The role of hormones in the female reproductive system.

Extracts from this essay...

Introduction

The role of hormones in the female reproductive system The oestrus cycle is the continuing process of fertility and non-fertility controlled by several hormones and the endocrine system. This consists of the hypothalamus, the anterior pituitary gland, the ovaries and the uterus, known as the hypothalamic-pituitary-ovarian-uterine axis. Oestrus normally lasts for 18 to 24 days but this figure can vary in specific circumstances such as early puberty when the cycle lasts for a lot less time (3 to 12 days) and also when the cycle commences after pregnancy and parturition (Fuquay 2002). The oestrus cycle halts during pregnancy due to the large amounts of progesterone in the blood supplied by the Corpus Luteium (CL). Progesterone is vital for maintaining pregnancy and also for stimulating the growth of mammary alveoli for the purpose of lactation. Gonadotrophin releasing hormone (GnRH) begins a cascade of hormones through the animal that are responsible for the oestrus cycle taking place.

Middle

High concentrations of progesterone and oestradiol in the blood act to lower the amount of gonadotrophins released. The granulosa cells of follicles release inhibin, inhibins are a set of hormones that help control gonadotrophins as well by suppressing the synthesis and secretion of FSH. They are made up of two protein sub-units, ? and ?, that are linked by a disulphide bridge. It is these cells that form the CL due to the luteinization of them by LH and once they have been changed, they will respond to LH by producing progesterone. Prostaglandin F2? (PG) is the major luteolytic hormone in ruminants, it is secreted by the uterus. This also is secreted in a pulsing manner and is responsible for the lysis of the luteal cells (essentially the destruction of the CL) if pregnancy has not occured. If the ruminant is pregnant then the CL is maintained, as progesterone is needed in order to maintain the foetus.

Conclusion

The contractions soon become a lot stronger and regular, more frequent intervals until the foetus is pushed into the cervix that triggers the release of oxytocin from the posterior pituitary. It is this hormone that regulates the strength and timing of the contractions until the foetus has been expelled. Some contractions still occur and a second surge of oxytocin is connected to the expulsion of the placenta. Nearly all hor monal activity ceases once the cow has calved, with some levels dropping at a very high rate. The cow returns to a normal cycle after 20 to 30 days but with the difference of showing no visible signs of it happening. This is known as a quiet or silent oestrus and will usually only happen once and will be followed by a completely normal oestrus approximately 50 days after parturition. Suckling can affect the length of time it takes to return to oestrus, with LH, FSH and GnRH pulses being inhibited by the suckling reflex. ANIM 221 Reproductive Physiology James Crawley Animal Science (Behaviour & Welfare) James Crawley Animal Science (Behaviour & Welfare)

The above preview is unformatted text

Found what you're looking for?

  • Start learning 29% faster today
  • Over 150,000 essays available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Over 180,000 student essays
  • Every subject and level covered
  • Thousands of essays marked by teachers

Related University Degree Developmental & Reproductive Biology

  1. The polymerase chain reaction (PCR) is an in vitro technique, which allows the amplification ...

    Since all DNA polymerases require primers to initiate strand synthesis, the target for PCR amplification can be specified by designing primers to anneal to particular unique DNA sequences. 2. PCR primers are chemically synthesized oligonucleotides and their design is crucial for the success of the PCR.

  2. The Endocrine systems involvement in the control of the female reproductive system.

    Oxytocin encourages the contraction of the smooth muscle cells in the uterus and around the milk glands in the breasts. Anti diuretic hormone (vasopressin) endorses the re-absorption of water from the urine in the kidney, consequently controlling the salt levels in the blood.

  1. Discuss The Significance Of Normal And Abnormal Mitosis And Meiosis In The Lifecycle Of ...

    There is no Interphase between Meiosis I and Meiosis II and the latter begins with Prophase II. A new set of spindle fibers forms and the chromosomes begin to move toward the equator of the cell. All the chromosomes in the two cells align with the metaphase plate.

  2. Life cycle

    Cell division has two major roles. It enables a fertilized egg to develop through various embryonic stages, and an embryo to develop into an adult organism. It ensures the continuity from generation to generation; it is the basis of both asexual reproduction and sperm and egg formation in sexual reproduction.

  1. Should reproductive hormones be used to alter fertility?

    Are infertility drugs worth the cost that possible side effects have?" http://serendip.brynmawr.edu/biology/b103/f01/web3/pendzich.html . . Fertility drugs can often be seen as a factor which can increase a woman's chances of having ovarian cancer. "One factor is that an increased number of uninterrupted ovulations in a woman's lifetime increase her chance of developing ovarian cancer.

  2. Contrast the Biological Differences between Heterosexual Males and Homosexual Males

    observed that there would be wide variation between mothers as to how much stress they could deal with before they were overwhelmed and their offspring affected (Dorner, et al., 1983, as cited in Ellis & Ames, 1987). Lastly in regards to hormones, research has determined that several female contraceptives based on anti-androgen chemical effects.

  1. The Female Orgasm: Adaptation, Artefact or culturally learned? ( Department of Psychology - University ...

    influences shaping definitions, ideas and experiences of the female orgasm. The first explanation revolves around the notion of a pair bond - an enduring monogamous partnership between males and females (Crook, 1972). The majority of adaptive explanations of the human female orgasm are based on the idea that a male-female

  2. Explain the treatments available to help infertile couples have children.

    The advantages of using IVF are it has been around for a long time and so far no medical problems have been linked with IVF. The disadvantages are the fertility drugs have strong side effects and there is a high chance of having twins.

  • Over 180,000 essays
    written by students
  • Annotated by
    experienced teachers
  • Ideas and feedback to write
    your own great essays

Marked by a teacher

This essay has been marked by one of our great teachers. You can read the full teachers notes when you download the essay.

Peer reviewed

This essay has been reviewed by one of our specialist student essay reviewing squad. Read the full review on the essay page.

Peer reviewed

This essay has been reviewed by one of our specialist student essay reviewing squad. Read the full review under the essay preview on this page.