Which of the following muscle is called non-striated muscles?

NVS Staff Nurse - 2022

Applied Anatomy

Easy

Appeared in: NVS Staff Nurse - 2022

Explanation

Smooth muscles are classified as non-striated because they do not have the visible, repeating bands (sarcomeres) that are seen in skeletal and cardiac muscle.
This smooth appearance is due to a different arrangement of the contractile proteins, actin and myosin.
They are also known as involuntary muscles as their function is not under conscious control.
Smooth muscles are primarily found in the walls of hollow organs like the intestines, stomach, and blood vessels.

Option A: This is not a standard classification. 'Plain muscle' is another name for smooth muscle. Therefore, 'non-plain' would imply a muscle that is not smooth, i.e., a striated muscle.
Option C: Cardiac muscle, found in the heart, is a type of striated muscle. It has visible bands, similar to skeletal muscle, but is involuntary.
Option D: Skeletal muscles, which are attached to bones and responsible for movement, are the primary example of striated, voluntary muscles.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of muscle tissue based on microscopic appearance (striations) as background academic context rather than a clinical decision trigger.
Understanding the function of smooth muscle is crucial in pharmacology. Many drugs, like bronchodilators for asthma or vasodilators for hypertension, target smooth muscle to achieve their therapeutic effect.
In gastrointestinal disorders like Irritable Bowel Syndrome (IBS), the abnormal contraction of smooth muscles in the gut wall leads to symptoms like cramping and bloating.
What if? If a patient is given a beta-blocker drug, it can affect the smooth muscle in the airways. In a patient with asthma, this can lead to bronchoconstriction (narrowing of airways), worsening their symptoms. This is why non-selective beta-blockers are used with caution in asthmatic patients.

How to Approach the Question

First, identify the key term in the question: 'non-striated muscles'.
Recall the three main types of muscle tissue: skeletal, cardiac, and smooth.
Remember the key characteristics of each type, specifically whether they are striated (have visible bands) or non-striated.
Skeletal muscle is striated. Cardiac muscle is striated. Smooth muscle is non-striated.
Based on this recall, identify 'Smooth muscles' as the correct answer.
Evaluate the other options to confirm your choice. 'Skeletal' and 'Cardiac' are incorrect because they are striated. 'Non-plain muscles' is a distractor term designed to confuse, as smooth muscle is also called 'plain muscle'.

Concept Tested & Keywords

Concept Tested: Classification of muscle tissue based on microscopic appearance (striations).
Stem keywords: muscle, non-striated muscles
Lead-in keywords: Which of the following
Negative lead-in flag: false

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