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.
Table of Contents
Factors Regulating Blood Flow To Skeletal Muscle
The blood flow through the skeletal muscle is regulated by three factors:
- Mechanical factors
- Chemical factors
- 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).
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