A2 Biology Unit 5 Flashcards - Muscle Contraction

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What are the 3 types of muscle in the body?
Cardiac, Smooth and Skeletal
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Which muscle type is under voluntary control?
Skeletal muscle
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Which muscle types are not under volutary control?
Cardiac and smooth
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What are muscles made up of?
Tiny muscle fibres called myofibrils
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What do muscle fibres share?
Nuclei, cytoplasm and sarcoplasm
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What is within the sarcoplasm?
A large concentration of mitochondria and endoplasmic reticulum
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What are the 2 types of protein filaments that myofibrils are made up of?
Actin (consists of two strands twisted around each other) and myosin (consits of long-rod shapes fibres with bulbous heads)
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What is the light bands of myofibrils called and why do they appear lighter?
Isotrophic bands (I-bands) they appears lighter due to actin and myosin filaments not overlapping in this region
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What is the darker bands of myofibrils called and why do they appear darker?
Anisotrophic bands or (A-bands) they appear darker because the actin and myosin filaments overlap in this region
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What is at the centre of each anisotrophic band?
A lighter region called the H-zone
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What is at the centre of each isotropic band?
A line called the Z - line, the distance between Z - lines is called the sarcomere
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What happens to the sarcomere when a muscles contracts?
It shortens and the pattern of light and dark bands changes, the I-bands become narrower, the Z-lines move closer together and the H-zone becomes narrower, the A-band remains the same width
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What are 2 important proteins are found in muscle?
Tropomyosin - which forms a fibrous strand around the actin filament, Troponin - involved in muscle contraction
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What are Slow-twitch fibres?
Contract more slowly and provide less powerful contractions over a longer period, they are adapted for aerobic respiration in order to avoid a build up of lactic acid
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What are Fast-twitch fibres?
Contract rapidly and produce powerful contractions, more common in muscles needed for short-bursts
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What is a neuromuscular junctions?
Point where a motor neurone meets a skeletal muscle fibre, many junctions along the muscles
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What happens during muscle stimulation?
An Ap reaches neuromuscular junctions, calcium ion channels open and calcium ions move into the synaptic knob, causes acetylchloine to release which causes it to depolarise
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What does Tropomyosin do in muscle contraction?
Prevents the myosin head attaching to the binding site on the actin molecule
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What makes Tropomyosin pull away from the binding site on the actin molecule?
Calcium ions released from the endoplasmic recticulum
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What happens once myosin head attaches to the binding site on actin?
Head of myosin changes angle, ADP released, ATP causes myosin head to release, Hydrolysis of ATP provides energy for myosin head to resume normal position and the cycle is repeated
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Other cards in this set

Card 2

Front

Which muscle type is under voluntary control?

Back

Skeletal muscle

Card 3

Front

Which muscle types are not under volutary control?

Back

Preview of the front of card 3

Card 4

Front

What are muscles made up of?

Back

Preview of the front of card 4

Card 5

Front

What do muscle fibres share?

Back

Preview of the front of card 5
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