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

Circulatory system

2017-10-23T21:49:15Z

160052435:

The circulatory system (also known as the cardiovascular system) is one of the organ systems of the body, the primary function of which is to transport blood and nutrients around the body. It is comprised of the [[Heart|heart]], [[Blood vessels|blood vessels]] and [[Blood|blood]].<ref>Silverthorn, D (2012). Human Physiology. 6th ed. United States: Pearson. 463</ref>.

Humans (along with the majority of mammals), possess a double circulatory system. The pulmonary circuit transports deoxygenated blood to the lungs so oxygen can move into the blood and carbon dioxide can be removed, before the oxygenated blood is transported back to the heart where it can be moved around the body via the systemic circuit. 

=== References ===

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Cardiovascular system

2017-10-23T21:42:31Z

160052435: moved Cardiovascular system to Circulatory system

#REDIRECT [[Circulatory system]]

Circulatory system

2017-10-23T21:42:31Z

160052435: moved Cardiovascular system to Circulatory system

The cardiovascular system (also known as the vascular or circulatory system) is one of the organ systems of the body, the primary function of which is to transport blood and nutrients around the body, and is comprised of the [[Heart|heart]], [[Blood vessels|blood vessels]] and [[Blood|blood]].<ref>Silverthorn, D (2012). Human Physiology. 6th ed. United States: Pearson. 463</ref>.

=== References ===

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Circulatory system

2017-10-23T21:36:42Z

160052435:

Nucleus

2017-10-17T14:32:31Z

160052435:

The Nucleus controls all the activities of the cell and acts as the information centre. It is only found in [[Eukaryotes]] ([[Prokaryotic|prokaryotic ]]DNA is loose in the cytoplasm). It contains [[Chromosomes|chromosomes]], which is the genetic material for the cell. [[DNA|DNA]] and [[RNA|RNA]] synthesis occurs here, in addition to being the site of transcription . After transcription, [[MRNA|mRNA]] exits the nucleus through the nuclear membrane where it then travels to the [[Cytoplasm|cytoplasm]], the site which is responsible for associating the mRNA with [[Ribosomes|ribosomes]] and protein translation.

It is comprised of:

#A [[Nuclear envelope|Nuclear envelope]] (nuclear membrane) = twin membrane that protects contents from cytoplasm and macromolecules that could interfere with internal processes. [[Nuclear pores|Nuclear pores]] perforate the membrane and allow small [[Molecule|molecules]] to diffuse freely in and out of the structure. Macromolecules (like [[Nucleic acids|nucleic acids]]) are moved into the nucleus via [[Active transport|active transport]].
#[[Nucleoplasm|Nucleoplasm]] (karyoplasm) = this material comprises mostly of [[Chromatin]] and is bound by the nuclear envelope.
#[[Nucleolus|Nucleolus]] = a densely packed, small body, known more so as the 'core' of Nucleus, built around the nucleolar organiser. It is a relatively unstable structure without a membrane, it contains [[RRNA|rRNA]] ([[RRNA|ribosomal RNA]]) and is the site of [[Ribosome|Ribosome]] synthesis. These ribosomal proteins are then packaged into ribonucleoproteins which later mature. 

A nucleus is also the centre of an [[Atom|atom]], comprised of [[Protons|protons]] and [[Neutrons|neutrons]].

The nuclear envelope is supported by the nuclear lamina, found on the inner nuclear membrane, which is made up of interconnecting intermediate filaments in a sheet-like formation<ref>Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the Cell, 5th edition, New York, Abingdon: Garland Science, Taylor &amp;amp;amp;amp;amp;amp; Francis Group, LLC</ref>. 

=== References ===

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Zebrafish

2016-12-05T10:04:05Z

160052435:

The zebrafish (''Danio rerio'') is a tropical freshwater fish native to southeast Asia. Approximately 2.5-4 cm in length, it is mainly recognised by the horizontal stripes that run along the length of its body<ref>Wellcome Genome Campus. Why use the zebrafish in research? 2014. Cited [4/12/16]. Available from: http://www.yourgenome.org/facts/why-use-the-zebrafish-in-research</ref>.

== Use of zebrafish as a model organism ==

Zebrafish are used as a [[Model organism|model organism]] to carry out research, primarily in the fields of [[Genetics|genetics]] and developmental biology. A number of their morphological and physiological features make them useful as a model organism, one of which is their robust, transparent [[Embryo|embryos]] that develop outside the mother. This makes it possible to view embryological development, and also allows for easier access to the embryo for manipulation (for example, altering the expression of certain genes through the use of [[Morpholinos|morpholinos]] <ref>Bedell VM, Westcot SE, Ekker SC. Lessons from morpholino-based screening in zebrafish. Briefings in Functional Genomics. 2011;10(4):181-188.</ref>).

The similarity of zebrafish to humans is another important factor; being [[Vertebrates|vertebrates]], they are more closely related to humans than other model organisms such as [[Escherichia coli|''Escherichia coli'']] or ''[[Drosophila|Drosophilia]]''. Following the sequence of the zebrafish [[Genome|genome]] in 2013, it was found that approximately 70% of human [[Gene|genes]] possess at least one zebrafish [[Orthologue|orthologue]] <ref>Howe K, Clark MD, Torroja CF, Torrance J, Berthelot C, Muffato M, et al. The zebrafish reference genome sequence and its relationship to the human genome. Nature 2013; 496 (7446): 498-503.</ref>. Furthermore, 84% of human genes that have some connection with human disease have counterparts in zebrafish, which suggests that further study of these genes in zebrafish would increase understanding of a number of human [[Disease|diseases]] <ref>Wellcome Trust Sanger Institute, Family ties: Relationship between human and zebrafish genomes. 2013. Cited [4/12/16]. Available from: http://www.sanger.ac.uk/news/view/2013-04-17-family-ties-relationship-between-human-and-zebrafish-genomes</ref>.

Zebrafish also have a short generation time of 2-4 months, meaning that it is possible to carry out experiments over a relatively short time frame. The large number of offspring produced (usually around 200 eggs) is also useful because it provides a large sample size to work with when carrying out research <ref>Spence R, Gerlach G, Lawrence C, Smith C. The behaviour and ecology of the zebrafish, Danio rerio. Biological Reviews, 2008; 83(1):13-34</ref>.

== Zebrafish in research ==

Zebrafish were first used as a model organism by George Streisinger in the late 1960s at the University of Oregon, with the research culminating in the cloning of zebrafish, making them the first vertebrates to be cloned <ref>Clark, K. J. , Ekker, S. C.. How Zebrafish Genetics Informs Human Biology. Nature Education 2015; 8(4):3</ref>. 

As explored by Verkerk AO and Remme CA. (2012), zebrafish can be used to research 'cardiac (patho)electrophysiology and [[Ion_channel|ion channel]] disorders'. According to Verkerk and Remme (2012), zebrafish and humans' embryonic and mature heart rates and electrocardiogram morphology resemble each other enough to make them a useful research tool <ref>↑ (Front Physiol. 2012;3:255. Epub 2012 Jul 10.)[PMID: 22934012] doi:10.3389/fphys.2012.00255</ref>. Many charities researching[[Heart_disease|heart disease]] have even advertised the use of zebrafish in their research, such as the British Heart Foundation's 'Mending Broken Hearts Appeal' due to the zebrafish's apparent ability to 'regenerate' its heart. Their original video can be found here: [http://www.youtube.com/watch?v=djFb8PGS34g Mending Broken Hearts (2011) ] 

=== References ===

<references />

Zebrafish

2016-12-05T10:02:21Z

160052435:

The zebrafish (''Danio rerio'') is a tropical freshwater fish native to southeast Asia. Approximately 2.5-4 cm in length, it is mainly recognised by the horizontal stripes that run along the length of its body<ref>Wellcome Genome Campus. Why use the zebrafish in research? 2014. Cited [4/12/16]. Available from: http://www.yourgenome.org/facts/why-use-the-zebrafish-in-research</ref>.

== Use of zebrafish as a model organism ==

Zebrafish are used as a [[Model organism|model organism]] to carry out research, primarily in the fields of [[Genetics|genetics]] and developmental biology. A number of their morphological and physiological features make them useful as a model organism, one of which is their robust, transparent [[Embryo|embryos]] that develop outside the mother. This makes it possible to view embryological development, and also allows for easier access to the embryo for manipulation (for example, altering the expression of certain genes through the use of [[Morpholinos|morpholinos]] <ref>Bedell VM, Westcot SE, Ekker SC. Lessons from morpholino-based screening in zebrafish. Briefings in Functional Genomics. 2011;10(4):181-188.</ref>).

The similarity of zebrafish to humans is another important factor; being [[Vertebrates|vertebrates]], they are more closely related to humans than other model organisms such as [[Escherichia coli|''Escherichia coli'']] or ''[[Drosophila|Drosophilia]]''. Following the sequence of the zebrafish [[Genome|genome]] in 2013, it was found that approximately 70% of human [[Gene|genes]] possess at least one zebrafish [[Orthologue|orthologue]] <ref>Howe K, Clark MD, Torroja CF, Torrance J, Berthelot C, Muffato M, et al. The zebrafish reference genome sequence and its relationship to the human genome. Nature 2013; 496 (7446): 498-503.</ref>. Furthermore, 84% of human genes that have some connection with human disease have counterparts in zebrafish, which suggests that further study of these genes in zebrafish would increase understanding of a number of human [[Disease|diseases]] <ref>Wellcome Trust Sanger Institute, Family ties: Relationship between human and zebrafish genomes. 2013. Cited [4/12/16]. Available from: http://www.sanger.ac.uk/news/view/2013-04-17-family-ties-relationship-between-human-and-zebrafish-genomes</ref>.

Zebrafish also have a short generation time of 2-4 months, meaning that it is possible to carry out experiments over a relatively short time frame. The large number of offspring produced (usually around 200 eggs) is also useful because it provides a large sample size to work with when carrying out research <ref>Spence R, Gerlach G, Lawrence C, Smith C. The behaviour and ecology of the zebrafish, Danio rerio. Biological Reviews, 2008; 83(1):13-34</ref>.

== Zebrafish in research ==

Zebrafish were first used as a model organism by George Streisinger in the 1970s at the University of Oregon, with the research culminating in the cloning of zebrafish, making them the first vertebrates to be cloned <ref>Clark, K. J. , Ekker, S. C.. How Zebrafish Genetics Informs Human Biology. Nature Education 2015; 8(4):3</ref>. 

As explored by Verkerk AO and Remme CA. (2012), zebrafish can be used to research 'cardiac (patho)electrophysiology and ion channel disorders'. According to Verkerk and Remme (2012), zebrafish and humans' embryonic and mature heart rates and electrocardiogram morphology resemble each other enough to make them a useful research tool <ref>↑ (Front Physiol. 2012;3:255. Epub 2012 Jul 10.)[PMID: 22934012] doi:10.3389/fphys.2012.00255</ref>. Many charities researching heart disease have even advertised the use of zebrafish in their research, such as the British Heart Foundation's 'Mending Broken Hearts Appeal' due to the zebrafish's apparent ability to 'regenerate' its heart. Their original video can be found here: [http://www.youtube.com/watch?v=djFb8PGS34g Mending Broken Hearts (2011) ] 

=== References ===

<references />