Cardiovascular System Lecture Notes

Overview

• Part of the circulatory system, which also includes the lymphatic system.
• Circulates blood, transporting oxygen and nutrients, and removing carbon dioxide and wastes.

Components of the Cardiovascular System

• Heart: A pump with two sides (each with two chambers) that moves blood through vessels.
  • Pulmonary Circuit: Right side; pumps deoxygenated blood to lungs.
  • Systemic Circuit: Left side; pumps oxygenated blood to body tissues.
• Blood: Composed of plasma and formed elements (red blood cells, white blood cells, platelets).
• Blood Vessels: Arteries, veins, and capillaries that transport blood throughout the body.

Heart Structure

• Chambers: Right and left atrium and ventricles.
• Valves: Ensure one-way blood flow through the heart.
  • Oxygen-poor blood: Right atrium → right ventricle → pulmonary arteries.
  • Oxygen-rich blood: Left atrium → left ventricle → aorta.
• Pericardium: Double-walled sac protecting the heart, with lubricating fluid.
• Heart Wall Layers:
  • Epicardium: Outer layer lining the pericardial cavity.
  • Endocardium: Inner layer lining heart chambers and valves.
  • Myocardium: Thick middle layer responsible for heart contractions.

Cardiac Conduction System

• Pacemaker Cells: Initiate heart muscle contractions via electrical impulses.
• SA Node: Primary pacemaker controlling heart rate.

Blood Functions

• Transports gases, nutrients, and wastes.
• Supplies tissues with nutrients absorbed from the digestive system.
• Carries hormones and plays a role in immune defense.

Blood Composition

• Plasma: Clear extracellular fluid.
• Formed Elements:
  • Red Blood Cells: Transport oxygen and carbon dioxide.
  • White Blood Cells: Defense mechanisms.
  • Platelets: Responsible for blood clotting.

Circulatory Pathways

• Arteries: Move blood away from the heart, usually oxygenated.
• Veins: Bring blood back to the heart, usually deoxygenated.
• Pulmonary Arteries and Veins: Reverse oxygenation state.
• Capillaries: Site of substance exchange with tissues.

Blood Vessel Structure

• Layers:
  • Outer Layer: Loose connective tissue anchoring vessels.
  • Middle Layer: Smooth muscles for vessel constriction/dilation.
  • Inner Layer: Thin squamous endothelium.
• Capillaries: Single-layer endothelium for diffusion.
• Arteries vs. Veins:
  • Arteries have more muscle to withstand higher pressure.
  • Larger vessels have more connective tissue and smooth muscle.