REPRODUCTIVE HORMONES AND THEIR FUNCTIONS. looking at the word hormone and their functions in living things, but here in this post I am going to treat reproductive hormones and their functions.
first, what is reproduction? this is the acting reproducing young living organisms or you can call it procreation.
Reproductive hormones play a vital role in the functioning and regulation of the reproductive system in both males and females.
These complex chemical messengers are responsible for the development, maturation, and maintenance of the reproductive organs, as well as the coordination of various reproductive processes
what are reproductive hormones?
Reproductive hormones are intricate chemical messengers that orchestrate the complex processes of human reproduction.
From regulating the menstrual cycle to facilitating ovulation, sperm production, and the maintenance of pregnancy, these hormones play a pivotal role in the functioning of the reproductive system.
Understanding the functions and interactions of these hormones is essential for comprehending fertility, reproductive health, and the overall dynamics of human reproduction
Follicle-Stimulating Hormone (FSH): FSH is a gonadotropin hormone released by the pituitary gland. In females, FSH stimulates the growth and development of ovarian follicles, which contain the eggs.
It also triggers the production of estrogen by the ovaries. In males, FSH stimulates the growth and maturation of the seminiferous tubules in the testes, aiding in sperm production.
Luteinizing Hormone (LH): LH is another gonadotropin hormone secreted by the pituitary gland. In females, LH surge triggers ovulation, the release of a mature egg from the ovary.
After ovulation, LH stimulates the transformation of the ruptured follicle into the corpus luteum, which produces progesterone.
In males, LH stimulates the production of testosterone by the Leydig cells in the testes, promoting sperm maturation and development.
Estrogen: Estrogen is primarily produced by the ovaries in females, with a small amount also secreted by the adrenal glands.
It plays a crucial role in the development and maintenance of secondary sexual characteristics, such as breast development and the distribution of body fat.
Estrogen also regulates the menstrual cycle, promotes the thickening of the uterine lining, and supports bone health.
Progesterone: Progesterone is primarily produced by the corpus luteum in females, following ovulation. It prepares the uterus for implantation and helps maintain pregnancy if fertilization occurs.
Progesterone also plays a role in regulating the menstrual cycle and preventing the contraction of the uterine muscles, which could lead to miscarriage.
Testosterone: Testosterone is the primary male sex hormone produced by the testes, with a small amount secreted by the adrenal glands in both sexes.
It is responsible for the development of male sexual characteristics, including the deepening of the voice, facial and body hair growth, and muscle mass development.
Testosterone also plays a crucial role in maintaining libido, sperm production, and overall reproductive function in males.
Prolactin: Prolactin is a hormone released by the pituitary gland, primarily known for its role in stimulating milk production in breastfeeding women.
However, it also plays a role in regulating the menstrual cycle and fertility by suppressing the release of FSH and LH.
Oxytocin: Oxytocin is often referred to as the \”love hormone\” due to its involvement in social bonding, trust, and emotional attachment.
In females, it plays a crucial role in labour and childbirth by stimulating uterine contractions and promoting the release of milk during breastfeeding. Oxytocin also contributes to the bonding between mother and child.
group of reproductive hormones
reproductive hormones concerned with reproduction in farm animals can be grouped into male and female reproductive hormones.
MALE REPRODUCTIVE HORMONES
Androgen (Testosterone)
Functions of male reproductive hormones
(i) Reproductive hormones imitate spermatogenesis (sperm formation)
(ii)reproductive hormones are responsible for the imitation of male secondary sex characteristics
(iii) reproductive hormones Maintains the sex drive (libido)
(iv) Enhances muscular and skeletal growth
(v) Reduces fat deposition
(vi) Promotes the growth of accessory sex glands
(vii) Sustains the life of sperms in the epididymis
FEMALE REPRODUCTIVE HORMONES OESTROGEN
(i) Stimulates the development of female secondary sex characteristics e.g. heart behaviour
(ii) female reproductive hormones Promotes the production of eggs through oogenesis
(iii) It is concerned with the preparation of the uterus lining for the reception of the fertilized ovum
(iv) It increases blood supply as well as the water content of the uterus
(v) Female reproductive hormones stimulate the growth of the duct system in the mammary glands (udder)
(vi) In the oviduct, it increases ciliary activities and mucous secretion
(vii) Induces the rapid multiplication of epithelium in the vagina
(2) Follicle Stimulating Hormone (FSH)
(i) Female reproductive hormones stimulate the growth of the ovarian follicle
(3) Luteinizing Hormone(LH)
(i) It causes the rupture of the follicle and subsequent release of ava (i.e ovulation)
(ii) female reproductive hormones stimulate the secretion or ovarian hormones i.e oestrogen and progesterone
(4) Progesterone (Pregnancy hormone)
(i) Female reproductive hormones ensure the development of the uterus and implantation of the fertilized ovum
(ii) It inhibits oestrus (i.e it prevents the ripening of more follicles)
(iii) It causes the development of alveoli in the mammary gland
(iv) It ensures the continuance of the pregnancy
(5) Oxytocin
(i) It aids in the contraction of the female uterine muscles during pregnancy
(ii) It affects the mammary gland after birth by causing milk let-down or milk production
(iii) It promotes the transport of spermatozoa in the female genital tract.
(1) Relaxin
(i) It causes the relaxation of the pelvic ligament during parturition for easy passage of the young ones.
In males, LH stimulates the production and secretion of testosterone from the testes via Leydig cells.
In females, Luteinizing Hormone(LH) stimulates the production of oestrogens and progesterone from the ovary via theca interna cells and luteal cells.
Concentrations of LH increase during ovulation and with the formation of the corpora lutea with progesterone secretion. The secretion of LH is regulated via the secretion of GnRH (see earlier section).
As shown previously, in males there are between 4 to 12 GnRH pulses per day and this therefore means that LH also peaks throughout the day.
During these peaks, the production and secretion of testosterone increase. Testosterone secretion also is pulsatile.
Follicle Stimulating Hormone (FSH)
FSH is a type of glycoprotein that is produced in the anterior pituitary via gonadotroph cells. FSH secretion is regulated by GnRH from the hypothalamus.
The target tissue of FSH in males are the Sertoli cells within the testes and in the female the granulosa cells of the ovary.
FSH stimulates the maturation of germ cells within the testes and ovaries. In the female, it also stimulates follicular development and oestradiol synthesis.
In the male FSH also stimulates the secretion of inhibin which has a negative feedback directly to the anterior pituitary.
Although GnRH is released in a pulsatile fashion and the other gonadotropic hormone LH is therefore also pulsatile, FSH concentrations do not fluctuate as much as that of LH.
This is because of the added regulatory feedback mechanism of inhibin within the regulatory pathways for FSH secretion.
Prolactin (PRL)
Prolactin is a protein that is produced by the anterior pituitary via lactotroph cells. This hormone exerts a stimulatory effect on milk synthesis within the mammary glands.
It has also been shown to have some degree of gonadal function in some domestic species and rodents.
In birds increased concentrations of prolactin have been linked with brooding behaviours and the associated metabolic changes that birds undergo during brooding.
Prolactin secretion is regulated by the hypothalamus which produces several neurohormones that affect prolactin concentrations.
The most important within this is dopamine (or prolactin inhibitory hormone, PRL-IH) which exerts a totally dominant inhibitory action on prolactin synthesis.
The hypothalamic regulation of prolactin secretion is via signals from the central nervous system. Prolactin synthesis is increased when the mother is suckling via a reflex stimulation of the teats.
This stimulation reflex reduces the secretion of dopamine and increases the hormone prolactin-releasing hormone (PRL-RH).
Once prolactin binds to its target receptors within the mammary gland cells, it activates an intracellular tyrosine kinase.
When this occurs in the developing animal this binding can also cause the differentiation of mammary epithelial cells during pregnancy. The half-life of prolactin is approximately 20mins.
Estradiol can also have an effect on the prolactin-producing cells within the anterior pituitary and is responsible for increased concentrations of prolactin in females undergoing puberty and may also contribute to the increased concentrations during late pregnancy.
Oxytocin (OT)
OT is a neuropeptide (an octapeptide) which is synthesised in the hypothalamus and stored in the posterior pituitary.
OT is primarily involved in upregulating the activity of smooth muscle cells in the uterus and the smooth muscles surrounding the alveoli ducts of the mammary glands.
At parturition, OT causes strong contractions from the myometrium. OT is also essential for \’milk let-down\’ in most domestic species.
