Muscle Biology

During anaerobic respiration in muscles, pyruvate is converted to lactic acid. When lactic acid accumulates faster than it can be cleared, it causes muscle fatigue and burning sensation.

Human hair erection (goosebumps) is caused by arrector pili muscles, which are smooth (unstriated) muscles attached to hair follicles. When they contract, hair stands up. Striated muscles are voluntary muscles like skeletal muscles, not involved in this reflex.

The biceps brachii (front of upper arm) and triceps brachii (back of upper arm) are muscles that cross the elbow joint. Biceps brachii flexes the forearm (bends the elbow), while triceps brachii extends the forearm (straightens the elbow). These muscles insert on the radius and ulna bones of the forearm, making them responsible for all forearm movements rather than thigh or shoulder movements.

The heart is composed of cardiac muscle, which is a specialized type of muscle tissue found only in the heart. Cardiac muscle is striated (has bands) like skeletal muscle but involuntary like smooth (unstriated) muscle. The heart is NOT made of unstriated muscle (smooth muscle is found in organs like stomach and intestines), and sinuses are air-filled cavities, not muscle tissue.

This option is correct. Rhabdomyosarcoma is a cancer that arises from striated muscle tissues.

Dystrophin is a rod-shaped cytoplasmic protein that connects the cytoskeleton of a myocyte to the surrounding extracellular matrix through the cytoplasmic membrane.

Heart muscle is a cardiac muscle. It is voluntary in structure, but involuntary in function. Thus, heart muscle is immune to fatigue.

This is the correct answer. Voluntary muscles are called skeletal muscles because they are mostly attached to bones and help in body movement. Voluntary muscles are also called striated muscles because these muscles show alternate light and dark bands or striations, when strained appropriately.

Actin and myosin are the two primary contractile proteins that interact to cause muscle fiber contraction.

It is the middle layer of the cardiac wall and is formed of cardiac muscle fibres.

Levator anguli oris originates from maxilla and is used while smiling. It elevates the angle of mouth.

Sarcoplasmic hypertrophy is due to increased muscle glycogen storage. 

Palmaris longus is not always present in many human bodies. It is absent in about 14% individuals. It is found in wrist and the absence of this muscle has no effect on the grip.

Acute muscle soreness is the pain felt in muscles during and immediately after strenuous physical exercise. It subsides after some time.

Sarcomere is the basic unit of striated muscle tissue. It is composed of long, fibrous proteins as filaments that slide past each other when a muscle contracts or relaxes.