Refractory period (sex) autonomic feedback mechanism, rather than through central chemicals like oxytocin, serotonin, and prolactin. Autonomic feedback is already known to regulate other physiologic systems, such as breathing, blood pressure, and gut motility. This theory suggests that after male ejaculation, decreased wall tension in structures such as the seminal vesicles leads to a change in the fine autonomic signals sent from these organs, effectively creating a negative feedback loop. Such a mechanism is similar to decreased gastric and bowel motility once gastric contents have passed through. Once the feedback loop has been created, the refractory period remains until the loop is broken
Human milk microbiome in mature milk. Taxonomic composition of human milk also varies across the lactation period, initially dominated by "Weisella, Leuconostoc, Staphylococcus, Streptococcus," and "Lactococcus" species, and later composed primarily of "Veillonella, Prevotella, Leptotrichia, Lactobacillus, Streptococcus, Bifidobacterium," and "Enterococcus" Human milk oligosaccharides, a primary component of human milk, are prebiotics which have been shown to promote growth of beneficial "Bifidobacterium" and "Bacteroides" species. Mode of delivery may influence composition of the human milk microbiome, vaginal births being associated with high taxonomic diversity and high prevalence of "Bifidobacterium" and "Lactobacillus," and the opposite trend being seen with Cesarean births, however, no relationship between