Biological Sciences
Reproductive Hormones
Reproductive hormones are chemical messengers produced by the endocrine system that regulate the reproductive processes in both males and females. In males, these hormones include testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH), while in females, they include estrogen and progesterone. These hormones play a crucial role in the development and functioning of the reproductive system.
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4 Key excerpts on "Reproductive Hormones"
eBook - ePub- Jiro J. Kaneko(Author)
- 2014(Publication Date)
- Academic Press(Publisher)
Murphy, 1964 ). These techniques have added new dimensions to the study of reproductive mechanisms. The assay systems are sensitive, specific, relatively inexpensive, and require small amounts of assay material. They have been of special value for studying endocrinological reproductive functions in domestic animals in that they have made possible the study of dynamic endocrine changes through the assay of serial blood samples from the same animal. Radioimmunoassay and competitive protein binding techniques are suitable not only for physiological research, but also as diagnostic aids for the identification and elucidation of clinical reproductive problems. In clinical practice, these methods are becoming important from both a diagnostic and therapy-monitoring point of view.Because this book deals with clinical biochemistry in domestic animals, the main emphasis of the chapter is on the determination of hormones and the use of the data as diagnostic aids. General reproductive endocrinology in domestic species is broadly covered. Readers specifically interested in this subject are referred to specialized books dealing with this matter.A Definition of Hormones
Hormones are chemical substances synthesized and secreted by ductless endocrine glands directly into the bloodstream, by which they are carried to other parts of the body, where they regulate (decrease or increase) the rates of specific biochemical processes. The endocrine glands include the pituitary (the adenohypophysis and neurohypophysis), thyroid, parathyroid, adrenal cortex and medulla, islets of Langerhans of the pancreas, ovary, testis, placenta, and pineal gland.B Chemical Classes of Reproductive Hormones
1 Protein Hormones
a Releasing Hormones.
Several types of hormones are involved in the regulation of reproduction. Releasing hormones are peptide hormones which are produced within the hypothalamus and transferred via the hypothalamohypophyseal portal veins to the adenohypophysis, where they regulate the synthesis and/or release of adenohypophyseal hormones. The gonadotropin-releasing hormone (Gn-RH), a decapeptide with the sequence pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2 , regulates the release of two important Reproductive Hormones, namely, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Thyrotropin-releasing hormone, a tripeptide (pGlu-His-Pro-NH2
eBook - PDF- E. S. E. Hafez, B. Hafez, E. S. E. Hafez, B. Hafez(Authors)
- 2013(Publication Date)
- Wiley-Blackwell(Publisher)
PhysiologYu P AR T I I eproduction C RAPTER 3 Hormones, Growth Factors, and Reproduction E.S.E. HAFEZ, M.R. }AINUDEEN,AND Y. ROSNINA Over the passage of time, the control of mammalian repro ... duct ion has shifted from the central nervous system (CNS) to regulation by two separate systems, the CNS and the endocrine systems (Fig. 3 ... 1). Then followed the discovery that the hypothalamus linked the two systems through the hypothalamo ... hypophyseal portal system to coordinate the functions of the gonads. However, many phenomena could I not be explained solely on neuroendocrine controL There ... fore, the past decade has witnessed the discovery of chemical messengers (growth factors) and the presence of regulatory autocrinc/paracrine systems within the gonads. These ad ... vances have helped to unravel phenomena that hitherto could not be explained solely on neuroendocrine controL Both the endocrine and nervous systems function to initiate, coordinate, or regulate the functions of the repro ... ductive system. Unlike the nervous. system, which controls body function through rapid,electric nerve impulses e.g., musculoskeletal system, the endocrine system uses chemical messengers orIiormones to regulate slow body processes, e.g., growth and reproduction. The classic definition of a hormone is a physiologic, organic, chemical substance synthesized and secreted by a ductless endocrine gland, which passes into the circulatory system for transport. Hormones inhibit, stimulate, or regu ... late the functional activity of the target organ or tissue. However, organs like the uterus and the hypothalamus pro ... duce hormones, which do not meet the classic definition of a hormone. Besides hormones from the endocrine glands, extensive investigations during the last decade have revealed the role of peptide growth factors, commonly known as "Growth Factors" in reproduction.
eBook - PDFCrash Course Endocrinology: Updated Edition - E-Book
Crash Course Endocrinology: Updated Edition - E-Book
- Ronan O'Neill, Richard Murphy, Daniel Horton-Szar(Authors)
- 2015(Publication Date)
- Mosby Ltd.(Publisher)
Hormones of the reproductive system 11 Objectives After reading this chapter, you should: • Know the relevant anatomy of both male and female genitalia • Understand the hormones secreted by the different organs and their function • Understand the hormonal changes in the body associated with pregnancy, labour and lactation. The reproductive systems in both men and women are controlled in many ways by the endocrine system, as seen in puberty. The reproductive organs themselves produce hormones that can influence the rest of the body. This chapter focuses on the normal functions of these organs and the actions of the hormones they release. The main functions of the female reproductive sys- tem are: • Oogenesis and ovulation – production and release of oocytes (female gametes) • Fertilization – allowing the sperm and oocyte to meet and fuse • Pregnancy – providing a suitable environment for the fetus to grow • Parturition – expelling the fetus with minimal trauma to the baby and mother • Lactation – providing nutrition for the baby. After menarche (the start of periods), the female body prepares for pregnancy every month until menopause. This process is regulated by four main hormones (Fig. 11.1): • Follicle-stimulating hormone (FSH) • Luteinizing hormone (LH) • Oestrogen • Progesterone. The male reproductive system consists of the testes, prostate, seminal vesicles and the penis. Its principal functions are: • Sperm production (spermatogenesis) and release • Production of hormones involved in male reproduc- tion and libido. After puberty, the testes begin to produce sperm and they continue to do so until death. This process is regu- lated by four main hormones (Fig. 11.2): • Follicle-stimulating hormone (FSH) • Luteinizing hormone (LH) • Testosterone • Inhibin B. Further details on development and disorders of the re- productive systems are covered in other textbooks (Crash Course Renal and Urinary Systems and Crash Course Obstetrics and Gynaecology).
eBook - PDF- Gerald Litwack(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
For the present, considerations of the mechanism of sex hormone action must recognize that the primary event may be of either a positive (restorative) or a negative (derepressive) nature. The action of humoral agents at the subcellular level may be studied from two standpoints: (1) what the hormone does to the tissue and (2) what the tissue does with the hormone. During the past decade, considerable information relevant to endocrine mechanisms has been acquired from both types of experimental approach. The influence of administered sex hormones on the rates of incorporation of labeled pre-cursors into cellular constituents, both in vivo and in vitro, has demon-strated many rapid biochemical effects in dependent tissues of hormone-deprived animals. The sensitivity of these responses to what presumably are selective inhibitors of protein or ribonucleic acid biosynthesis has provided some insight as to their chronologic interrelation. Determination of the uptake and chemical fate of physiological amounts of radioactive hormones in various tissues of experimental animals has led to the recog-nition that target tissues contain unique amounts of characteristic extra-nuclear proteins, now generally called hormone receptors, which associ-ate with the steroid and accompany it to its ultimate site of fixation in the nucleus. It is presumed that the hormone-receptor interaction and the acceleration of biosynthetic processes are closely interrelated. In the following presentation, an attempt is made to summarize the early biochemical effects of the estrogenic and progestational hormones in target tissues, to describe the nature of the hormone-receptor interac-tion, and finally, to consider the possible role of the receptor proteins in the elicitation of hormonal response.
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