Problem 165 - Objective Biology for NEET

Question

Assertion: Smooth muscles are involuntary muscles Reason: Their activities are not under voluntary control of the nervous system.

Step-by-Step Solution

Answer

Yes. The assertion and reason are both correct and the reason correctly explains the assertion.

Step 1: Understand the Key Terms

Smooth muscles are a type of muscle found in the human body. They are located in walls of hollow visceral organs, excluding the heart, and they contract and relax without conscious control, thus termed involuntary. The nervous system plays a role in the voluntary and involuntary control of the body's muscles.

Step 2: Evaluate Assertion

The assertion states: 'Smooth muscles are involuntary muscles'. This is correct, as smooth muscles do not require conscious thought to function and are automatically controlled by the nervous system.

Step 3: Evaluate Reason

The reason given is: 'Their activities are not under voluntary control of the nervous system'. This statement is also correct, as smooth muscles are not consciously controlled. They are regulated by the autonomic part of the nervous system, which is not under voluntary control.

Step 4: Establish Connection

Finally, the given reason correctly explains the assertion. The assertion about smooth muscles being involuntary is supported by the reason that their activities are not under voluntary control, and thus, can operate without conscious command.

Key Concepts

Involuntary Muscles

In our body, muscles can be classified into voluntary and involuntary muscles. Voluntary muscles are those you can control, like the muscles in your arms and legs.
However, smooth muscles are a type of involuntary muscle.
These are muscles you cannot consciously control. Often found in the walls of internal organs like the stomach, intestines, and blood vessels, they function automatically.

• Examples include the movement of food through the digestive system and the regulation of blood flow in the arteries.
• They operate without any conscious effort from us which is essential for many vital bodily functions.

While intentional actions use skeletal muscles (which are voluntary), involuntary muscles work independently to ensure our body's systems work properly.

Nervous System

The nervous system is like a complex communication network in the body. It controls and coordinates how different parts of our body work together.
It is made up of two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS includes the brain and spinal cord, acting as the command center.
On the other hand, the PNS consists of nerves that branch out from the spine to other areas.

• The nervous system detects changes both within and outside the body, processes that information, and then responds accordingly by sending signals to different body parts to take action.
• These actions can be voluntary or involuntary depending upon the situation.

By understanding the role of the nervous system, we can appreciate how it keeps millions of processes in balance every second, ensuring our survival and functionality.

Autonomic Nervous System

The autonomic nervous system (ANS) is a special part of the peripheral nervous system. It controls the involuntary muscles and various internal organs.
One of its primary functions is to regulate processes that occur without conscious thought, like your heartbeat or digestion.

• It has two main parts: the sympathetic and parasympathetic nervous systems.
• The sympathetic division prepares the body for intense physical activity and is often referred to as the 'fight or flight' response.
• The parasympathetic division, on the other hand, relaxes the body and is often called the 'rest and digest' response.

The ANS ensures that your body runs smoothly without you having to even think about it!

Muscle Control

Controlling muscles can be a complicated process that involves signals from the nervous system.
When it comes to smooth muscles, control does not involve consciousness. This means that they do not need the brain's direct commands to function.
The autonomic nervous system handles these processes.

• For example, when you eat, smooth muscles in your digestive tract help move the food along without any need to focus on the process.
• Heartbeats are another situation where autonomic control is crucial, with cardiac muscles working tirelessly and rhythmically.

This automatic muscle control is vital for maintaining homeostasis and ensuring that the body responds appropriately to different demands and conditions.