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What are the roles of the sinoatrial node (SAN) and the atrio-ventricular node (AVN)?

The heart muscle is myogenic and initiates a heartbeat through an electrical conduction system; both the sinoatrial node and atrio-ventricular node are essential in this mechanism. The sinoatrial node (SAN) ...
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Answered by Shelby P. • Biology tutor
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What events occur during the cardiac cycle?

Within the heart the atria contract creating a high pressure and squeezing blood into the ventricles. The semi lunar valves are closed so pressure within the ventricles builds up.Pressure within the ventricl...
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Answered by James H. • Biology tutor
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What is the order of Phylogenetic divisions?

Phylogeny is the study of the evolutionary relationships of organisms. A good acronym to learn this is King Plays Cards on Fat Girls Stomach.K - Kingdomp - PhylumC - ClassO - OrderF - Family G - Genus S - Sp...
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Answered by Nidhish J. • Biology tutor
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Describe how negative feedback is used to control blood glucose concentration (6 marks)

Throughout your answer to this question make sure that you are cramming as much key language into it as possible! Phrases like 'islets of Langerhans', 'beta/alpha cells', and 'transporter proteins' will all ...
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Answered by Matt H. • Biology tutor
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What is the cardiac cycle?

The cardiac cycle is what happens during a single heartbeat. To understand the cycle it helps to know that the heart is made up of four chambers, the top 2 chambers are called the atria and the lower 2 chamb...
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Answered by Megan P. • Biology tutor
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