Muscles and Muscle Contraction

Skeletal muscles always work _____.

• in groups

• in pairs

• singly

• none of the above

Tags

NGSS.MS-LS1-3

What is shown in the colored part of this diagram?

• a whole muscle

• five muscle fibers

• five muscle fascicles

• five myofibrils

What is labeled "4" (the blue/purple part) in the diagram?

• sarcolemma

• sarcoplasmic reticulum

• transverse tubules

• myofibril

____________ attaches to actin to form the cross bridge.

• Troponin

• Tropomyosin

• Myosin

• Calcium

Which step occurs second in muscle contraction?

• the brain sends a signal

• acetylcholine is released from the axon terminals

• Ca ions are released from the sarcoplasmic reticulum

• Myosin grabs actin pulling it inward

Skeletal Muscle contraction is initiated when the ________ sends a message to the muscle cell.

• Muscle cell

• Gland

• Neuron

• None of the above

When a muscle is in a contracted position, what is the relationship between actin filaments?

• They are on top of one another

• They are beside each other

• They are close to each other

• They are far apart from each other

What must occur first before a muscle can contract?

• An action potential must develop as energy/nutrients is gained from the digestive system

• An action potential must travel to the muscle through the circulatory system

• An action potential must enter the body through the respiratory system

• An action potential must be sent through neurons in the nervous system

What is the name of the place where a nerve meets a muscle fiber

• Nerve junction

• Neuromuscular junction

• Muscle junction

• Crossbridge

What two chemicals are necessary for muscle contraction to occur?

• Niacin and Potassium

• Calcium and ATP

• Sodium and Potassium

• Acetylcholine and Potassium