13.9 Voluntry And Involuntry Muscles Flashcards
What is syncitium?
A multinucleated cell
What is the plasma membrane surrounding a skeletal muscle cell called?
Sarcolemma
What are the three types of muscle?
Skeletal
Cardiac
Involuntary
Which types of muscle are striated?
Skeletal
Cardiac (specialised striated)
Which types of muscle are involuntary?
Cardiac
Involuntary
Describe the arrangement of skeletal muscles, and what this does.
Regular so the muscle contracts in one direction.
Kind of in lines.
Describe the arrangement of cardiac muscles, and what this does.
Cells branch and interconnect, resulting in simultaneous contraction.
Describe the arrangement of involuntary muscles, and what this does.
No regular arrangement, so cells can contract in different directions.
Describe the contraction speeds of the three muscle types.
Skeletal- short
Cardiac- intermediate
Involuntary- (relatively) long time
Which muscle type is multinucleated?
Skeletal
What does uninucleated mean?
Only one nucleus in each cell.
Why are skeletal muscle fibres longer than normal cells?
Individual embryonic muscle cells fused together, to form them, these share cytoplasm.
What is the cytoplasm in skeletal muscle cells called?
Sarcoplasm
What does the sarcoplasmic reticulum contain, in skeletal muscle fibres?
Calcium ions- these are required in muscle contraction.
What are skeletal muscles made up of?
Bundles of muscle fibres, which are made of myofibrils.
What two types of protein filament do myofibrils contain?
Actin
Myosin
Briefly describe the structure of actin.
Two strands twisted
Thinner
Briefly describe the structure of myosin.
Long rod-shaped fibres with bulbous heads.
Thicker.
What is the H-band in a myofibril?
Where there is just myosin.
It is still quite dark but not as dark as the A band.
What is the A band in a myofibril?
Where myosin and actin overlap.
Very dark.
What is the Z line in a myofibril?
The thin dark line in the middle of the light zone.
What is the I band in a myofibril?
Where it is just actin.
Lighter
What is the sarcomere in a myofibril?
The area between two Z lines
Compare and contract slow twitch and fast twitch muscles.
Slow: less powerful contractions
Fast: more powerful contractions
Slow: long periods
Fast: short periods
Slow: don’t tire easily
Fast: tire easily
Slow: energy from aerobic respiration
Fast: energy from anaerobic respiration
Slow: red (rich in myoglobin and blood vessels)
Fast: pale (low in myoglobin and blood vessels)
Slow: contain lots of mitochondria
Fast: store lots of creative phosphate
