What are the three types of muscle tissue, where are they found and are they controlled consciously or subconsciously?

  1. Skeletal muscle - attached to the bones of the skeleton, controlled consciously
  2. Cardiac muscle - only found in the heart, controlled subconsciously
  3. Smooth muscle - found in the walls of hollow organs like blood vessels and the intestines, controlled subconsciously

Answer in your head, out loud, or on paper, then tap the card to flip.

What makes up individual muscles, and why is this beneficial?

Individual muscles are made up of numerous muscle fibres.


The muscle cells are fused into muscle fibres to avoid weakness at the junctions between cells and to increase overall muscle strength.

Answer in your head, out loud, or on paper, then tap the card to flip.

What is the cytoplasm in muscle fibres called, and what organelles does it contain?

The cytoplasm in muscle fibres is called sarcoplasm.


Within the sarcoplasm, there are:

  1. Multiple nuclei
  2. Many mitochondria that provide ATP for muscle contraction
  3. A modified version of the endoplasmic reticulum (sarcoplasmic reticulum), which contains calcium ions that are essential for muscle contraction

Answer in your head, out loud, or on paper, then tap the card to flip.

What are the two main types of protein filaments in myofibrils, and how do they differ?

  1. Actin - thin filament composed of two strands twisted around each other
  2. Myosin - thicker filament composed of long rod-shapes with bulbous heads that project to the side

Answer in your head, out loud, or on paper, then tap the card to flip.

What is the function of slow-twitch muscle fibres, and how are they well adapted for this function?

Slow-twitch fibres are adapted for endurance work, such as running a marathon.


Their adaptations include:

  1. Large store of myoglobin
  2. Rich blood vessel supply
  3. Many mitochondria for ATP synthesis

Answer in your head, out loud, or on paper, then tap the card to flip.

What is the function of fast-twitch muscle fibres, and how are they well adapted for this function?

Fast-twitch fibres are adapted for intense, short bursts of activity, like weight-lifting.


Their adaptations include:

  1. More myosin filaments
  2. High concentration of glycogen
  3. High concentration of enzymes involved in anaerobic respiration
  4. Store of phosphocreatine

Answer in your head, out loud, or on paper, then tap the card to flip.

What gives myofibrils their striped appearance?

Myofibrils appear striped due to alternating light-coloured (I bands) and dark-coloured (A bands) bands.

Answer in your head, out loud, or on paper, then tap the card to flip.

Why do I bands appear lighter in myofibrils?

I bands appear lighter because the thick and thin filaments do not overlap in this region.

Answer in your head, out loud, or on paper, then tap the card to flip.

What is the central, lighter-coloured region within each A band called?

The central, lighter-coloured region within each A band is called the H-zone.

Answer in your head, out loud, or on paper, then tap the card to flip.

What is the central line within each I band called?

The central line within each I band is called the Z-line.

Answer in your head, out loud, or on paper, then tap the card to flip.

What is the distance between adjacent Z-lines called, and what happens to it during muscle contraction?

The distance between adjacent Z-lines is called a sarcomere.


During muscle contraction, sarcomeres shorten, causing a change in the pattern of light and dark bands.

Answer in your head, out loud, or on paper, then tap the card to flip.