Cardiovascular System Overview

Key Components:

• Heart: Functions as a pump with two sides, each having two chambers.
• Blood: Carries oxygen, nutrients, hormones, and waste products.
• Blood Vessels: Arteries, veins, and capillaries circulate blood throughout the body.

Circulatory System:

• Includes:
  • Cardiovascular System (focused on blood circulation).
  • Lymphatic System (circulates lymph).

Heart Functionality:

• Pulmonary Circuit:
  • Oxygen-poor blood returns to the right side of the heart, moves to the lungs for oxygenation.
  • Oxygen-rich blood returns to the left side of the heart.
• Systemic Circuit:
  • Left side pumps oxygen-rich blood to body tissues.
  • Oxygen is delivered while carbon dioxide is collected.

Structure of the Heart:

• Valves:
  • Ensure one-way blood flow: Right atrium ➔ Right ventricle ➔ Pulmonary arteries; Left atrium ➔ Left ventricle ➔ Aorta.
• Pericardium:
  • Double-walled sac enclosing the heart, containing lubricating fluid.
• Heart Wall Layers:
  • Epicardium: Outer layer aligning the pericardial cavity.
  • Myocardium: Muscle tissue responsible for the heart's contraction.
  • Endocardium: Inner layer lining heart chambers and valves.

Cardiac Conduction System:

• Pacemaker Cells:
  • Generate electrical impulses for heart contraction.
  • SA node acts as the primary pacemaker.

Blood Functions:

• Transportation:
  • Gases, nutrients, hormones, metabolic wastes.
  • Nutrients absorbed through small intestine walls, filtered by the liver.
• Components:
  • Plasma: Clear fluid.
  • Formed Elements: Red blood cells, white blood cells, platelets.
• Roles:
  • Red blood cells: Transport oxygen and carbon dioxide.
  • White blood cells: Defense mechanisms.
  • Platelets: Blood clotting.

Blood Circulation:

• Closed Loop System:
  • Blood remains within vessels.
  • Arteries: Carry blood away from the heart.
  • Veins: Return blood to the heart.
• Vessel Structure:
  • Three layers: Outer connective tissue, middle smooth muscle, inner squamous endothelium.
  • Arteries have thicker muscle layers for high-pressure blood flow.

Capillary Function:

• Substance Exchange:
  • Occurs in capillaries with thin endothelial walls.

Summary of Blood Flow:

• Heart ➔ Large arteries ➔ Smaller arteries ➔ Arterioles ➔ Capillaries ➔ Venules ➔ Larger veins ➔ Heart.