Heart rate in increased when the sympathetic nervous system releases various hormones and it is decreased when the parasympathetic nervous system releases acetylcholine. The nervous system works with the muscular system by controlling muscle contraction. This happens when a neuron sends acetylcholine to the muscle cell. The nervous system works with the respiratory system by controlling how much air the lungs take in. This is controlled by the medulla in the brain sending signals to the diaphragm and intercostals. The nervous system works with the epithelial system by controlling sweat glands, arrector pili muscles and the constriction and dilation of blood vessels to control body heat. This is achieved by receptors in the skin sending distress signals to the hypothalamus in the brain which then sends signals back, activating either the sweat glands, vasoconstriction, vasodilation, or the arrector pili muscles. The nervous system works with the digestive system by controlling the rate of digestive. The sympathetic nervous system directs blood away from the digestive system, slowing the rate of