<prompt> Which of the following is characteristic of saliva?Hypotonicity relative to plasmaA lower HCO3- concentration than plasmaThe presence of proteasesSecretion rate that is increased by vagotomy  <response>: Saliva is characterized by: Hypotonicity High HCO3- concentration relative to plasma because of secretion of HCO3- into saliva by the ductal cells. Presence of a-amylase and lingual lipase not proteases Because control of saliva production is parasympathetic, it is abolished by vagotomy. 