Muscle Contraction and Neuromuscular Junction Quiz

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Questions and Answers

Which of the following is a function of the muscular system?

Constriction of organs and vessels

What is the major source of movement of blood in the body?

Cardiac muscle

Which type of muscle is responsible for locomotion and facial expressions?

Skeletal muscle

Which property of muscle allows it to respond to a stimulus?

Excitability Signup and view all the answers

Which type of muscle tissue is composed of long, cylindrical, multinucleated fibers?

Skeletal muscle Signup and view all the answers

Which connective tissue surrounds a whole muscle?

Epimysium Signup and view all the answers

Which type of muscle tissue is striated?

Striated muscle Signup and view all the answers

What is the function of transverse (T) tubules in muscle cells?

Ensure that action potential excites all parts of the muscle fiber at the same time Signup and view all the answers

Which protein stabilizes the position of myosin and accounts for much of the elasticity and extensibility of myofibrils?

Nebulin Signup and view all the answers

What is the function of tropomyosin in muscle contraction?

Regulates the interaction between active sites on G actin and myosin Signup and view all the answers

What is the region in the A band where actin and myosin do not overlap called?

H zone Signup and view all the answers

What is the protein that links thin filaments to the sarcolemma?

Dystrophin Signup and view all the answers

Which of the following best describes the resting membrane potential of a neuron?

The inside of the cell is more negative compared to the outside of the cell Signup and view all the answers

What is the main driving force behind the establishment of the resting membrane potential?

Concentration gradient of K+ Signup and view all the answers

Which type of ion channels open and close in response to small voltage changes across the plasma membrane?

Voltage-gated channels Signup and view all the answers

What is the main difference between depolarization and repolarization during an action potential?

Depolarization is the change in charge difference across the plasma membrane, while repolarization is the return of the resting membrane potential Signup and view all the answers

Which of the following is true about the neuromuscular junction?

The neuromuscular junction is the site where communication occurs between a motor neuron and a muscle fiber. Signup and view all the answers

What is the role of acetylcholinesterase in the synaptic cleft?

Acetylcholinesterase prevents the accumulation of acetylcholine in the synaptic cleft. Signup and view all the answers

What happens when acetylcholine binds to ligand-gated Na+ channels on the postsynaptic membrane?

Ligand-gated Na+ channels open, allowing Na+ to enter the postsynaptic cell and causing depolarization. Signup and view all the answers

What is the role of calcium ions in muscle relaxation?

Calcium ions move back into the sarcoplasmic reticulum by active transport, which requires energy. Signup and view all the answers

According to the text, what is the response of a muscle fiber to a sub-threshold stimulus?

No action potential; no contraction Signup and view all the answers

According to the text, what determines the strength of a muscle contraction?

Both the size of the motor unit and the number of units recruited Signup and view all the answers

What is the term for the phenomenon where each subsequent contraction in a rested muscle is stronger than the previous one?

Treppe Signup and view all the answers

What happens to muscle tension as the frequency of action potentials increases?

Muscle tension increases Signup and view all the answers

What is the term for the phenomenon where muscle fibers partially relax between contractions?

Incomplete tetanus Signup and view all the answers

What is the term for the phenomenon where there is no relaxation between muscle contractions?

Complete tetanus Signup and view all the answers

During the depolarization phase of the action potential, the membrane potential changes from approximately -85 mV to approximately +20 mV.

The membrane potential increases from -85 mV to +20 mV Signup and view all the answers

During the repolarization phase of the action potential, the inside of the plasma membrane changes from approximately +20 mV back to -85 mV.

The membrane potential decreases from +20 mV to -85 mV Signup and view all the answers

Action potentials cause calcium ions to be released from the sarcoplasmic reticulum into the muscle cell.

Action potentials cause calcium ions to be released from the sarcoplasmic reticulum into the muscle cell Signup and view all the answers

The decrease in calcium ion levels in the muscle cell leads to muscle relaxation.

Decreasing calcium ion levels in the muscle cell leads to muscle relaxation Signup and view all the answers

Study Notes

Muscular System

The muscular system is responsible for movement of blood in the body
Skeletal muscle is responsible for locomotion and facial expressions

Muscle Structure

Skeletal muscle tissue is composed of long, cylindrical, multinucleated fibers
Epimysium is the connective tissue that surrounds a whole muscle

Muscle Properties

Irritability is the property of muscle that allows it to respond to a stimulus
Titin protein stabilizes the position of myosin and accounts for much of the elasticity and extensibility of myofibrils