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Physiology · Secretion and Reception

Bioelectric processes in secretory cells

When glandular tissue is activated, a specific electrical response occurs — the secretory potential. It is these bioelectrical shifts that create the conditions for the synthesized substance to move within the cytoplasm and successfully leave the cell.

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Baseline VoltageAt rest, the cell's electric field has a voltage of 20–30 mV.
Upon ExcitationDuring activity, the voltage of the intracellular electric field doubles.
Movement VectorThe field directs mature granules strictly toward the apical pole (apex).
Modes of SecretionThe final release of the substance occurs via diffusion or exocytosis.
2 min readFor medical studentsUpdated 09/24/2026
Material prepared by WhiteCoat Pro editorial team based on platform study guidesReviewed by medical editor: Aulov A. A., general practitioner · 09/24/2026

Nature of Secretory Potentials

Any excitation of secretory cells is inextricably linked to a change in their membrane charge. The resulting secretory potentials are not absolutely identical for all types of glandular tissues.

Depending on the specific cell type, the membrane potential can change in two opposite ways:

  • Depolarization — a decrease in the level of membrane polarization (characteristic of one group of cells).
  • Hyperpolarization — an increase in the membrane charge (observed in other cell types).

Both of these variants of membrane potential change serve a single purpose — triggering a cascade of reactions leading to the release of the synthesized product.

Intracellular Electric Field

A key factor in intracellular transport is the spatial charge asymmetry. The basal membrane (base of the cell) and the apical membrane (its apex) possess different degrees of polarization.

This difference creates the cell's own intrinsic electric field. Its main characteristics:

  1. At rest, the potential difference between the poles creates a field with a voltage of 20–30 mV.
  2. At the moment of cell excitation, the voltage of this electric field doubles (reaching 40–60 mV).

The function of the electric field is to ensure directed transport. The increased voltage facilitates the active movement of mature secretory granules. They are directed toward the apical pole of the cell, where they interact directly with the cell membrane for subsequent release.

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Modes of Secretion Release

After the electric field has moved the mature granules to the apical membrane and ensured their interaction, the final stage takes place — the release of the substance to the exterior.

According to physiological mechanisms, secretion release can occur through two main ways:

  • Diffusion — passive penetration of secretion molecules through the membrane.
  • Exocytosis — an active process of fusion of the secretory granule with the cell membrane and the ejection of its contents into the extracellular space.
How to memorize

To memorize the transport mechanism, imagine a magnet: the charge difference at the poles (basal and apical) creates a field (20–30 mV) that attracts granules to the "exit" (apical membrane), and upon excitation, this magnet becomes twice as strong.

Class and exam questions

How does the membrane potential change upon excitation of a secretory cell?

Depending on the type of secretory cell, a secretory potential arises, which manifests either as membrane depolarization or hyperpolarization.

Why does an electric field arise inside a secretory cell?

The electric field is formed because the basal and apical membranes of the cell have different degrees of polarization. At rest, this creates a voltage of 20–30 mV.

What is the main function of the electric field in a secretory cell?

It ensures the targeted movement of mature secretory granules to the apical pole of the cell and also promotes their interaction with the membrane for release to the exterior.

How does the intracellular field voltage change upon cell activation?

Upon excitation of a secretory cell, the initial voltage of the electric field (20–30 mV) doubles.

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What else to study on this topic

  • Mechanisms of depolarization and hyperpolarization in various types of glandular cells
  • Molecular bases of interaction between secretory granules and the apical membrane
  • Comparative characteristics of exocytosis and diffusion during secretion release
  • Effect of the doubled electric field on the rate of granule transport

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