- know what the gonadotropin hormones are
- know which gland synthesizes and secretes gonadotropins
- know which cells specificially synthesize and secrete gonadotropins
- know what the target organs for the gonadotropins are
- know what effects gonadotropins stimulate
- know the differences yet similarities about gonadotropins between males and females
- know how the gonadotropins are regulated
This packet covers the basics of the human gonadotropins: functions, target tissues, regulation of secretion, and gland they are secreted from. Their functions will be gone into with more depth in reproductive system packets.
The hormones known as gonadotropins are secreted from the anterior pituitary (adenohypophysis). Their names are follicle stimulating hormone (FSH) and luteinizing hormone (LH). The target tissues for these hormones are in their name, the gonads. Both males and females synthesize and secrete these hormones but their effects are different based on which sex organs a person has. These cells are synthesized and secreted by the gonadotropes of the anterior pituitary and are regulated in a few different ways.
Males, in my opinion, are a little more simple physiologically. In males the target organ for LH and FSH are the testes. The specific cells within the testes that have FSH receptors are the Steroli cells. Steroli cells are where sperm are produced through a complex process called spermatogenesis. When FSH interacts with the Steroli cells this stimulates and enhances spermatogenesis.
The testes are also the target tissue for LH, but a different group of cells have LH receptors (Leydig cells). LH stimulates and enhances the production of the male androgen known as testosterone. The main function of testosterone is to promote spermatogenesis in a paracrine fashion. Testosterone's secondary function is to promote the development of secondary sex charateristics.
The regulation of these hormones are better explained in the video with some images.
In females the target tissue for LH and FSH are the ovaries. These hormones are part of a very complex monthly cycle females undergo on a monthly basis. In females these hormones are secreted in a very cyclical fashion every month, and is explained more in the video with some images.
In females FSH stimulates the maturation of the ova within the ovaries. Unlike males, females are born with their sex cells (gametes) already present within their ovaries. They are not mature though and have to go through a process to become ready for fertilization, which begins at puberty. After menarche (onset of menstruation) FSH levels are normally high toward the beginning of her cycle, which stimulates the maturation of ova.
Once the ova become mature then they must be released (ovulated) from the ovary so it can come in contact with sperm for fertilization. About midway through the monthly cycle LH levels dramatically increase which stimulates ovulation to occur. The reminesce of the ovulated ova is left within the ovary and forms into a cell called the corpus luteum. The corpus luteum secretes estrogen but not for long if the ovulated ovum does not become fertilized. If fertilization does not occur then the corpus luteum dies, estrogen levels drop and the process starts over. There is more about this regulator process in the video with some images.
Source: Mind of Aaron
Source: Self made
Source: Self made