The School of Biomedical Sciences Wiki - User contributions [en]

Autophagy

2018-12-06T20:37:46Z

180050055:

Autophagy is an essential cellular process, used by [[Cell|cells]] to degrade damaged and unnecessary cytosolic macromolecules and [[Organelles|organelles]], for example, [[Proteins|proteins]]<ref>Klionsky, DJ. Autophagy revisited: A conversation with Christian de Duve. Autophagy. 2008;4(6):740-3. Available from: DOI: 10.4161/auto.6398.</ref>. This prevents cell functions and pathways from being damaged, or interrupted, by protein agggregates or non-functioning [[Organelles|organelles]], a key cause of disease. Diseases associated with abnormal autophagy include [[Parkinson's Disease|Parkinson's Disease]], [[Ostearthritis|osteoarthritis]] and [[Cancer|cancer]]<ref>Glick D, Barth S, Macleod KF. Autophagy: cellular and molecular mechanisms. The Journal of pathology. 2010;221(1):3-12. Available from: doi:10.1002/path.2697.</ref><ref>Levine, B. Cell biology: Autophagy and cancer. Nature. 2007;446:745-747. Available from: doi:10.1038/446745a.</ref>. Autophagy proceeds via a five-step mechanism that starts with the sequestration of cytosolic material by a double-membrane, known as a 'phagophore'. The phagophore membrane ends fuse, forming a specialised vesicle called an [[Autophagosome]]. Once sequestration is complete, the [[Autophagosome|autophagosome]] fuses with a [[Lysosome|lysosome]] and up to 40 [[Hydrolytic enzymes|hydrolytic enzymes]] digest the autophagosome's cargo<ref>Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Tokyo 113-8519, Japan; Solution Oriented Research for Science and Technology, Japan Science and Technology Agency, Tokyo 102-0075, Japan</ref>.

Autophagy helps the cell maintain a stable internal environment, preventing damage to the cell and tissues by removing harmful [[Molecules|molecules]], stopping their accumulation<ref>Mizushima N. Autophagy: process and function. Genes and Dev. 2007;21: 2861-2873. Available from: DOI:10.1101/gad.1599207.</ref>. It is extremely prominent in the case of starving cells where nutrients are required to perpetuate cell survival, or when the cell experiences other stresses such as hypoxia or drug treatment<ref>Yang Z J, Chee C E, Huang S, Sinicrope F A. The Role of Autophagy in Cancer: Therapeutic Implications. Molecular Cancer Therapeutics. 2011;10(9): 1533-1541. Available from: DOI: 10.1158/1535-7163.MCT-11-0047.</ref>.

One of the key products of autophagy, [[Amino acids|amino acids]], can be used for anabolic processes within the cell.

Autophagy is controlled by mTOR (Mechanistic target of rapamycin), a [[Kinase|kinase]] coded for by the mTOR gene. When mTOR is active, autophagy is suppressed. However, mTOR can be suppressed by low amino acid concentrations, allowing autophagy to produce more amino acids.

=== Types of autophagy ===

''Macroautophagy'' - This is widely considered to be the most used pathway of autophagy in the body. It deals with the recycling of dysfunctional organelles and proteins which may have been damaged or incorrectly folded during their synthesis. The process starts with a piece of cellular machinery termed the isolation membrane or “phagophore”. This is a double membrane structure that elongates and encloses part of the cytoplasm, as well as the target organelles or proteins. The resulting specialised vesicle is termed an “autophagosome”. The autophagosome then migrates to a lysosome to which it fuses via the outer membrane. It is important to note the outer membrane stays intact thus keeping the contents and [[Hydrolases]] within the “autolysosome” for recycling<ref>Mizushima N, Komatsu M. Autophagy: Renovation of Cells and Tissues. Cell, 2011, Volume 147, Issue 4</ref><ref>Glick D, Barth S, Macleod KF. Autophagy: cellular and molecular mechanisms. The Journal of Pathology. 2010; 221(1): 3-12. Available from: doi: 10.1002/path.2697</ref>.

''Microautophagy'' - This process differs from macroautophagy as it is only concerned with the degradation and recycling of cytoplasm in the cell. It also uses a different mechanism. No [[Autophagosome|autophagosome]] is formed as the [[Lysosome|lysosome]] itself directly degrades the cytoplasm by inward invaginations in its membrane<ref>Li W, Li J, Bao J. Microautophagy: lesser-known self-eating. Cell and Molecular Life Science. 2012, Volume 69, 1125-1136.</ref>.

''Chaperone-mediated autophagy'' - Only involves specific proteins within the cytoplasm. The target protein which is being degraded is recognised by a chaperone protein Hsc70 which binds to the target protein. This can then be recognised by specific receptors on the lysosomal membrane, where it is unfolded and taken into the organelle for degradation<ref>Kaushik S, Cuervo AM. Chaperone-mediated autophagy: a unique way to enter the lysosome world. Trends in Cell Biology. 2012, Volume 22 Issue 8, 407-417</ref>.

''Mitophagy'' - The selective degradation of [[Mitochondria|mitochondria]] by autophagy. This is used by the cell in order to remove damaged mitochondria, or as a mechanism to regulate the number of mitochondria present in the cell. This process is essential during some developmental processes, such as the maturation of [[Reticulocyte|reticulocytes]], as [[Erythrocyte|mature red blood cells]] do not contain any mitochondria; all the mitochondria present in the cell before [[Differentiation|differentiation]] must be removed<ref>Youle RJ, Narendra DP. Mechanisms of mitophagy. Nature Reviews Molecular Cell Biology. 2010; 12:9-14</ref><ref>Deas E, Wood NW, Plun-Favreau H. Mitophagy and Parkinson’s disease: The PINK1-parkin link. Biochimica et Biophysica Acta. 2011; 1813(4): 623-633 Available from: doi: 10.1016/j.bbamcr.2010.08.007</ref>.

=== Conclusion ===

Autophagy has been a remarkable discovery. Knowing about the process of cell recycling has opened several possible therapeutic opportunities that will definitely be a point of interest in research in the following years. Exploiting autophagy in humans can lead to delayed ageing and prevention of neurodegenerative and cancerous diseases. Further study will also educate us about how bacterial pathogens prevent autophagosomes from working effectively at the onset of a pathogenic invasion. This would lead to the understanding of countless bacterial diseases, and will hopefully provide an insight on how they can be cured. Therefore, the study on autophagic mechanisms need to continue to have a better understanding of this remarkable process.

=== References ===

<references />

Isomerase

2018-12-06T20:35:50Z

180050055:

Isomerase is a type of [[Enzyme|enzyme]] that catalyses [[Isomeration reactions|isomeration reactions]]<ref>Berg J.M., 2012. Biochemistry, 7th Edition. W. H. Freeman and Company Publishing.</ref>. In these reactions, a [[Molecule|molecule's]] structure is altered, but the [[Molecular formula|molecular formula]] and the number of [[Atom|atoms stay]] the same.

An example of this is [[Phosphoglucose isomerase|phosphoglucose isomerase]] which is important in the process of [[Glycolysis|glycolysis]], where it catalyses the isomeration of [[Glucose-6-phosphate|glucose-6-phosphate]] to [[Fructose-6-phosphate|fructose-6-phosphate]]. 

More examples of isomerase would be [[Alanine racemase|Alanine racemase]] and [[Mutarotase catalyzes|mutarotase catalyzes]]. Alanine racemase converts [[L-alanine|L-alanine]] into [[D-alanine|D-alanine]]. Mutarotase catalyzes converts [[Α-D-glucose|α-D-glucose]] into [[Β-D-glucose|β-D-glucose]]<ref>Britannica, https://www.britannica.com/science/isomerase, Date accessed- 3/12/18</ref>. 

Phosphoglucose isomerase is also a key enzyme involved in the process of [[Gluconeogenesis|gluconeogenesis]][2]   



=== <ref>http://www.ebi.ac.uk/interpro/entry/IPR001672</ref> ===



<references />

Isomerase

2018-12-06T20:35:30Z

180050055:

Isomerase is a type of [[Enzyme|enzyme]] that catalyses [[Isomeration reactions|isomeration reactions]]<ref>Berg J.M., 2012. Biochemistry, 7th Edition. W. H. Freeman and Company Publishing.</ref>. In these reactions, a [[Molecule|molecule's]] structure is altered, but the [[Molecular formula|molecular formula]] and the number of [[Atom|atoms ]]stay the same.

An example of this is [[Phosphoglucose isomerase|phosphoglucose isomerase]] which is important in the process of [[Glycolysis|glycolysis]], where it catalyses the isomeration of [[Glucose-6-phosphate|glucose-6-phosphate]] to [[Fructose-6-phosphate|fructose-6-phosphate]]. 

More examples of isomerase would be [[Alanine racemase|Alanine racemase]] and [[Mutarotase catalyzes|mutarotase catalyzes]]. Alanine racemase converts [[L-alanine|L-alanine]] into [[D-alanine|D-alanine]]. Mutarotase catalyzes converts [[Α-D-glucose|α-D-glucose]] into [[Β-D-glucose|β-D-glucose]]<ref>Britannica, https://www.britannica.com/science/isomerase, Date accessed- 3/12/18</ref>. 

Phosphoglucose isomerase is also a key enzyme involved in the process of [[Gluconeogenesis|gluconeogenesis]][2]   



=== <ref>http://www.ebi.ac.uk/interpro/entry/IPR001672</ref> ===

Luteinizing hormone

2018-12-06T20:33:04Z

180050055:

===  Leutinizing Hormone ===

Leutinizing hormone (LH) is a [[Glycoproteins|glycoprotein]] hormone produced and secreted by the anterior [[Anterior pituitary gland|pituitary gland]]<ref>Neal J. How the Endocrine system works.2nd ed. West Sussex: John Wiley &amp;amp;amp;amp;amp;amp; Sons;2016. 129.</ref> . This is in response to the[[Growth Hormone|Growth hormone-releasing hormone (GHRH)]] secreted by the [[Hypothalamus|hypothalamus]]<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 109p</ref> . It is an essential hormone in regulating the female [[Ovaries|ovarian cycle]] and stimulates the production of [[Testosterone|testosterone]] in males<ref>O'Neil R, Murphy R. Endocrinology crash course. 4th ed. Philadelphia: Elsevier Mosby; 2012. 109</ref> . Therefore the target tissues of LH are [[Gonads|Gonads.]] LH works in synergy with [[Follicle-stimulating Hormone|Follicle stimulating hormone (FSH)]] in both [[Male|males and]] [[Females|females]].

----

=== Ovarian Cycle regulation  ===

'''Follicular phase''' At the folicular phase, the loss of progesterone and higher [[Oestrogen|oestrogen increases]] frequency of GHRH secretion pulses from hypothalamus<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 227p</ref> . The LH to FSH secretion ratio increases. the decrease in concentration of FSH results in follicular atresia ([[Apoptosis|apoptosis]]), leaving the dominant follicle. This dominant follicle produces and secretes oestrogen. With Oestrogen level at >200pg/ml, a surge of LH is induced. this surge of LH is enhanced by [[Progesterone|Progesterone]], in which triggers the [[Oocyte|Oocyte to]] complete [[Meiosis I|meiosis 1]] and [[Ovulation|ovulation]]. '''Luteal phase''' Remnants from the follicle from the ovary form the [[Corpus luteum|corpus luteum]] this formation takes approximately 14 days to form. high levels in Progesterone inhibits and negatively feedbacks oestrogen, thus decreasing levels of FSH and LH. 

If no [[Fertilisation|fertilisation occurs]] following ovulation, then the corpus luteum degenerates to corpus albican. The level Oestrogen and Progesterone deplete allowing FSH and LH to rise. This release of negative feedback and the increase of FSH allows the recruitment of a crop of antral follicles to grow. Therefore iniating the start of another around of the Ovarian cycle.

If fertilisation does occur, the [[Placenta|placenta from]] [[Embryo|embryo formation]] releases human chorionic gonadotropin which allows the corpus luteum to stay<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 224p</ref>. 

----

=== Regulation of testicular function ===

LH targets<ref>Neal J. How the endocrine system works. 2nd ed. West Sussex: John Wiley &amp;amp;amp;amp;amp; sons; 2016. 93p</ref> Leydig cells. These cells synthesise testosterone. Similary to females, in males the hypothalamus secretes GHRH which triggers the secretion of LH and FSH from the pituatary gland. testosterone then negatively feedbacks to the  hypothalamus and pituitary gland and inhibits secretion of LH. This testosterone then results in differentiation of male sex tissue such as the scotum<ref>Norman AW, Henry HL. Hormones. 3rd ed. Oxford: Elsevier;2015. 266p</ref>'''.'''

----

'''References'''

<references />

=== ===

Luteinizing hormone

2018-12-06T20:31:02Z

180050055:

===  Leutinizing Hormone ===

Leutinizing hormone (LH) is a [[Glycoproteins|glycoprotein]] hormone produced and secreted by the anterior [[Anterior_pituitary_gland|pituitary gland]]<ref>Neal J. How the Endocrine system works.2nd ed. West Sussex: John Wiley &amp;amp;amp;amp; Sons;2016. 129.</ref> . This is in response to the[[Growth_Hormone|Growth hormone-releasing hormone (GHRH)]] secreted by the [[Hypothalamus|hypothalamus<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 109p</ref> ]]. It is an essential hormone in regulating the female[[Ovaries|ovarian cycle]] and stimulates the production of [[Testosterone|testosterone]] in males<ref>O'Neil R, Murphy R. Endocrinology crash course. 4th ed. Philadelphia: Elsevier Mosby; 2012. 109</ref> . Therefore the target tissues of LH are[[gonads|Gonads.]] LH works in synergy with [[Follicle-stimulating_Hormone|Follicle stimulating hormone (FSH)]] in both [[Male|males ]]and [[Females|females]].

----

=== Ovarian Cycle regulation  ===

'''Follicular phase''' At the folicular phase, the loss of progesterone and higher [[Oestrogen|oestrogen ]]increases frequency of GHRH secretion pulses from hypothalamus<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 227p</ref> . The LH to FSH secretion ratio increases. the decrease in concentration of FSH results in follicular atresia ([[Apoptosis|apoptosis]]), leaving the dominant follicle. This dominant follicle produces and secretes oestrogen. With Oestrogen level at >200pg/ml, a surge of LH is induced. this surge of LH is enhanced by [[Progesterone|Progesterone]], in which triggers the [[Oocyte|Oocyte ]]to complete [[Meiosis_I|meiosis 1]] and [[Ovulation|ovulation]]. '''Luteal phase''' Remnants from the follicle from the ovary form the [[Corpus_luteum|corpus luteum]] this formation takes approximately 14 days to form. high levels in Progesterone inhibits and negatively feedbacks oestrogen, thus decreasing levels of FSH and LH. 

If no [[Fertilisation|fertilisation ]]occurs following ovulation, then the corpus luteum degenerates to corpus albican. The level Oestrogen and Progesterone deplete allowing FSH and LH to rise. This release of negative feedback and the increase of FSH allows the recruitment of a crop of antral follicles to grow. Therefore iniating the start of another around of the Ovarian cycle.

If fertilisation does occur, the [[Placenta|placenta ]]from [[Embryo|embryo ]]formation releases human chorionic gonadotropin which allows the corpus luteum to stay<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 224p</ref>. 

----

=== Regulation of testicular function ===

LH targets<ref>Neal J. How the endocrine system works. 2nd ed. West Sussex: John Wiley &amp;amp;amp; sons; 2016. 93p</ref> Leydig cells. These cells synthesise testosterone. Similary to females, in males the hypothalamus secretes GHRH which triggers the secretion of LH and FSH from the pituatary gland. testosterone then negatively feedbacks to the  hypothalamus and pituitary gland and inhibits secretion of LH. This testosterone then results in differentiation of male sex tissue such as the scotum<ref>Norman AW, Henry HL. Hormones. 3rd ed. Oxford: Elsevier;2015. 266p</ref>'''.'''

----

'''References'''

<references />

=== ===

Luteinizing hormone

2018-12-06T20:20:55Z

180050055:

===  Leutinizing Hormone ===

Leutinizing hormone (LH) is a glycoprotein hormone produced and secreted by the anterior pituitary gland<ref>Neal J. How the Endocrine system works.2nd ed. West Sussex: John Wiley &amp;amp;amp; Sons;2016. 129.</ref> . This is in response to the Growth hormone-releasing hormone (GHRH) secreted by the hypothalamus<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 109p</ref> . It is an essential hormone in regulating the female ovarian cycle and stimulates the production of tesosterone in males<ref>O'Neil R, Murphy R. Endocrinology crash course. 4th ed. Philadelphia: Elsevier Mosby; 2012. 109</ref> . Therefore the target tissues of LH are Gonads. LH works in synergy with Follicle stimulating hormone (FSH) in both males and females.

----

=== Ovarian Cycle regulation  ===

'''Follicular phase''' At the folicular phase, the loss of progesterone and higher oestrogen increases frequency of GHRH secretion pulses from hypothalamus<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 227p</ref> . The LH to FSH secretion ratio increases. the decrease in concentration of FSH results in follicular atresia (apoptosis), leaving the dominant follicle. This dominant follicle produces and secretes oestrogen. With Oestrogen level at >200pg/ml, a surge of LH is induced. this surge of LH is enhanced by Prgesterone, in which triggers the Oocyte to complete meiosis 1 and ovulation. '''Luteal phase''' remnants from the follicle from the ovary form the corpus luteum this formation takes approximately 14 days to form. high levels in Progesterone inhibits and negatively feedbacks oestrogen, thus decreasing levels of FSH and LH. 

If no fertilisation occurs following ovulation, then the corpus luteum degenerates to corpus albican. The level Oestrogen and Progesterone deplete allowing FSH and LH to rise. This release of negative feedback and the increase of FSH allows the recruitment of a crop of antral follicles to grow. Therefore iniating the start of another around of the Ovarian cycle.

If fertilisation does occur, the placenta from embryo formation releases human chorionic gonadotropin which allows the corpus luteum to stay<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 224p</ref>. 

----

=== Regulation of testicular function ===

LH targets<ref>Neal J. How the endocrine system works. 2nd ed. West Sussex: John Wiley &amp;amp; sons; 2016. 93p</ref> Leydig cells. These cells synthesise testosterone. Similary to females, in males the hypothalamus secretes GHRH which triggers the secretion of LH and FSH from the pituatary gland. testosterone then negatively feedbacks to the  hypothalamus and pituitary gland and inhibits secretion of LH. This testosterone then results in differentiation of male sex tissue such as the scotum<ref>Norman AW, Henry HL. Hormones. 3rd ed. Oxford: Elsevier;2015. 266p</ref>'''.'''

----

'''References'''

<references />

=== ===

Luteinizing hormone

2018-12-06T20:20:01Z

180050055:

===  Leutinizing Hormone ===

Leutinizing hormone (LH) is a glycoprotein hormone produced and secreted by the anterior pituitary gland<ref>Neal J. How the Endocrine system works.2nd ed. West Sussex: John Wiley &amp;amp;amp; Sons;2016. 129.</ref> . This is in response to the Growth hormone-releasing hormone (GHRH) secreted by the hypothalamus<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 109p</ref> . It is an essential hormone in regulating the female ovarian cycle and stimulates the production of tesosterone in males<ref>O'Neil R, Murphy R. Endocrinology crash course. 4th ed. Philadelphia: Elsevier Mosby; 2012. 109</ref> . Therefore the target tissues of LH are Gonads. LH works in synergy with Follicle stimulating hormone (FSH) in both males and females.

----

=== Ovarian Cycle regulation  ===

'''Follicular phase''' At the folicular phase, the loss of progesterone and higher oestrogen increases frequency of GHRH secretion pulses from hypothalamus<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 227p</ref> . The LH to FSH secretion ratio increases. the decrease in concentration of FSH results in follicular atresia (apoptosis), leaving the dominant follicle. This dominant follicle produces and secretes oestrogen. With Oestrogen level at >200pg/ml, a surge of LH is induced. this surge of LH is enhanced by Prgesterone, in which triggers the Oocyte to complete meiosis 1 and ovulation. '''Luteal phase''' remnants from the follicle from the ovary form the corpus luteum this formation takes approximately 14 days to form. high levels in Progesterone inhibits and negatively feedbacks oestrogen, thus decreasing levels of FSH and LH. 

If no fertilisation occurs following ovulation, then the corpus luteum degenerates to corpus albican. The level Oestrogen and Progesterone deplete allowing FSH and LH to rise. This release of negative feedback and the increase of FSH allows the recruitment of a crop of antral follicles to grow. Therefore iniating the start of another around of the Ovarian cycle.

If fertilisation does occur, the placenta from embryo formation releases human chorionic gonadotropin which allows the corpus luteum to stay<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 224p</ref>. 

----

=== Regulation of testicular function ===

LH targets<ref>Neal J. How the endocrine system works. 2nd ed. West Sussex: John Wiley & sons; 2016. 93p</ref> Leydig cells. These cells synthesise testosterone. Similary to females, in males the hypothalamus secretes GHRH which triggers the secretion of LH and FSH from the pituatary gland. testosterone then negatively feedbacks to the  hypothalamus and pituitary gland and inhibits secretion of LH. This testosterone then results in differentiation of male sex tissue such as the scotum<ref>Norman AW, Henry HL. Hormones. 3rd ed. Oxford: Elsevier;2015. 266p</ref>.

<references />

=== ===

Luteinizing hormone

2018-12-06T19:37:40Z

180050055:

===  Leutinizing Hormone ===

Leutinizing hormone (LH) is a glycoprotein hormone produced and secreted by the anterior pituitary gland<ref>Neal J. How the Endocrine system works.2nd ed. West Sussex: John Wiley &amp;amp;amp; Sons;2016. 129.</ref> . This is in response to the Growth hormone-releasing hormone (GHRH) secreted by the hypothalamus<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 109p</ref> . It is an essential hormone in regulating the female ovarian cycle and stimulates the production of tesosterone in males<ref>O'Neil R, Murphy R. Endocrinology crash course. 4th ed. Philadelphia: Elsevier Mosby; 2012. 109</ref> . Therefore the target tissues of LH are Gonads. LH works in synergy with Follicle stimulating hormone (FSH) in both males and females.

----

=== Ovarian Cycle ===

'''Follicular phase''' At the folicular phase, the loss of progesterone and higher oestrogen increases frequency of GHRH secretion pulses from hypothalamus<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 227p</ref> . The LH to FSH secretion ratio increases. the decrease in concentration of FSH results in follicular atresia (apoptosis), leaving the dominant follicle. This dominant follicle produces and secretes oestrogen. With Oestrogen level at >200pg/ml, a surge of LH is induced. this surge of LH is enhanced by Prgesterone, in which triggers the Oocyte to complete meiosis 1 and ovulation. '''Luteal phase''' remnants from the follicle from the ovary form the corpus luteum this formation takes approximately 14 days to form. high levels in Progesterone inhibits and negatively feedbacks oestrogen, thus decreasing levels of FSH and LH. 

If no fertilisation occurs following ovulation, then the corpus luteum degenerates to corpus albican. The level Oestrogen and Progesterone deplete allowing FSH and LH to rise. This release of negative feedback and the increase of FSH allows the recruitment of a crop of antral follicles to grow. Therefore iniating the start of another around of the Ovarian cycle.

If fertilisation does occur, the placenta from embryo formation releases human chorionic gonadotropin which allows the corpus luteum to stay<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 224p</ref>. 

 

<references />

=== ===

Luteinizing hormone

2018-12-06T19:36:47Z

180050055:

===  Leutinizing Hormone ===

Leutinizing hormone (LH) is a glycoprotein hormone produced and secreted by the anterior pituitary gland<ref>Neal J. How the Endocrine system works.2nd ed. West Sussex: John Wiley &amp;amp;amp; Sons;2016. 129.</ref> . This is in response to the Growth hormone-releasing hormone (GHRH) secreted by the hypothalamus<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 109p</ref> . It is an essential hormone in regulating the female ovarian cycle and stimulates the production of tesosterone in males<ref>O'Neil R, Murphy R. Endocrinology crash course. 4th ed. Philadelphia: Elsevier Mosby; 2012. 109</ref> . Therefore the target tissues of LH are Gonads. LH works in synergy with Follicle stimulating hormone (FSH) in both males and females.

----

=== Ovarian Cycle ===

'''Follicular phase''' At the folicular phase, the loss of progesterone and higher oestrogen increases frequency of GHRH secretion pulses from hypothalamus<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 227p</ref> . The LH to FSH secretion ratio increases. the decrease in concentration of FSH results in follicular atresia (apoptosis), leaving the dominant follicle. This dominant follicle produces and secretes oestrogen. With Oestrogen level at >200pg/ml, a surge of LH is induced. this surge of LH is enhanced by Prgesterone, in which triggers the Oocyte to complete meiosis 1 and ovulation. '''Luteal phase''' remnants from the follicle from the ovary form the corpus luteum this formation takes approximately 14 days to form. high levels in Progesterone inhibits and negatively feedbacks oestrogen, thus decreasing levels of FSH and LH. 

If no fertilisation occurs following ovulation, then the corpus luteum degenerates to corpus albican. The level Oestrogen and Progesterone deplete allowing FSH and LH to rise. This release of negative feedback and the increase of FSH allows the recruitment of a crop of antral follicles to grow. Therefore iniating the start of anothe around of the Ovarian cycle.

If fertilisation does occur, the placenta from embryo formation releases human chorionic gonadotropin which allows the corpus luteum to stay<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 224p</ref>. 

 

<references />

=== ===

Luteinizing hormone

2018-12-06T19:18:51Z

180050055:

===  Leutinizing Hormone ===

Leutinizing hormone (LH) is a glycoprotein hormone produced and secreted by the anterior pituitary gland<ref>Neal J. How the Endocrine system works.2nd ed. West Sussex: John Wiley &amp;amp;amp; Sons;2016. 129.</ref> . This is in response to the Growth hormone-releasing hormone (GHRH) secreted by the hypothalamus<ref>White AW, Porterfield SP. Endocrine and reproductive physiology. 4th ed. Philadelphia: Elsevier Mosby; 2007. 109p</ref> . It is an essential hormone in regulating the female ovarian cycle and stimulates the production of tesosterone in males<ref>O'Neil R, Murphy R. Endocrinology crash course. 4th ed. Philadelphia: Elsevier Mosby; 2012. 109</ref> . Therefore the target tissues of LH are Gonads. LH works in synergy with Follicle stimulating hormone (FSH) in both males and females.

----

=== Ovarian Cycle ===

'''Follicular phase''' At the folicular phase, the loss of progesterone and higher oestrogen increases frequency of GHRH secretion pulses from hypothalamus . The LH to FSH secretion ratio increases. the decrease in concentration of FSH results in follicular atresia (apoptosis), leaving the dominant follicle. This dominant follicle produces and secretes oestrogen. With Oestrogen level at >200pg/ml, a surge of LH is induced. this surge of LH is enhanced by Prgesterone, in which triggers the Oocyte to complete meiosis 1 and ovulation. '''Luteal phase''' remnants from the follicle from the ovary form the corpus luteum this formation takes approximately 14 days to form. high levels in Progesterone inhibits and negatively feedbacks oestrogen, thus decreasing levels of FSH and LH. If no fertilisation occurs following ovulation, then the corpus luteum degenerates to corpus albican. The level Oestrogen and Progesterone deplete allowing FSH and LH to rise. This release of negative feedback and the increase of FSH allows the recruitment of a crop of antral follicles to grow. Therefore iniating the start of anothe rround of the Ovarian cycle.

 If fertilisation does occur, the placenta from embryo formation releases human chorionic gonadotropin which allows the corpus kluteum to stay. 

=== ===

Luteinizing hormone

2018-12-06T17:56:18Z

180050055: Created page with "===  Leutinizing Hormone === Leutinizing hormone (LH) is a glycoprotein hormone produced and secreted by the anterior pituitary gland . This is in response to the Growth h..."

===  Leutinizing Hormone ===

Leutinizing hormone (LH) is a glycoprotein hormone produced and secreted by the anterior pituitary gland . This is in response to the Growth hormone-releasing hormone (GHRH) secreted by the hypothalamus . It is an essential hormone in regulating the female ovarian cycle and stimulates the production of tesosterone in males . Therefore the target tissues of LH are Gonads. LH works in synergy with Follicle stimulating hormone (FSH) in both males and females.

----

=== Ovarian Cycle ===

'''Follicular phase''' At the folicular phase, the loss of progesterone and higher oestrogen increases frequency of GHRH secretion pulses from hypothalamus . The LH to FSH secretion ratio increases. the decrease in concentration of FSH results in follicular atresia (apoptosis), leaving the dominant follicle. This dominant follicle produces and secretes oestrogen. With Oestrogen level at >200pg/ml, a surge of LH is induced. this surge of LH is enhanced by Prgesterone, in which triggers the Oocyte to complete meiosis 1 and ovulation. '''Luteal phase''' remnants from the follicle from the ovary form the corpus luteum this formation takes approximately 14 days to form. high levels in Progesterone inhibits and negatively feedbacks oestrogen, thus decreasing levels of FSH and LH. If no fertilisation occurs following ovulation, then the corpus luteum degenerates to corpus albican. The level Oestrogen and Progesterone deplete allowing FSH and LH to rise. This release of negative feedback and the increase of FSH allows the recruitment of a crop of antral follicles to grow. Therefore iniating the start of anothe rround of the Ovarian cycle.

 If fertilisation does occur, the placenta from embryo formation releases human chorionic gonadotropin which allows the corpus kluteum to stay. 

=== ===