Muscles, part 2 - Organismal Level: Crash Course A&P

The video explores the functions and mechanics of skeletal muscles, explaining how they move and contract. It covers muscle groups, motor units, and the processes of summation and tetanus. The video also distinguishes between isotonic and isometric movements, highlighting how recruitment affects muscle force. The content is presented with examples and demonstrations to enhance understanding.

What is the primary role of skeletal muscles?

• To regulate body temperature

• To only support the skeletal structure

• To perform both necessary and delicate tasks

• To perform only heavy lifting tasks

How do muscles create movement?

• By expanding and contracting simultaneously

• By rotating around joints

• By pulling bones towards each other

• By pushing bones away

What are the muscles called that primarily produce a movement?

• Prime movers

• Synergists

• Antagonists

• Stabilizers

What is the role of antagonist muscles?

• To assist prime movers

• To reverse the action of prime movers

• To stabilize joints

• To initiate movement

Which muscle group helps stabilize joints during movement?

• Prime movers

• Flexors

• Antagonists

• Synergists

What is a motor unit composed of?

• Multiple neurons and multiple muscle fibers

• A single neuron and a single muscle fiber

• Multiple muscle fibers and a single neuron

• A single muscle fiber and multiple neurons

What happens during the latent period of a muscle twitch?

• Myosin heads bind to actin

• Muscle fibers relax

• Calcium ions flood into sarcomeres

• Muscle fibers contract

What is the difference between isotonic and isometric contractions?

• Neither change muscle length

• Both change muscle length

• Isometric contractions change muscle length, isotonic do not

• Isotonic contractions change muscle length, isometric do not

What is the process called when more motor units are stimulated to increase muscle contraction?

• Recruitment

• Temporal summation

• Tetanus

• Relaxation

What is the term for when muscle twitches combine to form a smooth, sustained contraction?

• Relaxation

• Tetanus

• Summation

• Recruitment