What is the statute of limitations for an action for professional negligence against a health care provider?

Section 340.5 provides that an action for professional negligence against a health care provider must be commenced three years after the date of the injury or one year after the plaintiff discovers the injury, whichever occurs first. "While ignorance of the existence of an injury or cause of action may delay the running of the statute of limitations until the date of discovery, the general rule in California has been that ignorance of the identity of the defendant is not essential to a claim and therefore will not toll the statute." (Bernson v. Browning-Ferris Industries (1994) 7 Cal.4th 926, 932.) "Aggrieved parties generally need not know the exact manner in which their injuries were 'effected, nor the identities of all parties who may have played a role therein.' " (Ibid.)