BIOM1060 Lecture Notes - Lecture 2: Cervical Effacement, Corticotropin-Releasing Hormone, Myosin Light-Chain Kinase
Document Summary
Many hormones/factors cooperating to stimulate massive positive feedback response induces profound inflammatory process causing uterine contractions and cervical ripening. Maintaining pregnancy: high progesterone (uterine quiescence due to association of contractions with low proteins and anti-inflammatory effects) and anti-inflammatory drugs (reduce synthesis of prostaglandins) Factors inducing labour: low progesterone: loss of uterine quiescence, high prostaglandins: cause contractions, stress: increased cortisol levels. Changes in uterine myometrium (muscle layer): increased sensitivity of myometrial smooth muscle cells to protein/factors that cause contractions, and strengthen connections between smooth muscle cells to cause concerted contractions. Cervical ripening (relaxation and dilation): becomes soft, thin and pliable due to decreased collagen and increased h2o. Intracellular mechanism of myometrial contraction: increased ca2+ entry into cells, ca2+ complexes with calmodulin activates myosin light chain kinase (mlck, phosphorylates myosin produces p-myosin which binds to actin, contraction occurs. Process of childbirth: change in corticotropin releasing hormone (crh) receptor isoforms to contractile state, increased plasma crh concentrations stimulate cortisol production by adrenal glands.
