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Topic 7: Run for Your Life
1 Demonstrate knowledge and understanding of the How Science Works areas listed in the table
on page 13 of this specification.
2 Describe the structure of a muscle fibre and explain the structural and physiological
differences between fast and slow twitch muscle fibres.

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Antagonistic pairs are made up of flexors and extensors: Flexors are muscles which contract to
bend a joint whilst extensors are muscles which contract to straighten a joint.
5 Describe the overall reaction of aerobic respiration as splitting of the respiratory substrate (eg
glucose) to release carbon dioxide as a…

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1. Pyruvate releases carbon dioxide as a waste product and a hydrogen atom (which is picked
up by NAD to form reduced NAD) which produces an Acetyl group
2. This reacts with Coenzyme A to form Acetyl coenzyme A
3. The acetyl group is taken to be used in the…

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1. The Sinoatrial node sends an electrical impulse to the muscles in the atrial walls, causing
them to constrict and push blood into the ventricles (a band of nonconducting collagen
tissues prevent the impulse from travelling straight to the ventricles)
2. After a short delay, the impulse then travels to…

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5. We also have voluntary control over breathing
Cardiovascular control centre:
1. Adrenaline is secreted from the Adrenal gland before and during exercise
2. This stimulates the SAN to increase its rate of contraction
3. Action potentials are sent along motor neurones from the cardiovascular control centre to
the SAN…

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Thermoreceptors in the hypothalamus detect a rise in temperature of blood, the hypothalamus
also receives signals from receptors in the skin. When this rise is detected, the hypothalamus
sends nerve impulses to various effectors which respond by:
Arterioles dilate so that a greater volume of blood can flow to the…

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specific B and T killer cells, less chance of
destroying pathogens)
Increases risk of cardiovascular disease
(increases blood pressure and LDL: HDL ratio ­
which can lead to atherosclerosis)

19 Explain how medical technology, including the use of keyhole surgery and prostheses, is
enabling those with injuries and disabilities to…

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Ethical relativists take into account different people and circumstances and believe it is wrong to
use performance enhancing rugs but in some cases it may be acceptable
Anabolic steroids ­ these bind to receptors on a molecule which takes it directly to the nucleus of
a cell. They act as…


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