Search results
Results from the WOW.Com Content Network
Smooth muscle is grouped into two types: single-unit smooth muscle, also known as visceral smooth muscle, and multiunit smooth muscle. Most smooth muscle is of the single-unit type, and is found in the walls of most internal organs (viscera); and lines blood vessels (except large elastic arteries), the urinary tract , and the digestive tract .
Muscle fibers contain numerous tubular myofibrils. Myofibrils are composed of repeating sections of sarcomeres, which appear under the microscope as alternating dark and light bands. Sarcomeres are composed of long, fibrous proteins as filaments that slide past each other when a muscle contracts or relaxes.
Vascular smooth muscle cells also play important roles during development, e.g. driving osteocyte differentiation from undifferentiated precursors during osteogenesis. [1] Arteries have a great deal more smooth muscle within their walls than veins, thus their greater wall thickness. This is because they have to carry pumped blood away from the ...
In the skin, smooth muscle cells such as those of the arrector pili cause hair to stand erect in response to cold temperature or fear. [19] Smooth muscle cells are spindle-shaped with wide middles, and tapering ends. They have a single nucleus and range from 30 to 200 micrometers in length. This is thousands of times shorter than skeletal ...
The submucosa (or tela submucosa) is a thin layer of tissue in various organs of the gastrointestinal, respiratory, and genitourinary tracts. It is the layer of dense irregular connective tissue that supports the mucosa (mucous membrane) and joins it to the muscular layer, the bulk of overlying smooth muscle (fibers running circularly within layer of longitudinal muscle).
Unlike the cardiovascular system, the lymphatic system is not closed and has no central pump. Lymph movement occurs despite low pressure due to peristalsis (propulsion of the lymph due to alternate contraction and relaxation of smooth muscle), valves, and compression during contraction of adjacent skeletal muscle and arterial pulsation. [3]
Structure of muscle fibre (sarcomere) under electron microscope with schematic explanation. By the time Hugh Huxley earned his PhD from the University of Cambridge in 1952 on his research on the structure of muscle, Szent-Györgyi had turned his career into cancer research. [12]
The muscular system is an organ system consisting of skeletal, smooth, and cardiac muscle. It permits movement of the body, maintains posture, and circulates blood throughout the body. [ 1 ] The muscular systems in vertebrates are controlled through the nervous system although some muscles (such as the cardiac muscle ) can be completely autonomous.