hormone epinephrine inhibits the heartbeat.
E) SA node detects lower levels of oxygen and sends faster signals to the AV node.

Question

Quizplus · Accepted Answer

The medulla oblongata, which is part of the autonomic nervous system, regulates the heart rate based on the body's needs, such as during times of activity or stress. When the body needs more oxygen, the medulla oblongata stimulates the heart to beat faster, and when the body has sufficient oxygen, it slows down the heart rate. Choices A, B, D, and E are incorrect as they do not accurately describe the physiological mechanisms that control heart rate.

The Heart Rate Speeds Up or Slows Down Because the