Circulation Through Skeletal Muscle

Circulation Through Skeletal Muscle Introduction

During resting condition, blood flow to skeletal muscle is 4-7 mL/100 gram/minute. During exercise, it increases to about 100 mL/100 grams/minute.

Factors Regulating Blood Flow To Skeletal Muscle

The blood flow through the skeletal muscle is regulated by three factors:

1. Mechanical factors
2. Chemical factors
3. Nervous factors.

Read And Learn More: Medical Physiology Notes

Mechanical Factors

• During the contraction of the muscle, the blood vessels are compressed and the blood flow decreases.
• And during the relaxation of the muscle, the compression of the blood vessels is relieved, and the blood flow increases.
• In severe muscular exercise, the blood flow increases in between the muscular contractions.

Chemical Factors

• The important chemical factors, which regulate the blood flow through the skeletal muscles are lack of oxygen, excess of carbon dioxide, and increased hydrogen ion concentration.
• All these chemical factors increase the blood flow to the muscle by causing vasodilatation.

Nervous Factors

• The blood vessels of the skeletal muscles are mostly innervated by sympathetic nerve fibers and, a few parasympathetic nerve fibers are also seen.
• The special feature of sympathetic nerve fibers supplying the skeletal muscles is that these nerve fibers are vasodilators and not constrictors.
• Since the sympathetic nerve fibers cause dilatation of blood vessels in muscle by secreting acetylcholine, these nerve fibers are called as sympathetic vasodilator fibers or sympathetic cholinergic fibers.

Applied Physiology-Varicose Veins

• A varicose vein is a vein that becomes irregularly swollen (twisted or tortuous) and enlarged.
• Mostly the superficial veins of the leg are affected. Varicose veins are common in individuals with occupations, which require standing for long periods.
• The absence of muscular activity for long periods in these persons is responsible for the development of varicose veins.
• However, the abnormality is because of the permanent dilatation caused by the incompetence of the valves of the veins.
• The varicose veins also develop in obese persons, pregnant women, and during thrombophlebitis (inflammation of veins associated with the formation of a thrombus).