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Questions and Answers
Which layer of a blood vessel separates tunica intima from tunica media?
Which layer of a blood vessel separates tunica intima from tunica media?
What is the main function of elastic fibers in a blood vessel?
What is the main function of elastic fibers in a blood vessel?
What type of muscle cells are found in the tunica media of a blood vessel?
What type of muscle cells are found in the tunica media of a blood vessel?
Which layer of a blood vessel contains collagen type 1 and elastic fibers?
Which layer of a blood vessel contains collagen type 1 and elastic fibers?
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What replaces the tunica media in capillaries and post-capillary venules?
What replaces the tunica media in capillaries and post-capillary venules?
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What is the function of smooth muscles in blood vessels?
What is the function of smooth muscles in blood vessels?
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Which layer of an elastic artery has the most fenestrated elastic laminae?
Which layer of an elastic artery has the most fenestrated elastic laminae?
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What is the key difference between the tunica media of an elastic artery and a muscular artery?
What is the key difference between the tunica media of an elastic artery and a muscular artery?
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Which of the following is true about arterioles?
Which of the following is true about arterioles?
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What is the function of pericytes found in capillaries?
What is the function of pericytes found in capillaries?
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Which type of capillary is found in the brain and muscle tissue?
Which type of capillary is found in the brain and muscle tissue?
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What is the key structural difference between fenestrated and continuous capillaries?
What is the key structural difference between fenestrated and continuous capillaries?
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Which layer of a blood vessel secretes its own basal lamina?
Which layer of a blood vessel secretes its own basal lamina?
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What is the function of the internal elastic lamina in a blood vessel?
What is the function of the internal elastic lamina in a blood vessel?
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Which layer of a blood vessel contains both collagen and elastic fibers?
Which layer of a blood vessel contains both collagen and elastic fibers?
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What is the key structural difference between an elastic artery and a muscular artery?
What is the key structural difference between an elastic artery and a muscular artery?
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What is the role of smooth muscle cells in blood vessels?
What is the role of smooth muscle cells in blood vessels?
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What replaces the tunica media in capillaries and post-capillary venules?
What replaces the tunica media in capillaries and post-capillary venules?
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What is the key structural feature distinguishing elastic arteries from muscular arteries?
What is the key structural feature distinguishing elastic arteries from muscular arteries?
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Which layer of a blood vessel contains the vasa vasorum?
Which layer of a blood vessel contains the vasa vasorum?
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What is the primary function of pericytes in capillaries?
What is the primary function of pericytes in capillaries?
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Which type of capillary is found in organs like the liver and endocrine glands?
Which type of capillary is found in organs like the liver and endocrine glands?
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What is the primary function of the internal elastic lamina in blood vessels?
What is the primary function of the internal elastic lamina in blood vessels?
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Which layer of a blood vessel contains the most collagen fibers?
Which layer of a blood vessel contains the most collagen fibers?
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Study Notes
Blood Vessel Structure
- The blood vessel wall consists of three layers: tunica intima, tunica media, and tunica adventitia.
- Tunica intima has a simple squamous epithelium, known as endothelium, which secretes its own basal lamina.
- Subendothelial tissue is a loose tissue formed by fine collagen and elastic fibers with occasional smooth muscle cells.
- Internal elastic lamina separates intima from media and consists of elastic fibers with fenestrae (gaps) that allow diffusion of substances for nourishment.
Tunica Media
- Tunica media consists of concentric layers of elastic and reticular fibers, proteoglycans, glycoproteins, and smooth muscle cells.
- Elastic fibers are arranged as fenestrated laminae, and the thickness and components vary depending on the type of blood vessel.
- Pericytes replace the media in capillaries and post-capillary venules.
Tunica Adventitia
- Tunica adventitia is a connective tissue layer that consists of collagen (type 1) and elastic fibers.
- Thickness varies in different vessels and contains small blood vessels and nerves.
Functions of Blood Vessel Layers
- Endothelium regulates transport of materials, secretes substances, and controls blood flow.
- Elastic fibers passively alter the size of the lumen to withstand and maintain blood pressure (elastic recoil).
- Smooth muscles regulate the amount of blood flow to an area by contracting and relaxing.
Vascular Tree
- The vascular tree consists of the heart, large elastic artery, large vein, muscular/medium artery, medium vein, arterioles, metarteriole, capillaries, venule, small vein, venule, post-capillary, and large/elastic/conducting artery.
Types of Arteries
Elastic Artery
- Tunica intima has all three layers and is thicker compared to other arteries.
- Subendothelial layer has fibroblasts, and the internal elastic lamina is not that distinguishable.
- Tunica media consists of 90% layers of fenestrated elastic lamina, and tunica adventitia is thin and relatively underdeveloped.
Muscular Artery
- Tunica intima has all three components, but it is thinner than the elastic artery.
- Tunica media is 50% thick with circularly arranged smooth muscle fibers, and the thickness decreases as the arteries become smaller.
- External elastic lamina is seen in large muscular arteries but absent in small muscular arteries.
Arteriole
- Less than 0.5mm in diameter, with a narrow lumen, and tunica intima is present.
- Internal elastic lamina is absent in small arterioles, and tunica media is made up of 1-2 smooth muscle cell layers.
Capillaries
- Endothelial tubes with a diameter of 7-9μm, resting on a basement membrane.
- Zonula occludens is present, and the vast surface area and low flow rate allow for efficient diffusion of substances.
- Single layer of endothelial cells resting on a basement membrane, with pericytes at various locations.
Types of Capillaries
- Continuous (somatic) capillaries have smooth, non-porous endothelial lining and continuous basal lamina, found in brain, muscle, nerves, connective tissue, and exocrine glands.
- Fenestrated capillaries have endothelial cells forming small openings called fenestrations, with a continuous basal lamina that acts as a filter, favoring rapid transport of substances.
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Description
Test your knowledge on the histological structure of blood vessels, focusing on the layers such as Tunica Intima, Subendothelial tissue, and Tunica Media. Learn about the composition of each layer and their functions.
