Exocytosis is a type of active transport in which the cell membrane fuses with secretory vesicles and expels their content (water-soluble molecules, hormones, neurotransmitters, etc.) into the extracellular space. Exocytosis can be regulated or constitutive. Regulated exocytosis occurs in response of a specific signal while constitutive exocytosis secretes molecules without the need of a signal. Ca2+ is an external signal that triggers regulated exocytosis which is particularly important in neuron synapses.
the hormone erythroprotein increases the production of red blood cells when oxygen levels are low best supports teh statement taht hormones are involved in the regulation of homesstasis.
