Question 1

Which of the following best describes the primary function of the sinoatrial (SA) node in cardiac muscle?

Accepted Answer

It serves as the heart's natural pacemaker, initiating electrical impulses.

Question 2

Which property allows muscle tissue to return to its original shape after being stretched?

Accepted Answer

Elasticity

Question 3

A patient is exposed to botulinum toxin. Which step at the neuromuscular junction is directly inhibited?

Accepted Answer

Release of acetylcholine from synaptic vesicles

Question 4

Which of the following is TRUE regarding the structure of skeletal muscle fibers?

Accepted Answer

They are multinucleated with nuclei at the periphery.

Question 5

During the sliding filament mechanism, what is the role of calcium ions ($$\mathrm{Ca$$^{2+}$$}$$)?

Accepted Answer

They bind to troponin C, causing tropomyosin to move and expose myosin-binding sites on actin.

Question 6

Which muscle type is responsible for peristalsis in the digestive tract?

Accepted Answer

Smooth muscle

Question 7

What would happen to muscle contraction if ATP were suddenly unavailable in a living muscle cell?

Accepted Answer

Myosin heads would remain bound to actin, resulting in rigor (rigor mortis).

Question 8

Which of the following best explains why cardiac muscle cells are described as 'functionally syncytial'?

Accepted Answer

They are connected by intercalated discs, allowing coordinated contraction.

Question 9

A drug that blocks acetylcholinesterase would have what effect at the neuromuscular junction?

Accepted Answer

It would prolong the action of acetylcholine, enhancing muscle contraction.

Question 10

Which protein directly covers the myosin-binding sites on actin in a relaxed skeletal muscle?

Accepted Answer

Tropomyosin

Question 11

Which of the following is a distinguishing feature of smooth muscle compared to skeletal muscle?

Accepted Answer

Smooth muscle cells are spindle-shaped and non-striated.

Question 12

Which of the following best describes the sequence of events in excitation-contraction coupling in skeletal muscle?

Accepted Answer

Action potential → Ca$$^{2+}$$ release from sarcoplasmic reticulum → Ca$$^{2+}$$ binds to troponin C → Tropomyosin moves → Cross-bridge formation

Question 13

Which of the following is a function of muscle tissue that is especially important for maintaining homeostasis?

Accepted Answer

Heat production

Question 14

Which of the following best explains why tetanic contraction produces greater tension than a single muscle twitch?

Accepted Answer

Repeated stimulation allows for greater calcium accumulation in the sarcoplasm.

Question 15

Which of the following is TRUE regarding the regulation of cardiac muscle contraction?

Accepted Answer

It is regulated by the autonomic nervous system, intrinsic pacemaker activity, and hormones.

Question 16

Which of the following best describes the role of the sarcoplasmic reticulum in muscle contraction?

Accepted Answer

It stores and releases calcium ions ($$\mathrm{Ca$$^{2+}$$}) $$necessary for contraction.

Question 17

Which of the following scenarios would most likely result in incomplete tetanus?

Accepted Answer

A muscle receives rapid, repeated stimuli with brief periods of partial relaxation.

Question 18

Which of the following is a correct pairing of muscle type and its primary location?

Accepted Answer

Smooth muscle – walls of blood vessels

Question 19

Which of the following best explains why curare causes muscle paralysis?

Accepted Answer

It blocks acetylcholine receptors at the neuromuscular junction.

Question 20

Which of the following is the correct order of muscle structure from smallest to largest?

Accepted Answer

Myofilament → Myofibril → Muscle fiber → Fascicle → Muscle

Contractile Tissue: Muscle Structure and Function in Biological Psychology

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