Your heart pumps blood at variable rates depending on your degree of physical activity or neural/hormonal activity (this is called heart rate). With exercise or fear, heart rate increases to pump more blood to an active body. Yet after exercise, heart rate decreases to a resting level. There are several nerves and hormones that stimulate heart rate to increase as needed, or decrease when needed, but there is no receptor that monitors heart rate. Is heart rate homeostatically regulated?

No, Homeostatic regulation requires Three components namely, a receptor, a control center and an effector. Without a receptor, there cannot be homeostatic regulation. Even though it seems that heart rate varies and returns to some number, this is not technically homeostatic regulation. Blood pressure is homeostatically regulated - it has baroreceptors that monitor pressure, the brainstem that receives the information and nerves that then activate blood vessels to constrict or dilate to correct pressure (as well as other effectors) - but heart rate is not. Heart rate is not monitored by any neuron. Absolute water content of the body is not homeostatically regulated either - no neuron detects the number of water molecules, although neurons do detect the relative saltiness of the body.