The heartbeat has two specialised areas of muscle (the sa node and the av node) that control and synchronise the heartbeat. The rhythm of relaxation and concentration of the pacemaker sets the rythym of the heartbeat.
Coat color in one breed of mice is controlled by incompletely dominant alleles so that yellow and white are homozygous, while cream is heterozygous. Thecross of two cream individuals will produce <span><u>equal numbers of white and yellow mice, with twice as many creams as the other two colors.</u></span>
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.
Uranium-235 is the answer
