1. What are the three components of cardiovascular circuits?
    • Arteries- transport blood away from the heart
    • Veins- return blood to the heart
    • Capillaries- smallest vessels where exchange of gases, nutrients, hormones, etc occurs
  2. What are the two cardiovascular circuits?
    • Pulmonary circuit (Arteries low O2) 
    • Systemic circuit (Arteries high O2)
  3. Which germ layer are blood vessels derived from?
  4. How are blood vessels organized?
    • Outer wall consists of up to three layers - tunica intima, tunica media, and tunica adventitia
    • Central lumen contains blood
    • Tunics vary in tissue composition and structure depending on the vessel type
  5. Describe the structure of the tunica intima.
    • endothelium=innermost lining=simple squamous to cuboidal epithelium
    • pericytes on the basal side- somewhat contractile
    • lamina propria 
    • internal elastic lamina = thin layer of elastic connective tissue
  6. What is the lamina propria?
    Subendothelial layer of connective tissue in the tunica intima
  7. Describe the structure of the tunica media.
    • varies widely depending on blood vessel type
    • connective tissue varies in amount and type
    • may have concentrically arranged smooth muscle 
    • may have concentrically arranged elastic fibers
  8. Describe the structure of the tunica adventitia.
    • Outermost connective tissue, varies in thickness and type
    • May contain 'vasa vasora' - small blood vessels that supply walls of large vessels
    • Largest veins may have longitudinal smooth muscle
  9. What are the three types of arteries?
    • 1.  Elastic arteries - largest, highest pressure
    • 2.  Muscular arteries - medium sized distributing arteries
    • 3.  Arterioles - smallest arteries
  10. Describe the structure of elastic arteries.
    • Very thick walls
    • T. Intima has prominent lamina propria
    • T. Media has prominent elastic fibers that allow for expansion and recoil with each heartbeat
    • T Adventita has prominent vasa vasorum
  11. What is an aneurysm?
    • Ballooning of the wall of a blood vessel
    • Caused due to a weakness in T.  Media/decreased elastic fibers in the elderly
    • Scarring occurs and collagen replaces the elastic fibers
    • Treatment:  monitor rate of expansion, put a stint in
  12. Describe the structure of muscular arteries.
    • T. Media has up to 40 layers of concentrically arranged smooth muscle fibers
    • T. Intima folds like an accordian when smooth muscle is contracted; has lots of elastic fibers
  13. What is Masson's Trichrome Stain used for?
    Shows collagen which is prominent in T. Adventitia- appears blue
  14. What is Weigert's histochemical stain used for?
    Shows elastin - appears blue
  15. Describe the structure of arterioles.
    • T. Intima = endothelium + basement membrane, little lamina propria
    • T. Media = 1-3 layers smooth muscle fibers
    • T.  Adventitia = very loose CT
  16. How is contraction of arterioles controlled?
    Contraction of smooth muscle cells controlled both by release of paracrine factors and by autonomic nerves (contraction/vasoconstriction=sympathetic/epinephrine; relaxation/vasodilation=parasympathetic/acetylcholine/nitric oxide)
  17. What is purpose does contraction of arterioles serve?
    Helps regulate blood pressure and blood flow into capillary beds at the smallest pre-capillary metarterioles
  18. What is the precapillary sphincter?
    • Regulates blood flow into the capillary beds at the metarteriole therefore determines blood pressure
    • Regulated by the autonomic nervous system
  19. What are the three types of capillaries?
    • 1.  Continuous Capillaries - Function where exchange between blood and the surrounding tissue is highly regulated
    • 2.  Fenestrated Capillaries- Function where exchange between blood and surrounding tissues is selective
    • 3.  Sinusoidal Capillaries (aka Venous Sinusoids) - Function where there is free exchange between blood and the surrounding tissues
  20. Which cell type associated with the exterior of capillaries?
    • Pericytes
    • Cytoplasmic processes wrap around endothelium discontinuously
    • Pluripotent stem cell activity; slight contractile activity
  21. Describe the structure of continuous capillaries.
    • Endothelium has tight junctions; most macromolecular transport is highly regulared; exchange across endothelium between capillary lumen and surrounding tissues is facilitated by vesicular trancytosis
    • Prominent in the brain and lungs
  22. Describe the structure of fenestrated capillaries.
    • Exchange is facilitated by small holes or fenestrations in the wall of the endothelium
    • May have a proteoglycan 'diaphragm' that prevents free passage of large macromolecules
    • Prominent in the kidney, intenstines, and endocrine glands
  23. Describe the structure of sinusoidal capillaries.
    • Endothelium has large gaps for free passsage of macromolecules and some cells
    • Often lg diameter lumen 
    • Prominent in liver, spleen, and bone marrow
  24. What are the three kinds of veins?
    • 1.  Venules - immediately post-capillary with prominent T. Intima
    • 2.  Small and Medium Veins - folds of T. Intima push into the lumen; prominent T. Adventitia
    • 3.  Large Veins - Very prominent T. Adventitia
  25. Contrast venules and arterioles.
    • Venules: larger diameter lumen, prominent TI, sparse CT in TM, diapedesis occuring in venule wall
    • Arterioles:  Smaller diameter lumen, less prominent TI, concentric smooth muscle in TM
  26. Describe the structure of small and medium veins.
    • Valves - characteristic folds of T. Intima with core of collagen I and elastin- open in one direction only
    • TM: Much less prominent than the corresponding arteries
    • TA:  Relatively thick, considerable collagen I
  27. How does the muscular (deep) venous pump work?
    • Skeletal muscles constrict vein
    • Blood moves towards heart
    • Connot backflow due to valve orientation
  28. Describe the structure of large veins.
    • Vena Cavae and Immediate suppliers
    • TI= prominent; lamina propria fibroelastic (dense) CT
    • TM = not well developed
    • TA = very prominent; fibroelastic CT and longitudinal smooth muscle; vaso vasora present
  29. What is atherosclerosis?
    • Subendothelial/Lamina Proprial Plaque formation, facilitated by excess LDL
    • In early stages, there is subendothelial inflammation and foam cells- results in tearing of the epithelium
    • In later stages, thrombus breaks away (thromboembolus) and triggers clot formation inside the lumen of blood cells
Card Set
ANAT390 Lecture 19 Circulatory System