nerves, vessels, lymphatics

• blood vessel

  closed system of endothelial tubes, distribute oxygenated blood from the heart to capillary beds and return deoxygenated blood to the heart
• tunica intima

  endothelium (simple squamous epithelium), little LCT
• tunica media

  smooth muscle and elastic tissue
• tunica externa

  connective tissue, sometimes has blood vessels
• arteries have thicker walls, more round, have a larger tunica intima compared to veins
• elastic arteries

  conducting vessels, that naturally recoil to transport blood
• muscular arteries

  radial or femoral, wavy tunica intima, 2-10 mm
• arteriole

  10-100um, regulate blood flow through capillary blood and systemic blood pressure
• capillaries

  lined by endothelial cells and basal lamina
• pericyte

  undifferentiated cells, resemble smooth muscle cells, can become endothelial or smooth muscle cells
• veins

  return deoxygenated blood to the heart, aided by tunica medias smooth muscle, valves, and contraction of surrounding skeletal muscle
• vein appearance

  large lumen, irregular shape, few layers of smooth muscle, blood cells in lumen, no internal elastic intima
• large muscular veins

  longitudinal smooth muscles in adventitia, peristaltic pumping of blood
• lymphatic vessels

  thin endothelial cells, absent basement membrane, no pericytes, lumen held open by elastic microfibrils, contains valves
• walls of large lymphatic vessels have smooth muscle
• lymph nodes

  DICT capsule, afferent lymph vessels penetrate capsule, trabeculae, drained by one or two efferent lymphatic vessels at hilum
• hilum

  where blood vessels enter and leave the lymph nodes
• parenchyma

  superficial cortex (densely packed lymphocytes), paracortex, medulla
• follicles in superficial cortex


  contain B cells that differentiate into plasma cells to produce antibodies
• paracortex

  contains T cells that can be stimulated to initiate an immune response