The nurse knows that ____________ will help decrease blood pressure, while _____________ will help prevent seizures.

Choice A rationale

While a newborn's liver is immature and can affect coagulation, phytonadione (vitamin K) is not administered to directly improve liver function. Its primary role is to provide the necessary co-factor for the synthesis of specific clotting factors, which are produced in the liver but are vitamin K dependent.

Choice B rationale

Newborns typically have insufficient dietary intake of vitamin K, but this is a secondary issue. The primary reason for administering the medication is the lack of vitamin K in the newborn's sterile gut, which is necessary for the production of clotting factors. The medication directly addresses the risk of bleeding.

Choice C rationale

Newborns have a sterile gut at birth and are unable to synthesize vitamin K, a fat-soluble vitamin essential for the hepatic synthesis of clotting factors II, VII, IX, and X. The administration of phytonadione prevents vitamin K deficiency bleeding, also known as hemorrhagic disease of the newborn. This statement shows correct understanding of the medication's purpose.

Choice D rationale

Phytonadione is not an immune system stimulant. Its function is confined to the coagulation cascade. The medication is specifically a vitamin that acts as a co-factor in the synthesis of prothrombin and other coagulation proteins. It does not play a direct role in stimulating or modulating the infant's immune response.

Choice A rationale

The let-down reflex is primarily mediated by oxytocin's effect on myoepithelial cells surrounding the alveoli in the mammary glands. This action causes milk ejection, not activation of the reflex itself. Prolactin is the hormone primarily responsible for milk production, while oxytocin's role is specifically in the mechanical release of the milk.

Choice B rationale

Involution, the process of the uterus returning to its pre-pregnancy size, is a gradual process that occurs over several weeks. While oxytocin's uterine contractions contribute to this process by compressing blood vessels and promoting uterine tone, it is not the immediate and primary outcome. This long-term process is influenced by many hormonal and physiological changes.

Choice C rationale

Oxytocin is a neuropeptide and a potent uterotonic agent. It works by binding to specific receptors on the smooth muscle cells of the myometrium, leading to increased intracellular calcium concentrations. This cascade of events triggers strong, rhythmic contractions, which are essential for labor induction and postpartum hemorrhage prevention.

Choice D rationale

While oxytocin-induced uterine contractions are crucial for the third stage of labor, which involves placental expulsion, the direct and primary action of the administered hormone is the stimulation of those contractions. The expulsion of the placenta is the clinical outcome resulting from the physiological action of the uterine muscle contracting.