(a) Pursuant to applicable rules and regulations established by the State Department of State Hospitals or the State Department of Developmental Services, the medical director of a state hospital may receive in that hospital, as a boarder and patient, a person who is a suitable person for care and treatment in that hospital, upon receipt of a written application for the admission of the person into the hospital for care and treatment made in accordance with the following requirements:

1. (1) In the case of an adult, the application shall be made voluntarily by the person, at a time when he or she is in a condition of mind as to render him or her competent to make it or, if he or she is a conservatee with a conservator of the person or person and estate who was appointed under Chapter 3 (commencing with Section 5350) of Part 1 of Division 5 with the right as specified by court order under Section 5358 to place his or her conservatee in a state hospital, by his or her conservator.
2. (2) In the case of a minor, the application shall be made by his or her parents, or by the parent, guardian, conservator, or other person entitled to his or her custody to a mental hospital as may be designated by the Director of State Hospitals or the Director of Developmental Services to admit minors on voluntary applications. If the minor has a conservator of the person, or the person and the estate, appointed under Chapter 3 (commencing with Section 5350) of Part 1 of Division 5, with the right as specified by court order under Section 5358 to place the conservatee in a state hospital the application for the minor shall be made by his or her conservator.