I meet Man today, he told me this
The phenomenon of exocrine fluid effusion from the oral cavity of a quadrupedal organism belonging to the family Felidae—taxonomically designated as \*Felis catus\*—initially appears to be a mere mundane reflex. However, under the lens of neurophysiology and thin-film fluid dynamics, this process (clinically termed \*\*Ptyalism\*\* or \*\*Hypersalivation\*\*) manifests as a microscopic masterpiece of interaction between intracellular biochemical cascades and macroscopic physical constants.
The pathogenesis of this bodily fluid flux originates not within the buccal cavity itself, but rather from the localized hyperstimulation of the autonomic nervous system. Peripheral olfactory or gustatory stimuli propagate action potentials along afferent nerve fibers toward the superior and inferior salivatory nuclei located within the medulla oblongata. Through the efferent pathways of cranial nerves VII (Facial nerve) and IX (Glossopharyngeal nerve), the neurotransmitter acetylcholine is released, rapidly binding to muscarinic receptors (predominantly M\_3) situated on the acinar cell membranes. This intracellular signaling cascade triggers an abrupt surge in intracellular Ca\^{2+} ion influx, compelling glycoprotein (mucin)-containing vesicles to fuse with the apical membrane via exocytosis, thereby expelling the secretion into the lumens of the parotid, submandibular, and sublingual glands.
The colloidal dispersion seeping from the mandibular commissure of the \*Felis catus\* entity is not pristine water, but rather a \*\*non-Newtonian fluid\*\* exhibiting complex viscoelastic deformational properties. The intrinsic nature of this fluidic stream comprises a cross-linked biopolymer network of glycoprotein macromolecules suspended within a solvent matrix containing an anisotropic concentration of Na\^+, K\^+, Cl\^-, and HCO\_3\^- ions. It is this specific mucin concentration that generates microscopic shear resistance, substantially elevating the kinematic viscosity of the solution system relative to the standard H\_2O solvent.
Once the volume of the colloidal solution surpasses the retention threshold of the oral cavity's physiological capacity, the liquid begins to overflow across the labial mucosal epithelium. At this juncture, a spectacle of surface physics unfolds. The fluid continuum must contend with a complex state of mechanical equilibrium before achieving complete detachment from the organism's somatic boundaries. The macroscopic dynamics of droplet formation and subsequent pinch-off detachment are directly governed by the structural competition between terrestrial gravitational pull and the intrinsic surface tension of the fluid itself. This correlation can be mathematically represented via the \*\*Bond number\*\* (Bo), a dimensionless parameter in fluid mechanics:
the apparent density differential of the secretion relative to the atmospheric medium, g represents the local gravitational acceleration, L signifies the characteristic radius of curvature at the anatomical boundary of the organism's commissure, and \\sigma corresponds to the surface tension coefficient of the mucin biofilm.
When the product of gravitational acceleration and the net mass of the fluid volume exceeds the threshold limits of capillary force, a \*\*pinch-off singularity\*\* emerges. The non-Newtonian fluid instantaneously undergoes a structural rupture of its polymer network at the micro-level. A transparent, anisotropically light-refracting spherical droplet officially detaches from the entity's masticatory apparatus, obeying Newtonian kinematic equations of free fall into the spacetime continuum below, leaving behind a highly elastic capillary thread that retracts upward into the labial mucosa.
Solely through the exocrine effusion event of the \*Felis catus\* entity, one witnesses a flawless convergence of central neuro-molecular physiology with the laws of thermodynamics and fluid mechanics. Beneath the facade of vacuous lethargy and the complete relaxation of the orbicularis oris muscle, the feline is inadvertently executing a biophysical experiment of profound precision and aesthetic magnitude regarding phase transitions and interfacial dynamics.
​
TL;DR : Cat drooling
​