1 / 30

Vascular Systems: Functions and Structures in Blood Circulation

Explore the intricate categories and functions of the vascular system, from arteries to capillaries, veins, and circulatory routes. Understand how blood circulation is regulated and the importance of vessel wall structure.

robertpablo
Download Presentation

Vascular Systems: Functions and Structures in Blood Circulation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 19 – Vascular System Chapter 19

  2. A. categories and general functions: • 1. arteries - carry blood • away from heart • 2. capillaries - allow • exchange of materials • between blood and • tissue fluid • 3. veins - return blood • to heart Chapter 19

  3. Chapter 19

  4. B. wall structure • most vessel walls have 3 layers • lumen = space inside vessel • 1. tunica intima / tunica interna • endothelium – • simple squamous e. • subendothelial layer – • loose c.t. (collagen) Chapter 19

  5. 2. tunica media • a. smooth muscle - cells circularly arranged • controlled by ANS and chemical factors • constriction decreases blood flow and increases systemic blood pressure • dilation increases blood flow and decreases systemic blood pressure • b. elastic c.t. Chapter 19

  6. 3. tunica adventitia / tunica externa • c.t. attaches vessel to surrounding structures • vasa vasorum nourish outer part of vessel wall Chapter 19

  7. C. arteries • 1. elastic (conducting) - large arteries near heart (aorta and major branches) • * conduct blood to muscular arteries • * low resistance • * tunica media = circular elastin sheets with few smooth m. cells • * recoil maintains blood pressure during diastole Chapter 19

  8. 2. muscular - middle-sized arteries, distal to elastic arteries • * distal to elastic arteries • * tunica media very thick; much smooth m. and some elastin • * regulate blood flow to organs • * have an internal and an external elastic lamina Chapter 19

  9. 3. arterioles - smallest arteries • * tunica media contains smooth m. only • * diameter controlled by ANS and chemical messengers • * diameter determines blood flow and blood pressure Chapter 19

  10. D. capillaries • * wall consists of endothelium and basal lamina (no tunica media or externa) • * 8 to 10 mm in diameter • * join and branch to form capillary beds • * cells are joined at spots around perimeter by tight junctions and desmosomes • * intercellular clefts are spaces between cells Chapter 19

  11. 1. types • a. fenestrated capillaries (high permeability) • * have fenestra (openings) in endothelial cells • * some fenestra are covered by a membrane, others are not • * also have intercellular clefts • * found in small intestine, synovial joints, kidney Chapter 19

  12. b. continuous capillaries • * intercellular clefts but no fenestra • * most common type • c. sinusoids • * wide, leaky capillaries, usually fenestrated • * fewer cell junctions • * allow passage of large particles • * found in bone marrow, spleen, liver Chapter 19

  13. d. low-permeability capillaries • * complete tight junctions • * no fenestra, no clefts • * restricted transport vesicles • * can transport specific molecules in or out • * found in brain (blood-brain barrier) Chapter 19

  14. 2. capillary beds • precapillary sphincter - smooth m. cell wrapped around origin of capillary • * controls blood flow through capillaries • * sphincter controlled by autoregulation • * when sphincter is closed, blood is diverted to thoroughfare channel Chapter 19

  15. E. veins • have thinner walls than arteries for the same diameter (larger lumen) • act as capacitance vessels - store extra blood (65%) • low pressure • tunica adventitia thicker than tunica media • venous valves prevent backflow Chapter 19

  16. F. vascular anastomosis • occurs when vessels join midstream • anastomoses provide alternate pathways (collateral channels) Chapter 19

  17. G. circulatory routes • 1. pulmonary circuit: right ventricle to lungs to left atrium • * pressure supplied by right ventricle • * low pressure system • * takes low oxygen blood (75% saturated) to lungs and brings high oxygen (98% • saturated) blood • back to heart Chapter 19

  18. right ventricle • pulmonary semilunar valve • pulmonary trunk • left and right pulmonary arteries • lobar arteries (3 R, 2 L) take blood to lung lobes • pulmonary capillaries • pulmonary veins (superior and inferior, L and R) • left atrium Chapter 19

  19. 2. systemic circuit: left ventricle to body to right atrium • * pressure supplied by left ventricle • * high pressure system • * takes O2 to tissues and removes CO2 • * distributes nutrients from digestive tract to body • * collects wastes and takes them to kidney for excretion Chapter 19

  20. a. circulatory pathways of the brain (cerebral arterial circle, circle of Willis) Chapter 19

  21. anterior communicating a. • anterior cerebral a. • internal carotid a. • posterior communicating a. • posterior cerebral a. • basilar a. • vertebral a. Chapter 19

  22. cross section of neck: Chapter 19

  23. b. hepatic portal circulation • portal system = two capillary beds in series, joined by veins or arteries Chapter 19

  24. Chapter 19

  25. capillaries of small intestine, part of large intestine and stomach • superior mesenteric vein • capillaries of spleen, stomach and pancreas • splenic vein • capillaries of distal large intestine and rectum • inferior mesenteric vein Chapter 19

  26. hepatic portal vein • liver • liver sinusoids • hepatic veins • inferior vena cava Chapter 19

  27. c. fetal circulation • placenta = organ formed from extra-embryonic membranes and endometrium to exchange materials between fetal and maternal blood • the umbilical veins take high-oxygen and high-nutrient blood from the placenta to the fetus • the umbilical arteries take low-oxygen, high-waste blood back to the placenta Chapter 19

  28. umbilical vein from placenta •   fetal liver • hepatic portal vein • ductus venosus • inferior vena cava • right atrium foramen ovale left atrium • right ventricle left ventricle • pulmonary trunk ductus arteriosus aorta • lungs •   internal iliac a. • umbilical a. to placenta Chapter 19

  29. adaptations: • 1) to bypass the fetal liver • ductus venosus - allows some umbilical vein blood to go through the fetal liver but diverts most of it directly into the inferior vena cava • 2) to bypass the non-functional fetal lungs • foramen ovale – opening in interatrial septum that allows blood to go from the right atrium directly into the left atrium • ductus arteriosus – vessel that connects pulmonary trunk and aorta Chapter 19

  30. Chapter 19

More Related