BY 312 Lecture (3/23)

Overview of Cardiovascular and Circulatory Systems

Coronary Arteries

• Patient may require multiple coronary arteries grafted for surgical intervention.

• Example cited: "I've seen a couch times five" indicates the necessity for five grafts.

Hepatic Portal Circulation

• Hepatic Portal System:

  • Transports nutrient-rich venous blood from digestive tract capillaries to liver capillaries.

  • Essential for the filtration and processing of nutrients and toxins.

• Function of the Liver:

  • Maintains chemical homeostasis through:

  • Filtration and reabsorption of sugars, fats, and proteins.

  • Detoxification of the blood.

• Blood Flow Process:

  • Blood tributaries from the stomach, pancreas, and parts of the large intestine drain into the splenic vein.

  • Splenic vein then drains into the hepatic portal vein.

  • The superior mesenteric vein receives tributaries from the small intestine and drains into the hepatic portal vein, continuing the pathway back to the liver.

  • Excessive filtration conducted in liver through sinusoids.

• Main Vessels in Portal Circulation:

  • Splenic vein

  • Superior mesenteric vein

  • Inferior mesenteric vein (drains into splenic vein).

  • Hepatic portal vein

  • Hepatic veins (return blood to the inferior vena cava).

• Importance for Exams:

  • Understand each vein's tributaries and paths of blood flow related to detoxification in the liver.

Fetal Circulation

• Unique Characteristics of Fetal Circulation:

  • Fetus's lungs, kidneys, and gastrointestinal tract are nonfunctional.

  • Nutrient and waste exchange occurs via maternal blood through the placenta.

  • There is no mixing of maternal and fetal blood.

• Key Structures in Fetal Circulation:

  • Umbilical Vein: Carries oxygenated blood from the placenta to the fetus.

  • Ductus Venosus: Bypasses the liver, connecting the umbilical vein to the inferior vena cava.

  • Foramen Ovale: Allows blood flow from the right atrium to the left atrium, bypassing the lungs.

  • Ductus Arteriosus: Connects the pulmonary trunk to the aorta, further circumventing the lungs.

  • Umbilical Arteries: Carry deoxygenated blood back to the placenta.

• Normal Blood Flow Path:

  • Oxygenated blood from placenta → umbilical vein → inferior vena cava (via ductus venosus) → right atrium → left atrium (via foramen ovale) → left ventricle → aorta.

  • Deoxygenated blood from systemic circulation → returns via umbilical arteries to placenta for reoxygenation.

• Post-Birth Changes:

  • At birth, the lungs expand, and the resistance in the pulmonary circulation decreases dramatically.

  • The severance of the umbilical cord leads to changes in blood flow patterns.

• Remnants of Fetal Circulation Post-Birth:

  • Ductus arteriosus → becomes ligamentum arteriosum.

  • Foramen ovale → becomes fossa ovalis.

  • Ductus venosus → becomes ligamentum venosum.

  • Umbilical vein → becomes ligamentum teres and attaches the liver to the anterior abdominal wall.

  • Umbilical arteries → become medial umbilical ligaments, with some function related to iliac arteries.

Upcoming Assessments and Topics

• Chapter 21 Test:

  • Focus on shock response and hepatic portal circulation.

  • Due date for submission is Wednesday by midnight.

• Introduction to Chapter 22 - Lymphatic System:

  • Description of lymphatic vessels carrying lymph fluid, highlighting their functions:

  • Draining interstitial fluid.

  • Transporting dietary lipids.

  • Immune responses.