Question: Nervous System included a second single which was co-written by which frequent writing partner?
Context: "Issues" is the debut single by American singer and songwriter Julia Michaels.  Michaels co-wrote the song with her frequent writing partner, Justin Tranter, as well as the song's producers, Benny Blanco and Stargate.  It was released on January 13, 2017 through Republic Records.  "Issues" is a confessional downtempo love song which Michaels has described as a raw ode to her own anxieties. Familial dysautonomia (FD), sometimes called Riley–Day syndrome and hereditary sensory and autonomic neuropathy type III (HSAN-III), is a disorder of the autonomic nervous system which affects the development and survival of sensory, sympathetic and some parasympathetic neurons in the autonomic and sensory nervous system resulting in variable symptoms, including insensitivity to pain, inability to produce tears, poor growth, and labile blood pressure (episodic hypertension and postural hypotension).  People with FD have frequent vomiting crises, pneumonia, problems with speech and movement, difficulty swallowing, inappropriate perception of heat, pain, and taste, as well as unstable blood pressure and gastrointestinal dysmotility.  FD does not affect intelligence.  Originally reported by Drs. Conrad Milton Riley (1913–2005) and Richard Lawrence Day (1905–1989) in 1949, FD is one example of a group of disorders known as hereditary sensory and autonomic neuropathies (HSAN).  All HSAN are characterized by widespread sensory dysfunction and variable autonomic dysfunction caused by incomplete development of sensory and autonomic neurons.  The disorders are believed to be genetically distinct from each other. Sir Charles Scott Sherrington {'1': ", '2': ", '3': ", '4': "} (27 November 1857 – 4 March 1952) was an English neurophysiologist, histologist, bacteriologist, and a pathologist, Nobel laureate and president of the Royal Society in the early 1920s.  He received the Nobel Prize in Physiology or Medicine with Edgar Adrian, 1st Baron Adrian, in 1932 for their work on the functions of neurons. Prior to the work of Sherrington and Adrian, it was widely accepted that reflexes occurred as isolated activity within a reflex arc.  Sherrington received the prize for showing that reflexes require integrated activation and demonstrated reciprocal innervation of muscles (Sherrington's law).  Through his seminal 1906 publication, "The Integrative Action of the Nervous System", he had effectively laid to rest the theory that the nervous system, including the brain, can be understood as a single interlinking network.  His alternative explanation of synaptic communication between neurons helped shape our understanding of the central nervous system. Nervous System is the debut EP by American singer and songwriter Julia Michaels, released on July 28, 2017, by Republic Records.  The album's first single, "Issues", was released on January 13, 2017, and peaked at number 11 on the "Billboard" Hot 100. " Uh Huh", the second single from "Nervous System", was released on June 2, 2017. Neuromodulation is the physiological process by which a given neuron uses one or more chemicals to regulate diverse populations of neurons.  This is in contrast to classical synaptic transmission, in which one presynaptic neuron directly influences a single postsynaptic partner.  Neuromodulators secreted by a small group of neurons diffuse through large areas of the nervous system, affecting multiple neurons.  Major neuromodulators in the central nervous system include dopamine, serotonin, acetylcholine, histamine, and norepinephrine. The enteric nervous system (ENS) or intrinsic nervous system is one of the main divisions of the nervous system and consists of a mesh-like system of neurons that governs the function of the gastrointestinal tract.  It is now usually referred to as separate from the autonomic nervous system since it has its own independent reflex activity.  The ENS is also called the second brain. "Uh Huh" is a song by American singer and songwriter Julia Michaels.  It was released on June 2, 2017, as the second single from her first EP, "Nervous System" (2017).  The song was written by Michaels and her frequent writing partner Justin Tranter, along with the song's producers, Mattias Larsson and Robin Fredriksson. The peripheral nervous system (PNS) is one of the two components of the nervous system, the other part is the central nervous system (CNS).  The PNS consists of the nerves and ganglia outside of the brain and spinal cord.  The main function of the PNS is to connect the CNS to the limbs and organs, essentially serving as a relay between the brain and spinal cord and the rest of the body.  Unlike the CNS, the PNS is not protected by the vertebral column and skull, or by the blood–brain barrier, which leaves it exposed to toxins and mechanical injuries.  The peripheral nervous system is divided into the somatic nervous system and the autonomic nervous system.  In the somatic nervous system, the cranial nerves are part of the PNS with the exception of the optic nerve (cranial nerve II), along with the retina.  The second cranial nerve is not a true peripheral nerve but a tract of the diencephalon.  Cranial nerve ganglia originated in the CNS.  However, the remaining ten cranial nerve axons extend beyond the brain and are therefore considered part of the PNS.  The autonomic nervous system is an involuntary control of smooth muscle and glands.  The connection between CNS and organs allows the system to be in two different functional states: sympathetic and parasympathetic. Physiological or biological stress is an organism's response to a stressor such as an environmental condition.  Stress is the body's method of reacting to a challenge.  Stimuli that alter an organism's environment are responded to by multiple systems in the body.  The autonomic nervous system and hypothalamic-pituitary-adrenal (HPA) axis are two major systems that respond to stress.  The sympathoadrenal medullary (SAM) axis may activate the fight or flight response through the sympathetic nervous system, which dedicates energy to more relevant bodily systems to acute adaption to stress, while the parasympathetic nervous system returns the body to homeostasis.  The second major physiological stress, the HPA axis regulates the release of cortisol, which influences many bodily functions such as metabolic, psychological and immunological functions.  The SAM and HPA axes are regulated by a wide variety of brain regions, including the limbic system, prefrontal cortex, amygdala, hypothalamus, and stria terminalis.  Through these mechanisms, stress can alter memory functions, reward, immune function, metabolism and susceptibility to diseases.  Definitions of stress differ; however, one system proposed by Elliot and Eisdorfer suggests five types of stress.  The five types of stress are labeled "acute time limited stressors", "brief naturalistic stressors", "stressful event sequence", "chronic stressors", and "distant stressors".  Acute time limited stressors involve short term challenges, while, on the other hand, brief naturalistic stressors involve an event that is normal but nevertheless challenging.  Stressful event sequences are a stressor that occur, and continue to yield stress into the immediate future.  Chronic stressors involve exposure to a long-term stressor and a distant stressor is a stressor that isn't immediate. Nerve injury is injury to nervous tissue.  There is no single classification system that can describe all the many variations of nerve injury.  In 1941, Seddon introduced a classification of nerve injuries based on three main types of nerve fiber injury and whether there is continuity of the nerve.  Usually, however, (peripheral) nerve injury is classified in five stages, based on the extent of damage to both the nerve and the surrounding connective tissue, since supporting glial cells may be involved.  Unlike in the central nervous system, neuroregeneration in the peripheral nervous system is possible.  The processes that occur in peripheral regeneration can be divided into the following major events: Wallerian degeneration, axon regeneration/growth, and nerve reinnervation.  The events that occur in peripheral regeneration occur with respect to the axis of the nerve injury.  The proximal stump refers to the end of the injured neuron that is still attached to the neuron cell body; it is the part that regenerates.  The distal stump refers to the end of the injured neuron that is still attached to the end of the axon; it is the part of the neuron that will degenerate but that remains in the area toward which the regenerating axon grows.  The study of peripheral nerve injury began during the American Civil War and has greatly expanded to the point of using growth-promoting molecules.
Answer: Justin Tranter