High resolution

Module 7: Figure uterus activation

A model for the activation mechanism of human uterus contractility.

Contractions of the uterus during labour are driven by an endogenous membrane oscillator (horizontal green to pink box) that induces the slow pacemaker depolarization responsible for triggering the excitation–contraction coupling mechanism (vertical green box). The oscillator depends on an interaction between ion channels, pumps and exchangers that are colour-co-ordinated to indicate their contribution to either depolarization (green) or hyperpolarization (red). When the pacemaker depolarization (ΔV) reaches the threshold for the activation of the L-type VOCs (dashed line in the membrane potential trace at the top), excitation–contraction coupling is triggered and the muscle contracts. See text for further details.