Chapter 14: Working muscles

Question 1

What are the three muscle types?

Answer 1

• Skeletal(Voluntary, attached to bones)
• Smooth(internal organs, involuntary)
• Cardiac(heart)

Question 2

What are the three muscle types?

Answer 2

• Skeletal(Voluntary, attached to bones)
• Smooth(internal organs, involuntary)
• Cardiac(heart)

Question 3

All abilities of muscles(3)

Answer 3

• Extensibility: ability to be stretched
• Elasticity: Ability to return to a previous state.
• Contractibility: Ability to shorten, bring together.

Question 4

Relationship b/w agonist and antagonist

Answer 4

• Agonist: Muscle causing a movement.
• Antagonist: Muscles with opposite movement. EG: triceps and biceps. As bicep contracts, the triceps relaxes to allow the bicep to bend the arm, vise versa when the triceps contracts.

Question 5

All abilities of muscles(3)

Answer 5

• Extensibility: ability to be stretched
• Elasticity: Ability to return to a previous state.
• Contractibility: Ability to shorten, bring together.

Question 6

Relationship b/w agonist and antagonist

Answer 6

• Agonist: Muscle causing a movement.
• Antagonist: Muscles with opposite movement. EG: triceps and biceps. As bicep contracts, the triceps relaxes to allow the bicep to bend the arm, vise versa when the triceps contracts.

Question 7

Key areas of the muscles

Answer 7

• Origin: End of the muscle fixed to stationary bone.
• Insertion: End of the muscle attached to the ‘moving’ bone.
• Belly: Fleshy middle section of muscle b/w origin and insertion.
• Tendons: Attach muscles to skeleton
• Muscles: Always grouped in pairs; if one ‘pulls’, the other ‘pushes’
• Synergist: Indirect muscles that help in steadying a joint during a particular movement.
• Fixator: Immobilization of a joint, via synergists.

Question 8

Structure of a muscle

Answer 8

-Fibres held together in big bundles;
-• Sarcolemma: Transparent plasma membrane.
• Sarcoplasm: Cytoplasm within the Sarcolemma.
• Myofibrils: Units of Sarcomeres, thread-like fibers . Myosin = Thick, Actin = thin.

Question 9

Sliding filament model

Answer 9

• Thin actin filaments slide over thick myosin filaments, z Lines are drawn closer and the sarcomere is shortened. Requires ATP energy to contract/relax.
• Nerve impulses from the brain are needed to make skeletal muscles contract.
• When a nerve touches the muscle, it branches out so that each branch goes to every muscle fibre.