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Overview of the General Structure of Vascular Walls and Vessel Types

This overview describes the general structure of vascular walls, including the three main layers: tunica intima, tunica media, and tunica adventitia. Each layer has unique components such as endothelial cells, smooth muscle cells, and elastic fibers, crucial for vascular function. The document also differentiates between various types of blood vessels, including arteries, arterioles, capillaries, veins, and lymphatic vessels, highlighting their structural details and roles in circulation.

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Overview of the General Structure of Vascular Walls and Vessel Types

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  1. VESSELSgeneral overview

  2. GENERAL STRUCTURE OF VASCULAR WALL • tunica intima • subedothelial layer of connective tissue • membrana elastica interna • tunica media • membrana elastica externa • tunica adventitia= tunica externa

  3. General structure of vascular wall • tunica intima • tunica media • tunica adventitia (externa)

  4. Tunica intima • endothelial cells (endotheliocyti) • simple flat/squamous epithelium • on basal lamina • subendothelial layer (stratum subendotheliale) • loose connective tissue • some smooth muscle cells • lamina elastica interna • elastin

  5. Endothelial cells (Endotheliocyti) • mesenchymal origin • zonulae occludentes, desmosomes, nexuses • intermediate filaments, microfilaments (contraction) • corpora multitubularia (Weibel-Palade‘s bodies) • f. VIII – vWF, P-selectin • receptors: adrenergic, histaminic, ADH • synthesis of vasoactive substances: NO, PG

  6. Tunica media • smooth muscle cells • spiral arrangement • elastic a collagen fibers (type III) • lamina elastica externa • only in thicker arteries

  7. Tunica adventitia (externa) • fibroblasts • collagen fibers (type I) • elastic fibers • vasa vasorum • nervi vasorum

  8. Vessel types • arteries (arteriae) - aer + térein • muscular x elastic x mixed • microcirculation: small arteries – less than 1 mm • arterioles (arteriolae) • less than 100 μm • several layers of smooth muscle cells • principal source of peripheral resistance !!! • metarterioly • one smooth muscle cell layer, precapillary sphincter • capillaries (vasa capillaria) • no nerve fibers • endotheliocyte + pericyte(Rouget‘ s cell) • caliber± 7 μm

  9. Vessel types • veins (venae) • few muscle cells, more valvules • venules (venulae) • capacity part of circulation (70% of blood) • lymph vessels(vasa lymphatica) • lymph capillaries (vasa lymphocapillaria) • originate as cul-de-sac • lymphatic trunks and ducts (trunci et ductus lymphatici) • collectors in limbs • valvules

  10. Elastic arteriesaorta, truncus pulmonalis, a. subclavia, axillaris, iliaca, femoralis, thoracica int.

  11. Elastic artery(Arteria elastotypica) • Tunica intima • lamina elastica interna –incoherent • Tunica media • elastic membranes with fenestrations – elastin • smooth muscle cells • lamina elastica externa • Tunica adventitia (externa) • frequent vasa vasorum • supply outer 2/3 of wall

  12. Elastic artery(van Gieson + elastin)

  13. Elastic artery(elastin)

  14. Muscular artery (arteria musculotypica) • Tunica intima • thin • lamina elastica interna – obvious • Tunica media • circular smooth muscle cell layer (up to 40 layerss) • each cell is covered with basal lamina – communication • synthesis of extracellular matrix • lamina elastica externa – several elastic membranes • Tunica externa • nerve bundles – contraction

  15. Muscular artery(HE) (van Gieson + elastin)

  16. Arterioles = Arteriolae caliber < 0.5 mm • Tunica intima • Weibel-Palade‘ s bodies within endothelail cells (not in capillaries!) • lamina elastica int. – absent in smallest arterioles • Tunica media • 1-3 layers of smooth muscle cells • lamina elastica ext. – absent • Tunica adventitia (externa) – very thin principal source of peripheral resistance

  17. Arteriola(HE)

  18. Arteriola(HE)

  19. Sensorystructures in arteries • Glomera supracardiaca (aortica) – sup., medium, inf. - baroreceptors • Sinus caroticus - baroreceptor • thicker, richly innervated tunica adventitia • thinner tunica media • Glomus caroticum - chemoreceptors • oval structures - 3-5 mm • glomus cells – large nucleus, vesicles with catecholamines • shield cells – cover neural endings as glia

  20. Capillaries (Vasa capillaria) • microvascular part of circulation • vas capillare arteriale, intemredium, venosum • site of gas and nutrients exchange • capillary • caliber 7-9 μm • length 1 mm (50 mm in renal glomerulus) • total length approximately 96 000 km • formed by endothelial cells on basal lamina

  21. Capillaries – wall structures • Endothelial cell (Endothelicytus) • Basal lamina (Lamina basalis) • Pericyte (Pericytus; Rouget‘s cells) • mesenchymal cells with long processes • stem, supporting and transporting cell • proper lamina basalis • contractile proteins (replaces tunica media)

  22. Capillary bed(HE)

  23. Capillary types • somatic capillaries • muscle, conncetive tissue, exocrinne glands (pinocytar vesicle in the wall), nervous tissue (no vesicles) • fenestrated (visceral) capillaries with diaphragms • fenestrations 60-80 nm (quick metabolic exchange) • kidneys, gut, endocrinne glands • fenestrated capillaries without diaphragms • glomeruli in kidney • sinusoids • caliber 30-40 μm, often without lamina basalis • hematopoetic organs – liver, spleen, bone marrow, dental pulp • glomus, glomi n. (vessel glomerule) – ball of fingers, nailbeds, auricle, penis / clitoris, uterus

  24. Capillaries -function • permeability • exchanger vessels (diffusion, pores, fenestration, vesicles) • metabolic function • activation of angiotensin I  angiotensin II (lungs) • inactivation of bradykinin, serotonin, prostaglandins • lipolysis • antithrombotic function • inhibition of tissue thromboplastin

  25. Somatic capillary(EG)

  26. Somatic capillary (EG)

  27. Fenestrated capillary (EG)

  28. Fenestrated capillary (EG)

  29. Other structures of vascular wall • vasa vasorum • vasa nervorum • nervi vasorum

  30. Other peculiar vascular structures • vas anastomoticum (anastomosis) • vas collaterale (collateral) • rete mirabile = portal system • 2 capillary beds series-connected • anastomosis arteriovenosa (arteriolovenularis) • endothel bulges of intimal cushions with myoepitheloid cells • simple (skin, lungs, kidneys) • composed (glomus coccygeum)

  31. Vessel network arrangement • terminal (retina, spleen, kidney) • functionally terminal (heart, brain) • anastomotic angiogenesis – hypoxia is the strongest factor !

  32. Clinical relevance • aneurysma • atherosclerosis (athere + skleros) • necrosis, infarctus • air embolism in large cervical veins • varices

  33. Blood distribution in vessels • veins 64% • arteries 13% • capillaries 7% • heart 7% • lungs 9%

  34. Blood distribution in organs • heart (coronary arteries) 5% • brain 15% • muscles 15% • viscera 35% • kidneys 20% • skin, skeleton 10% according to Stingl

  35. Development of arterial system

  36. Developmental arteries • Saccus aorticus (aortal sac) • Aa. arcuum pharyngeorum (pharyngeal arch arteries; „aortal arches“) • 5 pairs develop and change successively • Aorta dorsalis (original 2 merge into 1) • a.a segmentales ventrales ( a. omphalomesenterica, unpaired branches from AA) • truncus umbilicalis ( a. iliaca communis + int.) • a. umbilicalis • aa. segmentales laterales ( paired branches from AA) • aa. intersegmentales dorsolaterales ( branches from a. subclavia) • a. sacralis mediana

  37. Day 20-22

  38. Pharyngeal arch arteries derivates • 1st pair – arteria maxillaris + carotis externa • 2nd pair – arteria stapedia • 3rd pair – central – arteria carotis communis – peripheral – arteria carotis interna

  39. Pharyngeal arch arteries derivates • 4th pair • left – part of the arcus aortae • right – a. subclavia dx. • peripheral part of a. subclavia dx.is derived from aorta dorsalis dextra • a. subclavia sin. is NOT derived from the 4th aortic arch but from 7th intersegmental artery

  40. Pharyngeal arch arteries derivates • 5th – Ø • 6th pair • left central left pulmonary artery peripheral ductus arteriosus (Botali) • right central right pulmonary artery peripheral Ø

  41. Arteriae omphalomesentericae(vitellinae) • number of paired arteries • supply yolk sac • develop in vascular supply of gut → truncus coeliacus, arteria mesenterica superior et inferior

  42. Arteriae umbilicales • paired branches • central: truncus umbilicalis from aorta dorsalis • peripheral: within mass of diverticulum allantoicum • to placenta (originally to allantois) in embryonic (connective) stalk or later in umbilical cord • persist as arteriae iliacae internae and vesicales superiores • central: pars patens) • peripheral: ligamentum umbilicale mediale = pars occlusa

  43. Malformation of arteries • Ductus arteriosus patens • Coarctatio aortae • Arcus aortae duplex • Arcus aortae dexter • Arteria lusoria • abnormal origin of the right subclavian artery – obliteration of right aortic arch – origin of 7th segmental artery

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