Mod 4 Histology

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Mod 4 Histology
2012-11-16 21:25:13

Mod 4 Histology
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  1. Name and describe the three layers (tunics) of the heart
    • 1) Endocardium: glistening layer (smooth); simple squamous epithelium; subendothelial CT (elastin fibres); conduction system of the heart
    • 2) Myocardium; cardiac muscle connected end to end using intercalated discs; rich in capillaries;¬†
    • 3) Epicardium: visceral layer of the pericardium; serous membrane, mesothelium, lots of elastic fibres. nerves and coronary arteries
  2. Unique characteristics of cardiac myocytes
    • -striation less powerful
    • -central nucleus
    • -intercalated discs
    • -juxtanuclear region
    • -intrinsically capable of contraction
  3. Name and describe the three layers of blood vessels
    • 1) Tunica Intima: endothelium, basal lamina, loose CT
    • 2) Tunica media: circumferentially arranged smooth muscle, produce their own matrix
    • 3) Tunica adventitia: connective tissue, merges with surrounding connective tissue.
  4. Name the seven types of blood vessels
    • elastic artery (aorta)
    • muscular artery¬†
    • arteriole
    • capillaries
    • venules
    • veins
    • vena cava
  5. Describe the three layers in elastic arteries
    • Intima: endothelium with BL, subendothelium CT
    • Media: fenestrated elastic sheaths, smooth muscle
    • adventitia: vasa vasorum and nervi vasorum
  6. Describe the three layers in a muscular artery
    • intima: endothelium and BL; subendothelial CT (includes IEL)
    • media: LOTS of smooth muscle; external elastic lamina
    • adventita: CT and vasa vasorum
  7. Describe the three layers in arterioles (resistance vessels)
    • intima: endothlium and BL, less elastic tissue
    • media: 1-2 layers of smooth muscle
    • adventita: thin
  8. describe the three layers in capillaries
    • intima: endothelium and BL; +/- pericytes
    • media: none
    • adventitia: none
  9. What are the three type of capillaries?
    • 1) continuous enothelial: found in most tissues (lung, muscles, etc)
    • 2) fenestrated: epethelial cells have fenestrations but BL is intact, found where these is extensive exchange with the blood (e.g. intestines, kidneys)
    • 3) discontinuous: gaps in both basal lamina and endothelial cells, not common, liver, spleen, etc
  10. describe the three layers of venules
    • intima: endothelial cells and BL, +/- pericytes
    • no media or adventitia
  11. describe the three layers in veins (capacitance vessels)
    • intima: endothelium and BL, loose CT under this
    • media: smooth muscle (irregular orientation)
    • adventitia: CT
  12. describe the three layers in the vena cava
    • intima: endothelium and BL, underlying CT
    • media: smooth muscle
    • adventita: CT, some elastic tissue, longitudinal smooth muscle
  13. Describe the structure and function of arteriovenous anastomoses
    • Direct link from arteriole to vein
    • artery has very thick muscular walls
    • under sympathetic control
    • when the muscle contracts it forces blood through the capillary bed
    • one use is for thermoregulation
  14. Describe the structure and function of metarterioles
    • a larger "capillary" with isolated SM in its walls
    • acts as a throughfare between arterioles and venules
    • contraction of SM forces blood to flow through the capillary bed
  15. What is a glomus body?
    • An ateriovenous anastonomis with a CT capsule
  16. What are the six functions of epithelial cells
    • as epithelium: barrier
    • produce vasoactive substances (e.g. vasodilators)
    • participate in the control of blood coagulation
    • proliferate in response to signals (e.g. VEGF)
    • mediate interactions with leukocytes (diapodesis)
    • lipoprotein metabilism
  17. describe the three layers in a lymphatic capillary
    • intima: discontinuous endothelial with no basement membrane
    • no media, adventitia (does have anchoring filaments), or pericytes
  18. How do you distinguish a larger lymphatic vessel from a vein
    • -have more valves
    • -lymph and not rbcs in the lumen
    • -thinner wall with larger lumen
  19. describe the cross section of the thoracic duct
    • -tunica intima: endothelial lining; fibroelastic tissue; inner elastic lamina
    • -fibromuscular wall