Understanding Vascular Network Management

Oct 9, 2024

Vascular Network Lecture Notes

Recap of Previous Lecture

  • Cardiovascular system manages fluid volume to manage pressure.
  • "Managing volume to manage pressure" mantra.

Arteries and Veins

  • Focus on how they manage volumes and pressures.

Systemic vs. Pulmonary Circulation

  • Systemic circulation: blood vessels supply body.
  • Pulmonary circulation: blood vessels for lungs.
  • Pressure in arteries fluctuates due to heart contraction.

Pressure in the Aorta

  • Aorta receives large fluid bolus from heart ventricles.
  • Diastolic (80 mmHg) vs. Systolic (120 mmHg) pressure.
  • Elastic arteries: Aorta elastic structure helps withstand pressure.
  • Rubber band analogy: Elastic fibers help maintain pressure.

Arterioles and Pressure Drop

  • Arterioles reduce pressure moving into capillaries.
  • Resistance due to smaller vessel size.
  • Maximum capillary pressure: 40 mmHg.

Capillaries and Pressure Management

  • Capillaries have thin walls; excessive pressure can damage them.
  • Pressure levels off in venules and veins due to compliance.

Veins and Volume Management

  • Veins manage volume, not pressure.
  • Larger and more flexible vessels.

Pressure Changes in Different Arteries

  • From aorta to femoral to radial artery, pressure smooths.
  • Resistance and compliance help dampen pressure differences.

Concepts of Resistance and Compliance

  • Resistance: vessels constrict to smooth fluid movement.
  • Compliance: vessel flexibility helps manage pressure.

Blood Pressure Concepts

  • Normal Blood Pressure: 120/80 mmHg (individual normal may vary).
  • Pulse Pressure: Difference between systolic and diastolic (e.g., 40 mmHg).
  • Mean Blood Pressure: (Systolic + 2 x Diastolic) / 3.

Venous Pressure

  • Central venous pressure: 0 mmHg at right atrium.
  • Thoracic veins: 7-10 mmHg due to lung expansion.
  • Hydrostatic pressure causes higher pressure in leg veins.

Venous Pump Mechanism

  • Muscle contractions push fluids against gravity.
  • Reduces venous pressure in lower body.

Veins as Reservoirs

  • Act as blood storage, releasing it when needed.
  • Sympathetic nervous system can constrict veins to push extra fluid.

Blood Storage Locations

  • Spleen: 100 mL
  • Liver: 300 mL
  • Large Abdominal Veins: 300 mL
  • Subcutaneous Plexus: 300 mL
  • Heart: 100 mL
  • Lungs
  • Review cardiovascular network in terms of pressure and volume management.
  • Understanding these principles is crucial for further discussions and practical applications.