Circadian rhythm is a 24-hour sleep-wake cycle. It is controlled by hormone melatonin. Melatonin is secreted by pineal gland. This gland is attached via a stalk with the epithalamus and hence it is also known as epiphysis. It is also known as the third eye as this gland is present at the axis traced from the third eye. Melatonin secretion depends on light. It increases due to darkness and decreases due to light.
ANF is secreted by atria and it decreases the blood pressure raised due to RAAS. Oxytocin is the birth hormone as it plays an important role during parturition and milk production. Growth and maintenance of mammary glands is by sex hormones after puberty and by prolactin during pregnancy. Progesterone and Estrogen are secreted by the corpus luteum and these are responsible for repair of the endometrium of the uterus.