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The muscle fiber cells are arranged in 5 to 7 layers of circular and longitudinal smooth muscle with about 50μ in length and contain well-marked, rod-shaped nuclei, which are often slightly curved. Separating the tunica media from the outer tunica externa in larger arteries is the external elastic membrane (also called the external elastic ...
The tunica intima is well developed, with many smooth muscle cells in the subendothelial connective tissue, and often shows folds in cross section because of the vessel’s contraction with loss of blood pressure at death. Between the intima and the media lies the internal elastic lamina, usually better defined than the elastic laminae of the ...
Sympathetic nerve fibers travel around the tunica media of the artery, secrete neurotransmitters such as norepinephrine into the extracellular fluid surrounding the smooth muscle (tunica media) from the terminal knob of the axon. The smooth muscle cell membranes have α and β-adrenergic receptors for these neurotransmitters.
The tunica media may (especially in arteries) be rich in vascular smooth muscle, which controls the caliber of the vessel. Veins do not have the external elastic lamina, but only an internal one. The tunica media is thicker in the arteries rather than the veins. The outer layer is the tunica adventitia and the thickest layer in veins. It is ...
In elastic arteries such as the aorta, which have very regular elastic laminae between layers of smooth muscle cells in their tunica media, the internal elastic lamina is approximately the same thickness as the other elastic laminae that are normally present. [2]
The tunica media of the walls of arteries, arterioles, and veins is composed of smooth muscle and causes vasodilation and vasoconstriction. [3] Contraction of smooth muscle cells causes vasoconstriction, and relaxation of smooth muscle causes vasodilation. [1]
Chia seeds became a popular remedy for constipation on social media recently when influencers suggested mixing the seeds with water for a constipation remedy. The fiber and omega-3s in chia seeds ...
The outer tunica externa, also known as the tunica adventitia is a sheath of thick connective tissue. This layer is absent in the post-capillary venules. [8] The middle tunica media is mainly of vascular smooth muscle cells, elastic fibers and collagen. This layer is much thinner than that in arteries. [30]