Passage and Power Flashcards
any hallow body organ when stretched to capacity will necessarily contract and empty.
A. Uterine Stretch Theory
labor, being considered a stressful event, stimulates the hypophysis to produce oxytocin from the posterior pituitary gland. Oxytocin causes contraction of the smooth muscles of the body, e.g., uterine muscles.
B. Oxytocin theory
progesterone, being the hormone designed to promote pregnancy, is believed to inhibit uterine motility. Thus, if its amount decreases, labor pains occur.
C. Progesterone Deprivation theory
initiation of labor is said to result from the release of arachidonic acid produced by steroid action on lipid precursors.
D. Prostaglandin theory
causes contraction of the smooth muscles of the body, e.g., uterine muscles.
Oxytocin
is said to increase prostaglandin synthesis which, in turn, causes uterine contractions.
Arachidonic acid
because of the decrease in blood supply, the uterus contracts.
E. Theory of Aging of placenta
ESSENTIAL FACTORS OF LABOR (5Ps)
- Passages
- Power
- Passenger
- Person
- Position
PASSAGES
FUNCTIONS
(Sit Sit)
○ Serves as birth canal
○ It proves attachment to muscles, fascia, and ligaments
○ Supports uterus during pregnancy
○ It provides protection to the organs found within the pelvic cavity
– “provide and direct”
False pelvis
“the tunnel”
True pelvis
– entrance to true pelvis
Inlet or Pelvic Brim
midpoint of sacral promontory to the lower margin of symphysis pubis
Diagonal Conjugate
Diagonal Conjugate cm
12.5 cm)
midpoint of sacral promontory to the midline of symphysis pubis
Obstetric Conjugate
Obstetric Conjugate cm
(11 cm)
midpoint of sacral promontory to the upper margin of symphysis pubis
True Conjugate