FETAL PIG DISSECTION: THE CIRCULATORY SYSTEM

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FETAL PIG DISSECTIONTHE CIRCULATORY SYSTEM
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Digestive System Review
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Esophagus

• Greek Oisophagus gullet
• The part of the digestive tract between the
  pharynx and the stomach.

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Liver

• Removal of waste products
• Removes or converts toxins and poisons to less
  harmful chemicals such as changing ammonia to
  urea
• Produces bile
• Processes blood brought to it by the hepatic
  portal system
• Metabolic regulation of carbohydrates, amino
  acids, and lipids to maintain blood glucose
  concentrations
• Regulates levels of compounds produced by the
  body such as steroid hormones

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Gall Bladder

• A small sack attached to the liver in which bile
  accumulates before it is discharged into the
  intestine
• Green in most of your dissections

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Pancreas

• A large glandular organ near the stomach and
  duodenum
• Secretes many digestive enzymes
• Contains islets of Langerhans
• Small clusters of endocrine cells
• Produce hormones that regulate glucose metabolism
  (insulin and glucagon)

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Spleen

• A vascular organ near the stomach in which blood
  cells may be produced, stored, and eliminated.
• Plays a role in immunological processes by
  generating antibodies
• Produces lymphocytes (one type of white blood
  cell)

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Circulatory System Heart
Right auricle
Right ventricle
Coronary artery
Left auricle
Left ventricle
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Blood Flow Through Heart
superior
inferior
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Veins and Arteries
VEINS carry blood TO the heart. ARTERIES carry
blood AWAY from the heart. With two exceptions,
VEINS carry DEOXYGENATED blood, and ARTERIES
carry OXYGENATED blood. Which vessels are the
exceptions? Hint Where is blood
oxygenated? Note Because the latex is injected
under pressure, occasionally veins and arteries
appear the wrong color.
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Veins and Arteries
With two exceptions, VEINS carry DEOXYGENATED
blood, and ARTERIES carry OXYGENATED blood.
Which vessels are the exceptions? PULMONARY
AND UMBILICAL ARTERIES AND VEINS
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Carotid arteries
Internal jugular vein
External jugular vein
Left subclavian vein
Superior vena cava (Pre cava)
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Major Arteries
Brachiocephalic Trunk
Left subclavian artery
Aortic Arch
Pulmonary Trunk
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Arteries
Left Carotid
Right Carotid
Axillary Artery
Rt. Subclavian A.
Left Subclavian A.
Brachiocephalic Artery
Aortic Arch
Pulmonary Trunk
Ductus Arteriosis
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Mesenteric Arteries
Mesenteric Arteries
Spleen

Small Intestine
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Renal Artery and Vein
Renal Vein
Renal Artery
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Postcava
Internal Iliac Artery
Internal Iliac Vein
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Fetal Circulation

• Fetus in a fluid-filled environment (amniotic
  sac)
• Unable to use its lungs to obtain oxygen from the
  environment
• Lungs are one of the last of the fetal organs to
  mature
• Major concern with delivering babies prematurely
  (prior to 28 weeks gestation) lungs may not be
  developed enough for fetus to breathe on its own
• How does fetal blood become oxygenated?

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Fetal Circulation

• The fetus obtains oxygen from its mother.
• Fetus and mother have SEPARATE circulatory
  systems.
• Blood is NOT exchanged.
• Oxygen, carbon dioxide, nutrients, and waste
  products diffuse via the placenta.
• Therefore, fetal circulation is slightly
  different from adult circulation.

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Fetal Circulation

• Partially oxygenated blood enters right atrium.
• Most goes to the left atrium via the foramen
  ovale.
• (Why is it not necessary for blood to enter the
  right ventricle?)
• The rest ends up in the right ventricle and moves
  to pulmonary artery.
• Ductus arteriosus connects pulmonary artery to
  aorta to bypass lungs.
• Pulmonary vein is not used at this point.
• Blood moves from aorta to systemic circulation
  and becomes deoxygenated.

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Fetal Circulation

• Blood moves to umbilical arteries and is
  oxygenated in the placenta.
• Moves to umbilical vein (carrying oxygenated
  blood).
• Oxygenated blood in umbilical vein enters vena
  cava via ductus venosus.
• Deoxygenated blood from systemic veins enters
  vena cava and mixes with oxygenated blood.
• Vena cava carries blood to the right atrium of
  heart.
• Process starts over.

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What happens at birth?

• Changes in pressure cause a flap of tissue to
  close the foramen ovale, thus separating
  oxygen-poor blood from oxygen-rich blood.
• Lungs begin to function to supply oxygen and
  remove carbon dioxide.
• Ductus arteriosus and ductus venosus close and
  become supportive ligaments.
• Umbilical arteries and vein collapse.