FSH and LH affect reproductive structures to cause the formation of sperm and the preparation of eggs for release and possible fertilization. The Leydig cells produce testosterone, which also is responsible for the secondary sexual characteristics of males.
They regulate the female reproductive system which is divided into the ovarian cycle and the menstrual cycle. Menopause occurs when the ovaries lose their sensitivity to FSH and LH and the female reproductive cycles slow to a stop. Sertoli cell cell in seminiferous tubules that assists developing sperm and makes inhibin. Skip to content Chapter Animal Reproduction and Development. Learning Objectives By the end of this chapter, you will be able to: Describe the roles of male and female reproductive hormones Discuss the interplay of the ovarian and menstrual cycles Describe the process of menopause.
Male Hormones. Female Hormones. The Ovarian Cycle and the Menstrual Cycle. The ovarian and menstrual cycles of female reproduction are regulated by hormones produced by the hypothalamus, pituitary, and ovaries. LH and FSH are produced in the pituitary, and estradiol and progesterone are produced in the ovaries. Estradiol and progesterone secreted from the corpus luteum cause the endometrium to thicken. Both progesterone and estradiol are produced by the follicles.
Secretion of GnRH by the hypothalamus is inhibited by low levels of estradiol but stimulated by high levels of estradiol.
Rising and falling hormone levels result in progression of the ovarian and menstrual cycles. Progesterone levels rise during the luteal phase of the ovarian cycle and the secretory phase of the uterine cycle.
Menstruation occurs after progesterone levels drop. Estrogen levels rise before ovulation, while progesterone levels rise after. Reproductive Endocrinologist A reproductive endocrinologist is a physician who treats a variety of hormonal disorders related to reproduction and infertility in both men and women. Exercises Which of the following statements about hormone regulation of the female reproductive cycle is false?
Which hormone causes Leydig cells to make testosterone? Describe the events in the ovarian cycle leading up to ovulation. Inhibin is produced by Sertoli cells when the sperm count exceeds set limits. Increased levels of testosterone affect the release of both GnRH and LH, decreasing the activity of the Leydig cells, resulting in decreased testosterone and sperm production. FSH stimulates follicles on the ovary to grow and prepare the eggs for ovulation. As the follicles increase in size, they begin to release estrogen and a low level of progesterone into the blood.
The level of estrogen rises to a peak, causing a spike in the concentration of LH. This causes the most mature follicle to rupture and ovulation occurs. Previous: Human Reproductive Anatomy and Gametogenesis. Next: Human Pregnancy and Birth. Stimulates the ovaries to produce oestrogen and progesterone and the testes to produce testosterone and sperm. LH and FSH are known collectively as gonadotrophins. PRL Breasts Stimulates the breasts to produce milk.
This hormone is secreted in large amounts during pregnancy and breast feeding, but is present at all times in both men and women. GH All cells in the body Stimulates growth and repair. Research is currently being carried out to identify the functions of GH in adult life. MSH Exact role in humans is unknown. ADH Kidneys Controls the blood fluid and mineral levels in the body by affecting water retention by the kidneys. This hormone is also known vasopressin or argenine vasopressin AVP.
Oxytocin Uterus Breasts Affects uterine contractions in pregnancy and birth and subsequent release of breast milk. Control of hormone production is monitored continuously and regulated using feedback loops. Although there are a number of different hormones they can be split into two main types: hormones that tell the pituitary to switch on production of a hormone a releasing hormone hormones that tell the pituitary to switch off production of a hormone an inhibiting hormone.
Hormones produced by other glands in the body In total more than hormones or hormone-like substances have been discovered. It promotes normal metabolism, maintains blood sugar levels and blood pressure, provides resistance to stress and acts as an anti-inflammatory agent.
It also plays a part in regulation of fluid balance in the body. Thyroxine Thyroid Thyroxine controls many body functions, including heart rate, temperature and metabolism. It also plays a role in the metabolism of calcium in the body. Oestrogen Ovaries Oestrogen facilitates growth of the tissues of the sex organs and other tissues related to reproduction.
For these hormones, measuring a random blood sample does not provide useful information. For some of those hormones, doctors give a substance that would normally affect hormone production and then they measure the level of the hormone.
For example, if a doctor injects insulin , the levels of ACTH , growth hormone, and prolactin should increase. Rather than measuring growth hormone levels directly, doctors often measure another hormone, insulin -like growth factor 1 IGF Growth hormone is produced in bursts and its levels quickly fall, but IGF-1 levels reflect the overall daily production of growth hormone.
For all of these reasons, interpreting the results of blood tests for pituitary hormones is complex. Merck and Co. From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world.
The Manual was first published in as a service to the community. Learn more about our commitment to Global Medical Knowledge. This site complies with the HONcode standard for trustworthy health information: verify here. Common Health Topics. Anterior lobe hormones. Posterior lobe hormones. Pituitary gland malfunction.
Pituitary Gland Disorders. Test your knowledge. Amyloidosis is a rare condition in which abnormally folded proteins form structures called amyloid fibrils that accumulate in tissues and organs, sometimes leading to organ dysfunction, organ failure, or death.
More Content. The Pituitary and Its Target Organs. Pituitary: The Master Gland The pituitary, a pea-sized gland at the base of the brain, produces a number of hormones. The anterior lobe of the pituitary produces and releases secretes six main hormones:.
Prolactin, which stimulates the mammary glands of the breasts to produce milk. The posterior lobe of the pituitary produces only two hormones:.
Too little or too much of a pituitary hormone results in a wide variety of symptoms. Overproduction of pituitary hormones causes disorders, including. Underproduction of pituitary hormones causes disorders, including. Was This Page Helpful? Yes No. Central Diabetes Insipidus. Overview of the Pituitary Gland. Enlargement of the Pituitary Gland.
0コメント