15.8: Contraction of skeletal muscle

Question 1

This skeleton is made up of bone which is

Answer 1

Incompressible

Question 2

Muscle can’t … they can only …

Answer 2

Can’t PUSH, can only PULL

Question 3

Skeletal occur in…

Answer 3

Antagonistic pairs

Question 4

Antagonistic Paris of skeletal muscles

Answer 4

Pairs pull in opposite directions and when one is contracted, the other is relaxed.

Question 5

Sliding filament mechanism

Answer 5

The process of contraction of muscle fibre involving actin and myosin filaments sliding past each other.

Question 6

There will be more overlap of actin and myosin in a … muscle

Answer 6

In a contracted muscle

Question 7

Changes to the sacromere when a muscle contracts

3

Answer 7

• the I band becomes narrower
• the z-lines move closer together, or in other words, the sacromere shortens
• the h-zone becomes narrower

Question 8

What stays the same when a muscle contracts

Answer 8

The a-band remains the same width

And myosin filaments haven’t shortened

Question 9

Myosin is made up of two types of protein

Answer 9

• A fibrous protein, arranged into a filament made up of several hundred molecules (the tail)
• A globular protein formed into two bulbous structures at one end (the head)

Question 10

Actin

Answer 10

A globular protein whose molecules are arranged into long chains that are twisted around one another to form a helical strand

Question 11

Tropomyosin

Answer 11

Forms long thin threads that are wound around actin filaments

Question 12

The bulbous heads of myosin filaments form…

How?

Answer 12

…cross bridges with the actin filaments.

By attaching to binding sites on the actin filaments

Question 13

What happens after myosin bulbous heads are attached to the actin filaments?

Answer 13

They flex in unison and pull the actin filaments along the myosin filaments.