Smooth and Cardiac Muscle: Structure, Function, and Regulation

Question 1

Which muscle type contracts rhythmically without external nerve stimulation?

Accepted Answer

Cardiac muscle

Answer

Skeletal muscle

Answer

Smooth muscle

Question 2

Identify the characteristic feature of smooth muscle cells.

Accepted Answer

Branched cells with multiple nuclei

Answer

Striated appearance

Answer

Intercalated discs

Answer

Voluntary control

Question 3

Which of the following structures enables electrical communication between cardiac muscle cells?

Accepted Answer

Gap junctions

Answer

Tight junctions

Answer

Desmosomes

Answer

Myofibrils

Question 4

Which feature is NOT characteristic of intercalated discs in cardiac muscle?

Accepted Answer

Basement membrane

Answer

Electrical coupling

Answer

Mechanical coupling

Answer

Desmosomes

Question 5

Define the concept of plasticity in smooth muscle.

Accepted Answer

Ability to adapt contractile properties

Answer

Presence of multiple cell types

Answer

Voluntary control of contraction

Answer

Resistance to fatigue

Question 6

Which of the following best describes the primary difference in the regulatory mechanisms of smooth muscle and cardiac muscle contraction?

Accepted Answer

Smooth muscle contraction is controlled by the autonomic nervous system, whereas the sinoatrial node regulates cardiac muscle contraction.

Answer

Calcium ions initiate smooth muscle contraction, while sodium ions trigger cardiac muscle contraction.

Answer

Smooth muscle contraction is sustained, while cardiac muscle contraction is intermittent.

Question 7

Which of the following is NOT a typical clinical manifestation of asthma?

Accepted Answer

Hypertension

Answer

Wheezing

Answer

Chest tightness

Answer

Dyspnea

Question 8

Cardiac muscle is primarily responsible for:

Accepted Answer

Pumping blood

Answer

Moving the body

Answer

Digesting food

Answer

Storing energy

Question 9

Which of the following muscle types exhibits both multiunit and visceral activity?

Accepted Answer

Smooth muscle

Answer

Cardiac muscle

Answer

Skeletal muscle

Answer

Voluntary muscle

Question 10

The electrical impulses that initiate heart contractions originate in the:

Accepted Answer

Sinoatrial node

Answer

Atrioventricular node

Answer

Bundle of His

Answer

Purkinje fibers

Question 11

Which of the following actions does the sympathetic nervous system have on vascular smooth muscle tone?

Accepted Answer

Constricts by activating α1-adrenergic receptors

Answer

Relaxes by inhibiting α1-adrenergic receptors

Answer

Relaxes by activating β2-adrenergic receptors

Question 12

In which organs is smooth muscle commonly found?

Accepted Answer

Blood vessels, gastrointestinal tract, and reproductive system

Answer

Heart, skeletal muscles, and central nervous system

Answer

Lungs, kidneys, and liver

Answer

Skin, bones, and tendons

Question 13

Which regulatory mechanism is primarily responsible for controlling smooth muscle contraction?

Accepted Answer

Calcium ion influx

Answer

Electrical impulses

Answer

Hormonal signaling

Answer

Neurotransmitter release

Question 14

Identify the unique cellular junction in cardiac muscle that allows for synchronous contractions.

Accepted Answer

Gap junctions

Answer

Desmosomes

Answer

Adherens junctions

Answer

Hemidesmosomes

Question 15

Which of the following is a key physiological difference between cardiac and skeletal muscle?

Accepted Answer

Length of refractory period

Answer

Type of actin filaments

Answer

Number of nuclei per cell

Answer

Presence of T-tubules

Question 16

What is the main function of the sinoatrial (SA) node in the heart?

Accepted Answer

Initiating cardiac contractions

Answer

Conducting electrical impulses to the ventricles

Answer

Regulating heart rate

Answer

Preventing cardiac arrhythmias

Question 17

Which neurotransmitter decreases heart rate and contractility?

Accepted Answer

Acetylcholine

Answer

Dopamine

Answer

Epinephrine

Answer

Norepinephrine

Question 18

Identify the hormone that stimulates cardiac muscle contraction.

Accepted Answer

Adrenaline

Answer

Insulin

Answer

Cortisol

Answer

Testosterone

Question 19

Which type of muscle is responsible for propelling food through the digestive system?

Accepted Answer

Smooth muscle

Answer

Cardiac muscle

Answer

Skeletal muscle

Answer

Striated muscle

Question 20

Identify the type of muscle contraction that occurs without a change in muscle length.

Accepted Answer

Isometric contraction

Answer

Isotonic contraction

Answer

Concentric contraction

Answer

Eccentric contraction

Question 21

Where in the body is smooth muscle primarily found?

Accepted Answer

Walls of internal organs (viscera) and blood vessels

Answer

Heart

Answer

Brain and spinal cord

Answer

Skeletal muscles attached to bones

Question 22

What is the predominant type of muscle fiber in the ventricular walls of the heart?

Accepted Answer

Cardiac muscle fibers

Answer

Skeletal muscle fibers

Answer

Smooth muscle fibers

Answer

Connective tissue fibers

Question 23

Which structure in cardiac muscle cells allows for rapid and coordinated contractions?

Accepted Answer

Intercalated discs

Answer

Mitochondria

Answer

Troponin

Answer

Sarcomeres

Question 24

What is the primary function of cardiac muscle?

Accepted Answer

Pumping blood throughout the body

Answer

Sensation and perception

Answer

Digestion and absorption of nutrients

Answer

Movement of the skeleton

Question 25

What type of innervation primarily regulates heart rate?

Accepted Answer

Autonomic nervous system

Answer

Somatic nervous system

Answer

Peripheral nervous system

Answer

Central nervous system (brain and spinal cord)

Question 26

Which hormone directly increases heart rate and contractility?

Accepted Answer

Epinephrine (adrenaline)

Answer

Thyroxine (T4)

Answer

Glucagon

Answer

Insulin