Question 1

Which of the following best describes the effect of parasympathetic stimulation on the eye, as shown in the first image?

Accepted Answer

It causes contraction of the circular muscle, resulting in pupillary constriction.

Question 2

Sympathetic stimulation of the eye, as depicted in the second and third images, leads to which of the following outcomes?

Accepted Answer

Contraction of the radial muscle and pupillary dilation

Question 3

A patient presents with abnormally dilated pupils (mydriasis) even in bright light. Which autonomic pathway is most likely overactive or unopposed?

Accepted Answer

Sympathetic stimulation of the radial muscle

Question 4

Which of the following best describes the sequence of sound transmission through the ear as shown in the fourth image?

Accepted Answer

Sound waves → tympanic membrane → ossicles → oval window → cochlea

Question 5

In the cochlea, which structure is responsible for converting mechanical vibrations into electrical signals?

Accepted Answer

Hair cells

Question 6

Which of the following correctly matches the muscle structure with its description: 'Plasma membrane of muscle fiber'?

Accepted Answer

Sarcolemma

Question 7

What is the function of the triad in skeletal muscle fibers?

Accepted Answer

It transmits action potentials from the sarcolemma into the cell, triggering calcium release from the SR.

Question 8

Which of the following is the correct order of blood flow through the heart, as shown in the heart diagram?

Accepted Answer

Right atrium → right ventricle → pulmonary artery → lungs → left atrium → left ventricle → aorta

Question 9

During which phase of the cardiac action potential (as shown in the graph) does the plateau occur, and what is its physiological significance?

Accepted Answer

Phase 2; it prolongs depolarization to ensure adequate contraction time

Question 10

Which of the following best explains why cardiac muscle cannot undergo tetanus, unlike skeletal muscle?

Accepted Answer

The long refractory period due to the plateau phase prevents summation of contractions.

Question 11

Which of the following is a regulatory protein that binds $$\mathrm{Ca$$^{2+}$$}$$ reversibly and is responsible for starting the cross-bridge cycle by moving tropomyosin off the myosin-binding site?

Accepted Answer

Troponin

Question 12

A patient is exposed to a drug that blocks DHP receptors in skeletal muscle. What is the most likely effect on muscle contraction?

Accepted Answer

Decreased transmission of action potentials into the muscle fiber, reducing calcium release and contraction

Question 13

Which of the following regions of the sarcomere shortens during muscle contraction?

Accepted Answer

I band

Question 14

Which type of muscle tissue is characterized by the presence of gap junctions, pacemaker activity, and involuntary control?

Accepted Answer

Cardiac muscle

Question 15

Which of the following best describes the sliding filament model of muscle contraction?

Accepted Answer

Actin filaments slide past myosin filaments, shortening the sarcomere.

Question 16

Which of the following is the correct equation for the Nernst potential for a monovalent cation (e.g., $$\mathrm{K^+}) at $$body temperature?

Accepted Answer

$$E = \frac{61}{z} \log \left( \frac{[	ext{ion outside}]}{[	ext{ion inside}]} ight)$$

Question 17

Which of the following best explains why the plateau phase (phase 2) of the cardiac action potential is important for heart function?

Accepted Answer

It prolongs depolarization, ensuring sufficient time for ventricular filling and coordinated contraction.

Autonomic Regulation of the Eye, Auditory System, Muscle Structure, and Cardiac Physiology

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