Question

Which of the following is incorrect about visceral muscles? (a) Non-striated muscle (Smooth muscle) (b) Involuntary muscle (c) Located in inner walls of hollow visceral organs of the body (d) They are under in voluntary control

Short answer

The incorrect statement about visceral muscles is (d). They are under involuntary control, not voluntary.

Step-by-step solution

Feature Analysis

First, analyze the four given options based on what is known about the visceral muscles. (a) describes them as non-striated, which is correct as they appear visually smooth under a microscope. (b) states they are involuntary, also correct because they function automatically without conscious control (controlled by the autonomic nervous system). (c) states that they are located in the inner walls of hollow visceral organs, which is the correct location for them.

Identify Incorrect Information

Next, look at option (d) which states they are under voluntary control. This is in fact not true for visceral muscles. They are not under voluntary control, but instead operate involuntarily, meaning they function without conscious thought or intent.

Key concepts

Visceral Muscles

Visceral muscles, often referred to as smooth muscles, play a crucial role in the human body. They are primarily found in the walls of hollow visceral organs such as the stomach, intestines, blood vessels, and bladder. Unlike skeletal muscles that are attached to bones and help in voluntary movements, visceral muscles facilitate movements inside the body.

These muscles help in the contraction and relaxation necessary for functions like digestion and blood circulation. Interestingly, they work without us having to consciously think about it. This makes them essential for various automatic and reflexive activities of the body.

• Located in hollow organs
• Enable essential involuntary functions
• Composed of smooth muscle fibers

Involuntary Control

The term 'involuntary control' refers to the automatic regulation of bodily functions without conscious effort. Visceral muscles are controlled involuntarily, meaning that our brain does not need to send a specific command for these muscles to perform their functions. This functionality is crucial for maintaining vital processes like digestion and circulation.

For example, consider your heartbeat - it continues rhythmically without you having to think about it every moment. This efficiency is made possible due to the involuntary control of the visceral muscles, allowing the body to focus on other tasks.

The continuous, involuntary contractions are minor but essential for our survival. In case of visceral muscles, involuntary control ensures a constant internal environment, which is key for health and functionality.

• Critical for automatic bodily functions
• Allows brain focus on voluntary activities
• Ensures rhythm and constancy in bodily processes

Non-striated Muscle

Non-striated muscles, or smooth muscles, are characterized by a lack of striations or banding patterns seen in skeletal muscles. This absence of striations is due to the different arrangement of actin and myosin filaments.

Smooth muscles are spindle-shaped and have a central nucleus. They appear smooth under a microscope, hence the name, making them easily distinguishable from the striated appearance of skeletal and cardiac muscles.

With their unique structure, non-striated muscles are incredibly flexible and capable of sustaining long-term involuntary contractions, such as in the digestive tract where food is gradually pushed along.

• Spindle-shaped fibers
• Lack visible striations
• Ideal for sustained contractions

Autonomic Nervous System

The autonomic nervous system (ANS) plays a vital role in the involuntary control of visceral muscles. It is responsible for the regulation of body processes without conscious intervention. This system is subdivided into the sympathetic and parasympathetic nervous systems, each with distinct roles.

The sympathetic nervous system tends to stimulate body processes (e.g., increasing heart rate during stress), while the parasympathetic system calms the body (e.g., decreasing heart rate during rest). Together, they maintain the balance crucial for the body's homeostasis.

The ANS oversees functions like digestion, respiratory rate, and even pupillary response, ensuring they operate seamlessly. It's impressive how this system can adjust the body’s functions automatically based on immediate needs.

• Involuntary regulation
• Sympathetic and parasympathetic divisions
• Maintains bodily homeostasis