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Define neural crest as the ectodermal cells from the lateral neural plate. They go on to form various parts of the body such as: Skull + teeth, PNS, calcitonin producing cells, parathyroid glands, carotid bodies, spiral septum, adrenal chromaffin cells. They start from the neural tube but during development they migrate . Subsequently the study of these have given greater insight into cell migration mechanisms. Furthermore these neural crest cells are plastic and have allowed for improved understanding into how regulative development occurs. Finally labelling experiments have allowed us to trace the lineage of differentiated cells to form fate maps . This has enabled us to understand the origins of many types of cells are actually neural crest and subsequenty help us to understand why conditions such as DiGeorge’s which causes craniofacial deformities can also cause      thyroid gland agenesis and persistent truncus arteriosus. Neural crest fate mappi...

Segmentation is a key process in animal development defined as the serial repetition of tissue pattern along the axis of the body and allows differentiation of the developing organism. This differentiation in particular is mediated through Hox Genes. This essay will discuss their role and possible mechanisms for how they work. What are the hox genes? The hox genes are a set of genes that determine a segments identity. In the human there are 4 sets of 13 genes. These contain a homeobox domain which allows them to trigger the expression of various genes throughout the tissue. The exact nature of their expression is unknown however their role in patterning can be shown throughout various experiments. Experiments in flies The hox genes were originally discovered in the drosophila by Edward B lewis when he noticed that in some mutant drosphila some segments took the identity of segments above them. For example the drosophila expressed a pair of wings where it should have expressed ...

Discuss the relative importance of respiratory systems and kidney in regulating pH pH is a very tightly controlled parameter in the body 7.35-7.45 It is important to maintain pH to allow functioning of enzymes and ion channels (other proteins e.g haemoglobin bohr effect) Maintenance Buffers Carbonic anhydrase CO2 + H2O <-----> H2CO3 <-----> HCO3-  + H+ Respiration and affects CO2 Kidney excretes and produces HCO3- Kidney excretes H+ H+ can come from metabolism and diet. It varies greatly in diets e.g in vegans low H+ is while in meat eaters there is a high H+ pKa of the buffer system is 6.1 but desired pH is 7.4 so minute by minute control by lungs are required. The HCO3/0.03PCO2 must be set to 20. Repiration so pH changes are detected by the central and peripheral chemo receptors (more central) and altered signals are sent to the medulla to alter respiratory rate Show link between alveolar resp rate and pACO2 (CO2 can also be carried...

Written by Millicent Faraday He left the league in 33 Coz he wanted a bigger army In the same year he began rearmament 300k men and thousand planes in secret He tried to invade Austria Because he wanted to make Germany greater This all happened in 1934 But Mussolini stood up, there was no war 1935, the saar plebiscite was held It was a moral success and Hitler got the saar land Later he announced conscription This lowered the unemployment for all men Then came the anglo-german naval treaty This allowed Hitler to improve his naval military German began the Rhineland remilitarization But Abyssinia was france and britians main attention 1936, a civil war in Spanish territory Hitler used this to try out his new army Then Mussolini became allies with Hitler Hitler was no free to attack Austria Lastly Japan joined through the pact of anticomintern To get rid of communism was their main concern Hitler got away with crimes so terrifying Coz france and Britain did nothing.

Euthanasia is it for the good or bad?? In recent times euthanasia has been a hot topic in the newspapers and in the news on TV. Euthanasia is defined as the act of killing someone else to relieve their pain or stress. It could also be considered as the practice of supplying someone with the materials for another person to commit suicide. It is mostly done to relieve someone who has an incurable disease and to help them pass away painlessly. Some people believe that Euthanasia is a way for a person to die with dignity and it can also be known as mercy killing. The law in the UK states that Euthanasia is a criminal offence and is classed as murder. In some rare cases, a person can take their case to court and rarely a judge allows for Euthanasia. Doctors in the UK are cautious of the law and 94% of them do not want a change in the law that would make Euthanasia legal. Throughout the world many people have conflicting views about Euthanasia and whether it should be legal. The C...

I think that the conscience is a way of God reminding us how to behave but I think he isn’t reminding is but we already know how to behave and that we are born knowing what to do. I think that as we grow older we almost change our conscience and that we know how we have to behave and we change it a bit and we alter what we would think is acceptable. I think that in essence it is simply a way of God reminding us how to behave. But some people even if they do get reminded can chose to ignore or they can forget. Christians believe that the conscience is a gift from God and it is the gift to be able to reason and find out what is the right thing to do and what is the wrong thing to do. I think that it is a bit more subtle than this because God gives us the reasoning and if we pursue this reasoning we can know for sure what is right or what is wrong but if we do not pursue the reasoning we will have to refer to the bible or ask priests or look in the bible to find out what to do. Christia...

A Poem about the Holocaust written by Matthew Mayer The Holocaust Punished and tortured like a slave What did we do to deserve this? Why do we go through so much pain? Where is my beloved family I so badly want? I don’t want to work but I am forced But I stop and weep bitterly And think: why kill me for such a silly thing, For not being perfect, as one crazy man wishes. They make me work for my freedom, But instead they plan to take my life. Where is the justice? Where is the peace? Where is the love? Where is the kindness? Where is my god? Why has he left me? Where is the god that saved the Israelites from slavery? Where is the god that gave my ancestors freedom? Where is he for his people? Why has he deserted us? Can he not hear me crying? Can he not see us dying? Can he not feel our hunger or taste our pain? These monsters have tarnished my faith yet I still believe Why?