Heart rate is controlled by the two branches of the autonomic (involuntary) nervous system. The sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The sympathetic nervous system (SNS) releases the hormones (catecholamines - epinephrine and norepinephrine) to accelerate the heart rate. The parasympathetic nervous system (PNS) releases the hormone acetylcholine to slow the heart rate. Such factors as stress, caffeine, and excitement may temporarily accelerate your heart rate, while meditating or taking slow, deep breaths may help to slow your heart rate.
Answer:
mosses
Explanation:
Simple species that can tolerate the often- harsh environment become established first. These organisms help enrich the soil, allowing other species to become established. The first organisms to appear in areas of primary succession are often mosses or lichens.
C. your core will be made of protons will be made of protons and neutrons while being surrounded by "shells" of electrons.
