Endocrine System Part 2 PDF

ENDOCRINE SYSTEM part 2 PITUITARY GLAND  ESTROGENS Estrogens- a group of steroid hormones: estradiol, estrone, estetrol. Estradiol is an important reproductive hormone. It it is mainly created by the ovaries, but small amounts are also produced by adipocytes...

ENDOCRINE SYSTEM part 2 PITUITARY GLAND  ESTROGENS Estrogens- a group of steroid hormones: estradiol, estrone, estetrol. Estradiol is an important reproductive hormone. It it is mainly created by the ovaries, but small amounts are also produced by adipocytes and the adrenal glands. Estradiol helps regulate the menstrual cycle, pregnancy, breast development and secondary sexual characteristics. It also supports cardiovascular function (vessels, blood pressure), lipid metabolism and has numerous other effects on the neurological (mood, memory, cognitive process) and skeletal systems. Estradiol is a potent physiological modulator of the CNS and participates in neurogenesis, regulation of neurotrophic factors expression and also antioxidant mechanisms. It has important neuroprotective activity. Estradiol in men is essential for modulating libido, erection and spermatogenesis.  PROGESTERONE Progesterone is a steroid hormone secreted by the corpus luteum- a temporary endocrine gland that is produced after ovulation during the second part of the menstrual cycle. Progesterone prepares the endometrium (lining of the uterus) for the potential of pregnancy. After conception, progesterone continues to stimulate the body to provide the blood vessels in the endometrium that will feed the growing fetus. Once the placenta develops, it also begins to secrete progesterone, supporting the corpus luteum. This causes the levels to remain elevated throughout the pregnancy, so the body does not produce more eggs. It also helps prepare the breasts for milk production. Progesterone increases a body temperature in the second part of the menstrual cycle.  TESTOSTERONE Testosterone is the main male hormone regulating sex differentiation, male sex characteristics and fertility. Testosterone’s effects are first seen in the fetus. During the first 6 weeks of development, the reproductive tissues of males and females are identical. Then in female fetus a conversion of androgens to estradiol is observed and estrogens regulate female characteristics.  TESTOSTERONE Testosterone is the most common androgen. Androgens are produced in the ovaries and testes as well as in the adrenal glands (in both sexes). In all genders, androgens control: bone density muscle development puberty red blood cell production sexual desire and function.  INHIBIN Inhibin is nonsteroidal hormone that exerts a specific negative feedback action on the secretion of the follicle-stimulating hormone (FSH) in the pituitary gland and reduces the hypothalamic LH - releasing hormone content. During the menstrual cycle, inhibin has been shown to increase testosterone synthesis in the ovaries. Inhibin plays an active role in the regulation of follicular development and in limiting the number of ovulations through the negative feedback effect on FSH. MENOPAUSE  PLACENTAL HORMONES human chorionic gonadotropin human placental lactogen relaxin estrogens progesterone  HUMAN CHORIONIC GONADOTROPIN HCG Human chorionic gonadotropin (HCG) is a glycoprotein hormone produced by the placenta and is a key messenger in fetal-maternal communication during embryonic development. HCG promotes progesterone production and angiogenesis in uterine vessels, causes uterine growth parallel to fetal growth, suppresses any uterine contractions during the pregnancy, causes growth and differentiation of the umbilical cord and promotes growth of fetal organs during pregnancy. Serum level of HCG is used to monitor pregnancy and pregnancy disorders. Urine level of HCG is an indicator of pregnancy- it appears in the urine and blood of pregnant women as early as 10 days after conception.  HUMAN PLACENTAL LACTOGEN HPL Human placental lactogen is polypeptide hormone produced during pregnancy by the syncytiotrophoblast cells of the placenta which appears to have key metabolic functions in pregnancy. Along with estrogen, progesterone and PRL, HPL promotes third trimester mammary growth for lactogenesis. It also has important metabolic roles in carbohydrate and lipid metabolism and fetal nutrient availability. HPL has been implicated in pregnancy-induced insulin resistance, maternal beta cell adaptation to pregnancy, and regulation of fetal growth.  RELAXIN Relaxin is a hormone with a high structural similarity to insulin. It is secreted in the ovary by the corpus luteum and during pregnancy in the placenta and the uterine lining. Relaxin promotes growth and softening of the cervix before the birth and development of the mammary glands for lactation. It also inhibits uterine contractions and promotes relaxation of the pelvic muscles and ligaments. Besides the pregnancy, the hormone is also involved in bone remodeling and healing of injured ligaments and skeletal muscle.