Question

To increase the the contrast for better observation of the striations of striped muscle fibre of a cockroach

Answer 1

Explanation:

Skeletal muscle looks striped or "striated" – the fibres contain alternating light and dark bands (striations) like horizontal stripes on a rugby shirt. In skeletal muscle, the fibres are packed into regular parallel bundles.

Cardiac muscle

Cardiac muscle tissue, like skeletal muscle tissue, looks striated or striped. The bundles are branched, like a tree, but connected at both ends. Unlike skeletal muscle tissue, the contraction of cardiac muscle tissue is usually not under conscious control, so it is called involuntary.

Smooth muscle

Compared to skeletal muscle, smooth muscle cells are small. They are spindle shaped and have no striations. Instead, they have bundles of thin and thick filaments.

Looking closer at skeletal muscle

All skeletal muscle fibres are not the same. They differ in structure and function, for example, in the speed they can contract.

Skeletal muscle fibres contract at different speeds depending on:

their ability to split ATP (an energy-releasing chemical)

the way they produce ATP

how quickly they get tired

So skeletal muscle is classified into two broad types – fast twitch and slow twitch.

Slow twitch (also called Type I):

has lots of tiny blood vessels called capillaries (and so looks red)

has many mitochondria (sites of energy production)

has lots of myoglobin (the oxygen transporting and storage protein of the muscle)

carries more oxygen

doesn’t get tired easily (can sustain aerobic activity)

can contract slowly

is found in large numbers in the postural muscles of the neck