The proceeds of any taxes levied pursuant to the authorization contained in this part shall be used only for the purpose of providing funds to pay the costs of construction, maintenance, and operation of hospital facilities in the county. The entire proceeds derived by the county from the taxes herein authorized to be levied, including any income derived from the investment of such proceeds, shall be paid over and deposited, promptly upon receipt thereof, into a separate and distinct fund or account of the county, which shall be accounted for as other county funds; provided, however, the governing body of the county shall have the further power to designate as the agency of the county to construct, maintain, and operate the hospital facilities any public hospital corporation heretofore or hereafter organized for hospital purposes in the county. When a public hospital corporation shall be so designated, the proceeds of the taxes thereafter collected shall be paid over to it and shall be used by it for any one or more of the purposes for which the taxes are herein authorized to be levied. The county or the public hospital corporation may anticipate the proceeds from the taxes so required to be paid to it by issuing, for any of the purposes for which the taxes are herein authorized to be levied, funding or refunding bonds, warrants, or certificates of indebtedness of the county or the public hospital corporation, and may pledge for the payment of the principal thereof and interest thereon the proceeds from the taxes so paid to it. The designation by the governing body of the county of a public hospital corporation to receive the proceeds of the taxes levied pursuant to this part, the payment of such proceeds over to a public hospital corporation, and the pledge of such proceeds by the public hospital corporation for the payment of the principal of and interest on bonds, warrants, or certificates of indebtedness issued by such public hospital corporation shall constitute a part of the contract with the holders of the bonds, warrants, or certificates of indebtedness and such contract shall be protected from impairment to the fullest extent provided by the federal Constitution and the Constitution of Alabama of 1901, as amended.