tunica intima

(noun)

The innermost layer of a blood vessel.

Related Terms

Examples of tunica intima in the following topics:

  • Blood Vessel Structure

    • The inner layer (tunica intima) is the thinnest layer, formed from a single continuous layer of endothelial cells and supported by a subendothelial layer of connective tissue and supportive cells.
    • The tunica intima is surrounded by a thin membrane comprised of elastic fibers running parallel to the vessel.
    • Surrounding the tunica intima is the tunica media, comprised of smooth muscle cells and elastic and connective tissues arranged circularly around the vessel.
    • The outermost layer is the tunica externa or tunica adventitia, composed entirely of connective fibers and surrounded by an external elastic lamina which functions to anchor vessels with surrounding tissues.
    • This diagram of the artery wall indicates the smooth muscle, external elastic membrane, endothelium, internal elastic membrane, tunica externa, tunica media, and tunica intima.

  • Muscular Arteries

    • Muscular arteries can be identified by the well-defined elastic lamina that lies between the tunicae intima and media.

  • Artery Function

    • As with veins, arteries are comprised of three layers: the tunicae intima, media, and externa.
    • In arteries, the tunica media, which contains smooth muscle cells and elastic tissue, is thicker than that of veins so it can modulate vessel caliber and thus control and maintain blood pressure.
    • Arteries of the systemic circulation can be subdivided into muscular or elastic types according to the the relative compositions of elastic and muscle tissue in their tunica media.

  • Elastic Arteries

    • An elastic or conducting artery has a large number of collagen and elastin filaments in the tunica media.
    • Elastic arteries contain larger numbers of collagen and elastin filaments in their tunica media than muscular arteries do, giving them the ability to stretch in response to each pulse.
    • Due to position as the first part of the systemic circulatory system closest to the heart and the resultant high pressures it will experience, the aorta is perhaps the most elastic artery, featuring an incredibly thick tunica media rich in elastic filaments.
    • Arterial wall layers including the tunica intima and the tunica media.
    • In elastic arteries, the tunica media is rich with elastic and connective tissue.

  • Arteries, Veins, and Capillaries

    • The inner, tunica intima is a smooth, inner lining of endothelial cells that are in contact with the red blood cells.
    • Veins and arteries both have two further tunics that surround the endothelium: the middle, tunica media is composed of smooth muscle, while the outer tunica externa is connective tissue (collagen and elastic fibers).
    • Arteries and veins consist of three layers: an outer tunica externa, a middle tunica media, and an inner tunica intima.
    • Capillaries consist of a single layer of epithelial cells, the endothelium tunic (tunica intima).

  • Overview of Hemostasis

    • Blood vessel with an erythrocyte (red blood cell) within its lumen, endothelial cells forming its tunica intima or inner layer, and pericytes forming its tunica adventitia (outer layer).
    • Microvessel showing an erythrocyte (E), a tunica intima of endothelial cells, and a tunica adventitia of pericytes.

  • Development of the Heart

    • Blood vessel with an erythrocyte (red blood cell) within its lumen, endothelial cells forming its tunica intima or inner layer, and pericytes forming its tunica adventitia (outer layer).

  • Coronary Artery Disease

    • Characteristics of atherosclerosis shown here include thickening of the tunica intima, fragmentation of the internal elastic lamina (a very thin black wavy layer) between the intima and media, partial duplication of the internal elastic lamina, smooth muscle infiltration of the intima (from the media, red staining of the intima), and luminal narrowing.

  • Testes

    • Under a tough membranous shell, the tunica albuginea contains very fine coiled tubes called seminiferous tubules.
    • Tunica albuginea, 2.
    • Tunica vaginalis (parietal lamina), 11b.
    • Tunica vaginalis (visceral lamina), and 12.
    • Cavity of tunica vaginalis.

  • Structure of Synovial Joints

    • The inner layer, or intima, consists of a sheet of cells thinner than a piece of paper.
    • Where the underlying subintima is loose, the intima sits on a pliable membrane called the synovial membrane.
    • This membrane, together with the cells of the intima, acts like an inner tube, sealing the synovial fluid from the surrounding tissue and effectively stopping the joints from being squeezed dry when subjected to impact (such as when running).
    • Just beneath the intima, most synovia have a dense net of small blood vessels that provide nutrients for the synovia and the avascular cartilage.