Muscle Movement Flashcards
Skeletal muscle is antagonistic. What does this mean?
Muscles work in pairs as one contracts and the other relaxes.
Describe muscle structure.
Muscle contains fibres.
Fibres divide into myofibrils.
What is the cell membrane of a muscle cell called?
Sarcolemma
What is the cytoplasm of a muscle cell called?
Sarcoplasm
What is the endoplasmic reticulum of a muscle cell called?
Sarcoplasmic reticulum
Myofibrils are made of which 2 proteins?
Actin
Myosin
What is a sarcomere?
A section of myofibril.
What is the Z line?
Where the sarcomere ends.
What is the Z line made of?
Actin only
What is the M line?
The middle of the sarcomere
What is the M line made of?
Myosin only
Where is the H zone?
The whole region of muscle fibre containing myosin only.
What are I bands?
What is another name for I bands?
Sections of the sacromere containing actin only. Also known as the light band.
What are A bands?
What are A bands also known as?
Sections of the sarcomere containing both actin and myosin.
Also known as the dark band.
Compare the thickness of actin with myosin.
Actin is thinner, myosin is thicker.
What is tropomyosin?
Thin threads wound around actin filaments.
State what happens to the H zone, I band, A band and Z lines during muscle contraction.
H zones shorten
I band shortens
A band stays the same
Z lines become closer
Name the theory used to describe muscle contraction.
Sliding filament theory.
During muscle contraction, action potential causes the release of what ions from the sarcoplasmic reticulum?
These ions are released using which transport process?
Ca2+ Released using active transport
During muscle contraction, Ca 2+ released from the sarcoplasmic reticulum diffuses through where?
Where do the ions reach?
Ca 2+ diffuses through the sarcoplasm to the myofibril.
During muscle contraction, calcium ions bind to what protein?
Tropomyosin
During muscle contraction, binding of Ca 2+ to tropomyosin causes it do what?
What is now exposed by the tropomyosin?
Binding of calcium ions to tropomyosin causes it to move and change shape.
This leads to the myosin binding site on the actin becoming exposed.
During muscle contraction, what biomolecule is attached to the myosin heads?
ADP
During muscle contraction, how does the actin attach to the myosin?
What biomolecule is required for this process?
Myosin heads attach to binding sites forming a crossbridge. This requires ADP.
Describe the movement of actin and myosin during muscle contraction.
Myosin heads pull and slide along actin.
During muscle contraction, how is the crossbridge between actin and myosin broken.
Binding of ATP to myosin head causes it to detach from the actin binding site.
During muscle contraction, how do the myosin heads return to their original position?
(hydrolysis of what substance)
ATP is hydrolysed by ATPase, releasing energy for the myosin heads to return to their original position.
During muscle contraction, ATPase is activated by what ions?
Ca 2+
After the actin/myosin cross bridge has been broken, what occurs further along the actin?
Myosin reattaches to a different binding site.
What are slow twitch muscle fibres adapted to?
Give an example of an activity requiring slow twitch fibres.
Sustained muscle contraction (endurance).
Eg: long distance running
Why do slow twitch fibres contain lots of myoglobin?
To store large amounts of oxygen for aerobic respiration.
Why do slow twitch fibres contain lots of mitochondria?
Allows for high rate of respiration.
Why do slow twitch fibres contain lots of capillaries?
How does this prevent muscle fatigue?
Decrease diffusion pathway and increase surface area, providing a high supply of oxygen and glucose for aerobic respiration.
This reduces the need for anaerobic respiration to occur, stopping lactic acid build up and muscle fatigue.
What are fast twitch fibres adapted to?
Give an example of an activity that would require them.
Adapted for intense, short periods of rapid muscle contraction.
For example, sprinting.
Why are fast twitch muscles adapted for anaerobic respiration?
To produce ATP and release energy rapidly.
Why do fast twitch fibres have low levels of myoglobin?
The muscles typically respire anaerobically so large stores of oxygen are not required.
Why do fast twitch muscles contain large amounts of glycogen?
Why is this inefficient? Link this to ATP production in glycolysis.
This can be hydrolysed to glucose, which used in glycolysis.
Glycolysis only yields 2 ATP, which is inefficient
Explain how the rate of anaerobic respiration is increased in fast twitch muscles.
High concentration of enzymes used in anaerobic respiration in the cytoplasm
What is the benefit of fast twitch fibres containing large stores of phosphocreatine?
Name the process this molecule is involved in.
It can rapidly generate ATP from ATP by providing a phosphate. (phosphorylation)
Why do fast twitch muscles become fatigued more quickly?
They store high amounts of lactate.
Where is phosphocreatine stored in muscles?
Inside muscle cells.
What type of exercise is phosphocreatine used in?
Short bursts of vigorous exercise.
