Cardiovascular system (circulatory system) The cardiovascular system consists of the heart and a closed system of vessels: the arteries, veins, and capillaries. The heart is the muscular organ that pumps the blood around the circuit of vessels. red jagged line indicating heart monitor reading blood_circulation Characteristics of c-v system nis an unique and complex hydraulic system nis a closed circle ("circulatory system") nis elastic n n Function of c-v system nto maintain homeostasis and an optimal cellular environment. ntransport function of oxygen, nutrients and waste products nlining endothelium is important for these functions; is waterproof and incoagulable IN032a1 JMcGendo Endothelium is a specialized form of mesenchyme-derived epithelium simple squamous epithelium – one layer of flattened cells forms a thin, waterproof and antithrombogenic lining of all blood vessels, heart and lymphatic vessels endothelium2 endothelium Dvorak1 Zonula occludens lumen Pinocytic vesicles 1 2 Endothelial cells (1,2) in ELM Endothelial Pinocytic vesicles Function of endothelium nthe control of blood pressure by vasoconstriction and vasodilation, nblood clotting, nformation of new blood vessels (angiogenesis), ncontrol of the passage of materials and the transit of white blood cells into and out of the blood, nin some organs, there are highly differentiated endothelial cells to perform specialized 'filtering' functions (renal glomerulus in kidney, blood-brain barrier, placental barrier). Blood vessels are categorized by function nArteries conduct blood away from the heart and have proportionately more smooth muscle and elastic tissue than veins of comparable size. –Arteries are commonly sub-categorized into elastic arteries (the largest one), muscular arteries (middle-sized), and arterioles. nVeins return blood to the heart. nThe composition of the wall varies among arteries and veins. Bloodstream organization n MMHE_03_020_03_eps arteries arterioles precapillaries capillaries postcapillaries venules veins beating heart animation arrobend arrobend Blood capillaries Capillary_sketch Network of the smallest, thin- walled vessels, situated between arterial and venous portion of circuit Blood capillaries ndiameter from about 8 µm (to 30-40 µm) nlumen is lined by 1-2 endothelial cell nreticular fibers surround the capillaries ncapillary bed between arteries and veins npericytes n n3 types of capillaries continuous n fenestrated n sinusoids pericyte pure32r pure32r pure32r nerve8.jpg (58247 bytes) art-essr469492 11-Capillary Function of capillaries (1) nrespiratory gasses, nutrients and waste products change between blood and tissues n CellsHappy arrobend arrobend Function of capillaries (2) nallow the blood cells to pass throughout their wall into the connective tissue (by diapedesis) f3 Neutrophils microphages Eosinophils Basophils heparinocytes Lymphocytes Monocytes macrophages Continuous capillaries n nThe smallest: cca 8 mm nThe wall: - endothelium – 1-2 cells (zonulae occludentes and nexuses) - lamina basalis - pericytes - reticular fibers nonly allow small molecules, water and ions to diffuse capcont Example of occurrence: muscle tisue, brain cls2 Capillary Fenestrated capillaries nEndothelial cells with fenestra („windows“) 70 nm Æ, diaphragm (thinner than plasma membrane) boards fenestrum ncontinuous basal lamina nin the organs with quic and intensive metabolism and substances change nallow small molecules and limited amounts of protein to diffuse capfenn Exampl of occurrence: intestinal villi, endocrine glands Capillaries with pores nspecial type of fenestrated capillaries nnot fenestra with diaphragm, but opened pores are in endothelium nin glomeruli of renal corpuscles corp6 emgfc Pores capillary lumen arrobend Novinový papír Sinusoidal capillaries (sinusoids) nÆ from 8 to 40 mm n n nendothelium – fenestra, pores and intercellular clefts; some cells are able to phagocyte nincomplete basal lamina nreticular fibers nallow erytrhocytes and serum proteins to enter. capdcon Example of occurrence: liver, spleen, bone marrow Remember! nSinusoid = type of blood capillary n (between arterial and venous n part of bloodstream) nSinus = venous sinus belong to venous, n postcapillary part of bloodstream n practice sinusoid vs. sinus redbutn Pericytes n ncytoplasmic processes around capillary, ncontain actin, myosin, tropomyosin ntheir own basal lamina fuses together with that one of capillary pericyte icv17 ebv14 Precapillaries - Postcapillaries nÆ 12 – 40 mm nendothelium + LB, elastic + collagen fibers, smooth muscle cells nprecapillary sphincters nÆ to 200 mm nendothelium + LB, smooth muscle cells largearteriole 20070127062629827 Structure of blood vessel wall – generally – ntunica interna (intima) –endothelium + subendothelial connective tissue n________membrana elastica interna__________ ntunica media –smooth muscle tissue – circularly oriented n________membrana elastica externa__________ ntunica externa (adventitia) –loose connective tissue + nerves + vasa vasorum –(+ longitudinal smooth muscle – only in veins) n Stavba srdce a cév - 3 Céva Endothelium Tunica interna Membrana elastica interna Tunica media Tunica externa (Membrana elastica externa) Tunica interna (intima) TI nendothelium nsubendothelial connective tissue – thin layer of elastic + collagen fibers (longitudinally oriented) art-vena-02-l fsimplesquamos1 capillary_cs Tunica media TM nconsists of smooth muscle cells and elastic membranes in varying proportions (circularly oriented) nis thicker in arteries than in veins n laarvei40 Tunica externa (adventitia) TA nfibrous connective tissue + smooth muscle cells in veins (logitudinally) nis thicker in vein; is the thickest layer in large veins [1] and veins of low limbs [2] ncontains vessels and nerves (vasa et nervi vasorum) in large vessels n Stavba srdce a cév - 11 Vena 2 s384x 1 n f23-1_walls_of_an_arter_c Structural differences between arteries and veins – generally: (YES) Membrana elastica ext. NO YES Membrana elastica int. (YES) thick thin thin thick + + ++ (+) arrobend arrobend CR019b media (+ intima) adventitia Compare the wall structure of artery and vein you too can be wealthy you too can be wealthy Arterial part of bloodstream nAccording to diameter, morphological differences and ratio of elastic fibers and smooth muscle cells: n nArterioles Æ < 0.5 mm nMuscular arteries (small and middle-sized) n Æ 0.5 – 1 mm nElastic arteries (large: aorta and arteries n growing from aorta) Arteriole nÆ < 0.5 mm nThe wall nTI: endothelium + subendothelium nmembrana elastica int. nTM: smooth muscle cells (cca circular 5 layers) nTA: fibrocytes, reticular (+collagen) fibers n arteriole2 teacher Muscular artery nTI: endothelium + subendothelium (with smooth muscle cells (longit.) nmembrana elastica int. nTM: up to 40 layers of smooth muscle cells, elastic and collagen fibers nmembrana elastica ext. nTA: loose connective tissue 1-Small%20muscular%20artery „circular“ TM+TA arrangement is spiral, but … animated_pointer animated_pointer Elastic artery nTI: endothelium + subendothelium (100 mm wide layer of connective t.) nTM: up to 40-60 layers of fenestrated elastic membranes, small amount of smooth muscle cells and reticular fibers nTA: loose connective tissue (+ vasa et nervi vasorum) Stavba srdce a cév - 7 Aorta lupa Different types of arteries nArteriovenous anastomosis (artery contains smooth muscle cells in the wall before vein) n nArteries with intimal pillows (smooth muscle cells form pillows in t.media) n n – lumen can be closed by their contraction n anastomosis_arteriovenosa-simplex redbutn redbutn redbutn Portal circulation: arterial or venous ntwo capillary systems side-by-side urinary_nephron_loop_web 20070127062852912 img52 1 2 3 capillaries vessel capillaries WHERE? 1: glomerulus eferent arteriole renal tubules capillaries in KIDNEY 2: GIT organs vena portae hepatic sinusoids in LIVER 3: hypothalamus hypophyseal vein adenohypophysis in HYPOPHYSIS animated_pointer animated_pointer animated_pointer animated_pointer Venous part of bloodstream nVenules Æ 0.2 – 1 mm nSmall and medium sized veins Æ 1 – 9 mm nLarge veins (v. cava inf. et. sup. - the largest vein) n nValves - pocket-like duplication of endothelium scaffolded by elastic c.t. - protection against venous reccurence Valveani valve2 Venule nÆ < 0.2 - 1 mm nThe wall nTI: endothelium only nTM: smooth muscle cells (cca circular 1-3 layers) nTA: thick layer of loose connective tissue n Vein1.jpg (63203 bytes) teacher 12-Venule%20-B vls2 Small and medium-sized venules nÆ 1 – 9 mm nTI: endothelium + irregular layer of subendothelium + valves nTM: irregular, thin layer of smooth muscle cells, elastic and collagen fibers nTA: thick layer of loose connective tissue with smooth muscle cells n 221030_xlarge Stavba srdce a cév - 11 Vena Vein from lower part of body Vein + artery Large veins nTI: endothelium + subendothelium (+smooth muscle cells) nTM: thin layer of connective tissue + reduced amount of smooth muscle cells nTA: longitudinal bundles of smooth muscle cells in loose connective tissue (vasa et nervi vasorum) n Stavba srdce a cév - 13 Vena cava The heart is the hardest working muscle in the human body. n n n n nHollow muscular organ – blood pump nRythmic contraction nInvoluntary muscle n n n heart-diagram heart_pumping_md_wht Pericardial sac: pericardium + epicardium PERICARDIUM Outer (parietal) layer EPICARDIUM Inner (visceral) layer Pericardial cavity Pericardial cavity - contains 15 – 50 ml of serous fluid serves as lubricans; - is lined with mesothelium n nEpicardium nMyocardium nEndocardium n------------------- n n 64_02 The wall of heart layersofheart Endocardium (homologous to intima of blood vessels) nConsists of: nEndothelium nSubendothelium – thin connective tissue layer nElastic-muscular layer – dense c.t. (elastic fibers, smooth m. cells) nSubendocardium – c.t. + vessels, nerves and distal part of conducting system (ventricular bundles and Purkinje fibers) n n n Purkinje fibers ¹ Purkinje cells woman doctor writing notes in a chart. big_heart normal black square with neon green jagged reading of a heart monitor 78_06 78_07 Purkinje_fibers NEXUSES Myocardium ncardiomyocytes „working“ n „conducting“ ncells in right ventricle – natriuretic factor (when intravascular volume increases, this factor is released and causes natriuresis and diuresis in kidney) natrial myocardium is thinner than ventricular n„left heart“ myocardium is thinner than „right heart“ ncords of cardiomyocytes are ended on heart skelston ndamage of myocardium - infarction nlow regeneration of myocardium – by scar (decreases function of heart muscle) Heart skeleton valvedisease Trigonum fibrosum sin. Trigonum fibrosum dx. Anulus fibrosus sin. Anulus fibrosus dx. Pars membranacea interventricularis Endocardial valves heartValves Plates of dense connective tissue (continuous with heart skeleton) covered with endocardium. Epicardium s1940xp pag334 Mesothelium lines pericardial space and so it covers outer surface of epicardium and inner surface of pericardiu mesothelium connective tissue subepicardial c.t. myocardium hearty thanks for your attention http://lynx.uio.no/jon/gif/comics/mosquito-artery-hit.gif Practice No. … nSlides: n59. Artery of the muscular type with a vein (HE) n60. Artery of the muscular type with a vein (orcein) n61. Aorta (cross-section, HE) n62. Aorta (cross-section, orcein) n63. Vena cava (HE) n65. Myocardium (Heidenhain´s hematoxylin) Embryology: Cardiovascular system Development of heart and vessels fig1 Embryological Timetable nWeek 3 day 20 – cardiogenic plate n day 21 – endocardial tubes nWeek 4 day 22 – fusion into single tube n day 23 – first contraction n day 25 – cardiogenic loop nWeek 7 day 49 – 4-chamber heart n A6-43 3_2_2 3_2_7 cardev001-2 The cardiogenic (heart-forming) region is initially located at the anterior rim of the embryonic disc (rostral to the prechordal plate). As the embryo grows, the developing heart assumes a position ventral to the forming forebrain and foregut. cardev003-1all Fusion of the vascular channels in the cardiogenic region results in formation of endothelially-lined heart tube which is surrounded by a layer of splanchnic mesoderm. The intraembryonic coelom in this region becomes the pericardial cavity. the position of the forebrain, foregut and septum transversum relative to the developing heart. septum transversum is located just below the developing heart, which at this stage, begins to beat. As the heart tube elongates and begins to loop, the blood flows into the sinus venosus, then into the primitive atria, ventricles and bulbous cordis before entering the visceral arch vessels. cardev005-1 cardev009-2 arrobend arrobend cardev017 As the heart tube elongates and bends, the atrial segment assumes a position cranial to the ventricular segment. cardev013-2 the dorsal mesocardium suspends the heart from the dorsal body Blood flow into the sinus venosus is from three pairs of vessels: the cardinal veins that drain the embryo proper, the vitelline veins from the yolk sac, and the umbilical veins from the placenta. cardev015-2 cardev016-2 The umbilical and vitelline veins traverse the liver which forms within the tissue of the septum transversum. Ductus venosus (Arantii) ! primitive_heart embryonic_circulations Primitive blood circulation (¹ fetal blood circulation) cardev021-3 the course of blood flow through this part of the heart. The truncus arteriosus will later divide to form the aorta and pulmonary trunk. cardev024-2 superior, inferior, right, and left endocardial cushion are around the atrioventricular canal. cardev026 The superior and inferior cushions must fuse to separate the atrioventricular (AV) canal into a right and left channel. cushions form also to separate the outflow tract of the heart into a pulmonary and aortic trunk. cardev030-2 neural crest cells that form at the level of the 4th and 6th aortic arches populate the forming truncal cushions. cardev031-3 These cushions must fuse to form the aorticopulmonary septum separating pulmonary and aortic trunks. cardev033-2 change in position is indicative of the spiraling of the aorticopulmonary septum, aorta and pulmonary artery cardev034-2 Fusion of the outflow tract cushions results in separation of the blood flow; the blood exits the left ventricle through the aorta and exits the right ventricle through the pulmonary artery. cardev036-2 sinoatrial orifice since it is at the junction of the sinus venosus and the primitive atrium. cardev037-2 The atrial chambers are divided by septum primum, which grows down to fuse with the endocardial cushions. An opening, the ostium sccundum, forms in the septum primum. cardev038-2 cardev037-2 cardev039-1 cardev039-2 Septum secundum, remains incomplete. The resulting opening is termed the foramen ovale. cardev040-2 The primitive atria form the auricles, the rough-walled portions of the definitive atria. Incorporation of the walls of the sinus venosus on the right and the pulmonary veins on the left forms the smooth-walled portions of the definitive atria. cardev041-1 The aortic vessels, which extend from the aortic sac to the paired dorsal aortae, develop and regress asymmetrically. The left 4th arch and the left 6th arch . . . cardev041-2 contribute to the aortic arch and the pulmonary artery and ductus arteriosus cardev042-1 cardev042-2 CR023b arteriole1.jpg (45364 bytes) MuscularA1.jpg (60813 bytes) Stavba srdce a cév - 7 Aorta Stavba srdce a cév - 10 Vena Stavba srdce a cév - 11 Vena Stavba srdce a cév - 13 Vena cava Stavba srdce a cév - 15 Arterie svalového typu s vénou - barvení na elastiku Stavba srdce a cév - 14 Arterie svalového typu s vénou IN032b CR028b cav