The reaction of the shell of an adult living cell of human buccal epithelium to an external micromechanical stimulus was studied. The dependence of the magnitude of the reaction on the level of passive or active stimulation, namely, the level of force exposure, was established. It is shown that the cell can exhibit both active and passive reactions to an external micromechanical stimulus, as well as control the level of exposure to adhesive forces. Keywords: human buccal epithelium cell, shell, micromechanical stimulus, shell elasticity, AFM force spectroscopy.

The analysis of the shape of the Brownian relief of the surface of human buccal epithelium cells was carried out using the method of fractal geometry. The scaling coefficients eta, zeta and the fractal dimension Df were used to estimate their actual areas Sc(fact) and linear characteristics lf. Keywords: atomic force microscopy, buccal epithelium, fractal number.

Using AFM methods in air under normal conditions in a wide range of local force effects ($${F}_{const}$$ F const < 40 μN) the relief, functional micromechanical properties (elasticity coefficient $$K$$ K , Young’s modulus $$E$$ E , elastic $${\Delta h}_{dfrm}$$ Δ h dfrm and plastic $${\Delta h}_{stiff}$$ Δ h stiff deformations) and adhesive properties (work $$A$$ A of adhesive forces $${F}_{adh}={F}_{adh}(x;y)$$ F adh = F adh ( x ; y ) ) of the membranes of living adult cells of human buccal epithelium were studied in the presence of a protective layer < 100 nm of buffer solution that prevented the cells from drying. Almost all geometric and functional characteristics of the membrane in the local approximation at the micro- and nanolevels are affected by size effects and obey the laws of fractal geometry. The Brownian multifractal relief of the membrane is characterized by dimension $${D}_{f}$$ D f < 2.56 and irregularities < 500 nm vertically and < 2 μm horizontally. Its response to elastic (≤ 6 nN), active (6–21 nN), or passive (> 21 nN) stimulation ($${F}_{const}$$ F const ) is a non-trivial selective process and exhibits a correspondingly elastic ($$K=$$ K = 67.4 N/m), active ($$K=$$ K = 80.2 N/m) and passive ($$K=$$ K = 84.5 N/m) responses. $$K=K({F}_{const})$$ K = K ( F const ) and $$E=E({F}_{const})$$ E = E ( F const ) depend on $${F}_{const}$$ F const . Having undergone slight plastic deformations $${\Delta h}_{stiff}$$ Δ h stiff < 300 nm, the membrane is capable of restoring its shape. We mapped ($$E=E(x;y)$$ E = E ( x ; y ) , $${D}_{f}$$ D f = 2.56; $${\Delta h}_{dfrm}={\Delta h}_{dfrm}(x;y)$$ Δ h dfrm = Δ h dfrm ( x ; y ) , $${D}_{f}$$ D f = 2.68; $${\Delta h}_{stiff}={\Delta h}_{stiff}(x;y)$$ Δ h stiff = Δ h stiff ( x ; y ) , $${D}_{f }$$ D f = 2.42, $$A=A\left(x;y\right)$$ A = A x ; y and $${F}_{adh}={F}_{adh}(x;y)$$ F adh = F adh ( x ; y ) ) indicating its complex cavernous structure.