Question

Identify from the following list, the characteristics d ded muscles (A) and white muscles (B) and select the opir that correctly segregates the characters. (i) Less number of mitochondria (ii) More number of mitochondria (iii) Sarcoplasmic reticulum is abundant (iv) Myoglobin content high (v) Sarcoplamic reticulum moderate (vi) Aerobic muscles

Short answer

Red muscles: (ii) More number of mitochondria, (iv) Myoglobin content high, (vi) Aerobic muscles. White muscles: (i) Less number of mitochondria, (iii) Sarcoplasmic reticulum is abundant, (v) Sarcoplasmic reticulum moderate.

Step-by-step solution

Identify Characteristics of Red Muscles

Red muscles (Type A) are also known as slow-twitch or aerobic muscles. They have high myoglobin content, more mitochondria, and are adapted for sustained, endurance-type activities. Characteristics (ii) More number of mitochondria, (iv) Myoglobin content high, and (vi) Aerobic muscles are associated with red muscles.

Identify Characteristics of White Muscles

White muscles (Type B) are also known as fast-twitch muscles. They are adapted for quick, powerful bursts of speed and have less myoglobin content. They possess a less abundant supply of mitochondria and have a more moderate sarcoplasmic reticulum. Characteristics (i) Less number of mitochondria, (iii) Sarcoplasmic reticulum is abundant, and (v) Sarcoplasmic reticulum moderate are associated with white muscles.

Assign Characteristics to the Correct Muscle Type

Correctly segregate the characteristics as follows: Red muscles (A) are represented by characteristics (ii), (iv), and (vi). White muscles (B) are represented by characteristics (i), (iii), and (v).

Key concepts

Red Muscles Characteristics

When you think of red muscles, picture a marathon runner—built for endurance and long-lasting activity. These muscles get their color from a high content of myoglobin, a type of oxygen-storing protein. This myoglobin-rich nature gives red muscles their distinct hue and is crucial for maintaining their aerobic respiration.

Red muscles, also known as Type I fibers, are densely packed with mitochondria, the energy powerhouses of the cell. The abundance of mitochondria enables these muscles to generate ATP (adenosine triphosphate), the primary cellular energy currency, through oxidative metabolism, which requires oxygen.

Since red muscles are designed for endurance, they fatigue much slower compared to their white counterparts. They are highly efficient at converting carbohydrates and fats into energy over extended periods, making them the first choice for activities like distance running or cycling.

White Muscles Characteristics

Imagine a sprinter at the starting block, muscles coiled tight, ready to explode into action. This is the realm of white muscles, also called Type II fibers. White muscles are characterized by their ability to contract rapidly and forcefully but fatigue quickly.

They contain a lower myoglobin content than red muscles, which is why they're lighter in color and often referred to as 'white.' With fewer mitochondria present, white muscles rely more on anaerobic metabolism—meaning they can generate energy without oxygen, but only for short bursts.

This fiber type’s sarcoplasmic reticulum, which releases calcium ions to promote muscle contraction, is well-developed to facilitate the fast and forceful contractions necessary for explosive movements like jumping or weightlifting.

Muscle Mitochondria Content

The mitochondria's role in muscle fibers cannot be overstated. They are essentially the cellular engines, converting nutrients into ATP. The content of mitochondria in a muscle fiber correlates directly with how that muscle performs and its capacity for stamina.

In red muscle fibers, the high mitochondria content supports continuous aerobic respiration, which is efficient for long-duration activities and helps in burning fats and carbohydrates steadily. However, in white muscle fibers, low mitochondria content means these muscles can deliver quick energy through anaerobic pathways but for a limited time before fatigue sets in. This dichotomy is vital for athletes as it determines their muscle composition based on their sport or activity requirements.

Myoglobin Content in Muscles

Myoglobin’s role in muscles is akin to a reserve oxygen tank for divers; it stores oxygen within muscle fibers and releases it during muscle contraction, particularly when oxygen levels are low.

Red muscles are rich in myoglobin, allowing them to thrive during aerobic exercises where there's a steady and prolonged need for oxygen. This high myoglobin content also gives the muscle its red coloration. In contrast, white muscles contain low levels of myoglobin as they are primarily used for anaerobic exercises where oxygen is used up quickly and doesn't rely on continuous oxygen supply. Understanding the myoglobin content can be essential for athletes who are working to tailor their training to boost either their aerobic or anaerobic performance capacities.