Topic 7 specification notes

Here are some notes I made about each specification point for Unit 5, Topic 7!

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  • Created by: jknighton
  • Created on: 07-06-16 22:22
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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.
A muscle fibre is made up of bundles of myofibrils and contain several nuceli. Each myofibril
consists of filaments: Actin (thin filament) and Myosin (thick filament). The cell surface membrane
of a muscle fibre is called the sarcolemma. The specialised endoplasmic reticulum of a muscle
fibre is called the sarcoplasmic reticulum (this releases calcium ions in order for muscles to
contract). The cytoplasm of a muscle cell is called the sarcoplasm. The specialised synapse
between neurones and muscle cells is called the neuromuscular junction.
Slow twitch muscle fibres Fast twitch muscle fibres
Contain lots of mitochondria where lots of Contains few mitochondria as not much
ATP is produced energy is used
Is used for slower, sustained periods of Is used for short bursts of exercise
exercise
Carries out aerobic respiration Carries out anaerobic respiration
Lots of myoglobin to store oxygen Little myoglobin as less oxygen is used
Fatigue resistant Fatigue quickly
3 Explain the contraction of skeletal muscle in terms of the sliding filament theory, including the
role of actin, myosin, troponin, tropomyosin, calcium ions (Ca2+), ATP and ATPase
1. The sarcolemma receives an electrical impulse which travels down the Ttubules to the
sarcoplasmic reticulum
2. The sarcoplasmic reticulum released calcium ions which bind to the Troponin molecules
3. This causes the Troponin to change shape which causes the Tropomysin molecules to
unblock the actinmyosin binding site
4. The myosin head binds to the ActinMyosin binding site on the Actin filament and the
hydrolysis of ATP into ADP + Pi releases energy for the myosin head to change shape
5. This pulls the Actin filament along causing the sarcomere to shorten
6. Free ATP then binds to the myosin head causing the crossbridge to break and the myosin
head detaches from the Actin filament, reattaches to another binding site further down
the filament and pulls it along further
7. This continues until calcium ions stop being released from the sarcoplasmic reticulum and
existing calcium ions travel back into the sarcoplasmic reticulum by active transport using
ATP
4 Recall the way in which muscles, tendons, the skeleton and ligaments interact to enable
movement, including antagonistic muscle pairs, extensors and flexors.
Tendons are nonelastic fibrous tissue that join muscles to the skeleton (bones).
Ligaments are elastic connective tissue that join bones to bones.
Skeletal muscles are those which are attached to bones and normally arranged in antagonistic
pairs (pairs of muscles that pull in opposite directions).

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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 waste product and reuniting of hydrogen with
atmospheric oxygen with the release of a large amount of energy.…read more

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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 Kreb cycle and 1 x NADH produced which is
used in oxidative phosphorylation
Kreb Cycle:
1. The acetyl group from the acetylcoenzyme A is combined with oxaloacetate to form a
6carbon compound
2.…read more

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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 the atrioventricular node and then to the
Bundle of His before it travels into the Purkyne fibres to the apex of the heart
3.…read more

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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
4.…read more

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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.…read more

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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 participate in sports, eg cruciate ligaments repair
using keyhole surgery and knee joint replacement using prosthetics.…read more

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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.…read more

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