Muscle Tissue Flashcards
What are the three types of muscle in our bodies?
- Cardiac/heart muscle
- Smooth muscles found in internal organs
- Skeletal muscles (striped/voluntary), tendons join muscles to bone
Describe muscle structure. (3 points)
- Individual muscle fibres fuse together causing no weakness at the ends
- They share their nuclei and cytoplasm- sarcoplasm
- Each muscle is made up of tiny fibres called myofibril arranged parallel to each other
What is found in sarcoplasm?
Many mitochondria and ER.
Describe the structure of myofibril. (3 points)
- Has many nucleus and a distinctive pattern of bands
- Bound by a membrane- sarcolemma
- These fibres are bundled together into larger ones
What do myofibrils allows the muscles to do?
Contract.
What are the different coloured bands myofibrils appear in?
- A (dark band)
- I (light band)
What are myofibrils made up of?
Two types of protein filament: actin and myosin.
What is actin?
Protein filament found in myofibrils that is thin and made up of two strands around each other.
What is myosin?
Protein filament found in myofibrils that is thick and contains long rod shaoed fibres with bulbous heads that project to the side.
What is sarcomere and how does it work?
The contractile unit within a muscle fibre. Actin and myosin slide over each other and the sarcomere shortens in the muscle contraction.
What are the two types of muscle fibres?
Slow twitch (type I) and fast twtich (type II)
What are the two types of fast twitch fibres?
Type IIa and type IIx/IIb
Where are slow twitch fibres used more?
In muscles that contract for longer duration.
Where are fast twitch (Type IIa) fibres used more?
Fast contracting muscles
Where are fast twitch (Type IIb) fibres used more?
Fast contracting muscles
What is the main energy source of slow twitch fibres?
Oxidative metabolism as needs a large amount of oxygen.
How are slow twitch fibres adapted? (4 points)
- Abundance of mitochondria to use oxygen
- Abundance of myoglobin
- Surrounded by capillaries to facilitate transport of oxygen
- Thin
Are slow twitch fibres resistant to fatigue?
Yes.
Are type IIa fast twitch fibres resistant to fatigue?
Yes.
How are type IIa fast twitch fibres adapted?
Abundance of mitochondria and glycogen for faster ATP generation.
Are type IIa fast twitch fibres or type IIb fast twitch fibres similar to slow twitch fibres?
Type IIa fast twitch fibres.
What is the main energy source for type IIa fast twitch fibres?
Oxidative metabolism and glycolytic.
Are type IIb fast twitch fibres resistant to fatigue?
No- they do not last long.
Do type IIb fast twitch fibres have more or fewer mitochondria than the other fibres?
Fewer.
What type of concentration do type IIb fast twitch fibres have of myoglobin and why?
Low concentration because oxidative metabolism doesn’t take place meaning there are less oxidative enzymes.
What is the main energy source for type IIb fast twitch fibres and what does this cause?
Glycogen and phosphocreatine. This leads to a large amount of glycolytic enzymes which cause the fibres to be faster.
What colour are slow twitch fibres and why?
Red because have high myoglobin.
What colour are type IIa fast twitch fibres and why?
Red because have high myoglobin.
What colour are type IIb fast twitch fibres and why?
White because have low myoglobin.
What are 3 features of fast twitch fibres?
- Small amount of energy released quickly
- Rapid movements
- Anaerobic respiration
What are 3 features of slow twitch fibres?
- Large amount of energy released slowly
- Stamina and endurance
- Aerobic respiration.
What is the definition of fast twitch fibres?
Fibres that contract quickly, tire fast and rely on anaerobic respiration.
What is the definition of slow twitch fibres?
Fibres that contract slowly, tire slowly and rely on aerobic respiration.
