Structure of Muscles

Question 1

MICROSCOPIC
Muscle structure

Answer 1

• Muscles consist of thousands of muscle fibres running parallel.
• These fibres are grouped into bundles called fasciculi.
• Each skeletal muscle fibre is a single cylindrical muscle cell.

Question 2

Muscle fibres are

Answer 2

cylinder-shaped CELLS

Question 3

Cells contain -> Sarcolemma

Answer 3

• cell membrane surrounding each muscle fibre

Question 4

Cells contain -> Sarcoplasm

Answer 4

• gel-like fluid contained by the sarcolemma

Question 5

Inside a MUSCLE CELL (MUSCLE FIBRE)

Answer 5

• Mitochondria:
• Myoglobin
  -Fat, glycogen (carbohydrates & protein)
• Phosphocreatine (AC) and Adenosine triphosphate (ATP)
• Enzymes

Question 6

Mitochondria

Answer 6

site for aerobic energy production.

Question 7

Myoglobin

Answer 7

carries O² (oxygen) to mitochondria.

Question 8

Fat, glycogen (carbohydrates & protein)

Answer 8

energy nutrients.

Question 9

Phosphocreatine (AC) and Adenosine triphosphate (ATP)

Answer 9

energy sources

Question 10

Enzymes:

Answer 10

chemicals that speed up energy production.

Question 11

Muscle Fibre Structure:

Answer 11

• A muscle fibre is made up of smaller myofibrils.
• Myofibrils contain myofilaments, which are responsible for muscle contraction.

Question 11

Sliding Filament Theory (How Contraction Happens):

Answer 11

• Myosin heads attach to actin and pull, causing the filaments to slide.
• This shortens the sarcomere, leading to muscle contraction.

Question 11

Sarcomeres (Units of Myofibrils):

Answer 11

The basic contractile unit in myofibrils.

Made up of actin and myosin, which slide past each other to create movement.

Question 12

Myofilaments (Part of Myofibrils):

Answer 12

Thick filaments (Myosin) – Dark, form cross-bridges to pull actin.

Thin filaments (Actin) – Light, provide binding sites for myosin.

Question 13

sarcomere structure - smallest unit of muscle contraction = ?

Answer 13

SARCOMERE

Question 14

Sacromore structure- The cylindrical building blocks of the myofibril are called ?

Answer 14

sacomereS

Question 15

Each sarcomere consists of two protein myofilaments called ?

Answer 15

ACTIN and MYOSIN.

Question 15

ACTIN

Answer 15

a thin filament that attaches to the Z line. Light coloured in image

Question 16

MYOSIN

Answer 16

MYOSIN i

Question 17

what define the areas of each sarcomere:

Answer 17

Bands, zones and lines

– The ends are defined by a called a Z line/Z disc.
– The middle is defined by the M line.’

The A band, the length of the myosin filament, including where actin and myosin overlap. Dark in images.

It is the only zone/band that does not change length when muscle contracts.

The H zone, where only myosin is found. It is the gap between the ends of the actin.

The I band, where only actin is found.