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• Wipe down work area with tabletop disinfectant
• Announcements
• Todays Lab Arteries and Veins in the cat,
  Hepatic Portal System, Fetal Circulation
• Thursdays Lab Quiz 7 (covering Arteries,
  Veins, Hepatic Portal and Fetal Circulation)
  Special Senses (Eye and Ear)
• Next Tuesday Histology (Cardiovascular and
  Nervous Tissues), Review ALL

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Lab 19 Arteries and Veins in the cat, Hepatic
Portal System and Fetal Circulation

• References
• Exercise 22-24
• Chapter 21 in text
• Lab outlines and handouts
• Cat vessel dissection
• Lab models
• Penn State Website, AMA Atlas website

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• Hepatic Portal System
• Drains digestive viscera, spleen and pancreas and
  delivers blood to the liver for processing via
  the hepatic portal vein
• Splenic, gastric, intestinal veins
• Hepatic portal vein
• Liver
• Hepatic veins
• Inferior vena cava

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• Fetal Circulation
• Two major differences
• the fetus must supply blood to the placenta
  (through which oxygen and nutrients are obtained
  from the mothers uterus)
• the fetus sends very little blood around the
  pulmonary circuit, instead circulating blood
  between atria and from the pulmonary trunk into
  the aortic arch

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• Fetal vessels that carry blood to and from the
  placenta are called umbilical vessels and run in
  the umbilical cord
• umbilical arteries (paired) carry blood to the
  placenta to pick up oxygen and nutrients
• the umbilical vein (not paired) returns the blood
  to the fetus, delivering some of it to the portal
  vein so the nutrients are filtered by the liver
• Excess blood delivered to the liver via the
  portal vein is diverted through a shunt called
  the ductus venosus
• All blood diverted through the ductus venosus and
  all blood filtered in the liver returns to the
  right atrium of the fetal heart via the hepatic
  veins and inferior vena cava.

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• Post-birth
• remnant of the umbilical vein is called
  ligamentum teres (round ligament)
• the ductus venosus becomes the ligamentum venosum
• the umbilical arteries become the medial
  umbilical ligaments

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• Fetal respiratory organ is the placenta, not the
  lungs
• So as not to overload the fetal lungs
• slightly less than half the blood entering the
  right atrium of the fetal heart is diverted to
  the left atrium via a hole in the interatrial
  septum called the foramen ovale
• blood leaving the right ventricle via the
  pulmonary trunk passes by another shunt called
  the ductus arteriosus which leads to the aortic
  arch
• In the end, only a small amount of blood reaches
  the fetal lungs

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• Post-birth
• foramen ovale closes and is viewed as the fossa
  ovalis
• the ductus arteriosus closes and is viewed as the
  ligamentum arteriosum

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Umbilical arteries - carry blood high in wastes
and low in oxygen from the fetus to the
placenta Umbilical veins - carry blood high in
oxygen and nutrients from the placenta to the
fetus The oxygen rich blood from the umbilical
veins travels through the portal system and into
the right atrium of the fetus Therefor, the right
atrium is where you will find the most highly
oxygenated blood