Muscles Flashcards
What attaches skeletal muscles to the bone
Tendons
What do ligaments attach
Bone to bone
Why can bones act as levers
They are rigid
What are antagonistic pairs
Muscles that work together to move a bone
Agonist = contracts
Antagonist = relax
What are muscles made of
Muscle fibres
What is the cell membrane of muscle fibres called
Sarcolemma
What is the cytoplasm of muscle fibres called
Sarcoplasm
What are the folds in the sarcolemma called
Transvers (T) tubules
What is the function of the t tubules
Spread electrical impulses throughout sarcoplasm to reach all parts of the muscle fibre
What is the function of the sarcoplasm in reticulum
Stores and releases Ça ions
What is an adaption of muscle fibres
Lots of mitochondria for ATP
What does multinucleate mean
Lots of nuclei
What is the name of the thick myofilament
Myosin
What is the name of the thin myofilament
Actin
What is the dark band on a myofibril
Myosin and actin
A band
What is the light band on a myofibril
Actin only
I band
What is at the end of each sarcomere
Z line
What is the middle of a sarcomere
M line
What area only contains myosin
H zone
Explain the sliding filament theory
Myosin and actin filaments slide over each other making the sarcomere contract. Not contracting themselves.
The simultaneous contraction of lots of sarcomeres mean the muscle fibres contact
What happens to the individual sarcomeres as the muscle fibres contacts
A band stays the same length
I band shorter
H zone shorter
Sarcomere overall gets shorter
What is the structure of myosin
Has a globular head that’s hinged to move
It has 1 binding site for actin
And 1 binding site for ATP
What is the structure of actin
Has a binding site to myosin = actin myosin binding site
What the status of the actin myosin binding site at rest
It’s blocked by tropomypsin
Why does the actin myosin binding site being blocked mean the myofilaments can’t slide
The myosin heads can’t bind to the actin myosin binding site
Explain how muscle contract
- Ap from motor neurone stimulates muscle cells
- Sarcolemma depolarised
- Depolarisation spreads by t tubules to sarcoplasmic reticulum
- Ça released into sarcoplasm by sarcoplasmic reticulum
- Ça binds to protein attached to tropomyosin
- Protein changes shape.
- Tropomyosin pulled out of actin myosin binding site on actin
- Binding site is exposed
- Myosin head binds to actin forming an actin myosin cross bridge
- Ça activate ATP hydrolase = breaks down ATP
- Energy from ATP used to bend myosin head
- Pulling actin
- Energy from ATP breaks actin myosin cross bridge
- Myosin head reattaches to another binding site further along actin filament
- Sarcomere shortens
What happens to the muscle when it stops being stimulated
Ça ions leave binding site
Move back into sarcoplasm Reticulum by at
Tropomyosin moves back to block actin myosin binding sites
Actin filaments slide back to the relaxed positions
Sarcomere lengthens
How would u tell from the sarcomere it is not contracted
No actin myosin cross bridges
How is atp generated by aerobic respiration
Oxidative phosphorylation in mitochondria
Where does oxidative phosphorylation happen
Mitochondria
When is aerobic respiration a good atp source
Long duration
Low intensity
How is atp made during anaerobic respiration
Glycolysis makes pyruvate
Pyruvate -> lactate (by lactate fermentation)
Why can anaerobic respiration only be used in short periods
Lactate builds causing muscle fatigue
How is atp made by the atp-phosphocreatine system
Phosphorylate ADP by adding a pi group from PCr (créatine)
Where is PCr stored
Inside cells
How fast does the ATP-PCr system make atp
Very quickly
What type of excercise is the PCr-AtP system used for
Short duration
High intensity
Is atp-pcr system anaerobic or aerobic
Anaerobic
Is the atp-pcr system lactic or alactic
Alactic
What is créatine broken down into
Creatinine
Where is créatine broken down
Kidney
Who might have high creatinine levels
People who exercise a lot
People with high muscle mass
People with kidney damage
When are slow twitch muscle fibres used
Used for posture
Used in endurance
Long duration
What type of respiration do slow twitch muscle fibres use
Aerobic
What type of respiration do fast twitch muscle fibres use
Anaerobic
What are 2 specialisation of slow twitch muscle fibres
Lots of mitochondria = supply muscles with energy from atp
Lots of blood vessels = supply muscles with oxygen
When are fast twitch muscle fibres used
Fast movements
Short duration
High intensity
Why are slow twitch fibres red
Have lots of myoglobin (stores oxygen)
Why are fast twitch white
Don’t have much myoglobin
Don’t store much oxygen
