Question

Which type of muscle is always multinucleated? I. Cardiac muscle II. Skeletal muscle III. Smooth muscle A. I only B. II only C. III only D. I and II only

Short answer

Option B: II only

Step-by-step solution

Understand the Question

Identify which type of muscle is always multinucleated. Multinucleated means that the muscle cells have more than one nucleus per cell.

Examine Each Muscle Type

Consider the characteristics of each muscle type: 1. Cardiac muscle cells are usually mononucleated (one nucleus per cell) but can occasionally have two nuclei.2. Skeletal muscle cells are always multinucleated.3. Smooth muscle cells are always mononucleated.

Eliminate Incorrect Options

Review the options and the characteristics:- Option A (I only) is incorrect as cardiac muscle is not always multinucleated.- Option B (II only) is correct as skeletal muscle is always multinucleated.- Option C (III only) is incorrect as smooth muscle is mononucleated.- Option D (I and II only) is incorrect as cardiac muscle is not always multinucleated.

Select the Correct Answer

Given that only skeletal muscle is always multinucleated, the correct answer is option B (II only).

Key concepts

Multinucleated Cells

Multinucleated cells are cells that contain more than one nucleus per cell.
This means that these cells have multiple nuclei sharing the same cytoplasm.
In muscle tissue, the presence of multinucleated cells allows for efficient control and distribution of proteins needed for muscle contraction.
Such a structure is especially important in handling the high demands of muscle activities.
Different types of muscle tissues have specific nuclear configurations.

Skeletal Muscle

Skeletal muscle is a type of muscle tissue that is always multinucleated.
Each skeletal muscle cell, also known as a muscle fiber, has multiple nuclei that are located at the periphery of the cell.
This multinucleation occurs due to the fusion of myoblasts (muscle precursor cells) during the development process.
This unique structure helps skeletal muscles meet the high energy and protein synthesis requirements for muscle contraction.
Characteristics of skeletal muscle include:

• Voluntary control: We can consciously control these muscles.


• Striated appearance: Under a microscope, they show a striped pattern.


• Fast contraction: They can contract quickly, but can also tire easily.

An example is the biceps brachii in the upper arm.

Cardiac Muscle

Cardiac muscle, found only in the heart, has unique properties that distinguish it from skeletal muscle.
Cardiac muscle cells are usually mononucleated, meaning one nucleus per cell, but can sometimes have two nuclei.
Unlike skeletal muscle, cardiac muscle operates involuntarily and never tires throughout life.
Key characteristics of cardiac muscle include:

• Involuntary control: It works without our conscious effort.


• Striated appearance: Similar to skeletal muscle, they exhibit a striped pattern under the microscope.


• Intercalated discs: Specialized cell junctions that facilitate rapid and uniform contraction.

This ensures that our heart can pump blood effectively and consistently.

Smooth Muscle

Smooth muscle is one of the three main types of muscle in the body.
Unlike skeletal and cardiac muscle, smooth muscle cells are always mononucleated, containing one nucleus per cell.
Smooth muscle is found in the walls of hollow organs such as the intestines, blood vessels, and the bladder.
This type of muscle operates involuntarily and is non-striated, meaning it does not have the striated appearance seen in skeletal and cardiac muscle.
Characteristics of smooth muscle include:

• Involuntary control: It functions without conscious control.


• Slow and sustained contraction: It contracts slowly and can sustain long-term tension.


• Non-striated appearance: Does not show a striped pattern under the microscope.

These muscles are essential for activities like moving food through the digestive system and regulating blood flow.